Levitra is the trade name for the drug 'vardenafil', which was synthesized in the last decade as a treatment for erectile dysfunction.
Its main market competitor is Viagra, the trade name of the Pfizer drug 'sildenafil citrate', and Levitra works on the same principle as Viagra.
cGMP is responsible for causing the arterial muscles in the penis to relax. This, in turn, allows more blood to flow into the penis, and causes it to become rigid. PDE5 works on the body, breaking down the cGMP and preventing it from working to achieve an erection. PDE5 Inhibitors, such as Levitra, work by blocking the action of the cGMP and allowing the extra blood flow to the penis to continue.
This treatment is particularly effective because it works in conjunction with other mechanisms, brought on by sexual stimulation. This means that the drug is taken alongside erotic stimuli - and an erection is produced; but without the stimuli, there is no erection. Levitra should be taken between twenty-five and sixty minutes before sexual intercourse is to take place, and will continue to work on the body up to five hours after the dose has been adminstered.