Cenforce 150 Sildenafil citrate belongs to the class of drugs that inhibit the enzyme phosphodiesterase 5 (PDE-5). This category of drugs is known to relax blood vessels and improve blood flow. Therefore, they are used to treat pulmonary hypertension and erectile dysfunction. Cenforce 150 mg contains sildenafil which protects cyclic guanosine monophosphate (cGMP) from the destruction of the PDE-5 enzyme (present in the p*nis wall). CGMP is produced as a result of the release of nitric oxide in the muscles of the p*nis and the release of NO is the result of s*xual stimulation.