Sildenafil citrate is the salt present in the Cenforce brand. It obstructs the action of enzyme PDE- 5 which prolongs the duration of the erection of the penis in males. A variety of brands of this salt are available in the market. Also, it available in varying strengths. Your physician may prescribe the strength best suited for you. Initially, most men have prescribed 50 Mg and the dose may be escalated or reduced depending on the acceptance of the body.