Figure 5.
PDE5 inhibitors (e.g., Cialis and Viagra) increase the cyclic GMP levels in blood vessels that supply oxygen to skeletal muscles. PDE5 inhibitors are possibly effective for treating or preventing activity-induced fatigue and muscle damage in muscular dystrophy patients (e.g., dystrophinopathies, and possibly sarcoglycanopathies and dystroglycanopathies).