Atorvastatin vs Rosuvastatin

## Overview

Atorvastatin and rosuvastatin are the two most potent synthetic statins and account for the majority of statin prescriptions worldwide. Both competitively inhibit HMG-CoA reductase, the rate-limiting enzyme in hepatic cholesterol biosynthesis, but they differ in potency, pharmacokinetics, and metabolic interactions.

## Mechanism of Action

Both drugs act as competitive inhibitors of HMG-CoA reductase. Their open-acid forms mimic the transition-state intermediate of the natural substrate HMG-CoA, achieving nanomolar Ki values. Reduced hepatic cholesterol synthesis triggers compensatory LDL-receptor upregulation, increasing LDL clearance from plasma.

## Pharmacokinetics

Atorvastatin has an oral bioavailability of approximately 14% due to extensive first-pass hepatic extraction. It is primarily metabolized by CYP3A4, producing active ortho- and para-hydroxylated metabolites that contribute meaningfully to its effect. Its plasma half-life is 14 hours, but inhibitory activity persists for 20–30 hours due to active metabolites.

Rosuvastatin has a higher bioavailability (~20%) and is minimally metabolized, with only ~10% converted by CYP2C9. It is not appreciably metabolized by CYP3A4, making it far less susceptible to drug interactions with CYP3A4 inhibitors (e.g., azole antifungals, macrolides). Its half-life is approximately 19 hours.

## Pharmacodynamics

On a milligram-to-milligram basis, rosuvastatin is roughly twice as potent as atorvastatin in LDL-C lowering. Rosuvastatin 10 mg lowers LDL-C by approximately 46%, equivalent to atorvastatin 20 mg. Rosuvastatin also produces greater HDL-C increases and slightly greater reductions in hsCRP, though whether this confers additional cardiovascular benefit beyond LDL-C reduction is debated.

## Clinical Evidence

Both agents have landmark cardiovascular outcome trials. The ASTEROID trial demonstrated rosuvastatin could regress coronary atherosclerosis. JUPITER showed rosuvastatin reduced major cardiovascular events in patients with elevated hsCRP but normal LDL. Atorvastatin is supported by CARDS, ASCOT-LLA, and TNT, demonstrating consistent benefit across primary and secondary prevention populations.

## Safety

Myopathy risk is class-wide and dose-dependent. Rosuvastatin is associated with a higher rate of rhabdomyolysis in Asian populations at higher doses, leading to dose restrictions. Atorvastatin's CYP3A4-dependent metabolism creates more drug interaction risks but does not inherently increase myopathy risk.

## Key Takeaways

- Rosuvastatin is ~2× more potent per mg for LDL-C reduction
- Atorvastatin has more drug interactions via CYP3A4; rosuvastatin is safer in this regard
- Both have robust cardiovascular outcome data
- Rosuvastatin requires dose adjustment in Asian patients and renal impairment