Urinary metabolic ratio of pain management and substance abuse treatment drugs: Reference intervals.

We present data that show that quantitative urine drug concentrations obtained from individuals monitored for drug compliance as part of their participation in chronic opioid or substance abuse treatment can be used to quantify drug metabolism. We quantitatively monitor 18 drugs and their Phase 1 metabolite. These drugs were dextromethorphan, morphine, oxycodone, hydrocodone, quetiapine, tapentadol, tramadol, buprenorphine, clonazepam, fentanyl, imipramine, ketamine, carisoprodol, alprazolam, methadone, and amitriptyline. By using the ratio of metabolite/parent drug (prescribed medication), the expected or reference values for 18 drugs were obtained. Ratio values outside of this reference range could be considered to be caused by genetic metabolizing variants, drug-drug interactions, age, or deception. Alerting providers of the variance in metabolism from the expected norm might reduce overdosing or underdosing patients.