This updated Medicines Q&A evaluates the evidence for an interaction between erythromycin and statins.
- Erythromycin raises the plasma levels of statins which are metabolised by CYP3A4 (i. atorvastatin and simvastatin), but in practice not all patients are affected.
- Simvastatin is contraindicated in patients taking erythromycin and should be withdrawn if the antibiotic is required for the duration of the antibiotic treatment course and then restarted.
- Atorvastatin and erythromycin may be used together with caution. It may be prudent to withhold atorvastatin if erythromycin treatment is required to avoid any potential adverse effects. If concurrent administration is unavoidable, then a lower dose of atorvastatin (maximum 20mg daily) should be considered.
- The interaction between erythromycin and statins that are metabolised by CYP3A4 can be delayed such that the patient experiences the effects after the erythromycin course has been completed.
- Fluvastatin, pravastatin and rosuvastatin are not metabolised by CYP3A4, however pravastatin exposure is possibly slightly increased by erythromycin, suggesting that another mechanism of interaction may be involved such as inhibition of OATP1B1 and OATP1B3.
- Rosuvastatin and fluvastatin do not appear to be affected by erythromycin in pharmacokinetic studies, and therefore an increased risk of rhabdomyolysis with these statins and erythromycin would seem unlikely. However until more information is available in relation to other potential interaction mechanisms, caution is advised with the concomitant use of erythromycin with fluvastatin, pravastatin and rosuvastatin.
- If co-prescription with a drug that increases systemic exposure to statins is unavoidable, it is particularly important to start on the lowest statin dose. Any patient who is given a statin concomitantly with a macrolide antibiotic such as erythromycin should be warned to be alert for any signs of myopathy (i.e. unexplained muscle pain, tenderness or weakness or dark coloured urine). If myopathy does occur, the statin should be stopped immediately.