Vardenafil in Filitra 10 mg works by inhibiting the PDE5 enzyme, which normally breaks down cyclic GMP (cGMP) in the penis. Increased levels of cGMP allow the smooth muscles in the penis to relax, dilating the blood vessels and improving blood flow. This enhanced circulation makes it easier to achieve and sustain an erection when sexually aroused. Filitra typically begins working within 30 minutes and provides effects that last for up to 4-5 hours.