Comparison of the pharmacokinetic profiles of two oral controlled-release morphine formulations in healthy young adults.

The pharmacokinetic profiles of two oral controlled-release morphine formulations, MS Contin tablets and Roxanol SR tablets, were compared to evaluate their bioequivalence. In a sequential, crossover study, 18 healthy young male volunteers received single 60-mg doses (two 30-mg tablets) of each formulation and provided 15 serial blood samples over 24 hours, which were assayed to determine their morphine concentrations by high-performance liquid chromatography. Analysis of variance revealed significant differences between the treatments for maximum plasma concentration (P less than 0.001), area under the plasma concentration curve from zero to 12 hours (P less than 0.01), and apparent elimination half-life (P less than 0.001). No significant differences were found for time required to reach maximum plasma concentration and area under the plasma concentration-time curve from zero to 24 hours. The results show that the two morphine preparations are not bioequivalent.