Stability of Allopurinol in Extemporaneously Compounded Oral Suspensions with Oral Mix and Oral Mix SF

Allopurinol is a xanthine oxidase inhibitor used to reduce the production of uric acid in the body. Commercial tablets may be crushed and suspended in a compounding vehicle and provide an alternative dosage form for patients with difficulty swallowing, such as children. The stability of a compounded preparation of allopurinol 20 mg/mL was evaluated in ready-to-use vehicles, namely Oral Mix and Oral Mix SF. A stability indicating HPLC method was developed and validated to assess the amount of allopurinol over time. Formulations were stored in tightly closed, light resistant plastic containers at both room temperature and refrigerated conditions. Chemical analysis, pH measurement and organoleptic assessment were performed at predetermined time points up to 90 days. Antimicrobial effectiveness testing was also performed after 90 days of storage at room temperature. The stability study demonstrated that the allopurinol 20 mg/mL suspensions prepared from commercial tablets in Oral Mix and Oral Mix SF was stable up to 90 days under the tested conditions.