This is a human laboratory study that will assess the clinical pharmacology, safety and tolerance of 75mg oral doses of GBR 12909, which is 1-[2-[bis(4-fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl) piperazine dihydrochloride, in cocaine experienced volunteers. Particular interest is being given to the hematological safety data.

The primary objective of this study is to determine safety of GBR 12909 administration and if there are significant interactions between GBR 12909 treatment concurrent with i.v. cocaine infusions of 20 and 40 mg by measuring adverse events and cardiovascular responses [heart rate (HR), blood pressure (BP), and electrocardiogram (ECG)]. Note: A significant interaction is defined as: more than 50% of the subjects treated with GBR 12909 experience a pharmacodynamic interaction when challenged with cocaine, which brings the stopping criteria (section 12.4.5) into effect.

This 7-day double-blind, parallel-group, placebo-controlled inpatient study will compare the effects of 15 mg of intravenous methamphetamine given 60 hours before and 12 hours after a single oral dose of reserpine (0.5 or 1.0 mg) or placebo.