Inclusion Criteria:

1. Men and women between the ages of 18-60 who meet DSM-IV criteria for current cocaine dependence (DSM-IV-TR).
2. Used cocaine at least four days in the past month, with at least weekly cocaine use.
3. Must have a Body Mass Index (BMI) > 18 kg/m2
4. Alcohol Breathalyzer (BraC) at consent of < 0.04%
5. Individuals must be capable of giving informed consent and capable of complying with study procedures.
6. Women of child bearing age will be included in the study provided that they are not pregnant, based on the results of a blood pregnancy test drawn at the time of screening. They must also agree to use a method of contraception with proven efficacy and agree not to become pregnant during the study. To confirm this, blood pregnancy tests will be repeated monthly. Women will be provided a full explanation of the potential dangers of pregnancy while on the study medication. If a woman becomes pregnant, the study medication will be discontinued.

Exclusion Criteria:

1. Meets DSM-IV-TR criteria for bipolar disorder, Schizophrenia, or any psychotic disorder other than transient psychosis due to drug abuse
2. Individuals with any current Axis I psychiatric disorder as defined by DSM-IV-TR supported by the SCID-I/P that in the investigator's judgment are unstable or would be disrupted by study medication or are likely to require pharmacotherapy during the study period.
3. Individuals with current major depressive disorder.
4. Individuals physiologically dependent on any other drugs (excluding nicotine or cannabis) which require medical intervention.
5. Individuals with current psycho stimulant abuse or dependence.
6. Individuals with current suicidal risk.
7. Individuals with coronary vascular disease as indicated by history or suspected by abnormal ECG or history of cardiac symptoms.
8. Unstable physical disorders which might make participation hazardous such as uncontrolled hypertension (SBP > 150, DBP> 90, or HR > 100 when sitting quietly), acute hepatitis (patients with chronic mildly elevated transaminases < 3x upper limit of normal are acceptable), or uncontrolled diabetes.
9. Individuals with a history of seizures
10. History of allergic reaction to candidate medication (amphetamine and/or ER-MAS or topiramate).
11. Women who are pregnant or nursing.
12. Use of carbonic anhydrase inhibitors*
13. History of glaucoma, kidney stones*
14. History of failure to respond to a previous Adequate trial of either candidate medication for Cocaine dependence
15. Currently being prescribed psychotropic medication by another physician (other than sleep medication)
16. Individuals who are legally mandated (e.g., to avoid incarceration, monetary or other penalties, etc.) to participate in substance abuse treatment program -