Abstract: A process of making Form A of atazanavir sulfate comprises: a) mixing atazanavir free base with a solvent selected from the group consisting of methanol (MeOH), ethanol (EtOH), isopropanol (IPA), N-methylprrolidone (NMP) and combinations thereof; b) reacting sulfuric acid with the atazanavir free base in the mixture formed in step a) to form a reaction solution comprising atazanavir sulfate; c) mixing an antisolvent with the reaction solution; d) seeding the mixture formed in step c) with an effective amount of Form A of atazanavir sulfate to form a seeded mixture comprising Form A of atazanavir sulfate; and e) isolating Form A of atazanavir sulfate in solid form from the seeded mixture; wherein the antisolvent is selected from the group consisting of methyl tert-butyl ether (MTBE), ethyl acetate (EtOAc), acetonitrile (MeCN), isopropyl acetate (IPAc), cyclohexane, and combinations thereof. In one alternative, step c) may be performed before step b).

Abstract: A process of making Form A of atazanavir sulfate comprises: a) mixing atazanavir free base with a solvent selected from the group consisting of methanol (MeOH), ethanol (EtOH), isopropanol (IPA), N-methylprrolidone (NMP) and combinations thereof; b) reacting sulfuric acid with the atazanavir free base in the mixture formed in step a) to form a reaction solution comprising atazanavir sulfate; c) mixing an antisolvent with the reaction solution; d) seeding the mixture formed in step c) with an effective amount of Form A of atazanavir sulfate to form a seeded mixture comprising Form A of atazanavir sulfate; and e) isolating Form A of atazanavir sulfate in solid form from the seeded mixture; wherein the antisolvent is selected from the group consisting of methyl tert-butyl ether (MTBE), ethyl acetate (EtOAc), acetonitrile (MeCN), isopropyl acetate (IPAc), cyclohexane, and combinations thereof. In one alternative, step c) may be performed before step b).