June 1990

ß-Blockers and Cimetidine

Author Affiliations

Huntington, NY

Arch Intern Med. 1990;150(6):1348. doi:10.1001/archinte.1990.00390180146030

To the Editor.—The publication of the 1988 report from the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure1 presents an updating of a consensus among its members with regard to the treatment of essential hypertension in a concise and comprehensive fashion.

However, I believe that a serious error is contained in the report that may affect the treatment of a large number of patients. In particular, I refer to Table 5. Under β-blockers it is stated that "cimetidine may reduce the bioavailability of β-blockers metabolized primarily by the liver by inducing hepatic oxidative enzymes." In fact, the exact opposite of this statement is well accepted by clinical pharmacologists throughout the world. Cimetidine is known to inhibit hepatic oxidative enzymes of the cytochrome P-450 system, thus increasing the bioavailability of hepatically oxidized β-blockers and serum concentrations of these drugs.2

A pharmacokinetic interaction between cimetidine and

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