Zhewitra 20 mg contains Vardenafil, a potent PDE5 inhibitor that enhances blood flow to the penis. This mechanism is crucial for achieving and sustaining erections, as ED often stems from inadequate blood circulation to the genital area. By inhibiting PDE5 enzymes, Zhewitra 20 mg allows for smooth muscle relaxation in the penile region, facilitating increased blood flow during sexual stimulation.