MOA by class

Question 1

ACEI

Answer 1

Prevents conversion of angiotensin I to angiotensin II (potent vasoconstrictor) by competitive inhibition of ACE. Results in lower BP secondary to lower levels of angiotensin II, increased levels of plasma renin activity and a reduction in aldosterone secretion.

Question 2

ARBs

Answer 2

Selective, competitive angiotensin II receptor type 1 receptor antagonist, reducing the end organ responses to angiotensin II. Results in a decrease in total peripheral resistance (afterload) and cardiac venous return (preload). Reduction in BP occurs independently of the status of the renin-angiotensin system.

Question 3

Direct Renin inhibitors

Answer 3

Direct renin inhibition, decreasing plasma renin activity and inhibiting the conversion of angiotensinogen to angiotenisin I.

Question 4

Beta Blockers

Answer 4

Competitive inhibition of Beta receptors. (Beta 1 receptors are the ones that are important in hypertension).

Question 5

Thiazide Diuretics

Answer 5

Acts on the kidneys to reduce Na reabsorption in the distal convoluted tubule. By impairing Na transport in the distal convoluted tubule, natriuresis and concomitant water loss is induced. (However, blood pressure lowering action of thiazides cannot be adaquately explained by their diuretic actions alone).

Question 6

Loop Diuretics

Answer 6

Acts by reversibly binding to the Na, K, chloride co-transport mechanism on the luminal side of the ascending loop of Henle, thereby inhibiting the active reabsorption of these ions.

Question 7

K+ Sparing Diuretics

Answer 7

Blocks the epithelial Na channel on the luminal side of the kidney collecting tubule. Na channel blockers directly inhibit the entry of Na into the Na channels.

Question 8

Dihydropyridine CCBs

Answer 8

Act by relaxing the smooth muscle on the arterial wall, decreasing total peripheral resistance, and hence reducing BP; in angina, they increase blood flow to the heart muscle.

Question 9

Non-DHP CCBs

Answer 9

Acts as a potent vasodilator of coronary vessels, increasing blood flow and decreasing the HR by strong depression of atrioventricular node conduction. Also, acts as a potent vasodilator of peripheral vessels, reducing peripheral resistance and afterload. Has negative inotropic effects.

Question 10

alpha 1 blockers

Answer 10

Selective alpha 1 antagonist that works by blocking the action of adrenaline on smooth muscle of the blood vessel walls.

Question 11

Central alpha 2 agonists

Answer 11

Stimulates alpha 2 receptors in the brain, which decreases sympathetic outflow, cardiac output and peripheral vascular resistance, lowering BP and HR.

Question 12

Vasodilators

Answer 12

Direct acting smooth muscle relaxant that acts as a vasodilator primarily in arteries and arterioles.

Question 13

Aldosterone Receptor Blockers

Answer 13

Inhibit the effect of aldosterone by competing for intracellular aldosterone receptors in the cortical collecting duct. This decreases the reabsorption of Na, and water while decreasing the secretion of K.