title: Alfentanil infusions: relationship between pharmacokinetics and pharmacodynamics in man.
abstract: Fourteen fit young patients undergoing body surface surgery received an infusion of alfentanil at either 50 or 100 micrograms kg-1 hr-1 to supplement nitrous oxide anaesthesia. The alfentanil infusion was continued for two hours post-operatively at the lower rate of 20 micrograms kg-1 hr-1. Resting ventilation, carbon dioxide responsiveness and pain scores were measured post-operatively. Values for clearance and elimination half life were similar to data following single doses of alfentanil but showed considerable interindividual variation. However, there was a greater systemic clearance (P = 0.02) when determined using the post-infusion decay data compared with that calculated during anaesthesia (527 ml min-1 compared with 434 ml min-1). This is in accord with observations for other intravenous drugs.
mesh_terms: D000328:Adult; D015760:Alfentanil; D000701:Analgesics, Opioid / Q000008:administration & dosage*; D002245:Carbon Dioxide / Q000097:blood; D002986:Clinical Trials as Topic; D005260:Female; D005283:Fentanyl / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood / Q000494:pharmacology; D006801:Humans; D007262:Infusions, Intravenous; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D010149:Postoperative Pain / Q000517:prevention & control; D012119:Respiration / Q000187:drug effects; D013990:Tidal Volume
chemical_list: D000701:Analgesics, Opioid; D002245:Carbon Dioxide; D015760:Alfentanil; D005283:Fentanyl