Gemfibrozil-induced myositis in a patient with normal renal function.

OBJECTIVE

To describe a case of gemfibrozil monotherapy-induced myositis in a patient with normal renal function

CASE SUMMARY

A 68-year-old white man presented to his primary care clinic complaining of a 6-month history of total body pain. His past medical history was significant for hypertension, diabetes mellitus, hyperlipidemia, gastroesophageal reflux disease, benign prostatic hypertrophy, arthritis, impotence, and pancreatic cancer that required excision of part of his pancreas. His home drug regimen included bupropion 75 mg twice daily, gemfibrozil 600 mg twice daily for the past 8 months, glimiperide 1 mg daily, insulin glargine 5 units at bedtime, insulin aspart 5 units in the evening, lisinopril 10 mg daily, omeprazole 40 mg daily, pregabalin 100 mg daily, and sildenafil 100 mg as needed. Laboratory test results were significant for elevated aspartate aminotransferase (AST) 78 U/L (reference range 15-46 U/L), alanine aminotransferase (ALT) 83 U/L (13-69 U/L), and creatine kinase (CK) 3495 U/L (55-170 U/L). Serum creatinine was normal at 1.19 mg/dL. The physician determined that the elevated CK indicated myositis secondary to gemfibrozil use, and gemfibrozil was subsequently discontinued. The patient returned 1 week later to repeat the laboratory tests. Results were CK 220 U/L, AST 26 U/L, ALT 43 U/L, and serum creatinine 1.28 mg/dL. The patient was asked to return in 3 weeks to repeat the laboratory tests. At that time, CK had continued to decrease to 142 U/L, and the AST and ALT had returned to normal, at 22 and 29 U/L, respectively. The patient reported complete resolution of total body pain 3 weeks after discontinuation of gemfibrozil. Follow-up 5 weeks after discontinuation revealed no change compared to the 3-week follow-up.

DISCUSSION

Myositis most often produces weakness and elevated CK levels more than 10 times the upper limit of normal. The risk of developing myositis, myopathy, or rhabdomyolysis is low (1%) when fibrates such as gemfibrozil are used as monotherapy. Evaluation of the literature revealed one case of gemfibrozil-related myositis in a patient with chronic renal failure. There is also one report of myopathy associated with gemfibrozil monotherapy in a patient with normal renal function. The present case is the first documented case of gemfibrozil monotherapy-induced myositis in a patient with normal renal function. The Naranjo probability scale indicated a probable relationship between gemfibrozil treatment and the onset of myositis in our patient. Other potential causes of myositis were ruled out by patient interview and chart review.

CONCLUSIONS

Although the risk of myositis appears to be low with gemfibrozil monotherapy, clinicians should be aware of the potential for this adverse event. For patients taking gemfibrozil monotherapy who present with myalgia, discontinuation of the medication may be necessary for the alleviation of pain.