Psychiatric comorbidity and additional abuse of drugs in maintenance treatment with L- and D,L-methadone.

Sixty D,L- or L-methadone treated patients in maintenance therapy were interviewed for additional drug abuse and psychiatric comorbidity; 51.7% of the entire population had a comorbid Axis-I disorder, with a higher prevalence in females (P=0.05). Comorbid patients tended to have higher abuse of benzodiazepines, alcohol, cannabis, and cocaine, but not of heroin. They had received a significantly lower D,L- (P<0.05) and L-methadone dose than non-comorbid subjects. The duration of maintenance treatment showed an inverse relationship to frequency of additional heroin intake (P<0.01). Patients with additional heroin intake over the past 30 days had been treated with a significantly lower L-methadone dosage (P<0.05) than patients without. Axis-I comorbidity appears to be decreased when relatively higher dosages of D,L- (and L-methadone) are administered; comorbid individuals, however, were on significantly lower dosages. Finally, L-, but not D,L-methadone seems to be more effective in reducing additional heroin abuse.