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Safety of intravenous nitroglycerin after adminis-
Though the Viagra group tolerated less nitroglycerin than the tration of sildenafil citrate to men with coronary
placebo group, the difference was less dramatic than might have artery disease: A double-blind, placebo-con-
been feared, and cases of hypotension were short-lived upon dis- continuation of the nitroglycerin. In the Viagra group, 59% of the trolled, randomized, crossover trial.
men tolerated a nitroglycerin rate of 80 mcg/min, and 25% tolerated 160 mcg/min. The corresponding percentages were 88 and 59 for Crit Care Med. 2007; 35(8): 1863-8 If the need arises, despite the presence of Viagra, intravenous nitroglycerin may be safely administered to men with coronary Reviewer: Theodore A. Alston, MD, PhD
artery disease. Of course, it is necessary to titrate the nitroglycerin slowly and to monitor hemodynamics vigilantly (with Viagra on Abstract:
Comments:
The package inserts for Viagra, Levitra, and Cialis warn that Nitroglycerin and its congeners generate nitric oxide, which nitrates simply should not be administered while those phosphodies- stimulates an enzyme within vascular smooth muscle cells to pro- terase inhibitors are active. However, there are situations in which it duce cyclic-GMP, which causes the muscle cells to relax. Viagra may be desirable to do so. For instance, the inhibitors sometimes tee and its congeners inhibit phosphodiesterase 5, the smooth muscle up the prelude to an urgent need for coronary intervention. Also, the enzyme that destroys cyclic-GMP. So, the two classes of drugs are inhibitors reduce pulmonary vascular resistance in cardiovascular synergistic vasodilators. This synergy has prompted very conserva- patients who may develop angina or acutely worsened heart failure. tive recommendations in package inserts. It is said that all nitrates Consequently, investigators from Toronto, Minneapolis, Edinburgh, should be withheld for 24 h after Viagra and for 24 h after Cialis.
and Jacksonville (and from the Pfizer firm) have re-examined the The conservative recommendations are probably a good idea in contraindication of nitroglycerin by Viagra.
case of nitrates that are given in relatively uncontrolled doses or as Thirty-four men with stable angina and a >50% stenosis of at long-acting drugs. Examples include sublingual, transdermal, and least one coronary artery had any nitrates held and received Viagra spray-type nitroglycerin, and enterally absorbed nitrates. However, (100 mg PO) or placebo. After 45 min, intravenous nitroglycerin intravenous nitroglycerin (and nitroprusside) should be regarded was started at 5 mcg/min and, if tolerated, increased incrementally as reasonable options despite inhibition of phosphodiesterase 5. to 160 mcg/min over 1 h. The protocol was discontinued for non- The paper by Parker and colleagues should reduce the possibility invasive systolic blood pressure drop of >35 mmHg, systolic blood that some patients might urgently receive, for instance, intra-aortic pressure <100 mmHg, heart rate increase of 25 bpm, or heart rate balloon pumps or endotracheal intubation when intravenous nitro- >100 bpm. Crossover from the Viagra to placebo group, or vice glycerin would have sufficed to provide stabilization.
versa, occurred after a few days. Interestingly, 2 men did not receive nitroglycerin after Viagra because the systolic blood pressure fell after Viagra alone. In the other cases, very small changes occurred

Source: http://www.scahq.org/sca3/newsletters/2008aug/LitReview4.pdf