Could not obtain additional funding to continue the research.

This study is designed to explore the effects of acute pre-treatment with 1,25-dihydroxyvitamin D3 (calcitriol), as compared to placebo on the behavioral (e.g., attempts to self-administer and ultimate number of infusions/boluses of cocaine self-administered), neurocognitive (e.g., performance on computerized tests of reward related learning such as the probabilistic selection task or PST and probabilistic reward task or PRT), and subjective effects (e.g, computerized visual analog scale [VAS] ratings of euphoria/, craving, etc.) of cocaine in experienced, non-treatment seeking users of the drug.

Inclusion Criteria:

• Age 30-55 years
• Voluntary, written, informed consent
• Physically healthy by medical history, physical, neurological, ECG and laboratory examinations
• DSM-5 criteria for at least moderate Cocaine Use Disorder
• Recent street cocaine use in excess of quantities used in the current study
• Intravenous and/or smoked (crack/ freebase) use
• Positive urine toxicology screen for cocaine
• Laboratory evidence of vitamin D sufficiency (i.e., 25(OH)-vitamin D3 level ≥ 20/mg)
• For females, a negative serum pregnancy (HCG) test at screening and admission, and a negative urine pregnancy test (HCG) on cocaine administration days.

Exclusion Criteria:

• A history of other substance dependence (except for nicotine). Positive urine toxicology for cannabis is accepted for the study unless there is evidence for dependence per Structured Clinical Interview for DSM-5 (SCID) interview. Positive urine toxicology for other drugs at screening will be repeated. If positive again and/or positive at admission, subjects will be excluded
• < 1 year of cocaine abuse/dependence
• A primary DSM-5 Axis I major psychiatric disorder (e.g., schizophrenia, bipolar disorder, major depression, etc.) unrelated to cocaine as determined by the SCID-5
• Medical comorbidities including serum calcium ( > 10.5 mg/dl, serum phosphorus > 4.2 mg/dl), hyperparathyroidism, kidney disease (e.g., Serum creatinine > 1.3 mg/dl)
• A history of significant and uncontrolled medical (e.g., cardiovascular, diabetic/metabolic) or neurological (e.g., cerebrovascular, seizures, traumatic brain injury) illness
• A history of seizures
• Current use of psychotropic/potentially psychoactive medications or medications that can have drug drug interactions with calcitriol, including over the counter Vitamin D products, thiazide diuretics, and calcium supplements, etc, as referenced in the package insert for calcitriol
• Seeking treatment for drug abuse/dependence
• Hypersensitivity to calcitriol
• For females, physical or laboratory (HCG) evidence of pregnancy.