Monitoring opioid and benzodiazepine use and abuse: Is oral fluid or urine the preferred specimen type?

We found that OF is the preferred matrix for 6-AM, while UR is preferred for 7-aminoclonazepam, lorazepam, oxazepam, hydromorphone, and oxymorphone. However, OF should be considered if the risk of adulteration is high and use and/or misuse of benzodiazepines, hydromorphone, and oxymorphone is low.