Pharmacotherapy of hypertension

Systemic hypertension • long-lasting, usually permanent increase of systolic and

diastolic blood pressure

primary (essential) hypertension – unknown cause; usually coincidence of more factors – neural,

hormonal, kidney dysfunction, ...

secondary (symptomatic) hypertension – symptom (sign) of other disease

Isolated systolic hypertension • increased systolic blood pressure at normal or

decreased diastolic BP• pseudohypertension ← rigid arteries in old age

“white coat hypertension “ – induced by stress at physical examination

„masked hypertension“ - false finding of normal blood pressure during the examination; opposite of white coat hypertension

Secondary hypertension

essential hypertension – 90 to 95 % of high blood pressure

prevalence: • children...about 4 %, mostly secondary • middle age ... 11-21 % • 50-59 years old ... approximately 44 % • 60-69 years old ... approximately 54 % • more than 70 years old ... ≥ 64 %

(Standard guidelines, 2nd edition)

Classification of hypertension

7th report of

Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure

JNC 7

Classification of adult´s hypertension

• Previous classification of hypertension (JNC 6, WHO)

Reasons for actualisation of classification JNC 6 (1997):

• Completing of more new clinical studies with substantial consequences for the treatment of hypertension.

• Need for less complicated classification of hypertension.

• Need for new and clear guidelines suitable for physicians.

• Previous reports didn´t bring expected benefits.

Classification of adult´s hypertension

• New classification of hypertension according to JNC 7

Hypertenzia 3. štádia

• in Europe partly remains classification of hypertension to 3 stages

• ESH a ESC (European Society of Hypertension / E. S. of Cardiology) didn´t adopt JNC 7 classification without comments

Risk of cardiovascular diseases

• relationship between BP and CVD (cardiovascular disease) risk is continual, consistent and not dependent on other risk factors

• the higher BP, the higher risk of heart failure, stroke, renal diseases

• each increase of systolic BP by 20 and diastolic BP by 10 mm Hg doubles the risk of CVD

Benefit of BP reductionIn clinical studies was during antihypertensive therapy

recorded:

• 35-40% incidence reduction of stroke • 20-25% incidence reduction of myocardial infarction• more than 50% share at incidence reduction of heart

failure • it is assumed that among patients at first stage of

hypertension (140-159/90-99 mm Hg) and with other cardiovascular risk factors, permanent reduction of BP by 12 mm Hg during 10 years prevents one death from 11 treated patients (when CVS disease or organ affection, it is one from 9)

Effectivity of BP reduction• despite the fact that decreasing of BP below 140/90 mm Hg is successful

among more and more patients, still their number (34%) is less than intention (50%), 30% still doesn´t know about their disease

Evaluation of patientsAll of these datas influence the prognosis and therapy selection.

Evaluation of patients with diagnosed hypertension has importance to:

evaluate the way of living + reveal other CVS risk factors and/or associated diseases

- very important is the circadian rhythm of blood pressure!

- physiological profound nocturnal decline, mostly around 4 a.m. ("dipping"), acts as a protection against pathological lesions of blood vessels, resp. reduces them

- also hypertensive patients with significant nightime BP decrease have a more favorable prognosis ,as patients whose blood pressure at night compared to daytime values doesn´t decrease (worse prognosis)

- → according to it are patients diveded to „dippers“ versus „non-dippers“

- ≅ improvement of diagnosis ← broader application of 24-hour blood pressure monitoring

Circadian rythm of BP (dippers vs. non-dippers)

We gain information about patient from :

• anamnesis • physical examination (BP measurement, eyeground

examination, BMI calculation, listening to murmurs at large arteries, detailed examination of heart, lungs, stomach, searching for enlarged kidneys, palpation of glandula thyroidea, resistency and abnormal pulsation of aorta, palpation of lower extremities to search for oedemas and pulsations, neurologic examination)

• laboratory examinations (ECG, urine, blood glucose, haematokrit, kallium, calcium, creatin in serum, lipid spectrum of serum)

Treatment• The final goal of antihypertensive therapy

is reduction of mortality and morbidity to CVS and renal diseases.

• Primary goal is reduction of systolic BP. We wamt to reach BP less than 140/90 mm Hg (Torr), or less than 130/80 mm Hg among diabetic patients and patients with kidney diseases

• Needed is also increased detection!

Nonpharmacological treatment

Change of life-style:

• intake of salt ... ≤ 5 – 6 g per day

• prevention of obesity – dietetic modification

• alcohol ... ≤ 30 g per day

• smoking – stop

• physical activity

• psychical relaxation

Pharmacologic treatment

Antihypertensives

1st choice drugs: 1. diuretics 2. β-blockers 3. inhibitors of ACE 4. blockers of AT1 receptors (ARB) 5. calcium channel blockers

2nd choice drugs – mainly to drug combinations: α1-sympatholytics; α2-sympathomimetics; direct vasodilators; kallium channel openers; agonists of I1 receptors in CNS; other mechanisms of action

Diuretics

Diuretics • increase urination

1. carboanhydrase inhibitors (acetazolamid) – not used in the treatment of hypertension

2. loop diuretics (furosemide, etacrynic acid,

bumetanide) – strong short-lasting effect; ability to

excrete to 25 % of Na+ from filtrate

• block active reabsorption of Na+, Cl-, K+ from

ascending limb of Henle´s loop

• at treatment of hypertension is rarely used only

furosemide in low dosage – if simultaneously is very

much reduced G filtration;

they aren´t suitable for long-lasting application

3. thiazide diuretics (hydrochlorothiazide, chlorthalidone,

clopamide) • block reabsorption of Na+ and Cl- from distal tubulus • effect is weaker as at loop diuretics – they excrete about 5 % from Na+ filtrate • most suitable diuretics for long–lasting treatment of hypertension

thiazide-like diuretics: effect also in vessel wall (↓ volume of Na and ↓ reactivity to norepinephrine; regression of media hypertrophy) !!

this effect is characteristic for indapamide and metipamide  (at administration increase of diuresis is negligible) →   also called "diuretics without diuretic effect"

Mechanism of Action of Thiazide Diuretics

4. K-sparing diuretics (spironolactone (aldosterone antagonist), amiloride, triamterene)

• at hypertension only assistant drugs to combinations

– to correct hypokalemia

5. other diuretics

• osmotic (mannitol, sorbitol)

• xanthine

• diuretics are suitable mainly for older patients and at simultaneous chronic heart failure

• ADRs - hypokalemia, hypovolemia, hyperuricemia, metabolic ADRs (impaired glucose tolerance and dyslipidemia - mostly after high doses), erectile dysfunction

Adrenergic Receptor with Agonist

β-blockersClassifications:

1. non-selective (β1- aj β2-effect – propranolol, metipranolol, ...);

selective (β1-effect – metoprolol, bisoprolol, atenolol, ...);

hybrid substances (beside β-effect have also other effects, additional, resp. β2-mimetic effect), through which they induce vazodilation – labetalol, carvedilol, nebivolol, ...)

– the most important classification

2. β-blockers with ISA (intrinsic sympathomimetic activity – pindolol, acebutolol, ...; ≈ parcial agonists) and without ISA

3. hydrophilic (atenolol, celiprolol, ...) and lipophilic β-blockers

(propranolol, metoprolol, carvedilol, ...)

4. classification according to generations

....... and other different classifications....

β-blockers• preferenced are selective and hybrid substances before

nonselective • don´t differ very much in antihypertensive effect, selection

according to adverse effect profile • suitable for younger patients with ↑ sympathicoadrenal activity, hyperkinetic circulation, patients under psychical

stress; patients with existent ischaemic heart disease and mainly after myocardial infarction

• in our country are mainly prescribed : metoprolol (Vasocardin) bisoprolol (Concor) karvedilol (Talliton)

and according to tradition nonselective metipranolol (Trimepranol)

Main Effects of β1- a β2-blockade

• β-blockers – possibilities of combinations:

diuretics, Ca2+ blockers – only dihydropyridines!, α1- sympatholytics, ACEI, vazodilators

ADRs: • tendency to bronchoconstriction and to vasoconstriction

in the periphery – mainly at non-selective βB • metabolic ADR – worsening of lipidogram; mask

symptoms of hypoglycemia and can impair glucose tollerance – more at non-selective βB

• sleep disturbances, bad dreams → ... depression • at very high doses can worsen heart failure; if indicated

at chronic heart failure, dose should be increased step by step

• erectile dysfunction

! selectivity of action is only relative!- at higher doses is dissapearing - even among β1-selective agents appear β2-lytic effects

• they can´t be combined with verapamilom a diltiazem!

• treatment can´t be stopped abruptly – rebound effect!

stage fright

Indication for Self-medication with β-blockers:

Calcium Channel Blockers (CCB)Classification:

Ca2+ Channel Blockers (CCB)

• Different chemical structures, with different haemodynamic and clinic effects

• According to chemical structure divided to:- dihydropyridins (amlodipine, felodipine, lacidipine, nifedipine, isradipine)- phenylalkylamins (verapamil, gallopamil)- benzothiazepins (diltiazem)

CCB – Mechanism of Action

Block influx of calcium to cell through slow L-type channels, lower its intracellular concentration what causes relaxation of smooth muscle in vessel wall, decrease of contractility, decrease of electrical irritability and conductivity

Selectivity of CCB

Blood vesselsvasodilation of arterial vasculature

Heart: decrease ofHeart rate

AV conduction

Strenght of contraction

Calcium channel blockers • at treatment of hypertension are mostly used dihydropyridines; verapamil only at present tachycardia • prototype short-acting DHP nifedipine is contraindicated! - it reduces BP too rapidly, so induces reflex activation of sympaticus with subsequent increase of BP and such a repeated BP fluctuation causes worse vessel damage as untreated hypertension → instead of mortality decrease its increase! • pharmacokinetic explanation: effect fluctuates for fluctuation of level in blood – has low T/P (trough to peak ratio) • for antihypertensive to reduce mortality and morbidity, it has to reduce BP slowly and successively, without reflex activation of sympathicus → more steady level and higher T/P

→ FDA approves as antihypertensives only drugs, that have

T/P more than 50 %

• this applies for the 2nd generation of dihydropyridines (isradipine, felodipine, nitrendipine) and 3rd generation of dihydropyridines (amlodipine, lacidipine, lercanidipine).

• Ca2+ blockers are suitable to treat hypertonic patients with DM, metabolic syndrome, at ischaemic disease of lower extremities

• particularly advantageous are for isolated systolic hypertension

• possibilities of combinations: ACEI, βB (only dihydropyridines), diuretics

• ADRs: headache, red face, perimalleolar edemas, constipation, tachycardia (dihydrop.), severe bradycardia (non-dihydropyridins), steal phenomen

• nimodipine (1st generation) affinity to brain vasculature → ... effectively relieves spasms of cerebral arteries

→ used at subarachnoid bleeding • lercanidipine has high T/P ratio • in our country for the treatment of hypertension are

prescribed mainly following dihydropyridines:

2nd generation: felodipine (Presid, Plendil), isradipine (Lomir), nitrendipine (Nitresan, Lusopress)

3rd generation: amlodipine (Amlopin, Agen, Tenox, Norvasc), lacidipine (Lacipil), lercanidipine (Lercal)

Renin-angiotensin-aldosterone system

Pharmacologic Interference to AT Cascade

Inhibitors of AC enzyme • block the change of angiotensin I to angiotensin II and at the

same time block inactivation of bradykinin • vazodilation in both resistant and capacitance vessels • accented indication: - hypertonic people with heart failure (vasodilating therapy of cardial insuficiency), also after myocardial infarction - hypertonic people with DM and different forms of diabetic nephropathy starting with mikroalbuminuria (nephroprotective effect of ACEI) • excessive initial fall in BP → postural hypotension or

syncope; treatment should be started in bed from the lowest doses

• reaction of airways is often strong and irritating cough → intollerance of the whole group → replacement to AT1

receptor blockers

• they are administered as “prodrug“, to effective substance are changed in liver

• effect to reduce BP is in the whole group similar; they differ only in pharmacokinetic dependent from structure

→ division to hydrophilic (“blood“) and lipophilic (“tissue“)

ACEI

• hydrophilic act only inside vessels and in endothelium; lipophilic also on the outer side of vessels (on “adventicial“ angiotenzinconvertase) and in myocardial interstitium → probably more effectively at regression of left ventricule hypertrophy and vessel media

• typical hydrophilic ACEI: captopril (prototype substance – has SH-group; nowadays used only

in hypertension crisis, Tensiomin) enalapril (Enap, Ednyt), lisinopril (Dapril, Diroton) • typical lipophilic ACEI: perindopril (Vidotin, Stopress, Prestarium) trandolapril (Actapril, Gopten) quinapril (Quinpres, Accupro)

• ADRs: impaired renal function, hyperkalemia, hypotension, dry cough,

angioneurotic edema • contraindications: pregnancy!, high concentration of potassium and

creatinine, stenosis of a. renalis on both sides, severe aortal stenosis, angioneurotic edema in anamnesis

Main Benefits of ACE inhibition

AT1 receptor blockers • the most often replacement of ACEI in case of cough

• losartan (prototype; Cozaar), valsartan, kandesartan,

irbesartan (Aprovel)

α1-sympatholytics • beside BP reduction they reduce benign prostatic hyperplasia

→ indication mainly older man with simultaneous BPH

• in combination at severe resistant hypertension

• positively influence lipidogram

• strong 1st dose phenomenon! → postural hypotension, syncopes

• prazosin (prototype; Deprazolin), doxazosin (Cardura),

terazosin

α2-sympathomimetics

• central effect – stimulation of central α2 receptors

through negative feedback inhibit release of

norepinephrine on periphery → reflex BP reduction

• α-metyldopa (Dopegyt), clonidine

• ADR: central depression – sleepiness, bad dreams

• clonidine has significant rebound phenomenon

• α-metyldopa is advantageous during pregnancy –

doesn´t influence negatively blood circulation of

fetus

Direct vazodilators

hydralazines • specific mechanism of action is unknown; probably directly

influence contractile system of vessel wall myocytes

• ADR: tachycardia, palpitations, fluid retention → necessary combinations dihydralazine, hydralazine • suitable in pregnancy • hydralazine – genet. polymorphism of biotransformation

→ at slow acetylators can develop as syndrome similar to lupus erythematodes

Kallium channel openers • opening of K+ channels on the top of myocytes →

hyperpolarisation → induction of relaxation minoxidil • vazodilation in the area of arterioles • retention of Na+, hirsutism, hypertrichosis → used in the

treatment of alopecia • expensive diazoxide • only short-term use – at hypertension crisis • induces hyperglycemia – at short-term use not matters

Central I1 receptor agonists • I1 – imidazoline receptors type 1 in medulla oblongata

• stimulation → reflectory decrease of peripheral resistency

• without serious hemodynamic, metabolic ADR;

are metabolically neutral → promising to future

moxonidin (Physiotens, Moxostad, Cynt), rilmenidin (Rilmex, Tenaxum)

Other antihypertensives

• magnesium (MgSO4) – natural antagonist of calcium

• sodium nitroprusside – simple molecule releasing NO;

only i.v. at severe hypertension crisis, patient must lie,

cyanide is formed; max. lenth of therapy 3 days

• ketanserin – blocks S2 receptors for serotonin → prevents effect increase of catecholamines on symp. receptors

Direct renin inhibitors (PRI) • absolutely new group

• in many tissues is present own renin system

with individual receptors → (pro)renin is bind to cell surfaces; system acts pressorically and proliferatively

• it is activated when stimulation of AT1 receptors decreases → negative feedback

• this signal way apparently decreases benefit of ACEI! → inhibition of the level of renin → ... better control

of the whole RAAS → ... possible better prevention

of organ damage

Aliskiren

• first available peroral PRI • ↓ plasmatic renin activity

• indication in 2-combination aliskiren + ACEI or aliskirén + ARB

→ dual inhibition of RAAS system • product Rasilez

? - clinical results below expectations

Therapeutic algorithm of hypertension treatment (JNC 7)

Selection of pharmacotherapy

• Results gained in clinical studies show that BP reduction with using following antihypertensives – inhibitors of angiotensin converting enzyme(ACEI), blockers of angiotensin receptors(ARB), betablockers (βB), calcium channel blockers(Ca2+B) a diuretics, can reduce complications of hypertension.

• Base of medicament treatment of uncomplicated hypertension in the first stage should be according to JNC 7 thiazide diuretics alone, or in combination with other antihypertensives in the second stage of hypertension.

Advantages of thiazide diuretics

• according to more studies thiazide diuretics are considerably the most effective

• they increase antihypertensive effectivity of combined treatment

• they proved to reach BP normalisation• are less expensive than other

antihypertensives

Reaching BP improvement at specific patients

• Among most patients is necessary combination of 2 and more antihypertensives.

• Adminastration of other drug should start when monotherapy in required dose doesn´t reduce BP to intended value.

• If the BP is by 20/10 mm Hg higher than intended value, therapy should be started with combination of 2 antihypertensives.

• recently is a growing trend to use combination of 2 antihypertensive drugs already in stage I hypertension

• convincing evidence from relevant clinical trials →

combinations perindopril-amlodipine

perindopril-indapamide

Other factors influencing selection of antihypertensives

Potentially prosperous effects:• Tiazide diuretics slower the process of bone

demineralisation at osteoporosis• βB can have positive influence at ventricular

tachyarrhythmias and fibrilations, at migraine, short-termly at thyreotoxicosis, at essential tremor, perioperational hypertension

• Ca2+B can be applied at Raynaud syndrome and some arrhythmias

Other factors influencing selection of antihypertensives

Potentially negative effects: • tiazide diuretics at patients with gout and hyponatremia

in anamnesis• βB at patients with asthma, allergic diseases of airways

and with A-V blocks of 2nd and 3rd stage

• ACEI and ARB should not be given at probability of getting pregnant, are contraindicated in pregnancy, ACEI at angioneurotic oedema

• aldosterone antagonists and K-sparing diuretics can cause hyperkalemia