| Fexofenadine, a novel second-generation H1 receptor antagonist, is a metabolite of terfenadine and used to relieve allergic rhinitis and chronic idiopathic urticaria. The drug appears to be quite a promising one among the newer antihistamines since it fulfills almost all the criteria for an ideal H1 antagonist. Besides its high efficacy and safety, it has also shown good market potential. Fexofenadine can be obtained either by chemical synthesis or microbial transformation.In this research work, we introduced a microbial transformation process converting terfenadine to fexofenadine. A high transformation rate strain, named S. platensis -SIPI-L-076, was obtained by UV irradiation. It could oxidize 81.4% terfenadine to fexofenadine, 53% higher than that of the original strain S. platensis-SIPI-C-0309. Then the culture media and the transformation conditions were optimized. Under the optimum conditions, 90% terfenadine could be converted to fexofenadine in Erlenmeyer flasks. Based on these results, transformation was carried out in a 7L fermenter for further study, and the highest transformation rate could reach to approximately 90%, similar to the result in Erlenmeyer flasks.Isolation and purification of fexofenadine were also studied. By solvent extraction, column chromatography, and crystallization, fexofenadine (96.3% purity) was obtained with yield 63.5%. It was preliminary verified that the product obtained was fexofenadine by structure determination.
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