Effect of Bezafibrate on Muscle Metabolism in Patients With Fatty Acid Oxidation Defects

The investigators propose to evaluate the effect of bezafibrate on metabolism during exercise in 22 adult patients affected with carnitine palmitoyltransferase II (CPTII) or very-long chain acyl-CoA-dehydrogenase (VLCAD) deficiencies. This study will be an 9-month, randomized, double-blind, placebo-controlled crossover trial. The trial will be conducted in two centers: Institut de Myologie, Pitié-Salpêtrière Hospital in France, and Rigshospitalet, University of Copenhagen, in Denmark. The main criteria for assessing the potential effect of this drug will be the fat oxidation rate studied during a moderate workload on cycle ergometer, after infusion of stable isotopes (palmitate and glucose tracers).