Sildenafil Isosorbide dinitrate

A 58-year-old man with a history of angina for which he occasionally takes isosorbide dinitrate is having erectile dysfunction. He confides in a colleague who suggests that sildenafil might help and gives him three tablets from his own prescription. The potentially lethal combination of these drugs relates to... 

Isordil is a proprietary (trade name) preparation of isosorbide dinitrate, a nitrate. Sildenafil, the active ingredient of Viagra, interacts with nitrates and the two active ingredients should not be administered concurrently, as a significant hypotensive effect may occur. 

Isosorbide Dinitrate Hydralazine (BiDil) [Antianginal, Antihypertensive/Vasodilator, Nitrate] Uses HF in African Amer-icans improve survival functional status, prolong time between hospitalizations Action Relaxes vascular smooth muscle peripheral vasodilator Dose Initially 1 tab tid PO (if not tol ated reduce to 1/2 tab tid), titrate >3-5 d as tolerated Max 2 tabs tid Caution [C, /-] recent MI, syncope, hypovolemia, hypotension, hep impair Contra For children, concomitant use w/ PDE5 inhibitors (sildenafil) Disp Tabs SE HA, dizziness, orthostatic hypotension, sinusitis, GI distress, tach, paresthesia, amblyopia Interactions t Risk of severe hypotension W/ antihypertensives, ASA, CCBs, MAOIs, phenothiazides, sildenafil, tadalafil, vardenafil, EtOH X pressor response Wf i -1- effects W7 NSAIDs EMS Use ASA, antihypertensives and CCBs w/ caution, may t hypotension concurrent Viagra-type drug use can lead to profound hypotension concurrent EtOH use can t effects OD May cause N/V, profound hypotension, skin flushing, HA from ICP, bradycardia, confusion, and circulatory collapse activated charcoal may be effective, epi use is contraindicated... 

Patients suffering from angina pectoris should also use glyceryl trinitrate or isosorbide dinitrate as usual for pre-exertional prophylaxis 10 min before intercourse. They should be aware of the potentially fatal interaction of sildenafil (Viagra) with nitrates (see above, p. 545). 

The phosphodiesterase type-5 inhibitors potentiate the hypotensive effects of nitrates in a proportion of patients, which might re-suit in potentiaiiy serious hypotension or even precipitate myocardiai infarction. Therefore, the concurrent use of sildenafil, tadalafil or vardenafil with organic nitrates (glyceryl trinitrate (nitroglycerin), isosorbide dinitrate, isosorbide mononitrate, etc.) is contraindicated. The concurrent use of nicorandil and all phosphodiesterase type-5 inhibitors is also contraindicated. 

The interaction between phosphodiesterase type-5 inhibitors and nitrates is established, clinically important, potentially serious and even possibly fatal. Sildenafil and organic nitrates of any form are contraindicated both for erectile dysfunction (within 24 hours of each other ) and for pulmonary hypertension because of the risk of precipitating serious hypotension, or even myocardial infarction. The ACC/AHA Expert consensus document provides a useful list of many of the organic nitrates available, whieh inelude glyeeryl trinitrate (nitroglycerin), isosorbide mononitrate, isosorbide dinitrate and illicit substances such as amyl nitrite. ... 

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