A new chronically cannulated carotid artery preparation for determination of drug half-lives in guinea pig

Abstract

A reliable procedure for implanting a cannula into the carotid artery of the guinea pig is described. The gaseous anaesthetic used provided excellent control, rapid recovery, and caused no fatalities. There was no evidence of postoperative infection and patency of the cannula could be maintained for 21 days after surgery. There was no indication of postoperative trauma and removal of blood appeared to be painless.Efficacy of the preparation was demonstrated by repeated removal of 3-ml volumes of blood for the determination of the half-life of phenobarbital acutely in five animals and chronically in three guinea pigs treated with the drug for 14 days. Administration of pheobarbital twice daily (20 or 50 mg/kg, ip) for 1 week increased its clearance rate fivefold. Treatment for an additional week produced a further increase in pheobarbital clearance. The cannulated guinea pig preparation described should allow determination of the pharmacokinetics of many drugs in this species.