Ranitidine Calcium-channel blockers

ALCOHOL CALCIUM CHANNEL BLOCKERS 1. Acute alcohol ingestion may t hypotensive effects. Chronic moderate or heavy drinking 1 hypotensive effects 2. Verapamil may t peaked serum concentration and prolong the effects of alcohol 1. Additive hypotensive effect with acute alcohol excess. Chronic alcohol excess is associated with hypertension 2. Uncertain at present, but presumed to be due to inhibition of the hepatic metabolism of alcohol, a mechanism similar to that with cimetidine, ranitidine and aspirin 1. Monitor BP closely as unpredictable responses can occur. Advise patients to drink alcohol only in moderation and to avoid large variations in the amount of alcohol drunk 2. Warn patients about potentiation of the effects of alcohol, particularly the risks to driving... 

A. Cimetidine, and to a lesser extent ranitidine, reduces hepatic clearance and prolongs the elimination half-life of several dmgs as a result of inhibition of cytochrome P-450 activity and reduction of hepatic blood flow. Examples of drugs affected include phenytoin, theophylline, phenobatbital, cyclosporine, morphine, lidocaine, calcium channel blockers, tricyclic antidepressants, and warfarin. 

Ranitidine does not interact significantly with diltiazem, nimodipine, nisoldipine or nifedipine, and is possibly a non-interacting alternative for cimetidine with other calcium-channel blockers. Note that the nitrendipine AUC was increased by 50% and 89% by ranitidine, although this was not considered clinically relevant. 

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