Effects of Phenytoin on Cocaine Use in Humans - 2

The purpose of this study was to determine the effects of phenytoin on smoked cocaine-base self-administration using our laboratory self-administration model. A total of 12 patients randomized, 6 to phenytoin and 6 to placebo treatment group. There were 2 phases in this 10-day inpatient study. Phase 1 subjects underwent one cocaine self-admin session. Randomization took place at the start of Phase 2, Day 4 where subjects received either placebo or phenytoin. The subjects assigned to phenytoin treatment received an oral loading dose (20mg/kg) aimed at achieving plasma phenytoin concentration of (10-20 mg/L). During Phase 2, subjects had the opportunity to self-administer cocaine on Days 5, 7, and 9. The plasma phenytoin levels were expected to decrease gradually during Phase 2 which provided an opportunity to study the effect of decreasing phenytoin plasma concentrations on cocaine self-administration.

Inclusion criteria

Males/Females between the ages of 20-40. History of smoked cocaine use on the avg. of at least 2 times/week over a 6 month period. Have currently used at least 1 g of cocaine within a 4-6 hr period. Current history of good health, normal serum albumin levels and normal QTc intervals. Nonreactive for HIV. No participation in any of our studies for the past 6 months. For females: not pregnant as determined by pregnancy screening nor breat feeding, and using acceptable birth control methods (e.g. birth control pills, diaphragm, condoms plus foam).

Exclusion criteria

History of suicide attempt, bipolar disorder, schizophrenia, or generalized anxiety disorder. Current problem with major depressive disorder. Current use of alcohol or other durgs on a daily basis. History of major medical illnesses. Currently on parole, probation or a legal history of violence. Treated for chemical dependency within the past 6 months. Use of any psychotropic drugs including MAOIs in the past 6 months.