The active component Avanafil in Stendra is an S-enantiomer, a chemical derivative of pyrimidine. As Avanafil is a PDE5 inhibitor drug, it efficiently palliates ED by inhibiting the type-5 phosphodiesterase (PDE5) enzyme, which is a cGMP chemical. This process contracts the arteries and causes a lack of blood flow to the penile organ. After the inhibition of the PDE5 enzyme, the level of nitric oxide in the body elevates and improves blood supply. Simultaneously, nitric oxide stimulates the level of cGMP. This results in the enhanced blood supply to the phallus, which results in the desired erection.