Pharmacology Miscellaneous (Pharmacology) 13002cb8 Mechanism of action of sildenafil is A Inhibits PDE 2 B Inhibits PDE 4 C Inhibits PDE 5 D Inhibits PDE 3 High-Yield Explanation Ans. is 'c' i.e., Inhibits PDE 5 * Sildenafil (Viagra) acts to increase cGMP by inhibiting its breakdown by phosphodiesterase isoform 5 (PDE-5).