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Sildenafil can cause hypotension (abnormally low blood pressure that can lead to fainting and even shock) when given to patients who are taking nitrates (for heart disease). Therefore, patients taking nitrates daily should not take sildenafil. Nitrates are used most commonly to relieve angina (chest pain due to insufficient blood supply to the heart muscle because of narrowing of the coronary arteries); these include nitroglycerine tablets, patches, ointments, sprays, and pastes, as well as isosorbide dinitrate, and isosorbide mononitrate. Other nitrates such as amyl nitrate and butyl nitrate also are found in some recreational drugs called "poppers." buy generic cialis online no prescription cialis online
Who should not use vardenafil (Levitra)? Vardenafil (Levitra) can cause hypotension (abnormally low blood pressure, which can lead to fainting and even shock) when given to patients who are taking nitrates. People taking nitrates daily should not take vardenafil. Most commonly used nitrates are medications to relieve angina (chest pain due to insufficient blood supply to heart muscle because of narrowing of the coronary arteries). These include nitroglycerine tablets, patches, ointments, sprays, pastes, and isosorbide dinitrate and isosorbide mononitrate. Other nitrates such as amyl nitrate and butyl nitrate are found in some recreational drugs called "poppers." best place to buy levitra online cheap levitra online
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Viagra online usa Metabolism (breakdown) of sildenafil is slowed by aging, liver and kidney dysfunction, and concurrent use of certain medications (such as erythromycin -- an antibiotic, and protease inhibitors, for HIV). Slowed breakdown allows sildenafil to accumulate in the body and potentially may increase the risk of side effects. Therefore in men over 65, in men with substantial kidney and liver disease, and in men who also are taking protease inhibitors, the doctor will initiate sildenafil at a lower dose (25 mg) to avoid accumulation of sildenafil in the body. A protease inhibitor ritonavir (Norvir) is especially potent in increasing the accumulation of sildenafil, thus men who are taking Norvir should not take sildenafil doses higher than 25 mg and at a frequency of no greater than once in 48 hours. A study done at the Medical College of Georgia has found that venom from the Brazilian wandering spider contains a toxin, called Tx2-6, that causes erections. Scientists believe that combining this toxin with existing medication such as Viagra may lead to an effective treatment for erectile dysfunction. viagra online jersey buy viagra online
Erection begins with sexual stimulation. Sexual stimulation can be tactile (for example, by touching the penis) or mental (for example, by having sexual fantasies). Sexual stimulation or sexual arousal generates electrical impulses along the nerves going to the penis and causes the nerves to release nitric oxide, which in turn increases the production of cyclic GMP (cGMP) in the smooth muscle cells of the corpora cavernosa. The cGMP causes the smooth muscles of the corpora cavernosa to relax and allow rapid blood flow into the penis. The incoming blood fills the corpora cavernosa, making the penis expand. So, even if the nerves or blood vessels going to your penis are not working so well, a tablet can cause the blood flow to increase in your penis, and cause an erection. Tablets can treat ED caused by various underlying conditions. Note: none of these tablets will cause an erection unless you are sexually aroused. Duplex ultrasound is used to evaluate blood flow, venous leak, signs of atherosclerosis, and scarring or calcification of erectile tissue. Injecting prostaglandin, a hormone-like stimulator produced in the body, induces erection. Ultrasound is then used to see vascular dilation and measure penile blood pressure.