Study of Milnacipran in Patients With Inadequate Response to Duloxetine for the Treatment of Fibromyalgia

Inclusion Criteria: * Diagnosis of fibromyalgia * Have been treated with a stable dosage of duloxetine (60 mg/day) for ≥ 4 weeks immediately before Screening (Visit 1) * Duloxetine must have been prescribed for the treatment of Fibromyalgia * Have a VAS 1-week pain recall score ≥ 40 mm and ≤ 90 mm * At Visit 2, to be eligible to enter the randomized treatment period, must continue to have a VAS 1-week pain recall score ≥ 40 mm and be dissatisfied with current Duloxetine treatment. Exclusion Criteria: * Suicidal risk * History of mania, bipolar disorder, psychotic disorder, schizophrenia, or a current episode of major depressive disorder * Myocardial infarction and/or stroke within the prior 6 months * Systolic blood pressure \> 160 mm Hg or mean diastolic blood pressure \> 100 mm Hg at Screening (Visit 1) * Substance abuse * Pulmonary dysfunction * Severe renal impairment * Active cardiac disease * Liver disease * Uncontrolled narrow-angle glaucoma * Autoimmune disease * Cancer * Inflammatory bowel disease * Unstable endocrine disease * Prostatic enlargement * Female patients who are pregnant or breastfeeding