- Use of any prescription or over the counter medication, or herbal medication (not including non-steroidal anti-inflammatory drugs) within 2 weeks of the first PET scan. Of particular concern would be GABA-ergic compounds and CYP3A4 inhibitors. Exclusion should also be considered if the subject has taken a drug with a long half-life (or of any metabolite) even if taken outside the two week time window. However, the subject can still be enrolled if, in the opinion of the investigator, such medication taken in that timeframe will not interfere with the results of the study.