Assessing the impact of quaternary ammonium compounds with different stoichiometric ratio on atorvastatin calcium solubility

Co-crystallisation of atorvastatin calcium (ATC) at different molar ratio with choline chloride (CC) and benzalkonium chloride (BAC) was carried out using the solvent evaporation method in methanol. The solids obtained were characterised by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), and powder X-ray diffraction (PXRD). Solubility studies were performed in different media including distilled water, pH 1.2, pH 4.5 and, pH 6.8. PXRD revealed the co-amorphous nature of the developed formulations. FT-IR and DSC confirmed the structural changes and formation of amorphous structures. Results revealed that the solubility increased marginally. ATC-BAC showed the highest drug solubility and a 3.8-fold increase in drug solubility. These comprehensive approaches suggest that the ATC-BAC amorphous system had solubility advantages and it might provide a theoretical basis for its application in transdermal delivery of ATC.