Phenytoin in the treatment of cocaine abuse: a double-blind study

To evaluate the effectiveness of phenytoin in the treatment of cocaine abuse.

A 12-week, double-blind, placebo-controlled outpatient study of phenytoin in the treatment of cocaine abuse was conducted. Sixty cocaine-using subjects were randomly assigned to a daily fixed dose of 300 mg phenytoin or placebo. Forty-four subjects initiated treatment and returned for weekly visits. Primary measures of outcome included weekly quantitative and qualitative cocaine urinalysis, self-reported cocaine use, global functioning and improvement, craving intensity, and subject retention.

Cocaine use, as measured both by weekly urinalysis and self-report, was significantly lower in the phenytoin group. The phenytoin group was also rated as significantly less impaired and more improved than the placebo group. Craving intensity was lower in the phenytoin group, but the difference was not statistically significant. Among phenytoin subjects, serum phenytoin levels above 6.0 micrograms/ml were associated with lower rates of positive cocaine urine specimens and longer cocaine-free periods. No differences were observed between groups in study retention.

These findings suggest that phenytoin may be useful in the treatment of cocaine abuse. Further studies are needed to replicate these findings.