Antihypertensives

Question 1

Diuretics
Lower blood pressure by depleting the body of sodium thus reducing blood volume & cardiac output. (Effective in lowering BP by 10-15mmHg)

Answer 1

1. Thiazide diuretics
2. Loop diuretics
3. Potassium sparing diuretics
4. Aldosterone receptor antagonists

Question 2

Thiazide diuretics

Answer 2

Hydroclorthiazide & chlorthalidone

Question 3

Thiazide diuretics mechanism of action

Answer 3

Inhibits NaCl transport mainly at DCT➡️⬇️Nareabsorption in the renal tubules➡️⬇️ water reabsorption➡️⬇️blood volume

Question 4

Loop diuretics

Answer 4

Furosemide

Question 5

Loop diuretics mechanism of action

Answer 5

Inhibits Na/K/2Cl transporter at the thick ascending limb of the loop of henle➡️⬇️ Nareabsorption in the renal tubules ➡️⬇️ water reabsorption➡️⬇️ blood volume

Question 6

Potassium sparing diuretics

Answer 6

Amiloride and triametrene

Question 7

Potassium sparing diuretics mechanism of action

Answer 7

Inhibit Na+ reabsorption and K+ secretion in collecting tubules➡️⬇️ water reabsorption➡️⬇️ blood volume

Question 8

Aldosterone receptor antagonists

Answer 8

Spironolactone

Question 9

Aldosterone receptor antagonist mechanism of action

Answer 9

Block aldosterone receptor ➡️Inhibit Na+ reabsorption and K+ secretion in collecting tubules ➡️⬇️ water reabsorption ➡️⬇️ blood volume

Question 10

Centrally acting sympathoplegic agents

Answer 10

CIonidine & methyldopa

Question 11

Centrally acting sympathopelgic agents mechanism of action

Answer 11

Reduce sympathetic outflow from vasomotor centers in brainstem➡️⬇️BP

Question 12

Cause sedation as side effect

Answer 12

Clonidine & methyldopa

Question 13

1st line of choice for pregnant patients with mild to moderate hypertension

Answer 13

Methyldopaissafe

Question 14

Ganglion blocking agents mechanism of action

Answer 14

Blocks ganglion of both sympathetic & parasympathetic nerves

Question 15

Drugs that reduce norepinephrin

Answer 15

Guanethidine

Question 16

Guanethidine

• Mechanism of action:

Answer 16

Inhibit release of NE from postganglionic sympathetic neurons➡️ Significant anti-sympathetic effect
• Polarchemical➡️does not enter the CNS

Question 17

Drugs that block postsynaptic adrenoreceptors

Answer 17

A1 blockers

B-blockers (-olol)

Question 18

Characteristics of prazosin

Answer 18

– Dilates arterioles and venules
– Induce salt and water retention so better used in combination with diuretics
– Relaxes prostate muscle, so useful for men with urinary bladder obstruction such as benign prostatic hyperplasia

Question 19

B-blockers

Answer 19

• Non selective: Propranolol (others: nadolol, timolol, pindolol, labetolol)
• Cardioselective (most widely used β-blockers): Metoprolol (others: atenolol, esmolol, betaxolol)

Question 20

All beta-blockers have similar antihypertensive effects

List them

Answer 20

1. Reduction in CO but no change in BP initially but slowly
2. Adaptation by resistance vessels to chronically reduced CO –
   antihypertensive action
3. Other mechanisms – decreased renin release from kidney (beta-1 mediated)
4. Reduced NA release and central sympathetic outflow reduction

• β-blockers reduce morbidity & mortality in hypertensive patients with compelling;