The Zhewitra follows the usual principle of increasing the erection time that most drugs do. For a prolonged erection, two phenomena are essential. The first is muscle relaxation blockage, and the other is good blood circulation. The Zhewitra 40 blocks the phosphodiesterase PDE5 enzyme from reaching the genital muscles. As this enzyme is blocked, the muscles of the penis don’t get relaxed quickly and help you with the erection. Blockage of PDE5 allows cGMP production, which helps increase blood flow by opening the blood vessels. All the effects allow the penis to work better during the intercourse.