Inclusion Criteria:
1. Ages 21-50 (The lower limit is to avoid offering alcohol to individuals below the drinking age of 21. The upper age is determined by experience recruiting for our prior studies).
2. Ability to read English at 6th grade level or higher.
3. Meet DSM-V criteria for at least moderate AUD.
4. Average weekly alcohol consumption of 30-70 standard drinks for men and 20-65 drinks for women. The lower limits are consistent with the lower sex-specific cut-offs defining high-risk drinking based on World Health Organization Risk Levels (WHO, 2000); the upper limits are designed to avoid recruiting participants whose drinking is likely to exceed the number of drinks available in the alcohol drinking paradigm (ADP).
Exclusion Criteria:
1. Individuals who are seeking alcohol treatment or have been in alcohol treatment within the past 6 months.
2. Meet current DSM-V criteria for substance use disorder, except for tobacco use disorder or mild cannabis use disorder.
3. Positive urine drug screens at more than 1 baseline appointment for opiates, cocaine, benzodiazepines, and barbiturates.
4. Psychotic or other severe psychiatric disorders as determined by clinical evaluation.
5. Regular use of psychoactive drugs, except for individuals on a stable dose of an antidepressant for at least 2 months.
6. Medical conditions that would contraindicate the consumption of alcohol or use of nimodipine including untreated or not adequately controlled hypertension or hypotension. Blood pressure at or below 100/65 will be exclusionary.
7. Heart rate of less than 50 bpm.
8. Clinically significant abnormalities in screening laboratories, including aspartate aminotransferase (AST) \>3 times upper limit of normal (ULN); alanine aminotransferase (ALT) \> 3 times ULN; total bilirubin \>1.5 times ULN; serum creatinine \>2.0 times ULN.
9. Concurrent use of the following medications: CYP3A4 inhibitors and inducers, other calcium channel blockers, or other blood pressure lowering medications.
10. Neurological trauma or disease, delirium, or hallucinations, or clinically significant or unstable medical conditions, including uncontrolled hypertension or diabetes, or significant cardiac, pulmonary, renal, hepatic, endocrine, or other systemic diseases, which in the opinion of the study physician and PI, may put the patient at risk because of participation in the study.
11. Clinical Institute Withdrawal Assessment for Alcohol-Revised (CIWA-Ar) scores of 8 or greater or a history of significant repeated alcohol withdrawals to reduce the likelihood of withdrawal symptomatology if subjects reduce their drinking.
12. Women who are pregnant or nursing.
13. Participants who refuse to use a reliable method of birth control from the time of first medication administration to 7 days after. These include oral contraceptives, contraceptive sponge, patch, double barrier (diaphragm/spermicidal or condom/spermicidal), intrauterine contraceptive system, etonogestrel implant, medroxyprogesterone acetate contraceptive injection, complete abstinence from sexual intercourse, hormonal vaginal contraceptive ring, surgical sterilization, or true abstinence.
14. Subjects who report disliking spirits will be excluded because hard liquor will be provided during the ADP.
15. Subjects who have taken any investigational drug within 4 weeks of the anticipated date of the first study dose.
16. Individuals who report heavy drinking days in the 2 days prior to their intake appointment but have a negative ethyl glucuronide (EtG) test to rule out subjects who are misrepresenting their drinking history.
17. Subjects who have donated blood within the past 6 weeks.
18. Heart rate of less than 50 bpm.
19. Subjects with a history or presence of cirrhosis.
