Morphine Slow-release Capsules in Substitution Therapy

The subjects will be randomised to either 10 weeks of treatment with methadone or SROM. After an adjustment phase of one week they first will be medicated for 10 weeks with the treatment to which they have been randomised. The cross-over, in which all subjects change to their opposite treatment, will serve for an additional adjustment phase of one week. After the second and new adjustment phase they are treated for 10 weeks with the newly adjusted medication. After the end of week 22 all participants continue with or switch back to SROM for another 6 month (week 23 to 47).