Bioequivalence and Bioavailability Forum

Dear chandramohan,

this a tricky question!

On one hand virtually all studies I have seen in the last ten years included a test for drugs of abuse at screenening and prior to administration in every treatment period (actually the evening of hospitalization).
On the other hand all sponsors - and regulators as well - were happy just with the written acknowledgment that volunteers must not take any medicinal product without permission from the investigator for a certain period of time prior to the study and during the study.

So we trust volunteers (in the case of additional medications), but we distrust them in the case of drugs of abuse.
Clearly this is not a scientific rationale, but pragmatically I would recommend the drug tests