Safety Assessment of Potential Interactions Between IV Methamphetamine and Osmotic-Release Methylphenidate (OROS-MPH)

Inclusion Criteria: * Be volunteers who meet DSM-IV criteria for methamphetamine abuse or dependence determined using a Mini-International Neuropsychiatric Interview (MINI) and be non-treatment seeking at time of study and have a positive urine test for methamphetamine (greater than or = to 500 ng/mL) during screening. * Be able to verbalize understanding of consent form, able to provide written informed consent, and verbalize willingness to complete study procedures. * Have a negative urine test for methamphetamine and other drugs of abuse (opiates, cocaine, and benzodiazepines) after clinic intake before the first infusion session. * Have a history and physical examination that demonstrate no clinically significant contraindication for participating in the study, in the judgment of the admitting physician and the site Principal Investigator * Have vital signs as follows: resting heart rate between 45 and 100 bpm, systolic BP below 140 mm Hg and diastolic BP below 90 mm Hg. * Have electrolytes (Na, K, Cl, HCO3) and hematocrit that is clinically normal (+/- 10% of laboratory limits). * Have liver function tests (total bilirubin, ALT, AST, and alkaline phosphatase) less than three times the upper limit of normal. * Have kidney function tests (creatinine and BUN) less than twice the upper limit of normal. * Have an ECG performed that demonstrates sinus rhythm between 45 and 100 beats per minute (bpm), normal conduction, and no clinically significant arrhythmias. * Be able to swallow whole tablets of OROS-MPH due to the controlled release formulation. * If female, have a negative pregnancy test and agree to use one of the following methods of birth control, or be postmenopausal, have had a hysterectomy or have been sterilized. Birth control must be in effect starting at least 7 days (14 days for hormone-based methods used alone) prior to clinic intake, and should extend at least until the last follow-up visit. Exclusion Criteria: * Please contact site for more information