Previously, the authors reported that progesterone treatment attenuated reports of cocaine-induced high in male and female cocaine users. In this pilot clinical trial, the authors tested the safety and efficacy of oral progesterone as a treatment for cocaine dependence in methadone-stabilized male cocaine users. This was a 10-week, randomized, double-blind, placebo-controlled trial. Forty-five male methadone-stabilized cocaine users were randomized to receive placebo (n=15) or progesterone (n=30) for 9 weeks. The progesterone dose was gradually increased from 100 mg to 300 mg twice daily by Week 4 and maintained through Week 10. Treatment retention for the clinical trial was 80%, without significant group differences (log rank=2.4, p=.12). Hierarchical linear modeling estimates of obtaining a cocaine positive urine result across 10 weeks showed a very slight reduction in cocaine use for the progesterone group (Z=-2.89, p<.004). The placebo group showed a slight increase in cocaine use from Week 1 to Week 10 (Z=2.72, p<.007). These slopes significantly differed from each other (Z=-3.83, p<.0001). Overall, the placebo group showed significantly lower probability of having a cocaine positive urine result at treatment's end (Weeks 9 and 10) compared with the progesterone group (0.60 vs. 0.73; U=4837, p<.04). These preliminary findings do not support the efficacy of progesterone in male cocaine users. The efficacy of progesterone in female cocaine users remains to be determined in future studies.
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