Researchers at the University of Missouri recently reported on a new method for converting drugs from one crystalline form
to another by applying gas-induced transformations of the antibiotic clarithromycin and lansoprazole, the API in the gastrointestinal
For clarithromycin, the researchers converted the kinetic solvent and guest-free crystal forms to the commercially thermodynamically
stable polymorph with a reduction in energy costs relative to other commonly used methods. Typical methods involve desolvation
of the initial form to a second form, which is heated for 18 h at 110 °C to finally produce the desired polymorph. In the
gas-induced process, the clarithromycin crystals were pressurized with carbon dioxide at 350 psi for direct conversion of
the initial form to the final thermodynamically stable form in 4 h. For lansoprazole, the researchers also used carbon dioxide
to convert the ethanol hydrate of lansoprazole to the solvent-free form that is used commercially. This process improved the
approach used in synthesizing lansoprazole, which involves a solvate that readily decomposes and is stirred in water, filtered,
and dried intensively (8, 9).
Patricia Van Arnum is a senior editor at Pharmaceutical Technology, 485 Route One South, Bldg F, First Floor, Iselin, NJ 08830 tel. 732.346.3072, firstname.lastname@example.org
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