Enteral suspension of nifedipine for neonates. Part 2. Stability of an extemporaneously compounded nifedipine suspension

Objective: To investigate the chemical, microbiological and physical stabil ity of an extemporaneously prepared nifedipine oral suspension, packaged in disposable syringes and prepared in a hospital pharmacy for paediatric use . Methods: Two different suspensions were prepared, from nifedipine tablets a nd drug powder, by using an autoclaved 1.0% solution of hypromellose as the vehicle. The final theoretical drug concentration was 1 mg/mL. Doses of 1. 0 ml were packaged into a 2 ml syringe with a cap. Nifedipine suspensions w ere stored under three conditions: at room temperature (22 degreesC), in a refrigerator (6 degreesC) protected from light, and at room temperature (22 degreesC) exposed to artificial daylight (400 lux) under controlled circum stances. The nifedipine concentration was measured in suspensions protected from light on days 0, 1, 3, 5, 7, 14, 21 and 28, and in suspensions expose d to light at 0, 3, 6, 18 and 24 h, and on days 2, 3, 5 and 7 after prepara tion. Nifedipine was analysed by a reproducible and validated stability-ind icating HPLC-method. Microbiological and physical stability of the nifedipi ne suspension samples protected from light were examined for 28 days. Results: Mean nifedipine concentration remained over 90% of the initial con centration throughout the 4-week study period in light-protected unit-dose suspensions, prepared from either crushed tablets or drug powder with hypro mellose 1.0%. When exposed to light, however, nifedipine decomposed rapidly . Photodegradation of nifedipine exceeded 25% within 3 h and was essentiall y complete within 7 days. Conclusion: In the University Hospital of Kuopio, newborns have been treate d with nifedipine suspension prepared from tablets, and preliminary experie nces with administration of suspension have been encouraging. It may also b e possible to apply this methodology to other medicines used in paediatrics .