Stability of Olmesartan Medoxomil Extemporaneous Suspensions.

Background: Olmesartan medoxomil (OLM) is only available in the United States as tablets. The United States Pharmacopoeia (USP) has placed OLM on its priority list of preparations that require stability data to support practitioner compounding. Objective: The purpose of the study was to develop a stability-indicating assay and then determine the beyond-use date (BUD) for an extemporaneous OLM suspension. Methods: A reverse-phase high-performance liquid chromatography (HPLC) assay was developed and validated according to guidelines for USP official compounded monographs. OLM 2 mg/mL suspensions were compounded with Ora-Sweet and Ora-Plus and stored at room temperature or in a refrigerator. Suspensions were assayed periodically over 90 days for OLM concentration and observed for physical stability. The pH was measured at the beginning and end of the study. Results: The OLM concentration remained above 97% of the starting concentration for 90 days when stored in the refrigerator and above 94% of the starting concentration for 90 days when stored at room temperature. The suspension pH did not change and indicators of physical stability were unchanged for 90 days. Conclusion: OLM 2 mg/mL suspensions were chemically and physically stable at room temperature and in the refrigerator for 90 days. The BUD may be set at 90 days under either storage condition.