Description
Nitrocor Pharmacodynamics
The effects of nitroglycerin are due to its ability to release from its molecule nitric oxide, which is a natural endothelial relaxing factor. Nitric oxide increases the intracellular concentration of cyclic guanosine monophosphatase, which prevents the penetration of calcium ions into the smooth muscle cells and causes them to relax. The relaxation of the smooth muscles of the vascular wall causes vasodilation, which reduces the venous return to the heart (preload) and the resistance of the great circle of circulation (postload). This reduces heart function and myocardial oxygen demand. Dilation of the coronary vessels improves coronary blood flow and helps redistribute it to areas with decreased blood flow, which increases oxygen delivery to the myocardium.
Decrease of venous return leads to decrease of filling pressure, improvement of subendocardial blood supply, decrease of pressure in the small circle of circulation and regression of symptoms in pulmonary edema. Nitroglycerin has a central inhibitory effect on sympathetic vascular tone, depressing the vascular component of pain syndrome formation. Nitroglycerin also relaxes smooth muscle cells of bronchi, urinary tract, gall bladder, bile ducts, esophagus, small and large intestine as well as their sphincters. The action of Nitrocor® starts quickly, the effect develops within 1-1.5 minutes and lasts about 30 minutes.
Indications
For stopping and prophylaxis of angina attacks.
Contraindications
– shock;
– vascular collapse;
– acute myocardial infarction with low left ventricular filling pressure;
– Arterial hypotension (systolic BP below 90 mmHg);
– Recent head trauma;
– hemorrhagic stroke;
– conditions accompanied by decreased left ventricular filling pressure (constrictive pericarditis, isolated mitral stenosis);
– Closed-angle glaucoma;
– hypertrophic cardiomyopathy (exacerbation of angina pectoris is possible);
– toxic pulmonary edema;
– concomitant use of sildenafil;
– pregnancy;
– Lactation (breastfeeding);
– childhood;
– Hypersensitivity to nitrates.
Dosage and administration.
- In angina pectoris Nitrocor should be taken sublingually immediately after the occurrence of pain in a dose of 1 tablet. In many patients with stable angina pectoris the effect comes from a smaller dose (1/2-1/3 of a tablet). Therefore, if the pain goes away quickly, it is advisable to spit out the remainder of the tablet that has not dissolved. Usually the antianginal effect is seen after 0.5-2 min; in 75% of patients – after 3 min, in 15% of patients – within 4-5 min. If there is no antianginal effect during the first 5 min, 1 more tablet should be taken If there is no therapeutic effect after taking 2-3 tablets, the patient should immediately call the doctor. The duration of action of Nitrocor is about 45 min.
- With frequent attacks of angina it is advisable to prescribe prolonged forms of nitrates. If an angina attack occurs against the background of treatment with prolonged nitrates, sublingual nitroglycerin should be taken to stop an acute attack. Tolerance to sublingual nitroglycerin forms develops infrequently, however, if it occurs in some patients, the dose must be gradually increased to 2-3 pills.
