Kinetic study of degradation of Rosuvastatin calcium to Rosuvastatin-lactone under different solvents conditions

Rosuvastatin calcium (RST) is a medication used to lower cholesterol levels by increasing the number of low-density lipoprotein receptors on the cell surface. RST undergoes different degradation processes under different conditions (Thermal, light, acidity?etc.) leading to the formation of different degradation products; 5-oxo isomer, anti-isomer, and lactone form of RST. Lactone form of RST is the major degradation product. Chromatographic techniques were used to identify and quantitatively determine the concentration of RST and its degradation products, where the aqueous aprotic solvent mixture (acetonitrile (25): water (75)) is used as an extraction medium to release RST and its degradation product RST-Lactone from the dosage form. Unfortunately, the presence of water in the extraction mixture or mobile phase could enhance the acid hydrolysis of lactone (i.e., conversion of RST-Lactone into RST) during ?