Buprenorphine delays drug absorption and gastric emptying in man. 
The aim of the present study was to investigate the effects of buprenorphine on drug absorption and gastric emptying in man, using paracetamol absorption as an index of gastric emptying rate.  Paracetamol was given to eight healthy volunteers p.o.  together with or without a single i.v.  dose of buprenorphine 4 micrograms kg-1 body weight.  Nausea occurred in five of the subjects, four subjects vomited and one was excluded due to vomiting during the study period.  The mean peak serum paracetamol concentration (Cmax) was significantly (P less than 0.0002) lowered by a factor 3 by buprenorphine, the mean time from administration of paracetamol to its peak concentration (Tmax) was significantly (P less than 0.03) prolonged by a factor 6, and the area under the plasma concentration-time curve from 0 to 120 min was significantly (P less than 0.00006) reduced by a factor 3.  This demonstrates a marked inhibition of the rate of paracetamol absorption, indicating a clinically important reduction of gastric emptying following administration of buprenorphine.