Stability of neomycin and bacitracin in semisolid and powder dosage form

ABSTRACT

Stability of bacitracin and neomycin were comparatively studied in different batches of two topical preparations; powder and ointment. The results emphasizes that the ointments exhibit a progressive and gradual increase in their spreadability during storage. This indicated that ointment bacitracin content is acceptable for the first 3-6 months only, after which the antibiotic yield is less than 90%. Neomycin content in both forms decreased after 12 months to be less than 90%. Kinetic study of decomposition revealed that all are first order for both antibiotic. Bacitracin t 1/2 in powder form and ointment was 6.7 months and 5.58 months, respectively. For neomycin t 1/2 was 5.544 months in powder form and 5.25 months in ointment. The comparative stability of the antibiotic in both topical preparations showed no big difference in the decomposition rate. The so determined expiry date of these products was 24 months