A Phase I study of the pharmacokinetics, safety and tolerability of a novel tocopheryl phosphate mixture/oxymorphone transdermal patch system

Aim: Characterize the pharmacokinetic profile and tolerability of two tocopheryl phosphate mixture/oxymorphone patch formulations in healthy subjects, and the active metabolite (6-OH-oxymorphone). Materials & methods: Fifteen participants received a single application of oxymorphone patches +/− capsaicin for 72 h and were crossed-over for another 72 h. Results: Plasma oxymorphone was detected approximately 7 h and 6-OH-oxymorphone after approximately 18–19 h postapplication of both formulations, respectively. For oxymorphone, median t max was 24 h, and C max /C min ratio was approximately 2.4. The most frequently reported treatment-related adverse event was application site reaction, mainly with capsaicin formulation. Conclusion: Tocopheryl phosphate mixture/oxymorphone transdermal patches can successfully deliver therapeutic amounts of oxymorphone in a sustained manner over 72 h and are well tolerated. ANZCTR registration number: ACTRN12614000613606