And just what exactly does nitric oxide do? Blood vessels use the chemical as a signal to surrounding muscles to relax, which increases blood flow -- a necessity for staying erect. where to buy viagra online buy viagra Another treatment regimen is injection therapy. One of the following drugs is injected into the penis: papaverine, phentolamine, and prostaglandin E1. levitra no prescription What precautions should be taken when using tadalafil? In most healthy men, some of the drug will remain in the body for more than two days after a single dose of tadalafil. Metabolism (clearing of the drug from the body) of tadalafil can be slowed by liver disease, kidney disease, and concurrent use of certain medications (such as erythromycin, ketoconazole, and protease inhibitors). Slowed breakdown allows tadalafil to stay in the body longer and potentially increase the risk for side effects. online generic cialis cialis online levitra no prescription Several other medications are being studied for treating erectile dysfunction; these include IC351 (another PDE5 inhibitor), sublingual apomorphine, and the combination of yohimbine and L-arginine. Scientists also are researching gene therapy to treat erectile dysfunction. Medications: Many common medicines produce erectile dysfunction as a side effect. Medicines that can cause erectile dysfunction include many used to treat high blood pressure, antihistamines, antidepressants, tranquilizers, and appetite suppressants. Examples of common medicines that can cause erectile dysfunction include propranolol (Inderal) or other beta-blockers, hydrochlorothiazide, digoxin (Lanoxin), amitriptyline (Elavil), famotidine (Pepcid), cimetidine (Tagamet), metoclopramide (Reglan), indomethacin (Indocin), lithium (Eskalith, Lithobid), verapamil (Calan, Verelan, Isoptin), phenytoin (Dilantin), and gemfibrozil (Lopid). When Should I Call My Doctor About Sexual Dysfunction? Many men experience a problem with sexual function from time to time. However, when the problems are persistent, they can cause distress for the man and his partner and have a negative impact on their relationship. If you consistently experience sexual function problems, see your doctor for evaluation and treatment. Surgery to repair arteries (penile arterial reconstructive surgery) can reduce impotence caused by obstructions that block the flow of blood to the penis. The best candidates for such surgery are young men with discrete blockage of an artery because of a physical injury to the pubic area or a fracture of the pelvis. The procedure is less successful in older men with widespread blockage of arteries. levitra no prescription cialis online purchase generic buy cialis