[Buprenorphine and pentazocine for postoperative analgesia. A double blind study following abdominal surgery].

A randomized double-blind study was done to test the two opiates buprenorphine (0.3 mg i.v.) and pentazocine (30 mg i.v.) with regard to their applicability for the postoperative phase. These substances were chosen because they are not subject to drug prescription regulations. 60 patients who had undergone epigastric and hypogastric interventions under thiopental-sodium-induced halothane anesthesia received i.v. injections of one of the two analgetics as soon as they requested a pain-killer postoperatively. The subjective pain intensity registered by means of a visual analogue scale shows a gradual decrease after buprenorphine with maximal effects 1-3 h post injectionem (7.3 leads to 1.5). The duration of action is 8.2 +/- 0.7 h on the average (median 8 h; range 4-22 h). The maximal analgetic effect of pentazocine is already attained after 10 min (6.3 leads to 3.2). Thereafter the pain-intensity curve rises again. Pentazocine has a mean duration of action of 2.35 +/- 0.24 h (median 2 h; range 0.5-5 h). The inadequate analgetic effect of pentazocine manifests itself in an only slight initial reduction of the respiratory rate (19.5 leads to 17.5 min-1), which, on the other hand, decreases significantly and continuously under buprenorphine (20.8 leads to 13.5 min-1). Both substances cause increases of PaCO2 (buprenorphine 37.3 leads to 46.8 mmHg; pentazocine 36.3 leads to 43.0 mmHg), values greater than 50 mmHg being attained in individual cases.(ABSTRACT TRUNCATED AT 250 WORDS)