Stability of temozolomide in solutions aimed for oral treatment prepared from a commercially available powder for infusion

BACKGROUND: Temozolomide (TMZ) is an alkylating agent with a broad spectrum of antitumor activity, including brain tumors in children. The oral use of TMZ is hampered by the lack of a suitable galenic formulation, since the capsules of TMZ (Temodal™) are large and difficult to swallow. A powder for preparation of a TMZ solution for intravenous administration (2.5 mg/mL) has recently been approved. A possibility to use this formulation for oral administration would facilitate TMZ administration. AIM: The aim of the present study was to investigate the stability of TMZ in solutions prepared from the commercially available powder for intravenous infusion. MATERIALS AND METHODS: Solutions were prepared from the intravenous formulation by dissolving the powder in water. The degradation of TMZ was studied photometrically at 330 nm in two solutions, 2.5 mg/mL at room temperature (RT; 22°C) and 1.25 mg/mL at 5°C, prepared from the intravenous formulation. RESULTS: More than 90% of TMZ remained intact after storage for 9 days at RT (2.5 mg/mL) and 13 weeks at 5°C (1.25 mg/mL). CONCLUSIONS: The high stability of a TMZ solution prepared from the powder for infusion formulation makes it suitable for oral administration. Oral use of a TMZ solution facilitates administration of the drug to patients with difficulties to swallow capsules, and enables a more flexible and precise dosing.