Sustained release methadone salts and methadone-naloxone mixtures. Part 2: In vitro studies of methadone release.

Various tablet formulations, using two methadone salts namely methadone-alpha-naphthalenesulfonate and methadone-o-benzoylbenzoate and a number of methadone-naloxone combinations were prepared. The quantities of methadone released from these tablets in simulated gastric and intestinal fluids were examined using spectrophoto-metric studies. All formulations followed a typical release pattern, indicating a high degree of consistency of the formulations.