A Study of Neural Circuit Responses to Catechol-O-methyl Transferase (COMT) Inhibitors

Exclusion Criteria

• •Using cocaine, stimulants (other than THC, nicotine, \& caffeine)amphetamines, hallucinogens, "ecstasy", opiates, sedatives, pain pills, sleeping pills or other psychoactive drugs within two weeks of the start of the study OR more than 10 times in the last year.
• •Has a current dependence on, or addiction to any psychoactive drug (except nicotine or caffeine) including alcohol.
• •Clinically significant medical or psychiatric illness requiring treatment as determined by screening blood tests, medical history, and physical exam performed or reviewed by the study physician.
• •Subject has a history of major alcohol related complications within the proceeding 2 years (liver failure/cirrhosis, pancreatitis, esophageal varices, etc.)
• •Liver function test ≥ 3 times normal upper limit.
• •BAC level \> 0.05% at the beginning of screening visit (within margin of error of detection).
• •Has a neurological dysfunction or psychiatric disorder.
• •Has severe low blood pressure.
• •Has uncontrolled high blood pressure.
• •Regular use of any of the drugs on the tolcapone or entacapone contraindications list OR within 2 weeks of drug administration.
• •Regular use of SSRIs.
• •Has an allergy or intolerance to tolcapone or entacapone.
• •Subject has received an investigational drug within 30 days of screening visit.
• •Subject is considered unsuitable for the study in the opinion of the investigator or study physician for any other reason.
• •The subject has metal (metal plates, pins, wires or screws, artificial limb, joint replacement or anything that might have been inserted during an operation) in his/her body.
• •Subject has a pacemaker, defibrillator, stent, or any metal implants related to heart/blood flow problems.
• •Subject has worked with metals (ie. metallurgy, metal shaving, welding, soldering, etc).
• •Subject has been wounded with anything metal (bullet, shrapnel or metal filling).
• •Has ever gotten a piece of metal in the eye.
• •Has tattoos done with ink containing metal or permanent eyeliner.
• •Wears color contact lenses.
• •Has a hearing problem or hearing aid, cochlear implant or past ear surgery.
• •Has any irremovable dental bridges, dental plates, metal caps or any other non-removable metal in the mouth.
• •The subject is claustrophobic.
• •The subject is pregnant. (women only)
• •Has a IUD. (women only)
• •Significantly overweight.