Solubility and bioavailability improvement of pazopanib hydrochloride
Theanti-cancer drug pazopanib hydrochloride (PZH) has a very low aqueous solubility and a variable oral bioavailability. A new pharmaceutical formulation with an improved solubility may enhance thebioavailability and reduce the variability. A broad selection of polymer excipients was tested for their compatibility and solubilizing properties by conventional microscopic, thermal andspectrometric techniques. A wet milling and mixing technique was used to produce homogenous powder mixtures. The dissolution properties of the formulation were tested by a pH-switch dissolutionmodel. The final formulation was tested in vivo in cancer patient following a dose escalation design. Ofthe tested mixture formulations, the one containing the co-block polymer Soluplus® in a 8:1 ratio with PZH performed best in terms of in vitro dissolution properties. The in vivo results indicated that 300 mg of the developed formulation yields similar exposure and a lower variability(379 μg/mL∗h (36.7% CV)) than previously reported values for the standard PZH formulation (Votrient®) at the approved dose of 800 mg. Furthermore, the expected plasma-Cthrough levels (27.2 μg/mL) exceeds the defined therapeutic efficacy threshold of 20 μg/mL.