Buspirone reduces sexual risk-taking intent but not cocaine self-administration

Abstract

Impulsive sexual decision-making may underlie sexual risk-taking behavior that contributes to the disproportionately high prevalence of HIV infection among cocaine users. Delay-discounting procedures measure impulsive decision-making and may provide insight into the underlying mechanisms of sexual risk-taking behavior. The anxiolytic drug buspirone reduces delay discounting in rats and blunts the reinforcing effects of cocaine in some preclinical studies suggesting that it might have utility in the treatment of cocaine-use disorders. This study determined whether buspirone mitigates impulsive risky sexual decision-making in cocaine users on a sexual delay-discounting procedure. The effects of buspirone maintenance on the abuse-related and physiological effects of cocaine were also tested. Nine (N = 9) current cocaine users completed a repeated-measures, inpatient protocol in which sexual delay discounting was assessed after 3 days of maintenance on placebo and buspirone (30 mg/day) in counterbalanced order. The reinforcing, subject-rated, and physiological effects of placebo and intranasal cocaine (15 and 45 mg) were also assessed during buspirone and placebo maintenance. Buspirone increased the likelihood of condom use for hypothetical sexual partners that were categorized as most likely to have a sexually transmitted infection and least sexually desirable. Cocaine functioned as a reinforcer and increased positive subjective effects ratings, but buspirone maintenance did not impact these effects of cocaine. Buspirone was also safe and tolerable when combined with cocaine and may have blunted some its cardiovascular effects. The results from the sexual delay-discounting procedure indicate that buspirone may reduce preference for riskier sex in cocaine users. (PsycINFO Database Record

Figure 1

Data from the Sexual Discounting Task expressed as mean likelihood of condom use (raw proportion of VAS ± SEM) with hyperboloid best-fit functions for each of the four partner categories: Most Want to Have Sex With (Panel A), Least Want to Have Sex With (Panel B), Most Likely to Have a STI (Panel C), and Least Likely to Have a STI (Panel D). Closed squares (solid best-fit function) represent data from when participants were maintained on buspirone and open circles (dashed best-fit function) show data from placebo maintenance.

Figure 2

Hyperboloid best-fit parameter estimates (± SEM) for likelihood of using an immediately available condom (i.e., A parameter) under placebo and buspirone (30 mg/day) maintenance with hypothetical sexual partners classified based on sexual desirability (Panel A) and perceived STI risk (Panel B). An asterisk (*) indicates a statistically significant difference between partner conditions at a given dose of buspirone (p < .003). A dagger (†) indicates a statistically significant difference between Placebo and Buspirone within a given partner condition (p < .003).

Figure 3

Hyperboloid best-fit parameter estimates (± SEM) of the discounting rate parameter (i.e., k parameter) under placebo and buspirone (30 mg/day) maintenance with hypothetical sexual partners classified based on sexual desirability (Panel A) and perceived STI risk (Panel B). Remaining details are the same as those for Figure 2.

Figure 4

Mean number of drug choices (± SEM) for each dose of intranasal cocaine (0, 15, and 45 mg) from the Drug Choice Procedure under placebo or buspirone maintenance. The first drug choice corresponds with a breakpoint of 400 responses. Each subsequent choice required an additional 200 responses. Data points are offset for clarity. Filled symbols indicate a significant difference from Placebo during Placebo maintenance (open circle above PLB; p ≤ .05).

Figure 5

Mean time course data (± SEM) for subject ratings of Any Effect and Willing to Take Again from the Drug Effect Questionnaire. Figures on the left represent data collected under placebo maintenance and figures on the right show data when maintained on buspirone (30 mg/day). Filled symbols indicate a significant difference for active cocaine doses (15 and 45 mg) from Placebo during Placebo maintenance (open circles on the left side; p ≤ .05).

Figure 6

Mean time course data (± SEM) for Systolic Blood Pressure and Heart Rate. Remaining details are the same as those for Figure 5.