Pharmacy Letter to GP: Statin-Associated Muscle Pain

Dear Dr Ross, I am writing regarding your patient, Mr Peter Hall, who reported muscle pain when collecting his prescriptions today. I am concerned that this may be related to his atorvastatin, and I would be grateful if you could review his treatment. Mr Hall has been experiencing aching in his thighs and calves for the past two weeks. This began shortly after his atorvastatin dose was increased from 20 mg to 80 mg one month ago. He reports no dark urine or muscle weakness, and he takes paracetamol only occasionally. Furthermore, yesterday an out-of-hours doctor prescribed clarithromycin 500 mg twice daily for a chest infection. As clarithromycin significantly increases atorvastatin levels, this combination raises the risk of more serious muscle toxicity. I have advised Mr Hall to withhold his atorvastatin while he completes the clarithromycin course and to seek urgent advice if he develops weakness or dark urine. I would recommend checking his creatine kinase and reviewing his statin dose once the antibiotic course has finished. Thank you for your attention to this matter. Please do not hesitate to contact me if you require any further information. Yours sincerely, Community Pharmacist