(2006), acute lymphoblastic leukemia (2006), and dermatofibrosarcoma (2006). Imatinib is therefore a single orphan drug with seven different disease-based approvals. To cite a different situation, the combination product benzoate-phenylacetate was initially approved in 1987 as Ucephan (Immunex Corp.), an oral formulation for management of hyperammonemia, but the manufacturer later withdrew it from the market. Another company then sought new approval as an orphan product for the same indication (but in an intravenous formulation) under the name Ammonul (Ucyclyd, a subsidiary of Medicis Pharmaceutical Corp.) in 2005. For the purposes of analyzing the impact of the Orphan Drug Act in this study, benzoate-phenylacetate counted as two separate products because it appears to have originated from two separate manufacturers and also to differ in formulation.

This process identified a subset of 279 separate orphan products among the original sample that were approved for 347 designations or indications. Within this subset, 233 products had a single approved orphan designation, 36 products had two designations, 5 products had three designations, 3 drugs had four designations, and 2 products had seven designations each