The thermal antinociceptive effects of a high-concentration formulation of buprenorphine alone or followed by hydromorphone in conscious cats

Objective To evaluate the thermal antinociceptive effects of a high-concentration formulation of buprenorphine alone or followed by hydromorphone in conscious cats. Study design Randomized, blinded, placebo-controlled crossover study design. Animals A total of six purpose-bred, adult female ovariohysterectomized Domestic Short Hair cats. Methods Cats were allocated into three treatments each consisting of two injections, subcutaneous then intravenous (IV) administration, 2 hours apart: treatment SS, two injections of 0.9% saline; treatment BS, buprenorphine (0.24 mg kg(-1), 1.8 mg mL(-1)) and saline; and treatment BH, buprenorphine (0.24 mg kg(-1)) and hydromorphone (0.1 mg kg(-1)). Skin temperature (ST) and thermal threshold (TT) were recorded before (baseline) and for 24 hours following first injection. TT data were analyzed using mixed linear models and a Benjamini-Hochberg sequential adjustment procedure (p < 0.05). Results There were no significant differences among treatments for baseline ST and TT values, treatment SS over time and between treatments BS and BH. Compared with baseline, TT was significantly increased at all time points in treatments BH and BS except at 2 hours in treatment BS. TT was significantly higher than SS at 3-18 hours and 4-12 hours for treatments BS and BH, respectively. Maximal increases in TT were 47.5 degrees C at 2 hours, 53.9 degrees C at 3 hours and 52.4 degrees C at 6 hours in treatments SS, BS and BH, respectively. Conclusions and clinical relevance Administration of IV hydromorphone following high-concentration buprenorphine provided no additional antinociception and decreased the duration of effect when compared with high-concentration buprenorphine alone. Alternative analgesics should be considered if additional analgesia is required after administration of high-concentration buprenorphine.

Automated summary

Evaluation of thermal antinociceptive effects in conscious cats using high-concentration buprenorphine alone or in combination with hydromorphone showed that the combination did not provide additional analgesic effects.