Non-racemic mixtures of d- and l- methadone and method of treating pain

摘要

Compositions of non-racemic mixtures of d- and l-methadone and a method of treating pain using the composition. The composition is especially useful for treating pain of mixed origin. For predominantly neuropathic pain, a mixture of predominantly d-methadone, up to about 90%, is used. For predominantly somatic pain, a mixture of predominantly l-methadone, up to about 90%, is used. The non-racemic mixture of d- and l-methadone may be further combined with a pharmacologically effective amount of a nonopioid component. In another aspect of the invention, the methadone can be combined with an opioid antagonist such as naloxone, naltrexone, or the like.