Calcium channel blockers

Question 1

drug class of nifedipine

Answer 1

Dihydropyridine calcium channel blocker (CCB)

Antihypertensive, antianginal

Question 2

mechanism of action nifedipine

Answer 2

L-type voltage-gated Ca²⁺ channels (in vascular smooth muscle)
Inhibits Ca²⁺ influx → vasodilation

Little/no effect on SA or AV node

↓ Peripheral vascular resistance → ↓ BP
Reflex tachycardia may occur

Question 3

pharmacokinetics of nifedipine

Answer 3

A; oral
D;
M; hepatic
E; renal and fecal

Question 4

clinical application of Nifedipine

Answer 4

Angina
HTN
Raynauds
Prinsmetal angina
preterm labour

Question 5

drug class of verapamil

Answer 5

Non-dihydropyridine CCB

Phenylalkylamine subclass

Acts mainly on cardiac muscle & nodal tissue

Question 6

mechanism of action of verapamil

Answer 6

L type Ca channels - blocks both activated and inactivated channels
decrease Ca influx
‘cardiac’ Ca blocker
Greatly slows AV node conduction
reduces mycardial oxygen demand

Question 7

clinical use of verapamil

Answer 7

SVT/AF
HTN
angina
migraine

Question 8

toxic effect of verapamil

Answer 8

dose related
hypotension
bradycardia
AV block
cardiac arrest when given for VT
constipation

Question 9

drug class of diltiazem

Answer 9

Non-dihydropyridine calcium channel blocker (CCB)

Benzothiazepine subclass

Question 10

mechanism of action of Diltiazem

Answer 10

L type voltage gated Ca channels
decrease Ca influx
‘cardiac’ C a channel blocker

Balanced cardiac + vascular effects
Less potent at slowing conduction than verapamil, but better tolerated