Development and Stability Study of Oseltamivir Reconstitutable Dry Suspension from Capsules

Oseltamivir phosphate (OSEL) is recommended for the prevention and treatment of influenza virus infection. In a hospital pharmacy, OSEL liquid extemporaneous preparation is generally compounded on a case-by-case basis from the capsules because it can be stored for a certain period. Therefore, the objective of the current research was to develop an oseltamivir reconstitutable dry suspension (ORDS), and to evaluate the stability of the ORDS. The dry-suspending vehicles were first developed and subjected to stability tests. The stable vehicle was selected to mix with the content of OSEL capsules and dry powder was termed ORDS. The stability of ORDS was then tested in both dried and reconstituted states. It was found that the dry vehicle using xanthan gum as a suspending agent (at 0.25% w/v of the reconstituted suspension) was the most stable formulation at 25°C and 45°C under 75% relative humidity (RH) for 28 days. Upon mixing with OSEL capsule contents, ORDS in the dried state showed no change in either physical or chemical properties after storing at room temperature for 7 days. For the reconstituted state, the ORDS showed no change in odor and pH after storing at 2°C to 8°C in a refrigerator, and 25°C and 45°C under 75%RH for 14 days. However, its color was slightly darker after storing at 45°C. The percentage remaining OSEL at the refrigerator temperatures was 98.13% ± 1.63%, at 25°C was 100.30% ± 0.71% and at 45°C was 97.54% ± 1.38%. In conclusion, ORDS may be a convenient alternative to extemporaneous preparations. Keywords: Oseltamivir capsule, Reconstitutable dry suspension, Extemporaneous, Physico-chemical stability, Influenza