SINGLE-DOSE AND MULTIPLE-DOSE PHARMACOKINETICS OF DEZOCINE IN PATIENTS WITH ACUTE OR CHRONIC PAIN

The pharmacokinetic properties of dezocine were examined in 15 patient s with acute or chronic pain. In 3 groups of 5 patients each, serum le vels were determined at various intervals after single intravenous dos es of 5, 10, and 20 mg. After these single doses, dezocine was very ra pidly distributed (mean t(1/2 alpha) less than 2 minutes), and then ra ther rapidly eliminated (mean t(1/2 beta) about 4 hours); the apparent volume of distribution was large (mean V-z beta about 6 L/kg) as was the total clearance (mean CL about 1.5 L/h/kg). In 2 groups of 5 patie nts each, serum levels were determined after the first and third of 3 intravenous doses of 5 or 20 mg given at 3-hour intervals. The pharmac okinetic parameters after these multiple doses were consistent with th ose after the single doses. Although some observations were suggestive , there was no unequivocal evidence that the pharmacokinetics were dos e-related. In 7 serum samples containing dezocine at concentrations ra nging from 12.8 to 522 ng/mL, the mean (+/-SE) proportion of dezocine bound to protein was 91.6 +/- 0.8%.