effect of hyperlipidemia on the pharmacokinetics/pharmacodynamics of ketoconazole

1

The Effects of Hyperlipidemia on the Pharmacokinetic and

Pharmacodynamic Aspects of KetoconazoleSupervisor: Dr. Dion Brocks

PhD Student : Dalia Hamdy El Sayed(2005/2010)

HyperlipidemiaDefinition:

An elevation of one or more lipids including cholesterol, cholesterol esters, phospholipids and triglycerides in the bloodstream

Causes:genetic effect

diet drugs diseases

2

3

becoming an increasing risk with the ongoing increase in obesity world wide.

Hyperlipidemia

Centre of Disease Control, 2004

Adults age ≥ 20 with high cholesterol serum levels

17%

The packages via which lipid movement is accomplished through the body

classified into:Chylomicrons VLDLLDLHDL

Lipoproteins

4

Apolipoproteins responsible for identification and uptake by lipoprotein receptors

LDL Receptors family: group of cell surface receptors that transport a number of macromolecules into cells through receptor mediated endocytosis LDL Receptors :Highly expressed in Liver & Adrenal glands

Uptake at cellular level

Plasma membrane

Nucleus

Golgi

Chung NS, Adv Drug Deliv Rev. 56(9). 2004 5

VLDL Receptors: Highly expressed in heart , brain, adipose and muscle tissues

Uptake at cellular level

VLDL Chylomicron

LPL

IDL (VLDL remnant) Chylomicron remnant

Free Fatty acids

VLDL receptor

Myocardium

FAT/CD36FATPFABPpmSimple

diffusion

Takahashi S, Mol Cell Biochem. 48(1-2):.2003 6

LPL

LDL

LDL receptor

Hyperlipidemia and PKRecent studies have shown that HL could influence PK of some highly lipophilic drugs.

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Metabolising enzymes

8

Clearance and volume of distribution


NifedipineAmiodaroneHalofantrineCyclosporine

A

9

10

Hyperlipidemia and PDNifedipine:

trend of decreasing mean arterial pressure

Eliot LA et al.

Unbound plasma concentration

Nephrotoxicity was observed after repeated doses in HL

Aliabadi et al.

Cyclosporine:

Lipop

rote

in-re

cept

or

mediat

ed up

take

of dr

ug

lipop

rote

in co

mplex ?

I. Effect of HL

Ketoconazole

11

Keto

cona

zole

First orally introduced azole antifungal drug.

Chiral drug that is clinically administered as (1:1) racemate of the cis-enantiomers

12

A pair of non superimposable mirror image stereoisomers

Enantiomers??

13

Differ in optical activity ( rotation of plane polarized light)

Have same physicochemical properties May differ in their pharmacokinetics

and pharmacodynamics

Enantiomers??

polarizer observeranalyzer

14

Only one of the two enantiomers shown can achieve three point binding with hypothetical binding site (e.g. an enzyme)

Enantiomers??

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Mechanism of ActionCYP450 mediated 14-α-

demethylation of lanosterol

Ergosterol biosynthesis(fungi, mammalian tissues)Keto

cona

zole

Pharmacodynamics (-)-KTZ ~ 2 fold more potent CYP3A inhibitor and more

antifungal activity than its antipode

KTZ use has been limited by -serious drug-drug interactions (CYP3A and others) -adverse effects

In drug development, KTZ is used to study the possibility of drug interactions due to its ability to inhibit CYP3A isoforms

Keto

cona

zole

Protein Binding Strongly Bound to plasma proteins > 97%

Log P = 4.74

Lipophilic Drug !!

No information on lipoprotein binding

Keto

cona

zole

Hypothesis

HL can affect pharmacokinetics and pharmacodynamics of KTZ

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RationaleKTZ is a chiral compound

HypothesisKTZ, possesses stereoselective pharmacokinetics

ObjectiveDetermine the pharmacokinetics of KTZ enantiomers in rat after administration of racemate

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No Stereospecific assay for the quantitation of enantiomers in biological specimen

Problem!!

1ST Stereospecific HPLC Assay in Biological Specimen

Hamdy DA and Brocks DR. Biomed Chromatogr. 2008 May;22(5):542-7. 22

Chiral Column

Ster

eose

lect

ive

PK o

f KTZ

in R

at (+)-KTZ average plasma concentration (Cavg), clearance and volume of distribution was ~2.1, 0.5, 0.6 fold different than (-)-KTZ, respectively

same terminal phase half life

Moderate Extraction ratio 0.30 and 0.60 for the (+)-and (-) enantiomers,respectively.Hamdy DA and Brocks DR. . Chirality . 2008

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Ster

esel

ectiv

e PK

of K

TZ in

Rat

Hamdy DA and Brocks DR. . Chirality . 2008

(+)-KTZ Cavg is ~2.4 fold higher than (-)-KTZ

Similar absorption rate (t max)

There was no difference between oral bioavailability of both enantiomersThe half life increase with increasing dose

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The C max and AUC showed disproportional increase with escalating

dose

Ster

eose

lect

ive

PK o

f KTZ

in R

at

Ster

eose

lect

ive

PK o

f KTZ

in R

at

Hamdy DA and Brocks DR. . Chirality . 2008

There was no evidence of stereoselective metabolism in microsomal system.

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0

1

2

3

4

10mg/L 40mg/L

% u

nbou

nd fr

actio

n

(+)KTZ (-)KTZ

*†

*†Stereoselectivity in protein binding

ConclusionKTZ enantiomers show stereoselective pharmacokinetics

(+)-enantiomer showing higher concentrations and lower clearance which is due to its higher protein binding

KTZ enantiomers showed non linear pharmacokinetics

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RationaleKTZ is a lipophilic compound

HypothesisKTZ binds to lipoproteins

ObjectiveExamine the influence of hyperlipidemia on in vitro distribution of KTZ enantiomers in rat plasma

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29KTZ

lipop

rote

in d

istrib

utio

n in

vitr

o

0

10

20

30

40

50

60

70

80

90

100

LPDP TRL LDL HDL

(+)K

TZ P

erce

nt a

ssoc

iatio

n (a

s %

of r

ecov

ered

dru

g)

NL HL

*

*0

10

20

30

40

50

60

70

80

90

100

LPDP TRL LDL HDL

(-)K

TZ P

erce

nt a

ssoc

iatio

n (a

s %

of r

ecov

ered

dru

g)

NL HL

*

†

†

*

(+)-KTZ (-)-KTZ

• In NL plasma LPDP bound > 95% of the KTZ enantiomers

• In HL plasma > 20% of the KTZ recovered in the lipoprotein plasma fractions

Hamdy DA and Brocks DR. AAPS conference . 2008

Conclusion

KTZ binds to lipoproteins

HL changed the pattern by which the lipophilic KTZ enantiomers bind to plasma proteins in vitro

potential change in pharmacokinetics in HL in vivo ??

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RationaleKTZ binds to lipoproteins

HypothesisHL affects the stereoselective pharmacokinetics of KTZ

ObjectiveExamine the effect of HL on the pharmacokinetics of KTZ enantiomers in rat

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KTZ PK

(+)-KTZ (-)-KTZ

HL no change in Cavg But higher Vdss

Time (h)

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0.1

1

10

100

0 2 4 6

(+)-

KTZ

pla

smac

Con

cent

ratio

n (m

g/L)

Time (h)

0.1

1

10

100

0 2 4 6

(-)-K

TZ p

lasm

a co

ncen

tratio

n (m

g/L)

Time (h)

HL

NL

Hamdy DA and Brocks DR. Xenobiotics submitted

KTZ PK Stereoselectivity was changed in HL

rats

33Hamdy DA and Brocks DR. Xenobiotics submitted

Plasma and Liver POHL did not significantly alter drug in liver

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†Significant difference between liver and plasma AUC in the same lipidemic state (α =0.05)


Liver uptake Confirms the trend with

individual time points(-)-KTZ(+)-KTZ

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0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6

(+)

-KTZ

Kp

Time (h)

NL HL

0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6

(-)-

KTZ

Kp

Time (h)

***

*


Conclusion Severe HL caused higher Vss (unable to measure unbound fraction in HL)

Decrease in liver uptake of the (-) enantiomer

Does this affect the inhibitory potency of KTZ on CYP???

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Rationale(-)KTZ appears to change liver uptake in HL

HypothesisHL can modify the strength of drug-drug interactions involving KTZ

ObjectiveExplore the effect of HL on KTZ-midazolam drug-drug interaction in rat

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BackgroundMidazolam (MDZ) is:

short acting benzodiazepine, not P-gp substrate

Its clearance and oral bioavailability are primarily governed by CYP3A

used as a probe for measuring CYP3A activity

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Simultaneous Assay for MDZ and KTZ in Rat Specimen

Hamdy DA and Brocks DR. J. Pharm and Biomed Anal. 2010;53(3):617-22. 39

Simultaneous Assay for MDZ and KTZ in human Specimen

Hamdy DA and Brocks DR. J. Pharm and Biomed Anal. 2010;53(3):617-22. 40

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KTZ

–MDZ

Dru

g In

tera

ctio

n

10

100

1000

10000

0 1 2 3 4 5 6 7 8 9

Plas

ma

Con

cent

ratio

n (n

g/m

L)

Time (h)

NL MDZ NL MDZ + KTZ

NL MDZ KTZ+MDZ

AUCmg.h/L

2.41±0.597

3.23±0.450

CLL/h

2.17±0.458

1.57±0.200

Fu(%)

1.97±0.38 1.78±0.15

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KTZ

–MDZ

Dru

g In

tera

ctio

n

10

100

1000

10000

0 1 2 3 4 5 6 7 8 9

Plas

ma

Con

cent

ratio

n (n

g/m

L)

Time (h)

NL MDZ HL MDZ

NL MDZ HL MDZ

AUCmg.h/L

2.41±0.597 2.06±0.338

CLL/h

2.17±0.458 2.48±0.445

Fu(%)

1.97±0.38 0.760±0.29*

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KTZ

–MDZ

Dru

g In

tera

ctio

n

10

100

1000

10000

0 1 2 3 4 5 6 7 8 9

Plas

ma

Con

cent

ratio

n (n

g/m

L)

Time (h)

NL MDZ NL MDZ + KTZ HL MDZ + KTZ

NL MDZ NL MDZ+KTZ

HL MDZ+KTZ

AUCmg.h/L

2.4±0.59

3.2±0.45 4.8±0.98*

CLL/h

2.2±0.46

1.5±0.20 1.1±0.22*

Fu(%) 1.9±0.38

1.7±0.15 1.0±0.21*

KTZ

–MDZ

Dru

g In

tera

ctio

n

10

100

1000

10000

100000

0 1 2 3 4 5 6 7 8 9 10 11

KT

Z p

lasm

a co

ncen

trat

ion

(ng/

mL

)

Time (h)

NL HL

HL did not affect the KTZ parameters in presence of MDZ

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Conclusion HL decreased the unbound fraction of MDZ but did not affect its PK

HL decreased liver uptake of KTZ

It potentiates the KTZ-MDZ drug interaction causing higher MDZ Cavg and lower CL

MDZ did not affect the PK of KTZ in NL and HL

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II. Effect of HL

Amiodarone

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HL

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1. Increased AM heart uptake and electrocardiographic changes

2. and HL serum decreased AM metabolism in rat hepatocytes

Future Directions Study the mechanism by which HL affects the uptake of the lipoprotein bound drugs

Investigation of MDZ lipoprotein binding

Effect of HL on the antifungal activity of KTZ

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Thank You

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Dr. Dion R. Brocks Dr. Ayman El-Kadi Dr. Fakhreddin Jamali Dr. Kishor Wasan Jackie Fleischer

Lab colleagues

Egyptian ScholarshipDissertation Fellowship

effect of hyperlipidemia on the pharmacokinetics/pharmacodynamics of ketoconazole

Health & Medicine