Adults

The usual starting dose is 10 mg or 20 mg once daily. The dose can be titrated to 10 mg to 80 mg once daily based on patient response and lipid targets.

Elderly

No dosage adjustment is required based on age.

Renal_impairment

No dosage adjustment is required for patients with renal impairment.

Onset

Lipid-lowering effects typically observed within 2 weeks, with maximal effect usually within 4 weeks.

Excretion

Primarily excreted in bile after hepatic metabolism; less than 2% of the dose is recovered in urine.

Half life

Parent drug approximately 14 hours; active metabolites contribute to ~20-30 hours of HMG-CoA reductase inhibitory activity.

Absorption

Rapidly absorbed after oral administration; absolute bioavailability is approximately 12%. Peak plasma concentrations achieved within 1-2 hours.

Metabolism

Extensively metabolized in the liver by cytochrome P450 3A4 (CYP3A4) to ortho- and parahydroxylated derivatives and various beta-oxidation products. These metabolites are also active.

Warfarin

Atorvastatin may potentiate the anticoagulant effect of warfarin; INR should be monitored.

Colchicine

Cases of myopathy, including rhabdomyolysis, have been reported with co-administration of atorvastatin and colchicine.

Niacin (lipid-lowering doses)

Increased risk of muscle-related adverse events, including rhabdomyolysis.

Gemfibrozil and other fibrates

Increased risk of myopathy/rhabdomyolysis when co-administered with statins.

Strong CYP3A4 inhibitors (e.g., cyclosporine, clarithromycin, itraconazole)

May significantly increase atorvastatin plasma concentrations, increasing the risk of myopathy/rhabdomyolysis.