Pharmacology General e67beafc Tadalafil inhibits A PDE - 3 B PDE - 4 C PDE - 5 D PDE - 6 High-Yield Explanation Tadalafil & Sildenafil inhibits Phosphodiesterase - 5 (PDE -5) and increase cGMP, They are used in pulmonary hypertension & erectile dysfunction.