Mitochondrial myopathy--a result of clofibrate/etofibrate treatment? Case report.

A 66-year-old man had developed a myopathy while undergoing several periods of etofibrate and clofibrate therapy over the past 5 years. Discontinuation of etofibrate treatment failed to reverse his muscle illness which, however, did not progress. A muscle biopsy revealed a chronic myopathy marked by abundant, abnormally structured muscle mitochondria. His mitochondrial myopathy may represent a forme fruste of the Kearns-Sayre syndrome or other types of mitochondrial myopathy, clinically made evident by the etofibrate/clofibrate therapy, or a permanent, adverse side effect of clofibrate treatment. If the latter assumption proves to be correct, it will indicate that clofibrate therapy may induce an acutely painful but reversible neuromuscular illness, or also, though rarely, a chronic mitochondrial myopathy.