Preparation and stability of extemporaneous oral liquid formulations of oseltamivir using commercially available capsules

To develop a simple, standardized method for the extemporaneous compounding of an oral liquid form of oseltamivir from commercially available Tamiflu 75 mg capsules (Roche Pharmaceuticals) and to determine the stability of oseltamivir in this preparation. Chemical and microbial stability study. Laboratory. None. Extemporaneous oral liquid formulations of oseltamivir (15 mg/mL) were prepared in Cherry Syrup (Humco) and Ora-Sweet SF (Paddock Laboratories) using methods consistent with current compounding practice in a pharmacy setting. Preparations were stored in amber glass and amber polyethyleneterephthalate bottles at 5°C ± 2°C (41°F ± 4°F) and 25°C ± 2°C (77°F ± 4°F) at 60% ± 5% relative humidity (RH) for 35 days and 30°C ± 2°C (86°F ± 4°F) at 65% ± 5% RH for 13 days. Samples were monitored for appearance, pH, assay, degradation products, and microbiologic stability. The Cherry Syrup preparation, in either bottle type, was stable for up to 35 days under refrigeration (5°C) and up to 5 days at room temperature (25°C). It was not stable when stored at 30°C for 5 days. The Ora-Sweet SF preparation was stable for up to 35 days at 5°C or 25°C and for up to 13 days at 30°C in either bottle type. Both preparations maintained microbiologic stability for 35 days. Both preparations are stable under the described conditions and may provide an option in situations where the marketed suspension is unavailable.