Clarithromycin × Rosuvastatin

Cytochrome P450 enzymes play almost no part in breaking down rosuvastatin, so the rosuvastatin SmPC does not expect interactions through these enzymes. The documents contain no study of rosuvastatin with clarithromycin. The rosuvastatin SmPC lists macrolide antibiotics among drugs that increased the incidence of myositis and myopathy with other statins, and the clarithromycin SmPC reports rhabdomyolysis in patients taking clarithromycin with statins.

Unexplained muscle pain, weakness or cramps, especially with malaise or fever, and raised creatine kinase on blood tests (rosuvastatin SmPC). In rhabdomyolysis the urine turns dark and kidney function can suffer.

The clarithromycin SmPC asks for caution when clarithromycin is combined with any statin and for monitoring for signs of myopathy. If the combination cannot be avoided, the statin is prescribed at the lowest registered dose (clarithromycin SmPC), which for rosuvastatin is 5 mg. The same SmPC suggests considering a statin that does not depend on CYP3A4, such as fluvastatin. Ask the patient to report unexplained muscle pain, weakness or cramps promptly. Check creatine kinase if they occur; stop rosuvastatin if it is more than 5 times the upper limit of normal or if muscle symptoms are severe and cause daily discomfort (rosuvastatin SmPC).