best place to buy viagra online brand viagra without prescription online The first published efficacy trial of sildenafil involved only 12 patients, but it is the only study that included objective measurements of penile rigidity.20 In the first phase of this study, penile rigidity was measured using plethysmography during visual sexual stimulation in patients taking varying doses of sildenafil or placebo. In the men who took the 50-mg dose of sildenafil, the mean duration of erection was increased by 10 minutes at the base of the penis and six minutes at the tip of the penis compared with placebo. The second phase of this study involved a diary of erectile activity in which 10 of 12 patients reported improved erectile activity while receiving sildenafil. Thyroid function tests–Thyroid hormones regulate metabolism and the production of sex hormones; a deficiency may contribute to impotence. No reports proving benefit Erectile Dysfunction Medication Side effects
