Stability of suspension formulations of lansoprazole and omeprazole stored in amber-colored plastic oral syringes

OBJECTIVE: To determine the stability of lansoprazole and omeprazole suspensions at ambient and refrigerated temperatures using HPLC. DESIGN, The contents of lansoprazole and omeprazole capsules were suspended in separate flasks containing sodium bicarbonate 8.4% to concentrations of 3 and 2 mg/mL, respectively. The contents of each flask were drawn into six amber-colored oral syringes, with one-half of the syringes stored at 22 degrees C; (ambient) and the other half at 4 degrees C. Lansoprazole and omeprazole concentrations were determined by a stability-indicating HPLC assay at baseline and at 4, 8, 12, and 24 hours, and on days 4, 7, 14, 21, 30, 45, and 60 after mixing. Both omeprazole and lansoprazole were considered stable ii they retained greater than or equal to 90% of the baseline drug concentration. RESULTS: Omeprazole was stable for up to 14 days at 22 degrees C and 45 days at 4 degrees C. Lansoprazole was stable for eight hours at 22 degrees C a,,and for 14 days at 4 degrees C. CONCLUSIONS: When compared with ambient or refrigerated storage conditions, omeprazole was stable for a longer duration than lansoprazole. Pharmacists may use these results to guide compounding and storage of proton-pump inhibitor suspensions.