QUANTITATIVE ASPECTS OF TOLERANCE AND POSTTOLERANCE HYPERSENSITIVITY TO PENTOBARBITAL IN THE RAT

¹ Departments of Anesthesiology and of Physiology and Pharmacology, Wayne State University School of Medicine, Detroit, Michigan

A method is presented for quantifying the acute anesthetic tolerance potential of barbiturates in male rats in terms of an acute tolerance index. This index is equated to the apparent potency of the drug in tolerant, relative to pretolerant rats, using a graded end point (sleeping time) and a standard method of tolerance production. The acute tolerance index (apparent relative potency) for pentobarbital sodium was found to be 0.884 with 95% confidence limits of 0.819 to 0.953.

It was also found that, after 10 to 12 days of abstinence, male rats made tolerant to pentobarbital were significantly hypersensitive to the anesthetic effect of the drug. In such posttolerant animals pentobarbital was 14.1% more potent than in pretolerant rats. In both tolerant and posttolerant rats anesthetic induction times were reduced below those of pretolerant animals.

This article has been cited by other articles:

				R. Aston and P. Hibbeln Induced Hypersensitivity to Barbital in the Female Rat Science, September 22, 1967; 157(3795): 1463 - 1464. [Abstract] [PDF]