Buprenorphine is a partial mu opioid receptor agonist that is very useful in standard pain protocols in cats. The oral transmucosal administration of the drug has improved the ease of treatment as compared with the injectable route; however, some cats still resist due to the taste of the medication. This study compared use of oral transmucosal (OTM) buprenorphine with a sustained-release (SR) formulation administered subcutaneously (SC) for cats undergoing ovariohysterectomy. Twenty-one young healthy cats participated in the study; 10 cats received 6 doses of OTM buprenorphine at 12-hour intervals and 11 received a single SC dose of SR buprenorphine. The SC dose (0.12 mg/kg) was comparable with a cumulative OTM dose (0.02 mg/kg Q 12 H for 3 days). Both treatment groups had comparable pain scores and similar adverse event profiles. No cats required rescue protocols, and one cat in the injectable group had an injection-site reaction that resolved completely without intervention within 7 days. The SR formulation of buprenorphine developed for this study was similar to that used with the chemotherapeutic agent cisplatin. A delivery matrix of DL-lactide-co-caprolactone, a water-insoluble polymer that precipitates in body fluids, forms a depot for sustained release of the drug. Supported by Wildlife Pharmaceuticals

Buprenorphine is an important drug for treatment of both acute and chronic pain in cats. It is of particular interest recently due to periodic interruptions in supply of the drug nationwide. Use of an SR product would be a great alternative to the usual practice of dispensing multiple oral syringes to the client at surgical discharge. The inherent nature of noxious stimuli in a student-performed procedure, as in this study, suggests that cats in private practice may do as well or better with the SR formulation of buprenorphine.—Heather Troyer, DVM, Diplomate ABVP

Comparison of the efficacy and adverse effects of sustained-release buprenorphine hydrochloride following subcutaneous administration and buprenorphine hydrochloride following oral transmucosal administration in cats undergoing ovariohysterectomy. Catbagan DL, Quimby JM, Mama KR, et al. AM J VET RES 72:461-466, 2011.