Canadian Pharmacy
Viagra: Consumer Information (MedFacts)
Generic Name: Sildenafil Tablets 25 mg, Sildenafil Tablets 50 mg, Generic Viagra 100 mg.
Sildenafil citrate, sold under the names Viagra, Revatio, Generic Viagra and under various other names, is a drug used to treat male erectile dysfunction (impotence) and pulmonary arterial hypertension (PAH). Its primary competitors on the market are tadalafil (Cialis), and vardenafil (Levitra).
Viagra is used for:
Treating erectile dysfunction (ED). It may also be used for other conditions as determined by your doctor.
Viagra is a phosphodiesterase inhibitor. It works by helping to increase blood flow into the penis during sexual stimulation. This helps you to achieve and maintain an erection.
Mechanism of action
Part of the physiological process of erection involves the parasympathetic nervous system causing the release of nitric oxide (NO) in the corpus cavernosum of the penis. NO binds to the receptors of the enzyme guanylate cyclase which results in increased levels of cyclic guanosine monophosphate (cGMP), leading to smooth muscle relaxation (vasodilation) of the intimal cushions of the helicine arteries, resulting in increased inflow of blood and an erection.
Sildenafil is a potent and selective inhibitor of cGMP specific phosphodiesterase type 5 (PDE5) which is responsible for degradation of cGMP in the corpus cavernosum. The molecular structure of sildenafil is similar to that of cGMP and acts as a competitive binding agent of PDE5 in the corpus cavernosum, resulting in more cGMP and better erections. Without sexual stimulation, and therefore lack of activation of the NO/cGMP system, sildenafil should not cause an erection. Other drugs that operate by the same mechanism include tadalafil (Cialis) and vardenafil (Levitra).
Sildenafil is metabolised by hepatic enzymes and excreted by both the liver and kidneys. If taken with a high-fat meal, there may be a delay in absorption of sildenafil and the peak effect might be reduced slightly as the plasma concentration will be lowered.
How to use Viagra :
Use Viagra as directed by your doctor. Check the label on the medicine for exact dosing instructions.
An extra patient leaflet is available with Viagra . Talk to your pharmacist if you have questions about this information.
Take Viagra by mouth with or without food. Viagra may not work as quickly if you take it with a high-fat meal.
Viagra is usually taken about 1 hour before sexual activity. However, it may be taken anywhere from 4 hours to ½ hour before sexual activity. Talk with your doctor about the best way to take Viagra .
Do not take Viagra more often than once daily, or as directed by your doctor.
If you miss a dose of Viagra and you still intend to engage in sexual activity, take it as soon as you remember. Continue to take it as directed by your doctor.
Ask your health care provider any questions you may have about how to use Viagra .
Some information about Viagra Professional or Generic Viagra
Viagra is a prescription drug, but You can purchase viagra online at our licensed pharmacy shop: Online canadian pharmacy
Source: http://www.drugs.com/ & http://wikipedia.org