Active ingredient of Forzest is Tadalafil, third member of the family PDE-5 inhibitors.In the presence of sexual stimulation, Forzest enables a long-lasting and firm erection. It has properties that enhances the flow of the blood to the penis which cures erectile dysfunction. Sustaining a full erection is brought about by nitric oxide which increases the manufacture of cyclic Guanosine Monophosphate (cGMP) in the male organ. This cGMP causes muscle relaxation in the penis and increases blood flow in the erectile tissues. Synthesis of cGMP is regulated by Phosphodiesterase type 5 (PDE-5) in the body. This means that more the amount of PDE-5 present in the body, less is the level of cGMP. Inhibition of this enzyme by Forzest (containing Tadalafil) increases the production of cGMP thus producing a full-fledged erection for a long time.