Pharmacodynamic and Pharmacokinetic Interactions Between Intravenous Cocaine and Acetazolamide or Quinine

Background: Cocaine dependence is a public health concern worldwide, with no FDA-approved pharmacological treatment for this condition. Thus, there is a need for controlled clinical trials to evaluate potential new pharmacological treatments. Adherence to a medication regime is a major factor in the success of treatment. In controlled clinical trials, medication adherence is often monitored by measuring specific markers ingested with the medication. No such markers are validated for use in studies of cocaine dependence treatment.

Objective: Evaluate the feasibility of oral acetazolamide and quinine as adherence markers in trials of cocaine dependence treatment by determining their pharmacodynamic and pharmacokinetic interactions with intravenous (IV) cocaine.

Study Population: Up to 30 healthy cocaine users aged 18-50 years who smoked or used IV cocaine for at least one year and at least three times per month during the three months prior to screening and had a positive urine test for cocaine within the last 6 months.

Experimental Design and Methods: Participants are admitted to a secure residential research unit on and undergo baseline assessments on Day -1, receive training on Day 0, and receive single doses of IV cocaine (25 mg) on Days 1, 5 and 10. On Days 1, 5, and 10, dried blood spot specimens are collected up to 3 times daily over 1.5 h. Single oral doses of acetazolamide (15 mg) are given on Days 2-5 and quinine (80 mg) on Days 7-10. Blood, oral fluid, and breath specimens are collected for up to 71 h, 70 h, and 22 h, respectively, after drug administration on Days 1, 4, 5, 9 and 10. Participants will wear the AutoSense device on Days 1, 3, 4, 5, 8, 9 and 10 for up to 12 hours each day. All voided urine is collected throughout the study.

Outcome measures: Primary outcome measures include cocaine, benzoylecgonine, ecgonine methylester, norcocaine, acetazolamide, and quinine pharmacokinetics in plasma and urine and whether subjective and cardiovascular responses to IV cocaine are changed when coadministered with oral acetazolamide or quinine. Secondary outcome measures include cocaine pharmacokinetics in oral fluid and breath, plasma activity of BChE and carboxylesterase (enzymes which metabolize cocaine), and basal and post-cocaine administration serum concentrations of leptin and other appetitive peptides (e.g. ghrelin, GLP-1, insulin, PYY, amylin).