Stability of norfloxacin in an extemporaneously prepared oral liquid

Abstract

The stability of norfloxacin in an extemporaneously prepared suspension stored at room temperature and under refrigeration was studied over 56 days. A 20-mg/mL suspension was prepared from commercially available 400-mg norfloxacin tablets and equal amounts of Ora-Plus and strawberry syrup to make a final volume of 60 mL. Six identical samples of the suspension were prepared in amber plastic prescription bottles. Three were stored at room temperature (23-25 °C) and three under refrigeration (3-5 °C). Immediately after preparation and at 7, 14, 28, and 56 days, the samples were assayed in duplicate by stability-indicating high performance liquid chromatography. The samples were also inspected for color and odor changes and the pH of each sample was determined. At least 93% of the initial norfloxacin concentration remained throughout the 56-day study period. The color, odor, and pH of all of the samples did not change appreciably. An extemporaneously prepared suspension of norfloxacin 20 mg/mL was stable for at least 56 days when stored at either 23-25 or 3-5 °C.