An evaluation of the histological effects of intra-articular methadone in the canine model.

Methadone hydrochloride is an opiate that has pharmacodynamic and pharmacokinetic properties that suggest it may provide longer analgesia than morphine when administered via the intra-articular route. However, no studies to date have been conducted examining the effects of intra-articular methadone hydrochloride on local tissues. Therefore, the purpose of this study was to determine the histopathologic effects of intra-articular methadone hydrochloride on local tissues in the canine knee.