Stability of flecainide acetate in an extemporaneously compounded oral suspension

The stability of flecainide acetate in an oral diluent stored for 45 days under various conditions was studied. A suspension was prepared by triturating 100-mg tablets of flecainide acetate with a commercially available oral diluent. The final theoretical drug concentration was 5 mg/mL. The suspension was poured into 12 2-oz amber glass prescription bottles for a per-bottle volume of 60 mL. Three bottles were refrigerated at 5 degrees C and shaken before analysis, three were stored at room temperature and shaken, three were refrigerated and not shaken, and three were kept at room temperature and not shaken. On days 0, 15, 30, and 45, flecainide acetate concentrations were determined by stability-indicating high-performance liquid chromatography. The concentration of flecainide acetate in the sediment in each bottle was determined on day 46. On day 45, the mean flecainide acetate concentration for each group of bottles remained above 90% of the initial concentration. Mean +/- S.D. flecainide acetate concentrations in sediment ranged from 0.53 +/- 0.30 to 1.18 +/- 0.36 mg per gram. Eight of the 12 samples contained microbial growth on at least one of the test days. Flecainide acetate 5 mg/mL oral suspension was stable for up to 45 days under the conditions investigated.