Forzest is a very effective and quick acting oral medication to treat impotency and erection issues in men. This generic version of Cialis has been manufactured by Ranbaxy Pharmaceuticals. Forzest contains Tadalafil, which is the active ingredient that helps in increased blood circulation to the penile region. With improved blood flow, impotent men are able to obtain hard-on. This medicament remains effective for 24 to 36 hours in the body.