The goal of the proposed study is to evaluate the efficacy and safety of tolcapone in pathological gambling.

The proposed study will consist of 8 weeks of treatment with tolcapone in 10 subjects with pathological gambling. The hypothesis to be tested is that tolcapone will be effective in reducing the urges to gamble in patients with pathological gambling. The proposed study will provide needed data on the treatment of a disabling disorder that currently lacks a clearly effective treatment.

Inclusion Criteria:

1. Men and women age 21-75;
2. Meet diagnostic criteria for current pathological gambling based on DSM-IV criteria and confirmed using the clinician-administered Structured Clinical Interview for Pathological Gambling (SCI-PG) (Grant et al., 2004);
3. Gambling behavior within 2 weeks prior to enrollment;
4. Women of child bearing age are required to have a negative result on a beta-human chorionic gonadotropin pregnancy test;
5. Women of childbearing potential utilizing a medically accepted form of contraception defined as double barrier, oral contraceptive, injectable contraceptive, implantable contraceptive devices, and abstinence.

Exclusion Criteria:

1. Infrequent gambling (i.e. less than one time per week) that does not meet DSM-IV criteria for PG;
2. Unstable medical illness or clinically significant abnormalities on laboratory tests, EKG, or physical examination at screen as determined by the investigator;
3. History of elevated liver enzymes (AST/ALT) or other liver abnormalities;
4. History of seizures;
5. Myocardial infarction within 6 months;
6. Current pregnancy or lactation, or inadequate contraception in women of childbearing potential;
7. A need for medication other than tolcapone with possible psychotropic effects or unfavorable interactions as determined by the investigator;
8. Clinically significant suicidality (defined as score 2 or higher on HAM-D item 3);
9. Current co-morbid Axis I disorder determined by the Structured Clinical Interview for DSM-IV (SCID), (First et al., 1995) - except for nicotine dependence;
10. Lifetime history of bipolar disorder type I or II, schizophrenia, or any psychotic disorder determined by SCID;
11. Clinically significant cognitive impairment (defined as score less than 88 on 3MS);
12. Current or recent (past 3 months) DSM-IV substance abuse or dependence;
13. Positive urine drug screen at screening;
14. Initiation of psychotherapy or behavior therapy for pathological gambling within 3 months prior to study baseline;
15. Previous treatment with tolcapone;
16. Treatment with an investigational medication or depot neuroleptics within 3 months;
17. Refusal to sign the tolcapone information sheet.

This study did not assess treatment effects beyond an 8-week treatment period and these results may not generalize to the larger population of people with PG.