Physicochemical Properties and Excipient Compatibility studies of Probiotic Bacillus coagulans Spores

The probiotic formulations are susceptible to loss in viability due to formulation, processing, storage and in vivo environment. The aim of the present study was to perform preformulation studies of probiotic Bacillus coagulans spores to aid designing of stable formulations. Bacillus coagulans spores were studied for hygroscopicity, resistance to compaction force, aqueous pH stability, and excipient compatibility. The spores were found to be moderately hygroscopic with a significant loss of microbiological assay at water activity value of more than 0.5. Progressive loss of viability from 95% to 58% was observed with increase in compaction force from 1000 to 4000 psi. Aqueous suspension of Bacillus coagulans spores in buffer solutions of pH 1.2 to 8 showed rapid degradation with maximal stablility in pH 6.8. Excipient compatibility studies showed reduced assay with citric acid monohydrate, meglumine and sodium starch glycolate. The loss of activity seemed to be related to the moisture uptake, free and bound water present in the bulk.