Patent ID: 6936591

Claim:
A process for the preparation of a substantially pure amorphous 9-deoxo-9a-aza-9a-methyl-homoerythromycin A, wherein the procedure comprises the steps of: a) dissolving 9-deoxo-9a-aza-9a-methyl-homoerythromycin A material in (1) an organic solvent that is water-miscible or water-immiscible, (2) a mixture of organic solvents, (3) a mixture of organic solvents and water, or (4) a mixture of water and at least one inorganic or organic acid; b) crystallizing an orthorhombic isostructural pseudopolymorph of 9-deoxo-9a-aza-9a-methyl-9a-homoerythromycin A of the general Formula I: wherein S is a water-miscible or water-immiscible organic solvent, the pseudopolymorph being characterized by the orthorhombic space group P2 1 2 1 2 1 and average unit cell parameters comprising: crystal axis lengths of a=8.2 to 9.7 Å, b=11.5 to 13.5 Å, and c=44.5 to 47.0 Å, and angles between the crystal axes of α=β=γ=90°, from the solution thus prepared; c) isolating the orthorhombic isostructural pseudopolymorph of the general Formula I; and d) converting the orthorhombic isostructural pseudopolymorph of 9-deoxo-9a-aza-9a-methyl-9a-homoerythromycin A of the general Formula I to a substantially pure amorphous 9-deoxo-9a-aza-9a-methyl-9a-homoerythromycin A.