The purpose of this study is to evaluate whether or not buspirone is effective in preventing relapse in cocaine-dependent adults in inpatient/residential treatment who are planning to enter outpatient treatment upon inpatient/residential discharge.

The primary objective is to evaluate the efficacy of buspirone, relative to placebo, in preventing relapse in cocaine-dependent adults in inpatient/residential treatment who are planning to enter outpatient treatment upon inpatient/residential discharge. Secondary objectives include evaluating the impact of buspirone, relative to placebo, on other drug-abuse outcomes and on factors that may mediate buspirone's efficacy as a relapse-prevention treatment.

Inclusion Criteria:

1. be 18 years of age or older

2. be able to understand the study, and having understood, provide written informed consent in English

3. meet DSM-IV-TR diagnostic criteria for current (within the last 12 months) dependence for cocaine, must self-report having used crack cocaine a minimum of four times in the 28 days prior to inpatient/residential admission, and must report that their typical pattern of use is at least once a week

4. have a willingness to comply with all study procedures and medication instructions

5. be enrolled in an inpatient/residential program at a participating CTP, scheduled to be in inpatient/residential treatment for 12-19 days when randomized, and planning to enroll in local outpatient treatment through the end of the active treatment phase (i.e., study week 15)

6. if female and of child bearing potential, agree to use one of the following methods of birth control:

   • oral contraceptives
   • contraceptive patch
   • barrier (diaphragm or condom)
   • intrauterine contraceptive system
   • levonorgestrel implant
   • medroxyprogesterone acetate contraceptive injection
   • complete abstinence from sexual intercourse
   • hormonal vaginal contraceptive ring

Exclusion Criteria:

1. meet DSM-IV-TR diagnostic criteria for current (within the last 12 months) opioid dependence

2. have a medical or psychiatric condition that, in the judgment of the study physician, would make study participation unsafe or which would make treatment compliance difficult. Medical conditions that may compromise participant safety or study conduct include, but are not limited to:

   • AIDS according to the current CDC criteria for AIDS
   • liver function tests greater than 3X upper limit of normal
   • serum creatinine greater than 2 mg/dL

3. have a psychiatric disorder requiring continued treatment with a psychotropic medication

4. have a known or suspected hypersensitivity to buspirone

5. be pregnant or breastfeeding

6. have used any of the following medications within 14 days of randomization: monoamine oxidase (MAO) inhibitors such as phenelzine (Nardil), selegiline (Eldepryl), isocarboxazid (Marplan), or tranylcypromine (Parnate)

7. be taking any medications which, in the judgment of the study physician, may produce interactions with buspirone that are sufficiently dangerous so as to exclude the patient from participating in the study. Alternatively, the study physician, in consultation with the patient and his or her physician, may elect to withdraw the patient from the problem medications before randomization. Some of the possible interactions are discussed in section 8.8.

8. be anyone who, in the judgment of the investigator, would not be expected to complete the study protocol (e.g., due to relocation from the clinic area, probable incarceration, etc.)

9. be a significant suicidal/homicidal risk

Baseline characteristics of all randomized participants

Between the first dose of study drug and the last dose of study drug plus 7 days, for up to 16 weeks