drug induced hepatotoxicity ackerman zvi m.d. hadassah-hebrew university medical center

DRUG INDUCED DRUG INDUCED HEPATOTOXICITHEPATOTOXICIT

YY

Ackerman Zvi M.D. Ackerman Zvi M.D.

Hadassah-Hebrew University Hadassah-Hebrew University Medical CenterMedical Center

InputsInputs and and OutputsOutputs

Portal Vein

Hepatic Artery

Bile Duct

Hepatic Vein LIVER

Heart

Intestines

First pass ???

Hepatic recycle ???

PREDICTIVE PARAMETERS PREDICTIVE PARAMETERS OF DRUG-INDUCED LIVER OF DRUG-INDUCED LIVER

INJURYINJURY There are relatively few ways by which acute and There are relatively few ways by which acute and chronic liver diseases become clinically manifest..chronic liver diseases become clinically manifest..

Signs and symptoms of drug-induced liver Signs and symptoms of drug-induced liver disease are generally nonspecific and reflect disease are generally nonspecific and reflect more the extent of the liver injury than the cause.more the extent of the liver injury than the cause.

Slight elevations of aminotransferase or alkaline Slight elevations of aminotransferase or alkaline phosphatase levels do not of themselves cause phosphatase levels do not of themselves cause symptoms and may be present as only as an symptoms and may be present as only as an abnormality of one or more biochemical test abnormality of one or more biochemical test detected during a random predetermined detected during a random predetermined evaluation schedule. evaluation schedule.

Most instances of drug-induced aminotransferase Most instances of drug-induced aminotransferase elevations are transient and nonprogressive. elevations are transient and nonprogressive.

Spectrum of DILISpectrum of DILI

ALF(Death, Txp)

0.0001 - 0.01%

Symptomatic disease

0.01 - 1.0%

Mild liver injury(ALT < 3X ULN)

0.1 - 10%

Tip of the IcebergTip of the Iceberg

Death or TxDeath or Tx

Acute Liver FailureAcute Liver Failure

Serious DILI – ThreateningSerious DILI – Threatening

Detectable DILI – but Not SeriousDetectable DILI – but Not Serious

Patient Adaptation to New Agent ExposurePatient Adaptation to New Agent Exposure

Patients/People Tolerate Exposure Without Patients/People Tolerate Exposure Without

EffectsEffects

SPECTRUM OF SPECTRUM OF HEPATOTOXICITY INDUCED HEPATOTOXICITY INDUCED

BY DRUGS-1BY DRUGS-1 minimal, nonspecific alterations in minimal, nonspecific alterations in

biochemical tests of no clinical biochemical tests of no clinical consequence consequence

to acute hepatitisto acute hepatitis chronic hepatitischronic hepatitis acute liver failureacute liver failure prolonged cholestatic diseaseprolonged cholestatic disease cirrhosis cirrhosis hepatic tumors. hepatic tumors.

Drug-Induced Liver Injury Drug-Induced Liver Injury

(DILI)(DILI)““adaptorsadaptors””

Time Course of Liver Tests"adaptor" - M63 - transaminase rises only

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1.0

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100.0

-60 0 60

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Days Since Exposed to Drug

Test

Valu

es,

xU

LN

ALTx

ASTx

ALPx

TBLx

start drug stop drug

SPECTRUM OF SPECTRUM OF HEPATOTOXICITY INDUCED HEPATOTOXICITY INDUCED

BY DRUGS-1BY DRUGS-1 minimal, nonspecific alterations in minimal, nonspecific alterations in

biochemical tests of no clinical biochemical tests of no clinical consequence consequence

to acute hepatitisto acute hepatitis chronic hepatitischronic hepatitis acute liver failureacute liver failure prolonged cholestatic diseaseprolonged cholestatic disease cirrhosis cirrhosis hepatic tumors. hepatic tumors.

Typical Acute Hepatocellular DILI leading to Death

-1.0

-0.5

0.0

0.5

1.0

1.5

-60 0 60

120

180

Days on Study Drug

ALT

AST

ALP

TBL

startstop

10 xULN

3.2 xULN

ULN

32 xULN

death

jaundice

enceph

Days on drug Slide from Paul Watkins

Sulphasalazine Sulphasalazine HepatotoxicityHepatotoxicity

CAH from MethyldopaCAH from Methyldopa

SPECTRUM OF SPECTRUM OF HEPATOTOXICITY HEPATOTOXICITY

INDUCED BY DRUGS-2INDUCED BY DRUGS-2 Furthermore, some drugs have been Furthermore, some drugs have been

shown to cause :shown to cause : fatty liver (simulating alcohol-induced fatty liver (simulating alcohol-induced

liver disease) liver disease) granulomas (simulating sarcoidosis) granulomas (simulating sarcoidosis) acquired phospholipidosisacquired phospholipidosis predispose to development of the predispose to development of the

Budd-Chiari syndrome or veno-Budd-Chiari syndrome or veno-occlusive disease. occlusive disease.

Amiodarone induce NASHAmiodarone induce NASH

Post BMT veno- occlusive Post BMT veno- occlusive diseasedisease

Normal LiverNormal Liver

Mechanism of liver Mechanism of liver injury-1injury-1

Disruption of itra-cellular calcium Disruption of itra-cellular calcium homeostasis leads to disassembly of homeostasis leads to disassembly of actin fibrils at the surface of the actin fibrils at the surface of the hepatocyte, resulting in blebbing of hepatocyte, resulting in blebbing of cell membrane, rupture, and cell cell membrane, rupture, and cell lysislysis

Mechanism of liver injury-1Mechanism of liver injury-1


In cholestatic diseases, disruption of In cholestatic diseases, disruption of actin filament may occur next to the actin filament may occur next to the canaliculus, the specialized portion of canaliculus, the specialized portion of the cell responsible for bile excretion.the cell responsible for bile excretion.

Loss of villous process and the Loss of villous process and the interruption of transport pumps such interruption of transport pumps such as multidrug-resistance-associated as multidrug-resistance-associated protein 3(MRP3)protein 3(MRP3) prevent the prevent the excretionexcretion of bilirubin and other of bilirubin and other organic compoundsorganic compounds

Mechanism of liver Mechanism of liver injury-2ainjury-2a

Drugs that affect transport proteins at the Drugs that affect transport proteins at the canalicular membrane can interrupt bile canalicular membrane can interrupt bile flow. Certain drugs, for example, bind to flow. Certain drugs, for example, bind to or disable the bile salt export protein. This or disable the bile salt export protein. This process causes cholestasis; however, little process causes cholestasis; however, little cell injury occurs.cell injury occurs.

Genetic defects in transporters, as in the Genetic defects in transporters, as in the multidrug-resistance–associated protein 3, multidrug-resistance–associated protein 3, in combination with hormones may in combination with hormones may promote cholestasis during pregnancy or promote cholestasis during pregnancy or during treatment with estrogen-containing during treatment with estrogen-containing medications. medications.

Cholestasis from estrogensCholestasis from estrogens

Mechanism of liver Mechanism of liver injury-2binjury-2b

In mixed forms of hepatic injury, the In mixed forms of hepatic injury, the combined failure of canalicular pumps combined failure of canalicular pumps and other intracellular processes allows and other intracellular processes allows toxic bile acids to accumulate, causing toxic bile acids to accumulate, causing secondary injury to hepatocytes .secondary injury to hepatocytes .

If cells of the bile ducts are injured, a If cells of the bile ducts are injured, a likely outcome is protracted or likely outcome is protracted or permanent cholestasis, a disorder that permanent cholestasis, a disorder that has been termed the "vanishing bile has been termed the "vanishing bile duct syndrome." duct syndrome."

Mechanism of liver Mechanism of liver injury-3ainjury-3a

Drugs are relatively small molecules and, Drugs are relatively small molecules and, therefore, are unlikely to evoke an therefore, are unlikely to evoke an immune response.immune response.

However, biotransformation involving However, biotransformation involving high-energy reactions can result in the high-energy reactions can result in the formation of adducts — that is, drugs formation of adducts — that is, drugs covalently bound to enzymes. covalently bound to enzymes.

Mechanism of liver Mechanism of liver injury-3binjury-3b

Adducts that are large enough to serve Adducts that are large enough to serve as immune targets may migrate to the as immune targets may migrate to the surface of the hepatocyte, where they surface of the hepatocyte, where they can induce the formation of antibodies can induce the formation of antibodies (antibody-mediated cytotoxicity) or (antibody-mediated cytotoxicity) or induce direct cytolytic T-cell responses .induce direct cytolytic T-cell responses .

The secondary cytokine response thus The secondary cytokine response thus evoked may cause inflammation and evoked may cause inflammation and additional neutrophil-mediated additional neutrophil-mediated hepatotoxicity hepatotoxicity

Mechanism of liver Mechanism of liver injury-3 coninjury-3 con

Mechanism of liver injury-Mechanism of liver injury-3c3c

For a growing number of drugs, there is For a growing number of drugs, there is evidence that genetic polymorphism in evidence that genetic polymorphism in metabolic pathways are important in metabolic pathways are important in determining which individuals are likely to determining which individuals are likely to have an adverse reaction.have an adverse reaction.

Immunologic reactions of the immuno-allergic Immunologic reactions of the immuno-allergic type appear to play less important (or at best type appear to play less important (or at best augmenting) roles in the production of most augmenting) roles in the production of most drug-induced injuries. Haptens formed by a drug-induced injuries. Haptens formed by a drug product and a cellular constituent may drug product and a cellular constituent may provoke formation of antibodies to the neo-provoke formation of antibodies to the neo-antigen and add to injury.antigen and add to injury.

Reactions to several drugs, including Reactions to several drugs, including halothane, diphenylhydantoin, and sulindac, halothane, diphenylhydantoin, and sulindac, occur in settings suggesting occur in settings suggesting

Mechanism of liver Mechanism of liver injury-4injury-4 Programmed cell death (apoptosis) can Programmed cell death (apoptosis) can

occur in concert with immune-mediated occur in concert with immune-mediated injury, destroying hepatocytes by way of injury, destroying hepatocytes by way of the tumor necrosis factor (TNF) and the the tumor necrosis factor (TNF) and the Fas pathways, with cell shrinkage and Fas pathways, with cell shrinkage and fragmentation of nuclear chromatin fragmentation of nuclear chromatin

Proapoptotic receptor enzymes, if Proapoptotic receptor enzymes, if activated by drugs, will compete with activated by drugs, will compete with protective so-called survival pathways protective so-called survival pathways within the cell, and this dynamic within the cell, and this dynamic interaction may shift the balance either interaction may shift the balance either in favor of or against further cell in favor of or against further cell damage. damage.

Mechanism of liver injury-Mechanism of liver injury-5a5a

Certain drugs inhibit mitochondrial Certain drugs inhibit mitochondrial function by a dual effect on both -function by a dual effect on both -oxidation (affecting energy production by oxidation (affecting energy production by inhibition of the synthesis of inhibition of the synthesis of nicotinamide adenine dinucleotide and nicotinamide adenine dinucleotide and flavin adenine dinucleotide, resulting in flavin adenine dinucleotide, resulting in decreased ATP production) and the decreased ATP production) and the respiratory-chain enzymes.respiratory-chain enzymes.

Free fatty acids cannot be metabolized, Free fatty acids cannot be metabolized, and the lack of aerobic respiration and the lack of aerobic respiration results in the accumulation of lactate results in the accumulation of lactate and reactive oxygen species. and reactive oxygen species.

Mechanism of liver Mechanism of liver injury-5 binjury-5 b

. The presence of reactive oxygen . The presence of reactive oxygen species may further disrupt species may further disrupt mitochondrial DNA. mitochondrial DNA.

The presence of reactive oxygen species The presence of reactive oxygen species may further disrupt mitochondrial DNA. may further disrupt mitochondrial DNA.

This pattern of injury is characteristic This pattern of injury is characteristic of a variety of agents, including of a variety of agents, including nucleoside reverse-transcriptase nucleoside reverse-transcriptase inhibitors, which bind directly to inhibitors, which bind directly to mitochondrial DNA, as well as valproic mitochondrial DNA, as well as valproic acid, tetracycline, and aspirin.acid, tetracycline, and aspirin.

Mechanism of liver injury-6Mechanism of liver injury-6 Other cells within the liver may be the target Other cells within the liver may be the target

of drug injury or serve as modulators of an of drug injury or serve as modulators of an incipient reaction.incipient reaction.

For example, Kupffer's cells activate For example, Kupffer's cells activate cytokines that may amplify injury, and fat-cytokines that may amplify injury, and fat-storage cells (stellate cells) or macrophages storage cells (stellate cells) or macrophages may augment injury, produce fibrosis, or form may augment injury, produce fibrosis, or form granulomas.granulomas.

Chemotherapeutic agents can injure Chemotherapeutic agents can injure sinusoidal endothelial cells, a process that sinusoidal endothelial cells, a process that can lead to veno-occlusive disease.can lead to veno-occlusive disease.

Therapeutic hormone administration may Therapeutic hormone administration may induce hepatocyte dedifferentiation, resulting induce hepatocyte dedifferentiation, resulting in benign adenomas and, rarely, carcinomas.in benign adenomas and, rarely, carcinomas.

Clearly, multiple cellular pathways to liver Clearly, multiple cellular pathways to liver injury are possible. injury are possible.

Sinusoidal DamageSinusoidal Damage

Methotrexate induced Methotrexate induced fibrosisfibrosis

Vitamin A ToxicityVitamin A Toxicity

When to suspect DILI-1When to suspect DILI-1 There are few clinical or laboratory There are few clinical or laboratory

manifestations which specifically suggest that a manifestations which specifically suggest that a liver injury is the result of a therapeutic drug. liver injury is the result of a therapeutic drug. The most important clue is often the temporal The most important clue is often the temporal relationship between initiation of a drug (or relationship between initiation of a drug (or drugs) and the appearance of the injury, and of drugs) and the appearance of the injury, and of equal importance is the resolution of an equal importance is the resolution of an abnormality following withdrawal (deceleration). abnormality following withdrawal (deceleration).

In many (likely most) instances, a slight elevation In many (likely most) instances, a slight elevation of a serum aminotransferase is of no clinical of a serum aminotransferase is of no clinical importance and may well resolve through poorly importance and may well resolve through poorly understood adaptive mechanisms that develop understood adaptive mechanisms that develop with continued drug use. with continued drug use.


(DILI)(DILI)Most people exposed to a new drug show no Most people exposed to a new drug show no

injuryinjury;;

““toleratorstolerators””

Some people show transient injury, but adaptSome people show transient injury, but adapt;;

““adaptorsadaptors””

A few fail to adapt and show serious toxicityA few fail to adapt and show serious toxicity! !

““susceptiblessusceptibles””


(DILI)(DILI)““toleratorstolerators””

Time Course of Liver Tests"tolerator" - M47 - Gilbert's syndrome

0.1

1.0

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Days Since Exposed to Drug

Test

Valu

es,

(xU

LN

) ALTx

ASTx

ALPx

TBLx


When to suspect DILI-2When to suspect DILI-2 The combination of elevated The combination of elevated

aminotransferase (at least >3 × aminotransferase (at least >3 × ULN) and clinically evident jaundice ULN) and clinically evident jaundice (>3 mg/dL) identifies patients at (>3 mg/dL) identifies patients at heightened risk of developing severe heightened risk of developing severe injury. injury.

Definition of DILI for inclusion Criteria Serum ALT or AST >5 x ULN or A P’ase >2 x Serum ALT or AST >5 x ULN or A P’ase >2 x

ULN confirmed on at least 2 consecutive blood ULN confirmed on at least 2 consecutive blood draws. draws.

If baseline (BL) ALT, AST or A P’ase are known If baseline (BL) ALT, AST or A P’ase are known and elevated, then ALT or AST >5 x BL or A and elevated, then ALT or AST >5 x BL or A P’ase >2 x BL on at least 2 consecutive blood P’ase >2 x BL on at least 2 consecutive blood draws. draws.

or Any elevation of serum ALT, A P’ase, or or Any elevation of serum ALT, A P’ase, or AST, associated with (a) increased serum total AST, associated with (a) increased serum total bilirubin [ ≥ 2.5 mg/dL], in absence of prior bilirubin [ ≥ 2.5 mg/dL], in absence of prior diagnosis of liver disease, Gilbert’s syndrome, or diagnosis of liver disease, Gilbert’s syndrome, or evidence of hemolysis.evidence of hemolysis.

Acute DILIAcute DILI Hepatocellular:Hepatocellular: R > 5 and ALT > R > 5 and ALT >

2x ULN or baseline2x ULN or baseline

Cholestatic:Cholestatic: R < 2 and Alk > ULN R < 2 and Alk > ULN

Mixed:Mixed: 2< R < 5 2< R < 5

R= (ALT/ULN)/ (Alk / ULN)(J Hepatol 1990; 11: 272)

Hy Zimmerman

1917-1999

““Hy’s Law” Hy’s Law” ...for drug-induced hepatotoxicity...for drug-induced hepatotoxicity

If both hepatocellular injury If both hepatocellular injury and jaundice occur, look out and jaundice occur, look out for at least 10% mortality!for at least 10% mortality!

i.e., when both transaminase and i.e., when both transaminase and bilirubin elevations occur together.bilirubin elevations occur together.

Robert Temple, FDA, 1999Robert Temple, FDA, 1999

Prognosis in Acute Liver FailurePrognosis in Acute Liver Failure

Good prognosisGood prognosis::

AcetaminophenAcetaminophen Hepatitis AHepatitis A ShockShock

Etiology an important outcome determinantEtiology an important outcome determinant

Bad prognosisBad prognosis:: DrugsDrugs IndeterminateIndeterminate Hepatitis BHepatitis B Wilson DiseaseWilson Disease

… not DILI

Time Course of Liver Testsmale 72, placebo

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1.0

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-60

-30 0 30 60 90 120

150

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510

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Study Day

Te

st V

alu

es,

xU

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altx

astx

alkx

bilx


subacute hepatitis B

2xULN

A significant number of drugs has been A significant number of drugs has been proven, or at least suggested, to cause proven, or at least suggested, to cause hepatotoxicity.hepatotoxicity.

It must be recognized that a drug is a It must be recognized that a drug is a chemical or biologic agent that has been chemical or biologic agent that has been found to cause a favorable effect on a found to cause a favorable effect on a symptom or disease process, has been symptom or disease process, has been tested for safety (relative), has been given tested for safety (relative), has been given a name, and then if approved, is widely a name, and then if approved, is widely available.available.

Usually, the propensity to cause liver Usually, the propensity to cause liver injury is identified during preapproval injury is identified during preapproval evaluations, especially those in large evaluations, especially those in large pivotal Phase 3 trials.pivotal Phase 3 trials.

Attribution of liver injury to a Attribution of liver injury to a specific drug in a patient may be specific drug in a patient may be difficult, and the difficulties are difficult, and the difficulties are compounded if the patient has compounded if the patient has underlying acute or chronic liver underlying acute or chronic liver disease such as chronic hepatitis C, disease such as chronic hepatitis C, chronic hepatitis B, nonalcoholic chronic hepatitis B, nonalcoholic fatty liver disease, or alcohol-fatty liver disease, or alcohol-induced liver disease. induced liver disease.

Much attention has been given to the Much attention has been given to the identification of factors that identify identification of factors that identify individuals who are at increased risk of individuals who are at increased risk of developing an adverse hepatic reaction developing an adverse hepatic reaction from a drug.from a drug.

There are concerns not only about the There are concerns not only about the drug itself, but also about the effects of drug itself, but also about the effects of drug-drug and drug-disease drug-drug and drug-disease interactions. interactions.

In general, it appears that patients with In general, it appears that patients with acute or chronic liver diseases are not acute or chronic liver diseases are not more likely to develop a hepatotoxic more likely to develop a hepatotoxic reaction of the idiosyncratic type. reaction of the idiosyncratic type.

However, especially in patients who However, especially in patients who have advanced liver disease, any have advanced liver disease, any adverse hepatic reaction that occurs adverse hepatic reaction that occurs is more likely to lead to clinical is more likely to lead to clinical evidence of liver injury, in part evidence of liver injury, in part related to decreased liver mass and related to decreased liver mass and decreased abilities to respond to the decreased abilities to respond to the injury and appropriately regenerate injury and appropriately regenerate hepatocytes. hepatocytes.

Drug SignatureDrug Signature

Most drugs have a “signature” of Most drugs have a “signature” of hepatotoxicity regarding time of hepatotoxicity regarding time of onset, frequency, and type of onset, frequency, and type of hepatotoxicity that may be hepatotoxicity that may be encountered. encountered.

When to suspect DILI-3When to suspect DILI-3

There may be few clinical signs suggesting liver There may be few clinical signs suggesting liver injury, even in a patient who has biochemical and injury, even in a patient who has biochemical and histologic evidence of considerable damage.histologic evidence of considerable damage.

Early symptoms associated with drug-induced Early symptoms associated with drug-induced liver injury are usually nonspecific and include liver injury are usually nonspecific and include loss of appetite, lassitude, and occasionally a dull loss of appetite, lassitude, and occasionally a dull discomfort in the right upper quadrant of the discomfort in the right upper quadrant of the abdomen.abdomen.

With a few drugs, there is the presence of fever, With a few drugs, there is the presence of fever, rash, or eosinophilia: the hallmarks of immuno-rash, or eosinophilia: the hallmarks of immuno-allergic reactions. These reactions may (or may allergic reactions. These reactions may (or may not) be important in the pathogenesis of the liver not) be important in the pathogenesis of the liver injury.injury.

When to suspect DILI-4When to suspect DILI-4 Rechallenge with a suspected drug to Rechallenge with a suspected drug to

establish a diagnosis is seldom establish a diagnosis is seldom necessary and, if the initial reaction necessary and, if the initial reaction was clinically apparent, may not be was clinically apparent, may not be safe.safe.

Even histologic evaluation of the liver Even histologic evaluation of the liver only allows recognition of what type only allows recognition of what type and how much injury is present, and how much injury is present, rather than clearly indicating that the rather than clearly indicating that the liver injury is from a specific drug.liver injury is from a specific drug.


(DILI)(DILI)““susceptiblessusceptibles””

Time Course of AbnormalitiesPatient xxx F44, "susceptible"

-1.0

-0.5

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15 30 45 60 75 90

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AST

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TBL

start Drug stop Drug

------------hospitalized-----------------

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100xULN

FACTORS THAT AFFECT FACTORS THAT AFFECT SUSCEPTIBILITY TO SUSCEPTIBILITY TO

DILI-1DILI-1 Age, sex, and the concomitant use of Age, sex, and the concomitant use of

other medications are important factors other medications are important factors to consider in assessing an individual to consider in assessing an individual patient's susceptibility to drug-induced patient's susceptibility to drug-induced liver disease, as is weight and a history liver disease, as is weight and a history of previous reactions to drugs. .of previous reactions to drugs. .

For some drugs, there is a well-For some drugs, there is a well-established increase in the risk of established increase in the risk of adverse reactions with age, especially adverse reactions with age, especially for individuals who are older than 50 for individuals who are older than 50 yearsyears


DILI-2DILI-2 Older patients (>50 years) are quite Older patients (>50 years) are quite

likely to have some evidence of hepatic likely to have some evidence of hepatic toxicity from isoniazid (up to 2%).toxicity from isoniazid (up to 2%).

Few reactions have been reported in Few reactions have been reported in patients who are younger than 20 years.patients who are younger than 20 years.

There are a few agents, among them There are a few agents, among them valproic acid and erythromycin estolate, valproic acid and erythromycin estolate, which predominantly cause adverse which predominantly cause adverse hepatic reactions in children hepatic reactions in children


DILI-3DILI-3 Valproic acid-induced hepatotoxicity is also Valproic acid-induced hepatotoxicity is also

more prevalent in patients who have more prevalent in patients who have inherited mitochondrial disorders.inherited mitochondrial disorders.

Duration of therapy before a reaction occurs Duration of therapy before a reaction occurs is an important part of the “signature.”is an important part of the “signature.”

Phenytoin rarely causes significant hepatic Phenytoin rarely causes significant hepatic toxicity after 6 weeks of therapy.toxicity after 6 weeks of therapy.

Liver injury from nitrofurantoin-induced Liver injury from nitrofurantoin-induced hepatotoxicity may appear after many hepatotoxicity may appear after many months of therapy. months of therapy.


DILI-4DILI-4 For many drugs, females are at an For many drugs, females are at an

increased risk of developing an increased risk of developing an adverse hepatic reaction, far adverse hepatic reaction, far exceeding that found in males.exceeding that found in males.

Acute hepatitis: Differential DxAcute hepatitis: Differential DxUltrasound/ CT

Viral(A, B, C, CMV, EBV

HEV, HSV)

+ +

Mass

(AFP, MRI)

Drug

Autoimmune(SPEP, ANA, SmAb)

Metabolic(Iron, TIBC, ferritin,

ceruloplasmin, SPEP)

Ischemia(History, 2D-Echo)

NAFLD Biliary(ERCP)

Observe/ biopsy

Liver LobuleLiver Lobule

Liver FunctionExampleConsequence

Glucose metabolism, protein metabolism, storage of nutrients

Glucose storage as glycogenHypoglycemia, altered protein synthesis, decreased vitamin A,

Cu, Fe

FiltrationRemoval of polypeptides, lipoproteins coming from GI track

Endotoxemia

Protein synthesisAlbumenTransport proteins

Blood clotting factors

Hypoalbumenia, ascites ,decreased blood clotting

Removal of bile pigmentsBile acidsJaundice

Lipid metabolismCholesterolIncreased levels

Xenobiotic removal and metabolism

Drugs, toxins, metalsProtection, intoxication

Commonly Used Tests

enzymes

“transaminases”: ALT

AST

alkaline phosphatase

gamma-glutamyl transferase

substances

bilirubin (total, “direct”)

albumin

prothrombin (INR)

injury

hepatocellular

cholestatic

function

excretory

synthetic

synthetic

DILI DiagnosisDILI Diagnosis Temporal relationshipTemporal relationship

Not dose relatedNot dose related ? Clinical risk factors? Clinical risk factors

Biochemical injury patternBiochemical injury pattern ““Signature” vs proteanSignature” vs protean Prior reports/ casesPrior reports/ cases Exclude other likely causesExclude other likely causes

Improvement with discontinuationImprovement with discontinuation

Drug Induced Liver Drug Induced Liver InjuryInjury

Two types of hepatotoxicity are of Two types of hepatotoxicity are of interest:interest: Dose-related-or exposure related.Dose-related-or exposure related. Idiosyncratic-rare, unpredictable.Idiosyncratic-rare, unpredictable.

Factors in Factors in IdiosyncrasyIdiosyncrasy genetic, bestowed at genetic, bestowed at

onceptiononceptiongendergendercytochromes, enzymes, transport cytochromes, enzymes, transport systemssystems

acquired in life since acquired in life since conceptionconception

age, activities, travelsage, activities, travelsinfections, immunities, diseasesinfections, immunities, diseasesdiet, obesity, dietary supplementsdiet, obesity, dietary supplementsother drugs, chemical exposuresother drugs, chemical exposures

Especially Susceptible Especially Susceptible PatientsPatients

adverse effect, often not dose-adverse effect, often not dose-relatedrelated

may not be duration-relatedmay not be duration-related may not depend on prior diseasemay not depend on prior disease unexpected, unpredictable (up to unexpected, unpredictable (up to

now)now) risk factors not well knownrisk factors not well known toxicity often uncommon or raretoxicity often uncommon or rare who are they? how can they be who are they? how can they be

identified?identified?

Intrinsic vs Idiosyncratic Intrinsic vs Idiosyncratic ToxicityToxicity

““intrinsic”intrinsic” predictablepredictable dose-relateddose-related similar in animalssimilar in animals high incidencehigh incidence short intervalshort interval typestypes

directly destructivedirectly destructive indirect, metabolicindirect, metabolic cholestaticcholestatic

““idiosyncratic”idiosyncratic” unpredictableunpredictable not dose-related not dose-related not seen in animalsnot seen in animals low incidence, rarelow incidence, rare variably longer variably longer

intervalinterval typestypes

hypersensitivityhypersensitivity metabolicmetabolic

It may be DILI if it’s It may be DILI if it’s nothing elsenothing else

• Diagnosis of exclusion; no test FOR DILI• Must gather data to rule out other causes• Need to educate “docs” to do it better• Develop model for quantitative likelihood estimate• Prospective large safety studies needed:

• for true incidence• for risk factors and to design risk management plans• for ‘omic’ analyses (gen-, prote-, metabon-) specimens

for elucidation of mechanisms

Acetaminophen-induced Acetaminophen-induced hepatic injury 1hepatic injury 1

Acetaminophen-induced hepatic injury is Acetaminophen-induced hepatic injury is the most common form of drug-induced the most common form of drug-induced liver disease and more particularly of liver disease and more particularly of acute liver failure in the United States, acute liver failure in the United States, accounting for nearly 50% of all casesaccounting for nearly 50% of all cases..

Acetaminophen is likely the most widely Acetaminophen is likely the most widely used drug in the western world and is used drug in the western world and is found in a remarkable number of found in a remarkable number of prescribed and over-the-counter single prescribed and over-the-counter single and combination products, including cold and combination products, including cold remedies and medications for pain. with remedies and medications for pain. with names that in no way indicate names that in no way indicate acetaminophen is a component. acetaminophen is a component.

Acetaminophen-2Acetaminophen-2 In healthy individuals, there is apparently a In healthy individuals, there is apparently a

considerable therapeutic range between considerable therapeutic range between harmless and harmful doses of harmless and harmful doses of acetaminophen. In therapeutic doses (<3 acetaminophen. In therapeutic doses (<3 g/day), the drug is usually quite safe and well g/day), the drug is usually quite safe and well tolerated.tolerated.

Ingestion of excessive amounts of Ingestion of excessive amounts of acetaminophen (>10-15 g), often in suicidal acetaminophen (>10-15 g), often in suicidal attempts, predictably leads to liver injury and attempts, predictably leads to liver injury and occasionally death. occasionally death.

The issues lie in assessing the risk of patients The issues lie in assessing the risk of patients receiving acetaminophen of 3 to 10 g/day, receiving acetaminophen of 3 to 10 g/day, and whether there are settings in which liver and whether there are settings in which liver injury is more likely to occur when the injury is more likely to occur when the patient has not taken a large amount of the patient has not taken a large amount of the drug with a suicidal intent (so-called drug with a suicidal intent (so-called “therapeutic misadventures”).“therapeutic misadventures”).

AcetaminophenAcetaminophen

Sulfate Glucuronide

95%NAPQI(N-acetyl-p-benzoquinoneimine)

5%

P450

Glutathione Conjugate

Glutathione

Normal


Sulfate Glucuronide

95%NAPQI(N-acetyl-p-benzoquinoneimine)

5%

P450

Glutathione Conjugate

Glutathione Covalent Binding to

Macromolecules

Cell Death (Zone 3)

Saturated

Overdose

Acetaminophen- 3Acetaminophen- 3 Hepatic injury from acetaminophen is Hepatic injury from acetaminophen is

caused by the effects of a highly reactive caused by the effects of a highly reactive metabolic product, N-acetyl-metabolic product, N-acetyl-benzoquinone-imide (NAPQI).benzoquinone-imide (NAPQI).

Acetaminophen is predominantly Acetaminophen is predominantly metabolized by conjugation reactions to metabolized by conjugation reactions to form sulfate and glucuronide metabolites, form sulfate and glucuronide metabolites, which are excreted in the urine.which are excreted in the urine.

A lesser amount of the drug is A lesser amount of the drug is metabolized by cytochrome P450 2E1 to metabolized by cytochrome P450 2E1 to form NAPQI, which is rapidly bound to form NAPQI, which is rapidly bound to intracellular glutathione and excreted in intracellular glutathione and excreted in the urine as mercapturic acid. the urine as mercapturic acid.

Acetaminophen- 4Acetaminophen- 4 When excessive amounts of When excessive amounts of

acetaminophen are ingested, the ability to acetaminophen are ingested, the ability to conjugate is overwhelmed and metabolism conjugate is overwhelmed and metabolism by cytochrome P450 2E1 becomes of by cytochrome P450 2E1 becomes of much greater importance.much greater importance.

In these situations, the capacity of In these situations, the capacity of glutathione to serve as an effective glutathione to serve as an effective hepatoprotectant may be overwhelmed, hepatoprotectant may be overwhelmed, and the hepatocyte becomes relatively and the hepatocyte becomes relatively defenseless against attack by the reactive defenseless against attack by the reactive intermediates intermediates

Oxygenation ZonesOxygenation Zones Zone 1 – 9% to 13%Zone 1 – 9% to 13% Zone 2 – < zone 1 Zone 2 – < zone 1 Zone 3 – 4% to 5%Zone 3 – 4% to 5% Zone 3 has most of Zone 3 has most of

the biotransformation the biotransformation enzymes especially enzymes especially CYP2E1CYP2E1

Acetaminophen- 5Acetaminophen- 5 Two important factors determine the Two important factors determine the

likelihood of production of hepatic injury likelihood of production of hepatic injury by acetaminophen: the amount of NAPQI by acetaminophen: the amount of NAPQI produced by P450 2E1 and the produced by P450 2E1 and the availability of glutathione as a availability of glutathione as a hepatoprotectant.hepatoprotectant.

The intracellular concentration of The intracellular concentration of NAPQI and dose of acetaminophen NAPQI and dose of acetaminophen ingested are clearly associated. ingested are clearly associated. However, there is more to the story than However, there is more to the story than simply dosage. simply dosage.

Factors that affect the production of Factors that affect the production of cytochrome P450 2E1 and of glutathione cytochrome P450 2E1 and of glutathione are of importance are of importance

Acetaminophen- 6Acetaminophen- 6 With chronic ingestion of alcohol, doses of With chronic ingestion of alcohol, doses of

acetaminophen near or even with the acetaminophen near or even with the suggested therapeutic range may lead to suggested therapeutic range may lead to liver injury, promoted by anliver injury, promoted by an

alcohol-induced decrease in alcohol-induced decrease in intracellular glutathione intracellular glutathione

and an increase (actual or relative to and an increase (actual or relative to GSH) of cytochrome P450 2E1.GSH) of cytochrome P450 2E1.

The end result is overproduction of The end result is overproduction of NAPQ1 relative to the dispositional NAPQ1 relative to the dispositional pathway of GSH leading to a heightened pathway of GSH leading to a heightened likelihood of liver likelihood of liver

Acetaminophen- 7Acetaminophen- 7 There continues to be controversy There continues to be controversy

regarding the risk of acetaminophen use in regarding the risk of acetaminophen use in patients who drink alcohol.patients who drink alcohol.

Many discussions have occurred at the U.S. Many discussions have occurred at the U.S. Food and Drug Administration regarding Food and Drug Administration regarding labeling and the need for increased labeling and the need for increased awareness of risks by the public.awareness of risks by the public.

There is general agreement that an There is general agreement that an overdose of acetaminophen is more likely to overdose of acetaminophen is more likely to cause liver injury in a patient who is a cause liver injury in a patient who is a chronic alcoholic.chronic alcoholic.

The debate is the definition of overdose The debate is the definition of overdose and the amount of alcohol ingestion needed and the amount of alcohol ingestion needed to predispose the patient to injury to predispose the patient to injury

AcetaminophenAcetaminophen Toxic dose Toxic dose

150mg/kg in children less than 12150mg/kg in children less than 12 Estimated at 7.5 g for adolescents and adultsEstimated at 7.5 g for adolescents and adults

4 stages in untreated patients4 stages in untreated patients Stage I (0 - 24h) - nausea, vomitting, Stage I (0 - 24h) - nausea, vomitting,

diaphoresisdiaphoresis Stage II (24 - 48h) - clinical improvement, Stage II (24 - 48h) - clinical improvement,

RUQ painRUQ pain Stage III (72 - 96h) - peak liver function Stage III (72 - 96h) - peak liver function

abnormalities, GI symptoms may reappearabnormalities, GI symptoms may reappear Stage IV (4d to 2wks) - hepatic problems Stage IV (4d to 2wks) - hepatic problems

resolve, <1% will develop fulminant hepatic resolve, <1% will develop fulminant hepatic necrosis requiring a liver transplantnecrosis requiring a liver transplant


Measure a plasma Measure a plasma acetaminophen level at acetaminophen level at >>4h 4h after ingestionafter ingestion

Antidote is N-acetylcysteine Antidote is N-acetylcysteine - most effective within 8 - most effective within 8 hours of ingestionhours of ingestion

Give antidote if at risk for Give antidote if at risk for hepatotoxicityhepatotoxicity

Activated charcoal should Activated charcoal should be consideredbe considered

Amoxicillin/Clavulanic Amoxicillin/Clavulanic Acid HepatotoxicityAcid Hepatotoxicity

68 yo female68 yo female Referred for transplant evaluationReferred for transplant evaluation Jaundice and failure to thriveJaundice and failure to thrive 3 month illness3 month illness Laparotomy x 2, cholecystectomyLaparotomy x 2, cholecystectomy

and multiple pancreatic head biopsiesand multiple pancreatic head biopsies Biopsy profound cholestasis and bile duct Biopsy profound cholestasis and bile duct

injury injury

Small nasal scar, solar keratosis surgerySmall nasal scar, solar keratosis surgery Dermatologists records Dermatologists records

• No malignantNo malignant• InfectedInfected• Augmentin for 14 daysAugmentin for 14 days

Case PresentationCase Presentation

AmoxicillinAmoxicillin• Semisynthetic antibioticSemisynthetic antibiotic• CC1616HH1919NN33OO55S.3HS.3H2200• MW = 419.46MW = 419.46

clavulanate potassium (salt)clavulanate potassium (salt)• Potent Potent ββ- lactamase inhibitor- lactamase inhibitor• CC88HH88KNOKNO55• MW = 237.25MW = 237.25

Addition of clavulanate prevents Addition of clavulanate prevents degradation of amoxicillin by degradation of amoxicillin by ββ- - lactamases lactamases

Therapeutics: Prescribing Therapeutics: Prescribing InformationInformation

unclearunclear Idiosyncratic/immunologicIdiosyncratic/immunologic

• Not dose dependentNot dose dependent• Prevalence not uniformly assoc with re-Prevalence not uniformly assoc with re-

exposureexposure• EosinophiliaEosinophilia• HLA associationHLA association

Not seen with amoxicillin aloneNot seen with amoxicillin alone Presumed due to clavulantePresumed due to clavulante Cholestasis described with Timentim® Cholestasis described with Timentim®

• Ticarcillin + clavulanteTicarcillin + clavulante• Rarely observed with sulbactam, Rarely observed with sulbactam,

tazobactam; tazobactam; i.e. other i.e. other ββ lactamaseslactamases

Mechanism of ActionMechanism of Action

““Indicated for the treatment of Indicated for the treatment of infections caused by susceptible infections caused by susceptible strains of the following designated strains of the following designated organisms”:organisms”:• H. H. influenzae;influenzae; M. M. catarrhaliscatarrhalis; E. ; E. colicoli; S. ; S.

aureusaureus; ; KlebsiellaKlebsiella spp, spp, EnterobacterEnterobacter spp spp • Lower respiratory tract infections (COPD)Lower respiratory tract infections (COPD)• Otitis mediaOtitis media• SimusitisSimusitis• Skin and skin structure infectionsSkin and skin structure infections• Urinary tract infectionsUrinary tract infections


Augmentin®Augmentin® First introduced 1981First introduced 1981 Generics introduced 2001-2002Generics introduced 2001-2002 Hepatotoxocity first reported 1988Hepatotoxocity first reported 1988 Year 2000Year 2000

• 18.9 M new prescriptions18.9 M new prescriptions• Fourth most commonly prescribed Fourth most commonly prescribed

drugdrug


Assuming incidence between Assuming incidence between • 1: 100,000 and1: 100,000 and• 1:10,0001:10,000• ≈ ≈ 20 million new prescriptions 20 million new prescriptions

annuallyannually Number of expected cases HTXNumber of expected cases HTX

• ≈ ≈ 200-2,000 per year200-2,000 per year• ≈ ≈ 122-1,220 adult cases122-1,220 adult cases• ≈ ≈ 78-780 pediatric cases ??78-780 pediatric cases ??

US Frequency US Frequency HepatotoxicityHepatotoxicity

Pyrexia associated with bacterial Unclear, not Pyrexia associated with bacterial Unclear, not well documentedwell documented

infectionsinfections Acetominophen probably commonAcetominophen probably common 8/21 (38%) cases exposed to other HTX drugs8/21 (38%) cases exposed to other HTX drugs

• AcetominophenAcetominophen• NSAID’sNSAID’s• TrimethoprimTrimethoprim• FlucloxacillinFlucloxacillin• ValproateValproate• CarbamazepineCarbamazepine• imipramineimipramine

43% another potential or suspected agent 43% another potential or suspected agent

Frequent Concomitant Frequent Concomitant MedicationsMedications

Signs and Symptoms are nonspecificSigns and Symptoms are nonspecific• NauseaNausea• VomitingVomiting• FatigueFatigue• MalaiseMalaise• Abdominal painAbdominal pain• feversfevers• ItchItch• JaundiceJaundice• rashrash

Allergic phenomena: Allergic phenomena: • Eosinophilia 23-30% patientsEosinophilia 23-30% patients

Clinical PresentationClinical Presentation

TimingTiming• Interval start Rx to jaundice Interval start Rx to jaundice

4-63 days (89 days)4-63 days (89 days)

• Cessation Rx to onset jaundice Cessation Rx to onset jaundice 1-48 days1-48 days

• 80% developed jaundice after 80% developed jaundice after cessation Rxcessation Rx


Larrey D et al. Gut 1992;33:368-71Hautekeete ML et al. Gasroenterology 1999:117;1181-86

Laboratory testsLaboratory tests• Bilirubin Bilirubin 2-35 x ULN2-35 x ULN• ALT ALT 2-33 X ULN2-33 X ULN• AST AST 1.2-18 x ULN 1.2-18 x ULN • AP AP 1.7-13 x ULN1.7-13 x ULN• γγGT GT 2.5-52 x ULN 2.5-52 x ULN


Pattern of Laboratory testsPattern of Laboratory tests• CholestaticCholestatic

66-76%66-76%

• Mixed Mixed 14-23%14-23%

• HepatocellularHepatocellular 10-11%10-11%


Architecture normalArchitecture normal Mixed, LM portal infiltrateMixed, LM portal infiltrate Intralobular Bile ductsIntralobular Bile ducts

Nuclear irregularityNuclear irregularity VacuolizationVacuolization LM infiltrateLM infiltrate ProliferationProliferation

Cholestasis lobulesCholestasis lobules Variable degrees necrosisVariable degrees necrosis Mild cellular infiltrateMild cellular infiltrate

RarelyRarely granulomas; focal destructive cholangiopathygranulomas; focal destructive cholangiopathy

Clinical PresentationClinical PresentationLiver BiopsyLiver Biopsy

Fatalities rare but reportedFatalities rare but reported Chronicity uncommon Chronicity uncommon Jaundice can be prolongedJaundice can be prolonged

• up to 19 weeksup to 19 weeks• 1 case 2 years1 case 2 years

Cases associated withCases associated with• PBCPBC• Interstitial nephritisInterstitial nephritis• SialadenitisSialadenitis

? Underlying liver disease? Underlying liver disease Pre-exisiting DILIPre-exisiting DILI

Outcome of Outcome of HepatotoxicityHepatotoxicity

DRB1*1501-DRB5*0101-DQB1*0602DRB1*1501-DRB5*0101-DQB1*0602 35 cases, 300 donors35 cases, 300 donors 57% vs 11.7% (p < 0.0002)57% vs 11.7% (p < 0.0002) haplotype more frequently assoc. with haplotype more frequently assoc. with

cholestatic/mixedcholestatic/mixed

22 cases, 134 controls22 cases, 134 controls 70% vs. 20% (p < 0.00005; RR 6.43)70% vs. 20% (p < 0.00005; RR 6.43) More frequently homozygotesMore frequently homozygotes No clinical correlatesNo clinical correlates

? Formation neo-antigen and their recognition ? Formation neo-antigen and their recognition as foreignas foreign

HLA Class II HLA Class II AssociationAssociation

Start and stop date Start and stop date Age, sex, demographics Age, sex, demographics

Drug exposure within 8 weeks Drug exposure within 8 weeks Serologic testsSerologic tests

Additional but not necessaryAdditional but not necessary• Prior exposurePrior exposure• EosinophilsEosinophils• biopsy biopsy • DosageDosage• Imaging to exclude obstructionImaging to exclude obstruction• Concomitant medicationsConcomitant medications

Minimal Criteria for Minimal Criteria for CausalityCausalityAmoxicillin/clavulanic acidAmoxicillin/clavulanic acid

MaleMale Age > 50-55 yoAge > 50-55 yo Cholestatic patternCholestatic pattern Repeat exposureRepeat exposure EosinophiliaEosinophilia Imaging negativeImaging negative Onset after cessation of drug Onset after cessation of drug Recovery within 6-8 weeksRecovery within 6-8 weeks All serologies negativeAll serologies negative

““Definite” CaseDefinite” Case Amoxicillin/clavulanic acidAmoxicillin/clavulanic acid

Isoniazid Hepatotoxicity -1Isoniazid Hepatotoxicity -1 Isoniazid has been the mainstay therapeutic Isoniazid has been the mainstay therapeutic

agent for the treatment of tuberculosis for agent for the treatment of tuberculosis for more than 50 years. more than 50 years.

Combination therapies anchored by INH are Combination therapies anchored by INH are generally used to prevent the development generally used to prevent the development of resistance to a single therapeutic agent. of resistance to a single therapeutic agent.

In the 1960s, INH was used as a single agent In the 1960s, INH was used as a single agent in patients who were found to be at risk for in patients who were found to be at risk for developing tuberculosis because of the developing tuberculosis because of the findings of a positive tuberculin skin test. findings of a positive tuberculin skin test.

INH given alone often leads to elevations of INH given alone often leads to elevations of aminotransferase and occasionally to overt aminotransferase and occasionally to overt liver disease. liver disease.

Isoniazid Hepatotoxicity -2Isoniazid Hepatotoxicity -2

When INH was used as a sole agent, When INH was used as a sole agent, instances of hepatotoxicity appeared instances of hepatotoxicity appeared suggesting that when given in suggesting that when given in combination therapies ,the combination therapies ,the combination of drugs may have been combination of drugs may have been associated with a reduced associated with a reduced production of intermediate production of intermediate metabolites of INH. metabolites of INH.

Isoniazid Hepatotoxicity -3Isoniazid Hepatotoxicity -3 Elevations of aminotransferase levels Elevations of aminotransferase levels

from INH usually appear within several from INH usually appear within several weeks following initiation of treatment weeks following initiation of treatment and are found in 10% to 20% of patients.and are found in 10% to 20% of patients.

Usually, these elevations are modest and Usually, these elevations are modest and not associated with signs or symptoms not associated with signs or symptoms suggestive of liver disease.suggestive of liver disease.

In many (likely most) patients, continued In many (likely most) patients, continued use of INH is well tolerated and often the use of INH is well tolerated and often the aminotransferase levels return to or near aminotransferase levels return to or near normal.normal.

If INH is discontinued when the elevations If INH is discontinued when the elevations are noted, the aminotransferase levels are noted, the aminotransferase levels generally return to normal within 1 to 4 generally return to normal within 1 to 4 weeks. weeks.

Isoniazid Hepatotoxicity -4Isoniazid Hepatotoxicity -4 However, a few patients receiving However, a few patients receiving

INH develop significant clinical INH develop significant clinical hepatitis, and drug-induced hepatic hepatitis, and drug-induced hepatic failure may occur (0.1%-2.0%)failure may occur (0.1%-2.0%)

Patients older than 50 years are at Patients older than 50 years are at an increased risk of developing an increased risk of developing clinically evident hepatitis from INH. clinically evident hepatitis from INH.

Children rarely manifest any Children rarely manifest any clinically evident liver disease from clinically evident liver disease from INH.INH.

Women are more likely to be Women are more likely to be severely affected than men.severely affected than men.

Isoniazid Hepatotoxicity Isoniazid Hepatotoxicity -5-5

Presently, patient-monitoring schedules Presently, patient-monitoring schedules with discontinuation of treatment in those with discontinuation of treatment in those in whom there are significant or rising in whom there are significant or rising levels of aminotransferases are levels of aminotransferases are recommended and appear to be effective.recommended and appear to be effective.


The liver injury from INH appears to be The liver injury from INH appears to be mediated by toxic metabolic products, mediated by toxic metabolic products, including hydrazine and monoacetyl including hydrazine and monoacetyl derivatives formed during metabolism.derivatives formed during metabolism.

There are generally no signs or There are generally no signs or symptoms suggestive of symptoms suggestive of hypersensitivity. hypersensitivity.

INH is metabolized by N-INH is metabolized by N-acetyltransferase and CYP 2E1 to form acetyltransferase and CYP 2E1 to form reactive intermediates.reactive intermediates.


In the first phase, isoniazid is In the first phase, isoniazid is metabolized by N-acetyltransferase metabolized by N-acetyltransferase (NAT2) to acetylisoniazid, which is (NAT2) to acetylisoniazid, which is then hydrolyzed to acetylhydrazine.then hydrolyzed to acetylhydrazine.

Acetylhydrazine is further Acetylhydrazine is further metabolized by CYP 2E1 to produce metabolized by CYP 2E1 to produce hepatotoxic derivatives. hepatotoxic derivatives.

Isoniazid Hepatotoxicity -8Isoniazid Hepatotoxicity -8 In a study from Taiwan of 318 patients In a study from Taiwan of 318 patients

who had tuberculosis and were who had tuberculosis and were receiving INH, the genotypes of CYP receiving INH, the genotypes of CYP 2E1 and NAT2 were determined by a 2E1 and NAT2 were determined by a restriction fragment length restriction fragment length polymorphism methodpolymorphism method..

Forty-nine (5.4%) of the patients Forty-nine (5.4%) of the patients showed some evidence of showed some evidence of hepatotoxicity. hepatotoxicity.

The risk of hepatotoxicity based on CYP The risk of hepatotoxicity based on CYP 2E1 activity and the acetylator status 2E1 activity and the acetylator status (rapid or slow) was analyzed. (rapid or slow) was analyzed.

Isoniazid Hepatotoxicity -9Isoniazid Hepatotoxicity -9 The wild-type allele for CYP 2E1 is c1.The wild-type allele for CYP 2E1 is c1. The risk of hepatotoxicity was 3.94 for The risk of hepatotoxicity was 3.94 for

CYP 2E1 c1/c1 with rapidCYP 2E1 c1/c1 with rapid acetylation acetylation status to 7.43 for CYP 2E1 c1/c1 with slow status to 7.43 for CYP 2E1 c1/c1 with slow acetylation.acetylation.

Even after adjustment for acetylation Even after adjustment for acetylation status, CYP 2E1 c1/c1 was an independent status, CYP 2E1 c1/c1 was an independent risk factor for hepatotoxicity (P = 0.017).risk factor for hepatotoxicity (P = 0.017).

Volunteers who were CYP 2E1 c1/c1 had Volunteers who were CYP 2E1 c1/c1 had higher CYP2E1 activity than those with higher CYP2E1 activity than those with c1/c2 or c2/c2, suggesting accelerated c1/c2 or c2/c2, suggesting accelerated production of hepatotoxins production of hepatotoxins


Possible induction of CYP 2E1 by Possible induction of CYP 2E1 by alcohol may explain the increases in alcohol may explain the increases in INH hepatotoxicity seen in regular INH hepatotoxicity seen in regular to heavy users of alcohol. to heavy users of alcohol.

Based on these studies, Based on these studies, determination of the CYP 2E1 determination of the CYP 2E1 phenotype before institution of phenotype before institution of isoniazid therapy may prove isoniazid therapy may prove clinically useful. clinically useful.

Troglitazone Troglitazone Hepatotoxicity-1Hepatotoxicity-1

Troglitazone, a thiazolidinedione agent that is Troglitazone, a thiazolidinedione agent that is a PPAR-[gamma] agonist used in the a PPAR-[gamma] agonist used in the treatment of diabetes, was withdrawn from treatment of diabetes, was withdrawn from the market after early extensive use when the market after early extensive use when several instances of acute liver failure leading several instances of acute liver failure leading to death or the need for liver transplantation to death or the need for liver transplantation were identifiedwere identified

A debate has ensued as to whether there was A debate has ensued as to whether there was a signal in the prerelease clinical trials, which a signal in the prerelease clinical trials, which indicated likely major hepatotoxicity. In the indicated likely major hepatotoxicity. In the trials,trials,

2510 patients received the drug- Two 2510 patients received the drug- Two developed jaundice and 1.9% had developed jaundice and 1.9% had aminotransferase elevations of >3 times ULN aminotransferase elevations of >3 times ULN as compared with 0.6% in patients who as compared with 0.6% in patients who received placebo received placebo

Troglitazone Troglitazone Hepatotoxicity-2Hepatotoxicity-2

The hepatic injury in patients who The hepatic injury in patients who developed liver injury was developed liver injury was predominantly hepatocellular.predominantly hepatocellular.

The mechanism for troglitazone-The mechanism for troglitazone-induced liver injury has not been induced liver injury has not been established.established.

Other PPAR-[gamma] agonists Other PPAR-[gamma] agonists (rosiglitazone and pioglitazone) have (rosiglitazone and pioglitazone) have been associated with hepatotoxicity been associated with hepatotoxicity in rare instances.in rare instances.

Statins Hepatotoxicity-1Statins Hepatotoxicity-1 Few drugs have been as widely prescribed Few drugs have been as widely prescribed

as the statins. as the statins. There have been lingering concerns There have been lingering concerns

regarding statin-induced hepatotoxicity regarding statin-induced hepatotoxicity from the time of introduction in 1987 of from the time of introduction in 1987 of lovastatin, the first member of the class.lovastatin, the first member of the class.

Millions of patients have now received Millions of patients have now received these drugs.these drugs.

Asymptomatic increases in Asymptomatic increases in aminotransferase levels develop aminotransferase levels develop frequently.frequently.

Elevations to >3 times upper limit of Elevations to >3 times upper limit of normal occur in 1% to 3%.normal occur in 1% to 3%.

Statins Hepatotoxicity-2Statins Hepatotoxicity-2

In one study, 127 of 6,605 patients In one study, 127 of 6,605 patients treated with lovastatin had ALT treated with lovastatin had ALT elevations of 1.5 to 3 times the elevations of 1.5 to 3 times the upper limit of normal upper limit of normal

The elevations in ALT generally The elevations in ALT generally return to or toward normal despite return to or toward normal despite continued therapy.continued therapy.

There have been remarkably few There have been remarkably few well-documented instances of statin-well-documented instances of statin-induced severe liver injury. induced severe liver injury.

Statins Hepatotoxicity-3Statins Hepatotoxicity-3 There is evidence that suggests the There is evidence that suggests the

increases in aminotransferases may increases in aminotransferases may represent a pharmacologic effect represent a pharmacologic effect associated with lipid lowering.associated with lipid lowering.

An intracellular accumulation of An intracellular accumulation of precursors following HMG-CoA reductase precursors following HMG-CoA reductase inhibitors may lead to enlargement of inhibitors may lead to enlargement of hepatocyte and to ALT increases. hepatocyte and to ALT increases.

Exactly how lowering cholesterol or Exactly how lowering cholesterol or favorably affecting the lipid profile is favorably affecting the lipid profile is associated with aminotransferase associated with aminotransferase elevations remains unknown.elevations remains unknown.

Statins Hepatotoxicity-4Statins Hepatotoxicity-4 There is no evidence that patients who have There is no evidence that patients who have

elevated baseline ALT levels associated with elevated baseline ALT levels associated with diabetes, steatohepatitis, or chronic hepatitis diabetes, steatohepatitis, or chronic hepatitis C are at increased risk.C are at increased risk.

Therefore, present evidence supports the Therefore, present evidence supports the concept that statins are hepatically safe concept that statins are hepatically safe agents despite the rather frequent elevations agents despite the rather frequent elevations of ALT.of ALT.

Again, this supports the concept that mild to Again, this supports the concept that mild to moderate elevations of ALT do not equate to moderate elevations of ALT do not equate to liver injury. liver injury.

There is scant support for following a There is scant support for following a regular biochemical monitoring schedule in regular biochemical monitoring schedule in patients receiving statins.patients receiving statins.

Minocycline Minocycline Hepatotoxicity-1Hepatotoxicity-1

Minocycline, a semisynthetic Minocycline, a semisynthetic derivative of tetracycline that has been derivative of tetracycline that has been widely used in the treatment of acne, widely used in the treatment of acne, has been reported to cause acute has been reported to cause acute hepatitis, a chronic hepatitis with hepatitis, a chronic hepatitis with autoimmune features, and a systemic autoimmune features, and a systemic lupus erythematosus syndrome.lupus erythematosus syndrome.

Several deaths from liver disease have Several deaths from liver disease have occurred. occurred.


Positive rechallenges with recurrence Positive rechallenges with recurrence of liver disease have been observed.of liver disease have been observed.

The autoimmune hepatitis syndrome, The autoimmune hepatitis syndrome, which is more frequently observed in which is more frequently observed in females who have received the drug females who have received the drug for months to more than a year and is for months to more than a year and is characterized by the presence of characterized by the presence of fever, arthralgias, hyperglobulinemia, fever, arthralgias, hyperglobulinemia, antinuclear antibodies, and a liver antinuclear antibodies, and a liver biopsy indistinguishable from classic biopsy indistinguishable from classic type autoimmune hepatitistype autoimmune hepatitis


It is important for the clinician to recognize It is important for the clinician to recognize the role of minocycline and withdraw the the role of minocycline and withdraw the drug, which usually leads to rapid drug, which usually leads to rapid improvement.improvement.

If the patient is considered to have Type 1 If the patient is considered to have Type 1 autoimmune hepatitis and is treated with autoimmune hepatitis and is treated with corticosteroids while minocycline is corticosteroids while minocycline is continued, there is a risk of partially continued, there is a risk of partially masking the drug-induced injury. masking the drug-induced injury.

This masking was the case with This masking was the case with methyldopa-induced chronic hepatitis and methyldopa-induced chronic hepatitis and oxyphenistatin-induced chronic hepatitis.oxyphenistatin-induced chronic hepatitis.

The mechanism of minocycline-induced The mechanism of minocycline-induced liver injury is unknown.liver injury is unknown.

HERBAL HERBAL HEPATOTOXICITY-1HEPATOTOXICITY-1

There has been increasing recognition that There has been increasing recognition that herbal products of many types can cause herbal products of many types can cause hepatotoxicity.hepatotoxicity.

Patients who have underlying liver disease Patients who have underlying liver disease often use a variety of herbals as alternative often use a variety of herbals as alternative medicines. medicines.

Milk thistle (silymarin) has been widely Milk thistle (silymarin) has been widely embraced by patients with hepatitis C, embraced by patients with hepatitis C, despite lack of extensive controlled studies despite lack of extensive controlled studies supporting benefit.supporting benefit.

Fortunately, there is equally scant Fortunately, there is equally scant evidence of any hepatotoxicity from the evidence of any hepatotoxicity from the compound.compound.


Acute hepatitis and acute liver failure have Acute hepatitis and acute liver failure have been reported with a number of been reported with a number of compounds including kava. compounds including kava.

There are special difficulties in associating There are special difficulties in associating an herbal product with hepatic injury. an herbal product with hepatic injury.

These include problems in obtaining an These include problems in obtaining an accurate history of ingestion and often an accurate history of ingestion and often an unwillingness of the patient to fully unwillingness of the patient to fully disclose what has been ingested. disclose what has been ingested.

Traditional and alternative treatment Traditional and alternative treatment regimens abound throughout the world. regimens abound throughout the world. These products may vary from lot to lot These products may vary from lot to lot and are not manufactured to approved and are not manufactured to approved standards standards


Extracts of kava-kava, a plant in the pepper Extracts of kava-kava, a plant in the pepper family, has been used as a beverage for family, has been used as a beverage for centuries by South Pacific islanders for centuries by South Pacific islanders for reducing anxiety and as a remedy for reducing anxiety and as a remedy for sleeplessness and menopausal symptoms. sleeplessness and menopausal symptoms.

More recently, standardized extracts of More recently, standardized extracts of kava-kava containing concentrated extract kava-kava containing concentrated extract have been produced inhave been produced in Europe and Europe and subsequently introduced into thesubsequently introduced into the United United States. Instances of acute hepatic failure States. Instances of acute hepatic failure and death have been attributed to kava-and death have been attributed to kava-kava.kava.

The commercially available standardized The commercially available standardized extracts that have caused liver injury extracts that have caused liver injury contain 30% to 70% lactones contain 30% to 70% lactones

VITAMIN A (Retinol )-VITAMIN A (Retinol )-HEPATOTOXICITY-1HEPATOTOXICITY-1

Excessive ingestion of vitamin A is Excessive ingestion of vitamin A is an established cause of liver disease an established cause of liver disease leading to cirrhosis with ascites and leading to cirrhosis with ascites and portal hypertension. portal hypertension.

Chronic ingestion of large amounts Chronic ingestion of large amounts of vitamin A often used as part of the of vitamin A often used as part of the megavitamin generalized health megavitamin generalized health protection programs can lead to protection programs can lead to chronic intoxication and liver injury.chronic intoxication and liver injury.

Vitamin A ToxicityVitamin A Toxicity

VITAMIN A VITAMIN A HEPATOTOXICITY-2HEPATOTOXICITY-2

Hypervitaminosis A most often results Hypervitaminosis A most often results from self-medication. from self-medication.

The usual recommended dose of vitamin The usual recommended dose of vitamin A for adults is 5,000 IU per day.A for adults is 5,000 IU per day.

Hepatic injury has been seen in patients Hepatic injury has been seen in patients who received 15,000 to greater than who received 15,000 to greater than 40,000 units a day for a period of years.40,000 units a day for a period of years.

Even higher doses may produce signs of Even higher doses may produce signs of intoxication within several months..intoxication within several months..


The liver is a principal storage site for The liver is a principal storage site for retinol and, more specifically, the stellate retinol and, more specifically, the stellate cells bear the brunt of the attack.cells bear the brunt of the attack.

Many patients with liver injury from Many patients with liver injury from ingesting excessive vitamin A go ingesting excessive vitamin A go unrecognized, and only an astute clinician unrecognized, and only an astute clinician is likely to make the association between is likely to make the association between chronic ingestion of vitamin A and chronic ingestion of vitamin A and otherwise unexplained advanced hepatic otherwise unexplained advanced hepatic disease with cirrhosis, ascites, and portal disease with cirrhosis, ascites, and portal hypertensionhypertension


The clinical picture most often is one of The clinical picture most often is one of insidious onset of cirrhosis.insidious onset of cirrhosis.

Elevations of aminotransferases are Elevations of aminotransferases are found in over 70% of patients with vitamin found in over 70% of patients with vitamin A-induced liver injury, along with slightly A-induced liver injury, along with slightly elevated levels of alkaline phosphatase elevated levels of alkaline phosphatase and occasional minimal to modest and occasional minimal to modest elevations of serum bilirubin. elevations of serum bilirubin.

In patients with advanced vitamin A In patients with advanced vitamin A intoxication, hypoalbuminemia and intoxication, hypoalbuminemia and hypoprothrombinemia are present.hypoprothrombinemia are present.


Vitamin A is stored in stellate cells.Vitamin A is stored in stellate cells. A syndrome of hepatoportal sclerosis with A syndrome of hepatoportal sclerosis with

portal and perisinusoidal fibrosis as well as portal and perisinusoidal fibrosis as well as sclerosis of terminal venules and atrophy of sclerosis of terminal venules and atrophy of zone 3 of the hepatic lobule are zone 3 of the hepatic lobule are characteristic findings.characteristic findings.

Portal hypertension results from the Portal hypertension results from the compromising of sinusoids by the enlarged compromising of sinusoids by the enlarged stellate cells as well as by fibrous tissue stellate cells as well as by fibrous tissue deposited in the sinusoids and the sclerosis deposited in the sinusoids and the sclerosis of the terminal venules. of the terminal venules.

Occasionally microvesicular steatosis is Occasionally microvesicular steatosis is found.found.


Vitamin A-induced hepatic injury Vitamin A-induced hepatic injury apparently results from the intrinsic apparently results from the intrinsic toxicity of vitamin A, and the extent of the toxicity of vitamin A, and the extent of the injury depends on the dose and duration injury depends on the dose and duration of exposure. of exposure.

The increased levels of vitamin A in The increased levels of vitamin A in stellate cells lead to multiplication of the stellate cells lead to multiplication of the cells and conversion to myofibroblasts.cells and conversion to myofibroblasts.

Alcoholic patients appear to be unusually Alcoholic patients appear to be unusually susceptible to vitamin A intoxication.susceptible to vitamin A intoxication.

Alcohol potentiates the toxicity of vitamin Alcohol potentiates the toxicity of vitamin A in experimental situations.A in experimental situations.

The treatment is withdrawal, and the The treatment is withdrawal, and the diagnosis depends on careful history diagnosis depends on careful history taking and awareness taking and awareness

Acetaminophen Acetaminophen (APAP)(APAP)

Budget suicide: cheap, Budget suicide: cheap, accessible, popularaccessible, popular80% OD’s > 15 g80% OD’s > 15 gToxic dose >150mg/kg (~6g)Toxic dose >150mg/kg (~6g)S. levels useful 4-15 h outS. levels useful 4-15 h outNomogram: know it, use itNomogram: know it, use it

APAPAPAPDose-dependent Dose-dependent production production

of toxic metabolite of toxic metabolite (NAPQI)(NAPQI)

produced by P450produced by P450conjugated by glutathioneconjugated by glutathione

Cytochrome p450 2E1

(phase I)

OH

HNC

CH3

O

Sulfation

Glu

curo

nida

tion

(phase II)

Nontoxic Metabolites

NC

CH3

O

O

GSH

glutathione-S-transferase

HNC

CH3

O

OH

SG

Mercapturic Acid(nontoxic)

NAPQI(highly reactive intermediate)

Hepatocyte Damage•Covalent binding to cell proteins, including enzyme itself

•ADDUCTS

•Derangement of apoptosis?

•CAR?

Cytochromes P450 lead to unstable compounds!

APAPAPAPNAPQI directly cytotoxicNAPQI directly cytotoxic

HepaticHepaticRenalRenal

““Will tylenol Will tylenol taken taken withwith EtOH EtOH

prevent prevent hangover?”hangover?”EtOH UseEtOH Use

Increased p450 = more Increased p450 = more NAPQINAPQIEtOH metabolism depletes EtOH metabolism depletes

glutathione stores = more glutathione stores = more

NAPQINAPQI

APAPAPAPLabs gone wildLabs gone wild

TransaminitisTransaminitisHyperbilirubinemiaHyperbilirubinemiaCoagulopathy (INR)Coagulopathy (INR)ATN ATN + / - myocardial necrosis+ / - myocardial necrosis

APAPAPAP

NAC – glutathione substituteNAC – glutathione substituteload 140 mg/kg POload 140 mg/kg PO17 doses over 72 h17 doses over 72 hCan give by NGT / IVCan give by NGT / IV

Charcoal if < 4 hCharcoal if < 4 hAntiemetics prn Antiemetics prn

APAPAPAP

NACNACBest within 8-10 hBest within 8-10 hStill useful > 24 hStill useful > 24 hGive first, ask questions Give first, ask questions later!later!

Drug-Induced Liver DiseaseDrug-Induced Liver Disease

Predictable Predictable Dose-relatedDose-related

Unpredictable Unpredictable Not dose-relatedNot dose-related Immune-mediatedImmune-mediated Idiosyncratic Idiosyncratic

BileBile Composed of bile salts, glutathione, Composed of bile salts, glutathione,

phospholipids, cholesterol, bilirubin, phospholipids, cholesterol, bilirubin, organic anions, proteins, metals, ions, organic anions, proteins, metals, ions, xenobioticsxenobiotics

Bile formation essential for:Bile formation essential for: lipid uptake from small intestineslipid uptake from small intestines Protection of small intestines from oxidative Protection of small intestines from oxidative

injuryinjury Excretion of endogenous and xenobiotic Excretion of endogenous and xenobiotic

compoundscompounds

Bile ExcretionBile Excretion

MetalsMetals Uptake (facilitated diffusion vs. receptor)Uptake (facilitated diffusion vs. receptor) Excretion (lysosomes, transporters)Excretion (lysosomes, transporters) Copper, manganese, cadmium, selenium, gold, Copper, manganese, cadmium, selenium, gold,

silver, arsenicsilver, arsenic

ATP-dependent exportersATP-dependent exporters MDR (multiple-drug resistance)MDR (multiple-drug resistance) cMOAT (canalicular multiple organic ion cMOAT (canalicular multiple organic ion

transporter)transporter)

Bile FormationBile Formation

Conjugates of glutathione, glucuronide, sulfate

BilirubinBile Salts

BileCanaliculi

Organic cations, drugs, phospholipids

cMOAT

MDR

Metals

Drugs, hormones, xenobiotics

Bile ExcretionBile Excretion

CanaliculiCanaliculi

ChannelsChannels

Bile DuctsBile Ducts

Common Bile DuctCommon Bile Duct

SmallSmall IntestineIntestine

EnterohepaticCycling

Zones of Oxygenation of The Zones of Oxygenation of The LiverLiver

Fatty DegenerationFatty Degeneration Increased lipid content of the hepatocytes Increased lipid content of the hepatocytes

(liver parenchymal cells) steatosis(liver parenchymal cells) steatosis Etiology (cause) can be nutrition and it Etiology (cause) can be nutrition and it

can be due to a toxic substancecan be due to a toxic substance Over supply of fatty acids (FA)Over supply of fatty acids (FA) Alteration of triglyceride cycle Alteration of triglyceride cycle Increase FA synthesis Increase FA synthesis Decrease aproprotein synthesisDecrease aproprotein synthesis

Clinical Pathology

Mechanistic Pathology

Morphologic Pathology

AppropriateHepatobiliary Injury Classification

Characterization and Classification

Fatty Degeneration Fatty Degeneration (cont)(cont)

Toxic substancesToxic substances Liver may be enlargedLiver may be enlarged

Ethionine – metabolic inhibitorEthionine – metabolic inhibitor Valproic acidValproic acid

Hepatocellular NecrosisHepatocellular Necrosis

Necrosis and apoptosisNecrosis and apoptosis NecrosisNecrosis

Nucleus is often marginatedNucleus is often marginated Cell swellsCell swells Leakage of cytoplasmLeakage of cytoplasm Pyknosis of the nucleusPyknosis of the nucleus KaryorrhexisKaryorrhexis

Liver NecrosisLiver Necrosis Leakage of cytoplasmLeakage of cytoplasm

Enzymes in the hepatocyte are leaked Enzymes in the hepatocyte are leaked into systemic circulation, for exampleinto systemic circulation, for example Aspartate aminotransferaseAspartate aminotransferase Alanine aminotransferase Alanine aminotransferase Sorbitol dehydrogenaseSorbitol dehydrogenase Forms of lactic acid dehydrogenaseForms of lactic acid dehydrogenase

Hepatocellular NecrosisHepatocellular Necrosis Histopathology is evident for days Histopathology is evident for days

after the hepatocytes have died.after the hepatocytes have died. Described by the area of the hepatic Described by the area of the hepatic

cords or the lobule (acinus) that has cords or the lobule (acinus) that has undergone necrosisundergone necrosis

Toxic substances can produce Toxic substances can produce necrosis in certain areasnecrosis in certain areas Eg, CClEg, CCl44 is zone 3 or centrilobular is zone 3 or centrilobular

Canalicular CholestasisCanalicular Cholestasis Decrease in volume of bile or impaired Decrease in volume of bile or impaired

secretion of bilesecretion of bile Patient is jaundicePatient is jaundice May be bile plugs in the bile ductsMay be bile plugs in the bile ducts Have elevated bilirubin, icterus index, ectHave elevated bilirubin, icterus index, ect Toxic substancesToxic substances

Chlorpromazine Chlorpromazine CyclosporinCyclosporin EstrogensEstrogens

Canalicular CholestasisCanalicular Cholestasis

Decrease in the volume bile formed or Decrease in the volume bile formed or

impaired secretion of solutes into bileimpaired secretion of solutes into bile Compounds found in bile will be Compounds found in bile will be

elevated in blood (eg bilirubin elevated in blood (eg bilirubin

jaundice)jaundice)

CholestCholestasisasis

2

1

3

4

5

6

Chlorpromazine: 1, 4

Estrogen: 1, 2

Manganese: 6

Bile Duct DamageBile Duct Damage

Cholangiodestructive cholestasisCholangiodestructive cholestasis Increased serum activity of gamma Increased serum activity of gamma

glutamyltransferase (GGT) and other glutamyltransferase (GGT) and other enzymesenzymes

Damage to epithelium of bile ductsDamage to epithelium of bile ducts Increased cells - hyperplasiaIncreased cells - hyperplasia

Aflatoxins Aflatoxins Pyrrolizidine alkaloidsPyrrolizidine alkaloids

Bile Duct Damage Bile Duct Damage (Cont)(Cont)

Damage to epithelium of bile ducts Damage to epithelium of bile ducts (cont)(cont) Necrosis of bile duct cellsNecrosis of bile duct cells

Sporidesmin Sporidesmin A mycotoxinA mycotoxin

Methylene dianilineMethylene dianiline Human exposure in contaminated flourHuman exposure in contaminated flour Mistaken for a drug of abuseMistaken for a drug of abuse


Fenestration of endothelium for high Fenestration of endothelium for high permeabilitypermeability

Fills with bloodFills with blood Occurs with veno-occlusive diseaseOccurs with veno-occlusive disease

See with fibrosis of the liverSee with fibrosis of the liver Pyrrolizidine alkaloidsPyrrolizidine alkaloids

CyclophosphamideCyclophosphamide After GSH is used upAfter GSH is used up

CirrhosisCirrhosis Progressive liver injuryProgressive liver injury Accumulation of fibrous tissueAccumulation of fibrous tissue

Collagen fibersCollagen fibers Around central veinAround central vein Space of DisseSpace of Disse

Result of repetitive damage of liver cellsResult of repetitive damage of liver cells HumansHumans

EtOH abuseEtOH abuse Chronic aflatoxicosisChronic aflatoxicosis

Liver NeoplasmsLiver Neoplasms

Primary neoplasmPrimary neoplasm Neoplasm from cells in the liverNeoplasm from cells in the liver

Secondary neoplasmSecondary neoplasm Neoplasm outside the liverNeoplasm outside the liver

InvasionInvasion Metastasis Metastasis

AflatoxinsAflatoxins Hepatocellular carcinomas Hepatocellular carcinomas

Uptake of Toxic Uptake of Toxic SubstancesSubstances

First Pass EffectFirst Pass Effect Term used to describe the rapid uptake Term used to describe the rapid uptake

of some chemicals by the liverof some chemicals by the liver MicrocystinMicrocystin

Blue-green algaeBlue-green algae PlalloidinPlalloidin

Amanita phalloidesAmanita phalloides Block uptake with cyclosporin ABlock uptake with cyclosporin A

BioactivationBioactivation

EtOHEtOH EtOH rapidly metabolized by alcohol EtOH rapidly metabolized by alcohol

dehydrogenase to acetaldehyde dehydrogenase to acetaldehyde Acetaldehyde metabolized slowly by Acetaldehyde metabolized slowly by

aldehyde dehydrogenase to acetatealdehyde dehydrogenase to acetate Balance of Phase 1 and Phase II Balance of Phase 1 and Phase II

biotransformation reactionsbiotransformation reactions

Major Cell TypesMajor Cell Types

Hepatocytes (parenchymal)Hepatocytes (parenchymal) large - large - 75% of lobule 75% of lobule

Endothelial CellsEndothelial Cells line sinusoids – small - form fenestrate (pores) - line sinusoids – small - form fenestrate (pores) - 25% of 25% of

lobule lobule

Ito (stellate) CellsIto (stellate) Cells store fat – store & metabolism, vitamin A - synthesize store fat – store & metabolism, vitamin A - synthesize

collagencollagen

Kupffer CellsKupffer Cells few – phagocytic - immune - can release active molecules few – phagocytic - immune - can release active molecules

and secrete cytokines, present antigensand secrete cytokines, present antigens

DILI DiagnosisDILI Diagnosis DILI is a diagnosis of exclusion DILI is a diagnosis of exclusion

based on circumstantial evidence based on circumstantial evidence due to lack of objective due to lack of objective confirmatory lab test, confirmatory lab test, rechallenge, or rechallenge, or “GOLD”“GOLD” standard standard Requires a high index of suspicionRequires a high index of suspicion

DILI diagnosis is usually DILI diagnosis is usually retrospectiveretrospective Exclude other causesExclude other causes Dechallenge requires follow-upDechallenge requires follow-up

Bile FormationBile Formation

Conjugates of glutathione, glucuronide, sulfate

BilirubinBile Salts

BileCanaliculi

Organic cations, drugs, phospholipids

cMOAT

MDR

Metals

Drugs, hormones, xenobiotics

Blood Supply to The Blood Supply to The LiverLiver

The venous blood from the majority The venous blood from the majority of the gastrointestinal tract and of the gastrointestinal tract and peritoneum peritoneum flows to the liverflows to the liver in the in the hepatic portal vein. hepatic portal vein.

Hepatic artery is small and supplies Hepatic artery is small and supplies arterial blood to the liverarterial blood to the liver

Blood from the liver empties into the Blood from the liver empties into the vena cava below the heart vena cava below the heart

Issues: Issues: Idiosyncratic Drug Idiosyncratic Drug

Toxicity Toxicity Occurs despite careful preclinical Occurs despite careful preclinical testing in animalstesting in animals … … and despite careful and costly and despite careful and costly clinical trialsclinical trials Some problem (perhaps wrong) Some problem (perhaps wrong) assumptions:assumptions:

Assuming Assuming drugdrug variability is the key to variability is the key to safetysafety Obsolete concepts of “safe and Obsolete concepts of “safe and effective” – for all?effective” – for all? Assuming one dose/regimen suits all Assuming one dose/regimen suits all patientspatients Focus on efficacy, little on safety Focus on efficacy, little on safety (especially if rare)(especially if rare)


2

1

3

4

5

6

Chlorpromazine: 1, 4

Estrogen: 1, 2

Manganese: 6


2

1

3

4

5

6

Chlorpromazine:

Estrogen

Types of Liver InjuryTypes of Liver Injury

Hepatocellular deathHepatocellular death Fatty degenerationFatty degeneration Canalicular cholestasisCanalicular cholestasis Bile duct damageBile duct damage Sinusoidal damageSinusoidal damage Damage to cytoskeletonDamage to cytoskeleton CirrhosisCirrhosis NeoplasmNeoplasm

drug induced hepatotoxicity ackerman zvi m.d. hadassah-hebrew university medical center

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