Stability of Oseltamivir Phosphate in SyrSpend SF, Cherry Syrup, and SyrSpend SF (For Reconstitution).

Oseltamivir (Tamiflu) is widely prescribed to treat and prevent influenza virus A, influenza virus B, and H1N1 Flu. It is manufactured by Roche in 75-mg capsules. The need for other administration options for patients who cannot take capsules and cannot use suspending agents which contain alcohol, sorbitol, or preservatives has led to the compounding of oseltamivir into three suspending vehicles that do not contain these chemicals. All three contain neither alcohol nor sorbitol; the third also has no preservatives, a distinct advantage for special patient situations. The objective of this study was to determine the stability of oseltamivir in three different suspending agents: SyrSpend SF, Cherry Syrup, and SyrSpend SF (for reconstitution). The studied samples were compounded into 15-mg/mL suspensions and stored in low actinic plastic prescription bottles at temperatures between 2 degrees Celsius and 8 degrees Celsius. Triplicate samples were assayed at time intervals out to 30 days by a stability-indicating high-performance liquid chromatography method. The method was validated for its specificity through forced degradation studies. All of the samples tested remained within 90% to 110% of their initial concentrations throughout the course of the study. The shelf life of these products is at least 30 days, based on data collected when the aforementioned products are refrigerated and protected from light. Based on the final potency data at day 30, the shelf life may extend past the scope of this study, but 30 days was the limit of this study.