Study to Evaluate the Likeability, Safety, and Abuse Potential of NRP 104 in Adults With Histories of Stimulant Abuse

Inclusion Criteria: * Male or female subject is 18 to 55 years of age, inclusive. * Except for women who are post menopausal or surgically sterile, all female subjects must have a negative urine pregnancy test at screening and at admission. They must abstain from sexual activity, or use acceptable contraceptives throughout the study, and for 30 days after the last dose of study drug. Acceptable contraceptives include double barrier method (such as condom with spermicidal gel or diaphragm with spermicidal gel), IUDs and hormonal contraceptives which must be pharmacologically effective prior to study drug exposure. * Meet DSM-IV criteria for the diagnosis of substance abuse. * Subject must be in good health and have venous access sufficient for blood collection, as determined by medical history, physical exam, and clinical labs. * Agree to be admitted to the inpatient research unit for a minimum of 14 days, and will be able to complete all protocol-specified assessments. * Able to understand that they can withdraw from the study at any time. * Minimum reading level of Grade Six as determined by the REALM test, at the investigator's discretion. * Subject must voluntarily consent to participate in this study. * Able to swallow the study medication whole. Exclusion Criteria: * History of clinically significant gastrointestinal, renal, hepatic, endocrine, oncologic, hematologic, neurologic, psychologic, immunologic or pulmonary disorders; or cardiovascular disease, tuberculosis,…