(3R,5S)-Atorvastatin sodium is primarily used as a lipid-lowering agent in the treatment of hypercholesterolemia and dyslipidemia. It works by inhibiting HMG-CoA reductase, an enzyme involved in cholesterol synthesis in the liver, thereby reducing LDL cholesterol and triglycerides while increasing HDL cholesterol. This makes it effective in preventing cardiovascular diseases such as heart attacks and strokes, particularly in patients with risk factors like diabetes or hypertension. It is often prescribed as part of a comprehensive treatment plan that includes diet, exercise, and lifestyle modifications. Additionally, it is used in the management of familial hypercholesterolemia and as a secondary prevention measure in patients with existing cardiovascular conditions.