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1 Principal Pharmacist Pharmacy Department Conwy & Denbighshire NHS
Trust Glan Clwyd Hospital Rhyl LL18 5UJ, Wales fax 44-1-1745534695
uttam.chouhan{at}cd-tr.wales.nhs.uk
2 Specialist Registrar in Geriatrics and General Medicine Department of
Adult Medicine Conwy & Denbighshire NHS Trust
3 Pharmacist Pharmacy Department Conwy & Denbighshire NHS
Trust
Published Online, September 13, 2005. www.theannals.com, DOI 10.1345/aph.1G195
Case Report. A 56-year-old man was admitted to the coronary care unit with shortness of breath and palpitations. He had undergone coronary artery bypass grafting (CABG) 11 days prior to admission. His medication on admission included aspirin 75 mg/day, amlodipine 5 mg/day, simvastatin 40 mg/day, ferrous sulfate 600 mg/day, and lansoprazole 30 mg/day.
A diagnosis of supraventricular tachycardia (SVT) with pneumonia was made. Intravenous adenosine restored sinus rhythm, and oral clarithromycin 1 g/day and intravenous ceftriaxone 1 g/day were administered for the chest infection starting on hospital day 1.
On day 3, the patient had another symptomatic episode of SVT that terminated spontaneously after 10 minutes. Another symptomatic episode ensued 9 hours later that was treated with intravenous amiodarone 1.2 g/24 hours, followed by an oral loading dose of 600 mg/day for one week, then 400 mg/day for another week, and subsequently 200 mg/day. A cardiologist review on day 4 advised that amiodarone be continued for 3-4 months due to the history of recent CABG.
Over days 4-13, the patient's stay was complicated by slow-to-resolve infection, left pleural effusion, pericardial effusion, and bilateral pulmonary embolism. Even after appropriate treatment, he found it difficult to move and complained of general weakness and subsequently of muscle pain. Examination revealed proximal myopathy. As renal function was normal, statin-induced myositis was suspected. Appropriate blood tests were ordered, and results showed that creatine kinase was >20 000 IU/L. Simvastatin was stopped on day 19 and amiodarone was subsequently discontinued on day 22 due to abnormal results of liver function tests. Amiodarone plasma concentrations are not measured in our institution. The results of pertinent investigations and drug therapy in our patient are detailed in Table 1.
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Over days 22-31, the patient made slow but steady progress; he was discharged home on day 31 after admission. He was asymptomatic and appeared well when seen on day 93 in the outpatient department. Simvastatin was restarted at 10 mg/day, which the patient is tolerating well, with creatine kinase remaining within the normal range 9 months after discharge.
Discussion. A literature search revealed case reports of interactions between amiodarone and simvastatin1 and between clarithromycin and simvastatin.2 As of August 19, 2005, we are unaware of an interaction between simvastatin and the combination of amiodarone with clarithromycin. Use of the Naranjo probability scale indicated that the myositis was probably the result of an interaction between simvastatin and amiodarone/clarithromycin in this patient.3
This case illustrates the need to increase awareness of healthcare professionals of commonly used medications that, when combined with simvastatin, can lead to serious toxicity and add to a patient's length of stay.4 This case has been reported to the Committee for Safety of Medicines (CSM) in the UK and confirms the recent warning and guidance from the CSM concerning interactions with statins.5
References
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