Influence of preferred foodstuffs on the antinociceptive effects of orally administered buprenorphine in laboratory rats

Oral administration of buprenorphine is becoming a popular method of providing analgesia for laboratory rodents. The mixing of buprenorphine with flavoured jello, which rodents find palatable, is becoming a commonly used method as it is thought to improve the efficacy of oral buprenorphine by increasing the time available for it to be absorbed via the oral mucosa. The aim of this study was to assess the effect of various methods of buprenorphine administration (subcutaneous saline, subcutaneous buprenorphine [0.05 mg/kg], buprenorphine gavage [0.5 mg/kg], buprenorphine in jello [0.5 mg/kg] and buprenorphine in golden syrup [0.5 mg/kg]) on thermal antinociceptive thresholds in laboratory rats. Buprenorphine administered subcutaneously, by gavage, in jello and in syrup induced significant increases in thermal antinociceptive thresholds compared with saline. This effect was observed up to 5 h postadministration for buprenorphine administered subcutaneously and by gavage, but only for one hour postadministration for buprenorphine administered in jello and in syrup.