atorvastatin and erythromycin

MajorAvoid this combination where possible.

Mechanism

Erythromycin inhibits CYP3A4, the enzyme responsible for atorvastatin metabolism, leading to increased plasma concentrations of atorvastatin.

What it means clinically

Increased atorvastatin levels raise the risk of dose-related adverse effects, particularly myopathy and rhabdomyolysis. Patients may present with muscle pain, weakness, and elevated creatine kinase.

What to do

Avoid co-prescription when possible. If the combination is necessary, consider using a less interacting macrolide (e.g., azithromycin) or reduce the atorvastatin dose. Monitor patients for muscle symptoms and check creatine kinase if symptoms occur.

Evidence

Well-established interaction; documented in product labelling and multiple case reports and studies.

The two drugs

atorvastatinHMG-CoA reductase inhibitorsRead the monograph erythromycinmacrolide antibioticRead the monograph

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Other interactions involving atorvastatin or erythromycin

Educational reference for students and clinicians in training. It does not replace professional judgement, local protocols or current prescribing information.