Sildenafil (Viagra) is used to treat erectile dysfunction (impotence; inability to get or keep an erection) in men. Sildenafil (Revatio) is used to improve the ability to exercise in adults with pulmonary arterial hypertension (PAH; high blood pressure in the vessels carrying blood to the lungs, causing shortness of breath, dizziness, and tiredness). Children should not usually take sildenafil, but in some cases, a doctor may decide that sildenafil (Revatio) is the best medication to treat a child's condition. Sildenafil is in a class of medications called phosphodiesterase (PDE) inhibitors. Sildenafil treats erectile dysfunction by increasing blood flow to the penis during sexual stimulation. Sildenafil treats PAH by relaxing the blood vessels in the lungs to allow blood to flow easily. If you are taking sildenafil to treat erectile dysfunction, you should know that it does not cure erectile dysfunction or increase sexual desire. Sildenafil does not prevent pregnancy or the spread of sexually transmitted diseases such as human immunodeficiency virus (HIV). can i buy doxycycline online However, patient may take drug 30 minutes to 4 hours before sexual activity. as a single dose, p.r.n., 1 hour before sexual activity. Based on effectiveness and tolerance by patient, may increase dose to maximum single dose of 100 mg or decrease dose to 25 mg. A maximum recommended dosing frequency is once daily. Erectile action: Sildenafil has no direct relaxant effect on isolated human corpus cavernosum, but enhances the effect of nitric oxide (NO) by inhibiting phosphodiesterase type 5 (PDE5), which is responsible for degradation of cyclic guanosine monophosphate (c GMP) in the corpus cavernosum. When sexual stimulation causes local release of NO, inhibition of PDE5 by sildenafil causes increased levels of c GMP in the corpus cavernosum, resulting in smooth muscle relaxation and inflow of blood to the corpus cavernosum. 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Bonus 10 free pills, discounts and FREE SHIPPING. Cheapest drugs online - buy and save money. Links to other sites are provided as a convenience to the viewer. Pfizer accepts no responsibility for the content of linked sites. This website is neither owned nor controlled by Pfizer. Pfizer does not endorse and is not responsible for the content or services of this site. Continue You are now leaving to enter a website neither owned nor operated by Pfizer. Links to all outside sites are provided as a resource to our visitors and do not imply an endorsement or recommendation of a particular physician by Pfizer, nor an endorsement of any Pfizer product by a telehealth provider or any physician. Pfizer accepts no responsibility or liability for the content or services of other websites. Sildenafil is used to treat men who have erectile dysfunction (also called sexual impotence). Sildenafil belongs to a group of medicines called phosphodiesterase 5 (PDE5) inhibitors. These medicines prevent an enzyme called phosphodiesterase type-5 from working too quickly. The penis is one of the areas where this enzyme works. Erectile dysfunction is a condition where the penis does not harden and expand when a man is sexually excited, or when he cannot keep an erection. When a man is sexually stimulated, his body's normal response is to increase blood flow to his penis to produce an erection. By controlling the enzyme, sildenafil helps to maintain an erection after the penis is stroked. Sildenafil action Sildenafil Citrate, Sildenafil - Wikipedia Duloxetine 60 mg coupons Metoprolol and libido The following diagram shows how an erection is mediated and how sildenafil acts in the body. Nitric Oxide NO is released with sexual stimulation from nerve. Mode of action Sildenafil Action BestPrices! Sildenafil Mechanism of Action & Structure Efficacy and safety of sildenafil citrate Viagra for the treatment of erectile dysfunction in men in Egypt and South Africa. International Journal of Impotence Research ; 15suppl 1 S25-S29. McCullough, A. R. et al 2002. cytotec pastillas See risks and benefits of VIAGRA® sildenafil citrate. Find causes of erectile dysfunction ED, or impotence. Learn how VIAGRA® can help treat ED. Levitra and Viagra are very similar medications being prompt acting with a relatively short duration of action. Cialis has a longer onset and longer overall effect – in some men up to 3 days.