Interaction of the analgesic action of buprenorphine with hypnotic action of the thiopental sodium: experimental study in rats / Interaçäo da açäo analgésica da buprenorfina com a açäo hipnótica do tiopental sódico: estudo experimental em ratos

ABSTRACT

The interaction of buprenorphine-thiopental on analgesic and hypnotic doses, respectively, was studied in 60 male rats. Two groups were studied with some buprenorphine and thiopental doses, intra-peritoneal route, to achieve the ED50 values. Buprenorphine ED50 for reaction threshold to pressure tail (2,5 Kgf/cm²) was 17 µg/Kg and thipental ED50 hypnotic for block tighting reflex during 60 seconds was 19 mg/Kg. The responses were observed on 5, 10, 15, 20, 30, 40, 50 and 60 minutes after drugs adminsitration. The results shown that buprenorphine analgesic effect decreased while thiopental had hypnotic effect close to ED50, but when thiopental hypnotic effect was about 3,3 percent, a signficative increase of buprenorphine analgesic effect was observed. The results demonstrated a relative antagonism while thiopental had hypnotic effects, but was observed an additive interaction with buprenorphine analgesic effect when the thipental effect decreased to residual hypnotic effect