- Patients who are in a situation or have any condition requiring the use of prohibited drugs or unstable medical conditions where the risk of therapy would exceed any potential benefit i.e., hematological disorder such as unstable cardiac disorder (including acute myocardial infarction or unstable myocardial ischemia/angina within 30 days, ventricular arrhythmia within 30 days, uncontrolled atrial fibrillation, or atrial fibrillation/flutter with symptomatic bradycardia [sick sinus syndrome], or unstable congestive heart failure) or impairment expected to be unstable or progressive during the course of this study (e.g., recurrent or uncontrolled seizure disorders, demyelinating syndromes, or progressive peripheral neuropathy).