Stability of extemporaneous norfloxacin suspension

The stability of norfloxacin as extemporaneous suspensions compounded from two brands of film-coated tablets (formulas I and II) was studied. The vehi cle consisted of tragacanth, saccharin sodium, sorbitol solutio, glycerin, paraben concentrate, peppermint spirit BP, purified water, and syrup USP. T he final concentration of norfloxacin in the suspensions was 20 mg/ml. form ulas I and II were chemically stable for 28 days when stored in amber glass bottles at ambient temperature; however, their physical characteristics we re different.