Simvastatin vs Lovastatin

## Overview

Simvastatin and lovastatin are closely related semisynthetic statins. Simvastatin is a dimethylated derivative of lovastatin with about twice the potency. Both are prodrug lactones activated by in vivo hydrolysis and are extensively metabolized by CYP3A4.

## Mechanism of Action

Both are prodrugs hydrolyzed to active beta-hydroxy acids that competitively inhibit HMG-CoA reductase. Their structural similarity (simvastatin differs by one methyl group) means largely overlapping pharmacodynamics.

## Pharmacokinetics

Lovastatin bioavailability is only ~5% and is enhanced by food (should be taken with meals); simvastatin bioavailability is similarly low (~5%) and food interaction is less marked. Both have short half-lives (2–3 h) and are CYP3A4 substrates with comparable drug interaction profiles.

## Pharmacodynamics

Simvastatin is approximately 2× more potent than lovastatin on a weight basis. Lovastatin 40 mg achieves ~31% LDL-C reduction; simvastatin 20 mg achieves similar results. At maximum doses, lovastatin 80 mg reduces LDL ~40%, while simvastatin 40 mg (restricted maximum) reduces LDL ~38%.

## Clinical Evidence

Lovastatin's AFCAPS/TexCAPS trial demonstrated primary prevention benefit in normal-LDL, low-HDL patients. Simvastatin is supported by larger trials (4S, HPS). Neither is considered high-intensity; both are classified as moderate-intensity at standard doses.

## Safety

Both share the same CYP3A4-dependent interaction risks. Lovastatin 80 mg shares the same FDA concerns as simvastatin 80 mg. Grapefruit juice significantly increases lovastatin and simvastatin exposure (CYP3A4 inhibition in gut wall).

## Key Takeaways

- Simvastatin is structurally a dimethyl analog of lovastatin with ~2× potency
- Both are CYP3A4 prodrugs with overlapping interaction profiles
- Both largely superseded by atorvastatin and rosuvastatin for high-intensity use