nitroglycerin, Nitro-Bid, Nitro-Dur, Nitrostat, Transderm-Nitro, Minitran, Deponit, Nitrol (cont.)

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Transdermal patches also are used for prevention. The usual dose is 0.2-0.8 mg/hr applied for 12 hours and then removed. An additional 12 hours should be allowed before applying the next patch because a 12 hour nitroglycerin free period reduces the occurrence of tolerance to the effects (reduced effectiveness) of nitroglycerin. Patches may be applied to any hairless site but should not be applied to areas with cuts or calluses which can alter absorption. Firm pressure should be used over the patch to ensure contact with the skin. The patch should not be cut or trimmed. Patches are waterproof and should not be affected by showering or bathing.

Capsules of long-acting nitroglycerin also are used for prevention. The usual dose is 2.5-9 mg administered 2 to 3 times per day 1 to 2 hours after a meal. Capsules should be swallowed whole and not chewed.

DRUG INTERACTIONS: Since nitroglycerin can cause hypotension (low blood pressure), other medications which also cause hypotension may produce severe hypotension. Such drugs might include medicines used to treat high blood pressure, some antidepressants; some anti-psychotics, quinidine (Quinaglute, Quinidex), procainamide (Pronestyl, Procan-SR, Procanbid), benzodiazepines such as diazepam (Valium) or opiates, for example, morphine. Since alcohol also may intensify the blood pressure lowering effect of nitroglycerin, patients receiving nitroglycerin should be advised to drink alcoholic beverages with caution.

Sildenafil (Viagra), tadalafil (Cialis) and vardenafil (Levitra) exaggerate the blood pressure lowering effects of nitroglycerin and may cause excessive blood pressure reduction. Patients taking nitrates should not receive sildenafil, tadalafil or vardenafil.

Ergot alkaloids, for example, ergotamine with caffeine-rectal (Cafergot, Migergot), and sumatriptan (Imitrex) can oppose the vasodilatory actions of nitroglycerin and may cause angina. A similar effect can occur with ephedrine and the decongestants pseudoephedrine (Sudafed) and propanolamine which is contained in many drugs used for treating the symptoms of colds.

PREGNANCY: Nitroglycerin has not been adequately studied in pregnant women.

NURSING MOTHERS: It is not known if nitroglycerin is secreted in breast milk.

SIDE EFFECTS: A persistent, throbbing headache commonly occurs with nitroglycerin therapy. Aspirin, acetaminophen, or ibuprofen may be used to relieve the pain. Flushing of the head and neck can occur with nitroglycerin therapy as can an increase in heart rate or palpitations. This can be associated with a drop in blood pressure which can be accompanied by dizziness or weakness. To reduce the risk of low blood pressure, patients often are told to sit or lie down during and immediately after taking nitroglycerin.

Reference: FDA Prescribing Information

Last Editorial Review: 3/26/2009

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