Objective: To determine the stability of nifedipine in two oral suspensions stored at 4 degrees C and 25 degrees C in plastic prescription bottles over a 3-month period.
Design: Two suspensions were prepared: 1% methylcellulose:simple syrup NF (1:13) stored in ten 2 oz bottles; and Ora Plus:Ora Sweet (1:1) at a nifedipine concentration of 4 mg/mL also stored in ten 2 oz bottles. Five bottles of each formulation were stored at 4 degrees C, and the rest of the bottles were stored at 25 degrees C. Three samples were collected from each bottle at 0, 7, 14, 28, 42, 56, 70, and 91 days and analyzed by a stability-indicating high-performance liquid chromatography analytic method (n = 15).
Setting: Laboratory.
Results: At 4 degrees C, the mean concentration of nifedipine was nearly 100% that of the original concentration in both the Ora Plus-Ora Sweet and the 1% methylcellulose-syrup formulations during the 3-month study period. At 25 degrees C, the mean +/- standard deviation concentration of nifedipine was 98.9% +/- 2.36% of the initial concentration in the Ora Plus-Ora Sweet and 97.4% +/- 2.48% in the 1% methylcellulose-syrup formulation over the 3-month period. No changes in pH or physical appearance were observed.
Conclusion: Nifedipine can be prepared in two liquid dosage forms and stored for up to 3 months under refrigeration or at room temperature.