calcium channel blockers:
These are drugs used for treatment of various ailments of cardiovascular system.Calcium Channel Blockers have their clinical uses as antihypertensive, antianginal, and in arrhythmia like atrial fibrillation, ventricular tachycardia, atrial fibrilation etc.they are also used propylactically in migraine, in premature delievery cases and in
raynaurd’s phenomenon
.they meet up their major class in the following hiarchy.
Cvs drugs> antihypertensive >calcium channel blockers.
Following is a list of some common calcium channel blockers.
· Amlodipine besylate (zoodep, norvasc )
· Verapamil (calan, calan sr )
· Diltiazen (dilzem, calzem, herbessor )
Mechanism of action/pharmacodynamics:
The basic mechanism of action of calcium channel blocker is the blockade of voltage gated calcium channels.The calcium ions entry is necessary for smooth muscles contraction.there are 4 types of such gated channel throught our body namely L, P, N, T type gated calcium channels however the pharmacodynamics of these drugs are associated only with L-type channels.other channels are less effected which is a plus point in a sense that the pharmacological influence is limited to muscles.
When calcium channels are blocked the transmembranal calcium entrance is interrupted in smooth muscles leading to decreased intracellular calcium ion concentration and thus vasodilation and decreased cardiac activity results, and our required pharmacological action are achieved.
Classification of Calcium Channel Blockers:
Calcium blockers are classified into the following sub-classes namely..
· A) Dihydrophyradine derivatives (more selective for vascular side than cardiac side).
· B) Diphenyl alkyl amine derivatives (more selective for cardiac side).
· C) Benzothazapine derivatives (more selective for cardiac side)
· Diaryl amino prophyl amine derivatives.
· D) Miscellaneous
Dihydrophyradine derivatives include:
Nifedipine, nimodipine, nicardipine, nisoldipine, amlodipine besylate, isradipine
etc.
Diphenyl alkyl amine derivatives include:
verapamil (intense cardiac suppressant action among its class), gallopamil.
Benzothazapines include: diltiazem (intermediate action).
Diaryl amino propyl amine derivatives include
mibipradil and bipradil.
And among miscellaneous are
phenyl amine and lidoflazine.
Side Effects And Drug Interactions of Calcium Channel Blockers:
Following is a list of various side effects reported with the use of calcium channel blockers
· Bradycardia
· Hypotension
· Constipation
· Reflex sympathetic activity
· Dizziness and headache
· Flushing of skin
· Cardiac arrest, av blockade etc (if dose is high).
Verapamil or diltiazem when used together can cause cardiac arrest, and av blockade.
Dihydropyradine derivatives are with minimal side effects and serious drug interactions and are relatively more safe among than other calcium channel blockers.
