What are the side effects of long-term use of cimetidine?
REPLY:
Cimetidine (Tagamet) belongs to a family of drugs used to treat diseases such as ulcers of the stomach and duodenum. The drugs in this group are remarkably well tolerated by most people and free of side-effects to a significant degree. These drugs are not, however, approved for long-term use except in two very specific situations.
Cimetidine is commonly used to heal ulcers and is used for up to six or eight weeks in this setting. A reduced dose of 400 mg taken once a day in the evening is indicated in the maintenance treatment of some persons to try to minimize ulcer recurrence.
A very rare condition called pathological hypersecretion exists when certain malignant tumors produce a chemical which causes greatly excessive acid production. Cimetidine has been used to treat this disorder but newer and more potent drugs have largely replaced cimetidine in this setting.
While cimetidine has been used to heal inflammation of the esophagus due to acid reflux (regurgitation) such treatment is only approved over a relatively short time period and current FDA approved indications for this drug do not include its long-term usage in this setting. The actual package labelling requires that patients have "erosive esophagitis diagnosed by endoscopy" and treatment is approved for up to twelve weeks only. Other more potent and newer agents are more commonly used for this purpose these days.
Cimetidine is not without side-effects and it can cause breast enlargement (gynecomastia) when taken over a long period of time; this can be especially uncomfortable, from both a physical and cosmetic viewpoint, in men.
Cimetidine also interacts with the handling of numerous other drugs and can lead to clinically significant changes in the concentration of these drugs in the bloodstream. The package insert addresses this concern as follows:
DRUG INTERACTIONS: Tagamet, apparently through an
effect on certain microsomal enzyme systems, has
been reported to reduce the hepatic metabolism of
warfarin-type anticoagulants, phenytoin,
propranolol, nifedipine, chlordiazepoxide,
diazepam, certain tricyclic antidepressants,
lidocaine, theophylline and metronidazole,
thereby delaying elimination and increasing blood
levels of these drugs.
Clinically significant effects have been reported
with the warfarin anticoagulants; therefore,
close monitoring of prothrombin time is
recommended, and adjustment of the anticoagulant
dose may be necessary when Tagamet is
administered concomitantly. Interaction with
phenytoin, lidocaine and theophylline has also
been reported to produce adverse clinical
effects.
It is probably a good idea to discuss with your doctor the pro's and con's of taking any drug on a long-term basis however safe it may seem to you.
--
Bruce Sckolnick, M.D.
NOTICE: OFCN is not engaged in the rendering of professional medical services. The information contained on this system or any other OFCN system should not supplant individual professional consultation. It is offered exclusively as a community education service. Advice on individual problems must be obtained directly from a professional.
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