PDE5A and pulmonary arterial hypertension: Sildenafil (SIL) is a phosphodiesterase type 5 (PDE5) inhibitor, and used as a potent vasodilator approved by regulatory agencies for the treatment of erectile dysfunction (Viagra®) and pulmonary hypertension (PAH) (Revatio®) (Ghofrani et al., 2006; FDA, 2018; EMA, 2022).