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Nitrates : Definition, Mechanism, Therapeutic, Indications, Side effects, Precautions and Drug Interactions

Tuesday, September 11th 2012. | Medical Treatment

Nitrates Definition

Nitrates are drugs used for their vasodilatory properties, particularly in the treatment of angina (or angina pectoris) and heart failure.

Nitrates are drugs used for their vasodilatory properties, particularly in the treatment of angina (or angina pectoris) and heart failure.

There are several forms of nitrates, corresponding to specific situations.

  • The nitrated immediate action is the treatment of angina pectoris. They are administered sublingually, and the form of chewable pill slowly and keep in mouth or oral solution spray (spray).
  • The long-acting nitrates, used in the chronic treatment of coronary artery disease, they increase exercise tolerance in patients with stable angina of effort, delay the time to onset of angina and Sub-ST segment elevation.
  • Nitrates injecting intravenously used in acute heart failure.

Nitrates

Nitrates Mechanism

Nitrates are donors of nitric oxide (NO), which causes relaxation of smooth muscle fibers of the vessels.

The main actions of nitrates are:

  • Venous vasodilation predominant and responsible for a decrease in venous return, thus cardiac preload.
  • Coronary vasodilation, which associated with a decrease in the left ventricular pressure (due to the reduction of preload), leads to a redistribution of coronary perfusion, to subendocardial areas particularly susceptible to ischemia.
  • Antispastic action in coronary.
  • Peripheral arteriolar vasodilation resulting in a reduction in peripheral vascular resistance, and therefore cardiac afterload (blood volume remaining after injection).

All these effects contribute at rest or exertion, decreased myocardial oxygen demand and an increase in oxygen supply, which explains the use of nitrates in angina pectoris.

In addition, the decrease in cardiac venous return, which is accompanied by a decrease in pulmonary capillary pressures, coupled with the decrease in afterload, when high doses of nitrates are causing indications of nitrates in heart failure or left whole.

 Absorption, elimination, metabolism and half-life of a product are important parameters because they determine the mode of administration of the product and the number of daily doses to maintain efficacy.

Nitrates are metabolized in the liver, the effect of 1 st pass metabolism is very important because it makes their low bioavailability, oral, less than 10% of the ingested dose. Where the route of administration sublingual tablet or spray, to obtain therapeutic blood levels rapidly.But in this case, the effect duration is short, the half-life of about 15 minutes. However, it is quite suitable for the treatment of angina pectoris.

For sustained release forms, the half-life of about 5 hours due to active metabolites. The product is also metabolized by the liver and excreted in the urine administered doses are calculated based on the digestive absorption, which is not very high.

Nitrates Therapeutic Goals

Taking nitrates aims to:

  • Reduce the frequency and intensity of painful episodes in the myocardium.
  • Reduce morbidity mortality myocardial infarction.

Nitrates Indications

Nitrates are listed in:

  • The treatment and prevention of angina attacks, and sublingual forms for sustained release.
  • The acute pulmonary edema, left ventricular failure in the acute stage of myocardial infarction, unstable angina in for injectable forms.

Nitrates Side effects

These are some complications that can occur when taking the drug, knowing that induced side effects vary among individuals.

When taking nitrates have been reported:

  • Dose-dependent headache, flushing, rarely nausea, vomiting, worsening of migraines.
  • A decrease in blood pressure and discomfort by orthostatic hypotension.

Nitrates Precautions

The vasodilators, antihypertensives, diuretics and alcohol may increase the hypotensive effects of nitrates, for simple shapes.

For sustained release forms, the effective dosage should be achieved progressively, because of the risk of headache, and hypotension, and secondly not crash in case of prolonged treatment.

Pregnancy and lactation

Except in acute situations, the use of nitrates is not recommended during pregnancy.

Breastfeeding is not recommended during treatment.

Driving and using machines

Patients should be warned that early treatment, there is a risk of orthostatic hypotension may be accompanied by dizziness, fainting or exceptionally of syncope.

Nitrates lifestyle

Avoid drinking alcohol.

Nitrates drug interactions

Associations with derivatives: sildenafil, vardenafil, tadafil due to risk of sudden hypotension are cons-indicated.

Associations with alcohol nitrates, antihypertensives, diuretics and vasodilators are taken into account, due to a possible increase of hypotension.

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