The effect of naftidrofuryl on the metabolic response to exercise in man.

We have designed this investigation to determine whether naftidrofuryl has an effect upon metabolism in vivo in man. Five subjects were studied during and after steady exercise on a bicycle ergometer. On the first occasion they received naftidrofuryl (300 mg orally) 20-40 min before exercise; and on the second they exercised without the drug to provide control observations. Blood samples were taken for the estimation of glucose, pyruvate, lactate, glycerol, acetoacetate and 3-hydroxybutyrate. Exercise with naftidrofuryl caused a significantly greater rise in blood pyruvate concentration during the exercise and post-exercise period compared with the controls. Changes in glucose, lactate, glycerol and ketone-bodies were not significantly different from the control values. Lactate/pyruvate ratios were significantly reduced with naftidrofuryl during the post-exercise period. Exercise causes a rise in intracellular anaerobic metabolism with associated increases in blood lactate/pyruvate ratios. This is followed by enhanced oxidative capacity during the recovery period as adduced from falling lactate/pyruvate ratios. The greater decline in lactate/pyruvate ratios with naftidrofuryl during the post-exercise period is evidence that naftidrofuryl is able to enhance cellular oxidative activity in vivo in man. Further studies in clinical situations are therefore indicated.