OF is becoming increasingly popular as a tool to monitor compliance in the addiction setting.
CLON can be challenging to measure in OF due to its presence in low concentrations.
We demonstrate that 7AC is superior to CLON for monitoring CLON use.
Clinically, 7AC is superior to CLON for detection of both CLON compliance and undisclosed use.
Laboratories performing OF testing should validate and implement 7AC in OF for the assessment of CLON use.