Dose proportionality and pharmacokinetics of extended-release (OROS®) hydromorphone: a phase 1, open-label,...

Osmotic-controlled release oral delivery system (OROS®) hydromorphone - an extended-release preparation - is recommended long-term therapy for chronic pain patients. Dose proportionality of OROS hydromorphone has been shown in healthy Caucasian volunteers; however, no studies have been conducted in Asian populations. To determine whether ethnic differences affect the drug's pharmacokinetic (PK) profile, we evaluated the dose proportionality of OROS hydromorphone in healthy Taiwanese adults.

This 12-week, open-label, 4-way crossover, phase 1 study randomly assigned subjects to 1 of 4 treatment sequences - single oral dose OROS hydromorphone: 8 mg, 16 mg, 32 mg, or 64 mg - along with 50 mg naltrexone. Dose proportionality was assessed using a linear mixed-effects model to estimate the slope of the regression line and its 90% CI for Cmax, AUC0-48h, and AUClast. Descriptive statistics measured plasma hydromorphone concentrations, PK parameters, laboratory analytes, and vital signs.

23 subjects completed the study; a single-dose of OROS hydromorphone increased plasma concentration steadily for 6 hours and sustained it at or near maximum levels for ~ 24 hours. After dose normalization to a 16 mg dose, all studied doses demonstrated dose proportionality for Cmax, AUClast, and AUC0-48h,as the slopes of the regression lines for Cmax, AUClast, and AUC0-48h were close to zero, and the 90% CIs within pre-specified limits. Adverse events were as expected for hydromorphone administered with concomitant naltrexone.

Single doses of 8 mg, 16 mg, 32 mg, and 64 mg of OROS hydromorphone were found to be dose proportional for Cmax, AUClast, and AUC0-48h and were generally safe and well-tolerated in healthy Taiwanese adults.