Effects of paroxetine, a CYP2D6 inhibitor, on the pharmacokinetic properties of hydrocodone after coadministration with a single-entity, once-daily, extended-release hydrocodone tablet.

Purpose: A single-entity, once-daily, extended-release formulation of hydrocodone bitartrate (HYD) has been developed for the management of moderate to severe chronic pain. Hydrocodone undergoes cytochrome P-450 (CYP)-mediated metabolism involving the CYP3A4 and CYP2D6 isozymes. CYP3A4 yields norhydrocodone, a major inactive metabolite, whereas CYP2D6 yields hydromorphone, a minor active metabolite.

Once-weekly transdermal buprenorphine application results in sustained and consistent steady-state plasma levels.

Context: Transdermal formulations of buprenorphine offer controlled delivery of buprenorphine for sustained analgesic efficacy with reduced adverse events (AEs) compared with the other modes of administration. A buprenorphine transdermal system (BTDS) delivering 5, 10, or 20 mcg/hour for seven days is now marketed in the U.S.

Effect of ketoconazole on the pharmacokinetic profile of buprenorphine following administration of a once-weekly buprenorphine transdermal system.

Background And Objective: Buprenorphine is extensively metabolized by cytochrome P450 (CYP) 3A4. This study evaluated the effect of ketoconazole, a CYP3A4 inhibitor, on the metabolism of buprenorphine following the administration of a buprenorphine transdermal system 10 μg/hour (BTDS 10).

Methods: This single-centre study enrolled 20 healthy subjects who had demonstrated ketoconazole-mediated CYP3A4 inhibition via an erythromycin breath test.