Filitra works by blocking the PDE5 enzyme, which normally restricts blood vessel relaxation. When this enzyme is inhibited, the smooth muscles in the penile blood vessels relax more easily, allowing increased blood flow during sexual arousal. It does not create an erection on its own and requires sexual stimulation to work. It is usually taken about 25 to 60 minutes before sexual activity, and its effects generally last around 4 to 6 hours, depending on the dose, metabolism, and individual health factors. It can be taken with or without food, although heavy or high-fat meals may slow its onset.

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