Intravenous buprenorphine and norbuprenorphine pharmacokinetics in humans

Background: Prescribed sublingual (SL) buprenorphine is sometimes diverted for intravenous (IV) abuse, but no human pharmacokinetic data are available following high-dose IV buprenorphine. Methods: Plasma was collected for 72h after administration of placebo or 2, 4, 8, 12, or 16 mg IV buprenorphine in escalating order (single-blind, double-dummy) in 5 healthy male non-dependent opioid users. Buprenorphine and its primary active metabolite, norbuprenorphine, were quantified by liquid chromatography-tandem mass spectrometry with limits of quantitation of 0.1 mu g/L. Results: Maximum buprenorphine concentrations (mean SE) were detected 10 min after 2, 4, 8, 12, 16 mg IV: 19.3 +/- 1.0, 44.5 +/- 4.8, 85.2 +/- 7.7, 124.6 +/- 16.6, and 137.7 +/- 18.8 mu g/L, respectively. Maximum norbuprenorphine concentrations occurred 10-15 min (3.7 +/- 0.7 mu g/L) after 16 mg IV administration. Conclusions: Buprenorphine concentrations increased in a significantly linear dose-dependent manner up to 12 mg IV buprenorphine. Thus, previously demonstrated pharmacodynamic ceiling effects (over 2-16 mg) are not due to pharmacokinetic adaptations within this range, although they may play a role at doses higher than 12 mg. Published by Elsevier Ireland Ltd.