Bioavailability of azacitidine subcutaneous versus intravenous in patients with the myelodysplastic syndromes

The primary objectives of this study were to characterize the absolute bioavailability of azacitidine after subcutaneous (SC) administration and to compare the single-dose pharmacokinetics of azacitidine following SC and intravenous (IV) administration. Six patients with myelodysplastic syndromes were randomly assigned according to a crossover design to treatment A, consisting of azacitidine administered as a single 75-mg/m² SC dose, or treatment B, consisting of azacitidine administered as a single 75-mg/m ² IV infusion dose over 10 minutes. A minimum of 7 days and a maximum of 28 days were permitted between treatments. The study demonstrated good bioavailability of a SC azacitidine dose compared to an IV infusion treatment. The exposure profiles following SC drug administration illustrate measurable azacitidine levels with bioavailability (AUC) values within 89% of those measured following IV administration (range, 70%-112%). The median IV half-life was 0.36 ± 0.02 hours compared to 0.69 ± 0.14 hours for SC administration. Regardless of the route of administration, a single dose of azacitidine, 75 mg/m², was generally well tolerated.