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Labetalol, the main active ingredient of Trandat, an A-blocker, is 2-7 times less potent than phentolamine (regitin), and as a B-blocker it is 5-18 times less potent than propranolol; these facts promote the wide use of preparation. The drug blocks the A-and B-adrenergic receptors in a ratio of 1:3. The blood pressure reduction is mainly achieved due to a decrease in peripheral resistance while maintaining or slightly decreased cardiac output.
Trandat pharmacological action
Labetalol reduce plasma renin activity. However, in combination with a diuretic renin its activity increases and the hypotensive effect is significantly enhanced. This indicates the independence of the hypotensive effect of renin plasma. The drug increases the level of potassium in the blood plasma. When administered intravenously at a dose of 2.1 mg/kg of body weight rapidly Trandat relieves hypertensive crisis. Following intravenous administration, a slight tachycardia occurs. The noteworthy feature of labetalol (unlike in propranolol) of quick blood pressure lowering when administered intravenously indicates that the hypotensive effect largely depends on the B-adrenoceptor blocking properties of the remedy.
Indications for use:
• Hypertension of varying severity, especially juxtaposed with angina (the treatment course is started with minimal doses following a gradual increase);
• Hypertensive crisis
• Reducing high blood pressure both at rest and under stressful conditions;
• Reducing the level of renin and aldosterone in the blood plasma;
• Elimination of reflex tachycardia.
Labetalol is rapidly absorbed from the gastrointestinal tract. The maximum drug concentration in plasma observed within 2 hours after ingestion. Almost 50% of the drug is bound to the protein state. Following intravenous administration, the peak concentration occurs after 2 minutes, but after 8.5 minutes it drops. The half-life equals approximately 3.5-4.5 hours and is not altered in patients with renal insufficiency. The form release is typically tablets of 100 mg and 200 mg, 20 mL vials containing 100 mg of labetalol.
Trandat is administered intravenously or 100-125 mg in a single bolus or in the form of slow drip infusion (50-200 mg / day) in 200 ml of isotonic sodium chloride solution or 5% glucose solution. Pereorally it is prescribed to be taken at 100 mg 3 times daily after meals. Dose increased gradually at intervals of 1 week to a maximum of 2000-2400 mg/day. Labetalol may be and oftentimes combined with a variety of diuretics and B-blockers.
The drug is administered intravenously at a hypertensive crisis and pereorally in case of hypertension and pheochromocytoma (at 800-6400 mg/day).
Trandat is contraindicated in atrioventricular block, a tendency to bronchospasm, in the first months of pregnancy. It should be emphasized that in recent years, large volumes of data have been acquired on the high clinical efficacy with a mixed mechanism of action, which affects different links regulation of blood pressure (these products necessarily present B-adrenoceptor blocking properties). The medications are primarily applied within monotherapy courses.
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