Exploring solid states of atovaquone: crystal or glass?

Formulation design is necessary to improve drug solubility, particularly for drugs in Biopharmaceutics Classification System (BCS) classes II and IV. The formulating decision is often affected by the drug's physicochemical properties. To complement the available knowledge, the thermal and structural properties of atovaquone have been investigated. Heat was applied to raw atovaquone to observe the effect of temperature on crystalline polymorphic changes and physical state conversion. Physicochemical properties were assessed through drug content assay, differential scanning calorimetry, X-ray powder diffraction, single-crystal X-ray diffraction and attenuated total reflectance Fourier transform infrared spectroscopy. The surface morphology was observed under a scanning electron microscope. Thermal degradation of atovaquone was confirmed through drug recovery and the sublimating behaviour was observed during the heating process. Understanding the fundamental thermal and structural characteristics of atovaquone plays an important role in designing a stable product of high bioavailability.