Mechanism of Drug Release From Temperature-Sensitive Formulations Composed of Low-Melting-Point Microcrystalline Wax

Quality aspects in the development of pelletized dosage forms

The aim of this work was to identify and collate the major common challenges that arise during pellet development. These challenges focus on aspects right from raw material properties until the final drying process of the pelletization. The challenges associated with the particle size of drug and excipients, physicochemical properties, drug excipient interaction and the effect of type/grade and amount of raw material on the pellet properties are covered in this review. Technological and process related challenges within the commonly used pelletization techniques such as extrusion-spheronization, hot-melt extrusion and layering techniques are also emphasized. The paper likewise gives an insight to the possible ways of addressing the quality of pellets during development.

In vivo temperature-sensitive drug release system trigged by cooling using low-melting-point microcrystalline wax

Temperature-sensitive formulations are attractive controlled-release formulations, which release an incorporated drug by changes in body temperature induced by external temperature stimulation. Recently, it has been reported that wax matrix (WM) particles composed of a low-melting-point microcrystalline wax (MCW) released only a small amount of the drug at 37 °C, whereas faster drug release occurred at 25 °C. In this study, temperature-sensitive formulations composed of low-melting-point MCW that release drugs triggered by cooling, rather than heating, were developed. In an in vitro dissolution test in which the test medium was repeatedly cooled from 37 to 25 °C, control of the promotion and suppression of drug release was achieved. The drug concentration in the plasma of rats administered the particles was significantly increased by cooling compared with non-cooling, indicating that the drug release from the particles was promoted by cooling both in vitro and in vivo. Therefore, particles composed of low-melting-point MCW should be useful for the development of cooling-triggered, temperature-sensitive formulations.