IGIV Study for Chronic ITP Patients Ages 3-70

Key Inclusion Criteria: * Diagnosis of chronic ITP * Platelet count ≤ 20 x 10\^9/L * When administered corticosteroids at any time within 3 weeks before screening visit, the subject must have completed at least 3 weeks (21 days) of therapy at a stable and constant dose and schedule prior to screening visit * When administered azathioprine (immunosuppressant) at any time within 3 months before screening visit, the subject must have received a stable dose and schedule for at least 3 months prior to screening visit * When administered vinca alkaloids (eg., vincristine) at any time within 2 weeks before screening visit, the subject must have received a stable dose and schedule for at least 2 weeks prior to screening visit * When administered attenuated androgens (eg, danazol) at any time within 8 weeks before screening visit, the subject must have received a stable dose and schedule for at least 8 weeks prior to screening visit. * Females of childbearing potential must test negative for pregnancy Key Exclusion Criteria: * History or clinical evidence of medical conditions (other than ITP) felt to be the underlying cause of the thrombocytopenia * Diagnosis of secondary immune thrombocytopenia * History of severe (eg, anaphylactic) reactions to blood or any blood- derived product * History of intolerance to any component of the IP, such as sorbitol * Suffering serious and/or life-threatening hemorrhage/bleeding defined as: * Any intracranial or central nervous system bleeding * Any hemorrhagic event in which the subject is at risk of death at the time of the event * Females who are pregnant or nursing an infant child * Known to have immunoglobulin A (IgA) deficiency * Known to abuse alcohol, opiates, psychotropic agents or other chemicals or drugs, or has done so within 12 months of the screening visit * Documented diagnosis of thrombotic complications to polyclonal IVIG therapy in the past * Unstable or uncontrolled disease, or condition, related to, or impacting, cardiac function: unstable angina, congestive heart failure, uncontrolled arterial hypertension * Is anemic (hemoglobin \< 9 g/dL) * Renal impairment (ie, serum creatinine \> 1.5 x upper limit of normal \[ULN\]) * Aspartate aminotransferase or alanine aminotransferase levels \> 2.5 x ULN * Known to have a positive test for either HCV or HIV (HIV 1/2) * Splenectomy within the prior 8 weeks to the screening visit * currently receiving any treatment for ITP except corticosteroids, azathioprine, vinca alkaloids or danazol * Received an immune serum globulin (ISG) product within the prior 3 weeks (21 days) to the screening visit * Received any alkylating agent (eg, cyclophosphamide) within 5 weeks prior to the screening visit * Received rituximab within the prior 3 months to the screening visit * Was currently receiving, or received, any therapeutic drug or device that was not approved by a Regulatory Authority (US or Canadian) for any indication within the prior 12 weeks to the screening visit