Use of Prescribed Psychotropic Medications in an Opioid Substitution Therapy Cohort.

Objective: Comorbid mental illness is extremely common in individuals receiving opioid substitution therapy. The use of common psychiatric medications is complex in this cohort with increased risks of drug-drug interaction, overdose, and diversion or abuse of prescribed medication. We have therefore investigated rates of co-prescribing and psychiatric comorbidity in a cohort of individuals receiving therapeutic methadone or buprenorphine. Methods: Comprehensive electronic medical records were accessed for a cohort of individuals (n = 698) receiving opioid substitution therapy at a single center in London, United Kingdom. The following was collected for each individual: demographic data, current prescribed medications (including opioid substitution therapy agents), duration of prescription, indication for each prescription, and psychiatric diagnoses. Results: A total of 610 individuals were included in the final analysis. High rates of psychotropic co-prescribing were observed, with 36.7% of individuals receiving a psychotropic medication in addition to their opioid substitution drug, including 35.4% receiving an antidepressant, 9.2% an antipsychotic, 8.6% a benzodiazepine, and 4.5% a gabapentinoid, rates that are far in excess of the local population prescription frequency; 75.5% of antipsychotic prescriptions and 47.7% of benzodiazepine prescriptions were for an unlicensed indication. Conclusions: This highlights the need for evidence-based treatment of comorbid mental illness for individuals receiving opioid substitution therapy.