Viagra has come under repeated attention, especially regarding its interaction with nitrates. We feel, nonetheless, that repeating the warning that "Viagra and Nitrates Don't Mix" is important and may, we hope, save the lives of any persons who may now be taking the two types of drugs or may consider doing so in the future.
The US Food and Drug Administration (FDA) has warned against the use of the impotence drug Viagra by persons taking medications that contain nitrates. The FDA's warning was issued in conjunction with Pfizer, the manufacturer of Viagra (generic name: sildenafil).
Viagra and nitrates both cause the muscles that control the size of blood vessels to relax. When these muscles relax, the vessels enlarge in diameter and, as a result, blood pressure drops. When Viagra and nitrates are taken together, the effects are greater than when either one is used alone. There may be a marked relaxation of the muscles that control the vessels with a great drop in blood pressure.
A drastic drop in blood pressure is detrimental to patients who have angina pectoris (heart pain), a condition in which a higher blood pressure is necessary to supply the heart with blood. Lowering the blood pressure decreases the flow of blood to the heart and can precipitate a heart attack.
Persons who are using medications containing nitrates should therefore NOT take Viagra. As of November 1998, 130 deaths had been associated with the use of Viagra in the U.S. Sixteen of the men who died had also taken a nitrate.
Since sexual activity or exercise can precipitate a heart attack
in patients with angina pectoris, it may not have been the use of Viagra+ nitrates that was responsible for all of the deaths.
However, it would seem better to be safe than sorry and NOT mix Viagra and nitrates.
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Identifying a nitrate these days is far from simple. There are over 20 prescription forms of nitrate drugs. Given so many, it is nearly impossible to remember all of them.
Here is a list of some of the nitrate drugs to which you may refer. (In this list, the chemical name of drug is in bold lower case letters and the corresponding brand names are in capital letters).
Nitro-BID (and Nitro-BID ointment)
Nitrol ointment (APPLI-KIT)
Viagra also causes an additional reduction in blood pressure when administered with amlodipine (Norvasc, Lotrel), a calcium channel blocking drug used to treat high blood pressure and angina pectoris.
However, Viagra has not been reported to cause symptoms of low blood pressure (such as dizziness) in patients taking beta blockers (e.g., metoprolol), ace inhibitors (e.g., enalapril), alpha blockers (e.g., prazosin) or diuretics (e.g., hydrochlorothiazide).