Hypertension drugs

Question 1

Decision to treat hypertension?

Answer 1

sustained systolic BP ≥ 160 mm Hg OR
sustained diastolic BP ≥ 100 mm Hg. 
if known CV disease,  diabetes or organ damage:
sustained systolic 140-159 mm Hg AND/OR
diastolic BP 90-99 mm Hg

Question 2

Ideal anti-hypertensive drugs should…

Answer 2

reduce blood pressure
show predictable dose-effect relationship
have an acceptable profile of side effects
reduce incidence of hypertensive complications (e.g. CHD, stroke)
provide 24 hour control
- BP highest in the morning
be effective as once daily tablet
- improves compliance
- long half life in plasma

Question 3

Diuretics

Answer 3

act on kidneys to decrease diuresis 
decrease plasma volume then gradually TPR
actions:
-increase Na+ excretion, reduce salt re-absorption from glomerular filtrate
-water loss follows  
-reduce plasma volume
-reduce cardiac output
eg thiazides and loop diuretics

Question 4

Thiazides

Answer 4

Eg. Chlorothiazides, Hydrochlorothiazide, Bendrofluazide, Metalazone
- decrease systolic and diastolic BP
- inhibit sodium, chloride co-transport in distal tubule
- additional vasodilator action
- potentiate effects of other anti-hypertensives
- increase renin release
SE = increased frequency of urination

Question 5

Loop diuretics

Answer 5

very potent

used in patients with renal insufficiency, resistant hypertension or heart failure

Question 6

Vasodilators

Answer 6

directly lower TPR
act directly on smooth muscle cells of arteries and arterioles
decrease intracellular calcium concentration
cause muscle cell relaxation
vasodilation
eg calcium channel antogonists, alpha receptor antagonists, B-blockers, ACE inhibitors

Question 7

Calcium channel antagonists

Answer 7

block calcium entry through voltage operated calcium channels in arterial smooth muscle cells
Eg. Amlodipine, Nicardipine, Nidedipine (dihydropyridines - selective for smooth muscle) Diltiazem (benzothiasepine - block calcium channels in conducting tissues of the heart, slows HR
SE = flushing, ankle oedema, Diltiazem can cause cardiac depression, interation with B-blockers

Question 8

Alpha receptor antgonists

Answer 8

Eg. Prazosin
- short acting, x3 daily
- prevent vasoconstriction of endogenous noradrenaline
SE = postural hypotension = dizziness

Question 9

B-blockers

Answer 9

Eg. Atenolol, Metoprolol
- bind to and block B1-adrencoreceptors in the heart (SAN and ventricular muscle)
- block inhibition of noradrenaline
initial effects:
decreased rate of force and heart beat, decreased cardiac output
after continued treatment:
cardiac output returns to normal, BP remains low
SE= fatigue, may affect blood lipids

Question 10

ACE inhbitors

Answer 10

Eg. Captopril, Enalapril,
Lisinopril, Ramipril
- prevent conversion of angiotensin I to angiotensin II which is a potent vasoconstrictor
causes vasodilation
reduces plasma volume
SE = dry cough, hypotension initially especially if given with a diuretic

Question 11

Angiotensin II receptor antagonists

Answer 11

Eg Losartan, Candesartan
- blocks actions of angiotensin II at its receptors
competes to bind to AT receptors
in combination with ACE inhibitors it improves morbidity and mortality

Question 12

What are the calcium channel antagonist drugs?

Answer 12

Amlodopine, Nifedipine, Nidediprine, Diltaizem, SE = ankle oedema, flishing, Dialtezam causes heart failure

Question 13

What are the ACE inhibitor drugs?

Answer 13

Captropril, Enalopril, SE = dry cough, hypotension if given with diuretics

Question 14

What is the alpha-blocker drug?

Answer 14

Prozosin, SE = postural hypotension = dizziness

Question 15

What are the beta-blocker drugs and side effects?

Answer 15

Atenolol, Meteprolol, SE = fatigue, affects blood lipids

Question 16

What are the angiotension II receptor antagonist drugs?

Answer 16

Losartan, Candesartan