Effects of tadalafil administration on plasma markers of exercise‑induced muscle damage, IL6 and antioxidant status capacity

Introduction Physical exercise is associated to enhanced production of reactiveoxygen species which if uncontrolled can result in tissue injury. Phosphodiesterasetype 5 inhibitors (PDE5i) exhibit protective effect against oxidative stress both inanimals and in healthy/unhealthy humans. Purpose The present study was designedto evaluate the effect of the long-acting PDE5i tadalafil on oxidative status and muscledamage after an exhaustive exercise in healthy males, included in a double-blindcrossover trial. Hypothesis Tadalafil having a putative antioxidant activity, may reduce oxidative damage after a strenuous exercise. Methods Each volunteer randomlyreceived two tablets of placebo or tadalafil (20 mg/day) with 36 h of interval before performing the exhaustive exercise. After a 2-wks washout, the volunteers were crossed over. Blood samples were collected immediately before exercise, immediately after, and during recovery (15, 30, 60 min). Plasma total antioxidant status (TAS), glutathione homeostasis (GSH/GSSG), malonaldehyde (MDA), protein carbonyls,creatine kinase (CK), lactate dehydrogenase (LDH) and the inflammatory cytokine interleukin 6 were assessed. Results Tadalafil administration per se affected redox homeostasis (GSH/GSSG -36%; p<0.05), cellular (CK +75% and LDH +36%; p<0.05) and oxidative damage (MDA +41% and protein carbonyls +50%; p<0.05) markers. The exhaustive exercise increased all the above reported biochemical parameters, with subjects from tadalafil group that showed significantly higher values respect to placebogroup. Conclusions A prolonged exposure to tadalafil decreases antioxidant capacityat resting condition therefore making subjects more susceptible to the oxidative stress induced by an exhaustive bout of exercise.