Calcium Channel Blockers

Calcium channel blockers are used in medicine to treat:
– Hypertension
– Control heart rate
– Prevent cerebral vasospasm
– Angina

They were first discovered by a German pharmacologist, Albrecht Fleckenstein, in 1964. He reported that prenylamine and verapamil blocked the excitation-contraction coupling. This led to the discovery of calcium channel blockers (CCB’s).

There are some interesting things to know about CCB’s.

First, did you know that ethanol has calcium channel blocking activity. This leads me to the notion that people should not drink alcohol while on CCB’s. In addition, could this be the cause of flushing when drinking ethanol? https://en.wikipedia.org/wiki/Calcium_channel_blocker

Verapamil was approved for medical use in the USA in 1981, and still in use today. Why 17 years to come to market?

Prenylamine (Segontin) was introduced in the 1960s but was withdrawn in 1988 because it was shown to prolong the QT wave and cause Torsades de pointes. This is a good example of the value of post marketing surveillance because these effects were not detected during clinical trials, but only after it had been on the market.

There are four classes of CCB’s- dihydropyridine, non-dihydropyridine (phenylalkylamines and benzothiazepines), and nonselective. The majority of CCB’s belong to the dihydropyridine class (ex. nifedipine). These tend to lower blood pressure through vasodilation peripherally, thus sometimes inducing reflex tachycardia. The phenylalkylamines (verapamil) seem to be more cardio-selective and less peripherally vasodilatory making them good for angina without as much reflex tachycardia.

More interesting facts about CCB’s to come, especially diltiazem Stay tuned.

WG