CCB Flashcards
1
Q
What are the uses of CCBs
A
- Exertional angina
- Variant angina
- Unstable angina
Others - Supraventricular arrythmia
2.hypertension - Hypertrophic cardiomyopathy
4.migraine
5.Raynauds phenomenon
6.premature labour -nifedipine - Cerebral vasospasm-nimodipine
2
Q
Pharmacology actions of CCBs
A
- Verapamil: It is a phenylalkylamine and has predominant depressant action on heart.
• It decreases force of contraction (negative inotropic effect) and decreases heart rate (negative chronotropic effect). This reduces oxygen requirement of the myocardium.
• It depresses SA node and slows AV conduction (negative dromotropic effect) by prolonging effective refractoty period (ERP).
Verapamil is a less potent coronary and peripheral vasodilator than DHPs. - Diltiazem: It dilates peripheral and coronary arteries but its vasodilating property is less marked than DHPs and verapamil. It is a cardiac depressant and causes negative inotropic, chronotropic and dromotrepic effects. It is used in the treatment of hypertension and supra-ventricular arrhythmias and prophylaxis of angina.
- DHPs: These are more selective for calcium channels in vascular smooth muscle → arteriolar dilation → reduce peripheral vascular resistance. Do not produce significant cardiac depressant effect at doses which produce vasodilation.
Relax vasculat
Dihydropyridines
smooth muscle
Decrease peripheral vascular resistance
Coronary
Decrease
102 consumption
vasodilatation
afterload
of myocardium
(a) Nifedipine: It is the prototype drug. It has a predominant action on vascular smooth muscle. Peak levels in blood rapidly attained → causes rapid vasodilation → fall in BP → reflex tachycardia, flushing and palpitations. This can be minimized by using sus-tained-release preparation or counteracted by adding a B-blocker.
(b) Amlodipine: It is mainly used in angina and hypertension. Amlodipine is the preferred DHP because (i) it is more potent and has a longer duration of action than nifedipine,
