Diluted Nitroglycerin equivalent to Nitroglycerin 0.5 mg.
Pharmacology: Pharmacodynamics: Relaxation of vascular smooth muscle is the principal pharmacologic action of MYONIT INSTA. Although venous effects predominate, MYONIT INSTA produces, in a dose-related manner, dilation of both arterial and venous beds. Dilation of the post-capillary vessels, including large veins, promotes peripheral pooling of blood and decreases venous return to the heart, reducing left ventricular end-diastolic pressure (preload). Arteriolar relaxation reduces systemic vascular resistance and arterial pressure (afterload). Myocardial oxygen consumption or demand (as measured by the pressure-rate product, tension-time index and stroke-work index) is decreased by both the arterial and venous effects of MYONIT INSTA, and a more favourable supply demand ratio can be achieved.
Therapeutic doses of MYONIT INSTA may reduce systolic, diastolic and mean arterial blood pressure. Effective coronary perfusion pressure is usually maintained, but can be compromised if blood pressure falls excessively or increased heart rate decreases diastolic filling time.
Evaluated central venous and pulmonary capillary wedge pressures, pulmonary vascular resistance and systemic vascular resistance are also reduced by MYONIT INSTA therapy. Heart rate is usually slightly increased, presumably a reflex response to the fall in blood pressure.
Mechanism of Action: The mechanism of action of MYONIT INSTA has been extensively studied. It is believed that MYONIT INSTA and the other organic nitrates lead to the formation of the reactive free radical nitric-oxide(NO), which can interact with and active guanylyl cyclase and increase the synthesis of cGMP in smooth muscle and other tissues. The increase in cGMP leads to the increased stimulation of a cGMP-dependent protein kinase, which results in the alteration of the phosphorylation of various proteins in smooth muscle. This eventually leads to the dephosphorylation of the light chain of myosin. Since phosphorylation of the myosin light chain regulates the maintenance of the contractile state in smooth muscle, this dephosphorylation causes a relaxation in the smooth muscle and hence vasodilation.
Pharmacokinetics: MYONIT INSTA is rapidly absorbed following sublingual administration. Its onset of action is approximately one to three minutes. Significant pharmacologic effects are present for 30 to 60 minutes following administration by the previously mentioned route.
MYONIT INSTA is rapidly metabolized to dinitrates and mononitrates, with a short half-life, estimated at 1 to 4 minutes. At plasma concentrations of between 50 and 500ng/ml, the binding of nitroglycerin to plasma proteins is approximately 60%, while that of 1,2 dinitroglycerin and 1,3 dinitroglycerin is 60% and 30% respectively. The activity and half-life of 1,2 dinitroglycerin and 1,3 dinitroglycerin are not well characterized.
MYONIT INSTA as a short-acting vasodilator in the prophylaxis and continued treatment of angina pectoris; congestive heart failure.
The tablet should be dissolved under the tongue or in the buccal pouch at the first sign of an acute anginal attack. The dose may be repeated approximately every five minutes until relief is obtained. If the pain persists after a total of 3 tablets in a 15 minutes period, the physician should be notified. MYONIT INSTA tablets may be used prophylactically five to ten minutes prior to engaging in activities, which might precipitate an acute attack.
Mode of Administration: Oral-Sublingual.
Symptoms and Treatment of Overdose: Bluish skin, clammy skin, colic, coma, confusion, diarrhoea (may be bloody), difficult and/or slow breathing, dizziness, fainting, fever, flushed skin, persistent, throbbing headache, increased pressure within the skull, irregular pulse, loss of appetite, nausea, palpitations (an abnormally rapid throbbing or fluttering of the heart), paralysis, rapid decrease in blood pressure, seizures, slow or fast pulse/heartbeat, sweating, vertigo, visual disturbances, vomiting. If these occur, dose should be reduced.
Sublingual MYONIT INSTA therapy is contraindicated in patients with early myocardial infarction with right ventricular involvement, obstructive hypertrophic cardiomyopathy, pronounced hypovolemia, severe anemia, cardiac tamponade, increased intracranial pressure, and those with a known hypersensitivity to MYONIT INSTA.
Not recommended for phenyketonuric due to the substance aspartame.
Pregnancy: Animal reproduction studies have not been conducted with MYONIT INSTA. It is also not known whether nitroglycerin can cause fetal harm when administered to a pregnant women or can affect reproduction capacity. MYONIT INSTA should be given to a pregnant woman only if clearly needed.
Nursing Mother: It is not known whether MYONIT INSTA is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when intravenous MYONIT INSTA is administered to a nursing woman.
Nitroglycerin may cause flushing of the face, dizziness, tachycardia, and throbbing headache. Large doses cause vomiting, restlessness, blurred vision, hypotension (which can be severe), syncope and rarely cyanosis, and methaemoglobinaemia: impairment of respiration and bradycardia may ensue. Sublingual or buccal Nitroglycerin tablets usually produce a localized burning sensation.
Concomitant use of nitrates and alcohol may cause hypotension. Patients receiving antihypertensive drugs, beta-adrenergic blockers, or phenothiazines and nitrates should be observed for possible additive hypotensive effects. Patients on nitrates should not take sildenafil.
Carcinogenesis, mutagenesis, impairment of Fertility: No long-term studies in animals were performed to evaluate the carcinogenic potential of MYONIT INSTA.
Store below 30°C, protected from light and moisture.
Tablets should be stored in the original container which should be kept tightly closed.
Shelf-Life: 2 years.
Tablets should be stored in the original container which should be kept tightly closed and using tablets within 8 weeks after opening of a bottle and discard remaining tablets after 8 weeks of opening of bottle if unused.
C01DA02 - glyceryl trinitrate ; Belongs to the class of organic nitrate vasodilators. Used in the treatment of cardiac disease.
Myonit Insta SL tab 0.5 mg