[Cocaine abuse in maintenance therapy with methadone in narcotic dependent patients]

From a clinical point of view, additional consumption of cocaine by methadone maintained patients seems to have increased during the last few years. In order to verify this clinical impression, we carried out a retrospective analysis about cocaine abuse by opioid-dependent patients undergoing methadone maintenance therapy at the drug addiction clinic, Department of Psychiatry, University of Vienna.

Supervised urinalysis was performed on a frequent basis in 160 patients during the investigational time frame of 1997 and 1999. Concomitant consumption of opioids, cocaine and benzodiazepines in urine toxicology results (n = 2242) was compared in a post hoc analysis.

In 1997, 45% of urine toxicology tests were positive for opioids, 14.1% for cocaine and 22.1% for benzodiazepines. In 1999, however, 33.1% urine toxicology tests showed positive results for opioids, 22.2% for cocaine and 24% for benzodiazepines. It could be shown that the number of cocaine positive toxicology results increased significantly (p < 0.05) over the course of two years, and that the number of opioid positive tests decreased significantly (p < 0.05), whereas benzodiazepine consumption did not change. Age, and the duration of opioid dependence showed a significant influence on cocaine positive urinalysis.

The significant increase of additional cocaine consumption in methadone maintained patients reflects the enhanced availability of the substance in Austria, as it has been shown in other European countries and the USA. In addition, evidence based treatment trials are needed to prove the efficacy of alternative opioid maintenance therapy and to evaluate whether cocaine consumption is less of a problem.