Post-marketing stability monitoring of sulphacetamide sodium ophthalmic solutions marketed in Pakistan

ABSTRACT

Post-marketing stability testing of sulphacetamide ophthalmic solutions marketed in Pakistan was undertaken. Nine commercial batches of the drug belonging to six brands with different manufacturing dates covering the shelf-life were selected. The samples were collected from the local drug stores in two different cities namely D.I. Khan and Karachi, which differ in their climatic conditions. The analysis included pH measurement and quantitative determination of the active component sulphacetamide and its degradation product sulphanilamide by HPLC method. All the samples complied with pH limit specified by British Pharmacopoeia. However, only two samples from DI. Khan and four samples from Karachi passed the sulphacetamide assay test. The levels of hydrolytic product sulphanilamide varied between 1.5-7.3% for the samples from DI. khan and 1.02-5.2% for the samples collected from Karachi. It was concluded that ageing and storage conditions had deleterious effect on the stability of those ophthalmic solutions. The higher degradation of suiphacetamide in the samples collected from DI. Khan is attributed to the relatively higher temperature in this area as compared to Karachi