Two of these studies used fixed doses patients allocated to 25, 50 or mg and two studies were flexible patients started on 25 mg and could be moved to 50 or mg depending on their response. This medicine is authorised for use in the European Union. The logo is clickable and will appear on the sites of all online medicine retailers in the EU that are registered with their national regulatory authority. During normal sexual stimulation, cGMP is produced in the penis, where it causes the muscle in the spongy tissue of the penis the corpora cavernosa to relax, allowing the flow of blood into the corpora, producing the erection. In addition, there were studies in patients with spinal cord injury and with diabetes.For men experiencing erectile dysfunction (ED), exercising regularly can be nearly as .  · VIAGRA is supplied as blue, film-coated, rounded-diamond-shaped tablets containing sildenafil citrate equivalent to 25 mg, 50 mg, or mg of sildenafil. Tablets are debossed with PFIZER on one side and VGR25, VGR50 or VGR on the other to indicate the dosage strengths. 4. Contraindications. Although erectile dysfunction (ED) may be an upsetting diagnosis for some, many people .