Human aspects of Cardiovascular and Renal Pharmacology: Hypertension

Question 1

Phaeochromocytoma

Answer 1

Adrenaline-secreting tumour of chromaffin cells in the adrenal medulla.
Causes hypertension

Question 2

‘Clear’ causes of hypertension

Answer 2

Phaeochromocytoma

Renal artery disease

Question 3

‘Essential’ hypertension

Answer 3

Hypertension with no obvious single cause

Majority of cases

Question 4

Blood pressure in ‘mild’ hypertension?

Answer 4

Diastolic >90, systolic >140 (compared to ~80 and 120 in a normal adult)

Question 5

Propranolol

Uses?

Answer 5

non-specific β-adrenoceptor antagonist

Now used little clinically. Non-specific drugs can lead to bronchoconstriction & an asthma-like response

Question 6

Atenolol

Answer 6

β1-adrenoceptor specific antagonist
Hydrophillic- not very CNS penetrant
Very effective antihypertensive

Question 7

Bisoprolol

Answer 7

β1-adrenoceptor specific antagonist

Question 8

Pindolol

Effects on CO and plasma renin?

Answer 8

non-selective β-adrenergic partial agonist
Causes little change in CO
No effect on plasma renin

Question 9

Prazosin

Answer 9

α1 adrenoceptor antagonist

Question 10

Doxazosin

Mechanism?

Answer 10

α1 adrenoceptor antagonist

Dilates resistance & capacitance vessels
Lack of marked tachycardia- probably due to lack of block of presynaptic α2 receptors
Blockade of CNS α1 receptors modulates baroreceptor reflexes, decreasing sympathetic discharge

Question 11

Phentolamine

Answer 11

Causes non-selective α-adrenoceptor blockade

-> vasodilation and as a result a marked reflex tachycardia
Increased SNS activity also increases renin release

Question 12

Labetalol

Answer 12

α1, β1, and β2 antagonist

more so β than α

Question 13

Amlodipine

Answer 13

A dihydropyridine
Ca2+ channel antagonist

Cardiovascular effects, also mild diuretic effect
May inhibit aldosterone release

Question 14

Minoxidil

Answer 14

Potassium channel opener
Acts on ATP sensitive channels in vascular smooth muscle-> hyperpolarisation & relaxation

Sole KCO in general use- used in hypertension. Can be used in severe refractory hypertension.
Causes some hirsutism, some use as a topical hair loss treatment

Question 15

Nicorandil

Answer 15

Potassium channel opener

Used in angina

Question 16

Clonidine

Answer 16

Centrally acting α2/I1 agonist
Decreases blood pressure when microinjected into ventrolateral medulla (area rich in α2 Rs, but effect may be mediated by imidazoline I1 R)

Question 17

Guanfacine

Answer 17

Centrally acting α2/I1 agonist

More potent α2 agonist than clonidine, but low efficiacy as a hypertensive

Question 18

Moxonidine

Answer 18

Centrally acting I1 agonist (antihypertensive)
An imidazoline drug
Fewer side effects than α2 agonists

Question 19

α-methyldopa

Answer 19

Centrally acting α2/I1 agonist
Converted in the vesicles of adrenergic neurons -> α-methylnoradrenaline
Acts as a ‘false transmitter’
Less potent than NA on α1, more potent on α2

Question 20

Guanethidine

Answer 20

Sympatholytic

Side effect of postural hypotension

Question 21

Reserpine

Answer 21

Sympatholytic

Produces severe depression