Progesterone effects on cocaine use in male cocaine users maintained on methadone: A randomized, double-blind, pilot study

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 I 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.