COMPARING THE SUBJECTIVE, PSYCHOMOTOR AND PHYSIOLOGICAL-EFFECTS OF INTRAVENOUS PENTAZOCINE AND MORPHINE IN NORMAL VOLUNTEERS

The purposes of this study were to characterize the subjective, psycho motor and physiological effects of pentazocine in nondrug-abusing volu nteers and to compare and contrast the effects of pentazocine with tho se of morphine. Sixteen subjects without histories of opiate dependenc e were injected in an upper extremity vein with 0, 7.5, 15 or 30 mg/70 kg pentazocine or 10 mg/70 kg morphine, using a randomized, double-bl ind, crossover design. Pentazocine increased scores on the pento-barbi tal-chlorpromazine-alcohol group and lysergic acid diethylamide scales and decreased scores on the benzedrine group scale of the Addiction R esearch Center Inventory, increased adjective checklist ratings of ''n odding,'' ''sweating'' and ''turning of stomach'' and increased visual analog scale ratings of ''difficulty concentrating,'' ''drunk'' and ' 'having unpleasant bodily sensations.'' Pentazocine (30 mg) had a grea ter propensity to increase ratings associated with dysphoria than did 10 mg of morphine. Pentazocine produced impairment on four measures of psychomotor performance. Ten milligrams of morphine produced minimal psychomotor impairment. Both pentazocine and morphine induced miosis, but 10 mg of morphine had a greater magnitude of effect than 30 mg of pentazocine. The results of the present study demonstrate that 7.5 to 30 mg of pentazocine had orderly, dose-related effects on subjective, psychomotor and physiological variables. Further, a clinically relevan t dose of pentazocine, 30 mg, produced a greater magnitude of dysphori c subjective effects than did 10 mg of morphine, which is consistent w ith the literature reporting that pentazocine has a greater likelihood of inducing psychotomimesis than do other opioids.