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Eighty-one cocaine-dependent outpatients were assessed for their reactions to cocaine-related cues in a laboratory setting. All subjects contributed a urine sample prior to the session. Compared with non-drug control cues, the cocaine stimuli produced increases in physiological arousal, self-reports of high, craving, and withdrawal, and self-reports of negative mood. Subjects who tested cocaine-positive on the day of testing differed only in skin resistance responding from those who tested cocaine-negative. Changes in cue-induced physiological and self-report measures were also not associated with between-subject variations in mood as measured by the Profile of Mood States (POMS) questionnaire administered prior to cue assessment. Thus, variations in baseline mood and recent cocaine use history do not introduce an additional source of variability in cue reactivity measurements. However, negative mood states at the start of a session were associated with higher levels of self-reported craving, high, and withdrawal both before and after cue exposure.

Sixty-five cocaine-dependent subjects were enrolled into a 10-week randomized, double-blind study to determine the safety and efficacy of the serotonin-2 receptor antagonist, ritanserin (10 mg/day), in reducing cocaine consumption and craving. All subjects also participated in a structured intensive outpatient psychosocial program. Seventy-three percent of the participants completed the treatment program and follow-up. Subjects experienced a significant reduction in craving: 66.4% and 32.5% for the placebo and ritanserin groups, respectively. These reductions in craving were not paralleled by substantial decreases in cocaine use. Self-reported cocaine use was less frequent in the placebo group; paradoxically, blood levels of its metabolite, benzoylecgonine, were also higher although insignificantly so. Generally, ritanserin was well tolerated but significantly prolonged the QTc interval on the electrocardiogram. This outpatient program is effective at maintaining cocaine-dependent individuals in treatment and reducing craving. Ritanserin (10 mg/day) is not an efficacious adjunct to psychosocial treatment for cocaine dependence.

As part of a double-blind placebo-controlled study of the effects of ritanserin on cocaine use and craving, reactivity to cocaine-related events was assessed both before and during medication. Twenty-two patients receiving ritanserin and 23 receiving placebo were exposed to cocaine cues while continuous measures of heart rate, skin temperature, and skin resistance were taken. Self-reports of high, withdrawal, and craving were also collected. The cues produced significant physiological responding as well as significant increases in high and craving during both sessions. Ritanserin reduced cue-elicited decreases in skin temperature, but had no effect on heart rate and skin resistance or on cue-induced high and craving. The results demonstrate that cue reactivity is a robust phenomenon across two assessment sessions but fail to support the use of ritanserin as a means of reducing cue-elicited drug states.

Therapeutic drug development in alcoholism could be targeted at any of the following: direct antagonism, substitution, treatment of abstinence, enhancement of aversion, modification of biodisposition, or craving. Ritanserin is a potent, centrally acting, highly selective 5-HT1C/2 antagonist which, in addition to having a sleep-regulating and anti-depression/anti-axiety effect, displays a unique pharmacological action in several animal paradigms of substance abuse which assess drug-craving. In fact, the latter pharmacological action was demonstrated after initial clinical observations suggested an effect of ritanserin in the chronic withdrawal phase after detoxification from alcohol in patients. The results of a recent double-blind, placebo-controlled, trial indicated that ritanserin did not induce aversion to drink alcohol in normal volunteers who display social drinking, but are not suffering alcohol dependence. Currently, a full clinical development program of ritanserin in cocaine and alcohol abuse is ongoing. Three major double-blind, placebo-controlled trials in alcohol dependent patients are in progress. Patients of different severity levels, ranging from mild to very severe, are studied. The dosages of ritanserin tested (2.5 mg, 5 mg, and 10 mg o.d.) are known to be well tolerated and safe. Two trials aim for relapse prevention--clinically defined in one, biochemically defined in the other-, and one trial has improved (reduced) drinking behaviour as a therapeutic goal. This program, which involves close to 900 alcohol-dependent patients, is well under way, and is still picking up momentum.

Rats that had received 3% alcohol, 0.01% cocaine, or 0.002% fentanyl as the only beverage over 10 days showed marked preference for the drug solution when water was made available as a second fluid in a separate bottle. Treatment with low doses of ritanserin, a specific central serotonin 5-HT2 antagonist, rapidly reversed drug preference without changing total fluid intake. Quantitatively, the reduction in drug consumption was greater for alcohol than for cocaine and greater for cocaine than for fentanyl. This is probably related to differences in the reinforcing potential of the three drugs.