Stability of cisapride in a liquid dosage form at two temperatures

OBJECTIVE: To determine the stability of cisapride in a liquid dosage form stored in plastic bottles at 2 temperatures. DESIGN: Cisapride tablets were used to prepare a suspension in equal volumes of methylcellulose 1% and simple syrup to yield a concentration of 1 mg/mL. The cisapride suspension was stored in 10 amber plastic prescription bottles. Five bottles were stored at room temperature (25 +/- 0.1 degrees C) and 5 under refrigeration (4 degrees C). Samples were drawn from each bottle immediately after mixing (day 0), and at 7, 14, 28, 42, 56, 70, and 91 days of storage at each temperature. All samples were analyzed in duplicate on each day of analysis. Cisapride was measured by a stability-indicating HPLC method. RESULTS: The mean concentration of cisapride exceeded 90% of its initial concentration throughout the 91-day study period at 4 degrees C, but only during the first 28 days at 25 degrees C. No significant change in pH was observed during the study period. CONCLUSIONS: Cisapride was stable in a suspension for 91 days at 4 degrees C and 28 days at 25 degrees C in amber plastic prescription bottles.