EVALUATION OF PRESERVATIVE EFFECTIVENESS IN ANTACID, COUGH SYRUP AND OPHTHALMIC SOLUTION BY MICROBIAL CHALLENGE TEST

Pharmaceutical preparations having high water content face the problem of microbial spoilage which affects consumer safety. Control on such problem is generally done by the addition of a specific preservative to these pharmaceutical preparations, but sometimes some physical changes and clinical hazards are observed even after the addition of preservatives. The present study aimed to evaluate and compare the effectiveness of preservatives in market samples of antacids, cough syrups, and ophthalmic solutions through a microbial challenge test. The samples of antacids, cough syrups, and ophthalmic solutions were challenged with 3 bacterial, and 2 fungal strains and results were periodically (0, 7, 14 and 28 day) investigated. The number of surviving microorganisms were determined using standard microbiological dilution pour-plate technique. More than 1 log reduction of microbial counts were observed in all samples at 7 day. Moreover, the log reduction in microbial counts was significantly increased up to 28 day. Results showed that preservatives Sorbitol, Sodium Citrate, and Benzalkonium Chloride present in antacids, cough syrups, and ophthalmic solutions respectively were effective against all the challenged microorganisms. Benzalkonium chloride as a preservative in ophthalmic solution was found to be most effective. Hence, from this study, it is concluded that preservatives present in all tested liquid pharmaceutical preparations are effective in preventing contamination of the product during their use and storage.