Hypothesis of COVID‑19 Therapy with Sildenafil

Backgound: Bacterial or viral infections often cause acute and severe systemic inflammation, which affects the lungs lipopolysaccharide (LPS), a pathogenic component of the membrane of gram‑negative bacteria, stimulates active innate immune cells, monocytes, macrophages to produce inducible nitric oxide synthase (iNOS). Excess production of this compound occurs in COVID‑19 resulting in inflammatory cascade and thromboembolism. We intend to propose the use of sildenafil to reduce this production. Method: The analysis of biochemical pathways shows that viral infection produces a high amount of nitric oxide (NO), with an acute inflammatory process. Results: In the case of COVID‑19 infection we verified that numerous biochemical processes activate a cascade of inflammatory processes through the activation of iNOS with uncontrolled generation of (NO). Conclusions: iNOS is the cause of damage to host cells with a consequent pulmonary thromboembolic lung phenomenon in a contest of interstitial pneumonia. This study proposes the use of sildenafil to counter the inflammatory cascade and thromboembolic episodes.