MOA

Question 1

MOA of ACE inhibitors

Answer 1

1. Inhibiton of production of angiotensin2

Dilation of arterioles ↓ pvr ↓bp
↓aldesterone ↓ na and h2o retention
↓ sympathetic nervous activity

2.inhibit degradation of bradykinin( vasodilator) by ace

3.stimulate synthesis of PGs by bradykinin

Question 2

MOA of ARBs

Answer 2

ARBs competitively inhibit binding of ang2 to AT1 receptors and block its effect

Not affect bradykinin

Question 3

MOA of diuretics
Why thiazide prefer over loop diuretics and when to prefer loop?

Answer 3

Thiazide → inhibit na+ and cl- symport in early dct → promote na+ h2o excretion → ↓ CO ↓ bp
↓
On chronic therapy
↓ na+ in vascular smooth muscle ↓ pvr ↓ bp

Loop diuretics have short duration of action so sustained low level na+ not maintained in blood and thiazide have longer duration of action

Thiazide- in uncomplicated HNT
Loop- HNT with renal and cardiac failure

Question 4

MOA of CCBs :the first line drug for HNT
Which CCB safe in pregnancy

Answer 4

CCBs block voltage sensitive L type Ca+2 channel by binding to alpha subunit
↓
Prevent entry of ca+2 into cell
↓
No excitation contraction coupling in heart and vascular smooth muscle
↓bp

•Nifedipine safe in pregnancy .

Question 5

MOA of sympatholytic .centrally acting

Answer 5

1. Centrally acting
   Cross bbb

Clonidine stimulate alpha2A receptors in vasomotor center (brain stem)
↓
↓ SYM. outflow from vmc
↓. ↓
Heart. Bv
↓bp. ↓ pvr ↓ bp

Alpha methyl Dopa
↓
Alpha methyldopamine
↓
Alpha methyl noradrenaline
↓
Stimulate alpha 2 in vmc

Question 6

MOA of beta# and alpha #

Answer 6

Selective beta # - B1
Non selective - B1 B2

During initial therapy b1# - ↓co
B2 # ↑pvr
Overall bp unaffected
But chronic use - gradual decrease in pvr because of sustained ↓ vo ; bp ↓

Beta # - .Cns ↓ SYM. Outflow ↓ bp
.heart ↓ hr ↓foc ↓co. ↓ bp
Kidney ↓ renin release ↓ bp

Alpha #
Non selective
Block both a1 and a2 in blood vessel
↓
Vasodilation and ↓ bp( a1 block)
Tachycardia (due to ↑↑ noradrenaline dur to presynaptic a2 block)

Selective a1#
Block competitively a1
Vasodilation ↓ bp
Minimal tachycardia

Question 7

MOA OF Vasodilators

Answer 7

Minoxidil- activate k+ channel - k+ efflux - hyperpolarization of vascular smooth
Muscle - vasodilation - ↓ bp

Sodium nitroprusside
NO – arterioles and veno dilator
Arteriolar dilation. Venodilator
↓ ↓
↓ pvr pooling of blood
↓ afterload ↓venous return
↓bp. ↓ preload ↓co ↓bp

Fenoldopam -;d1 agonist - dilation of peripheral arteries and natriuresis - ↓ bp