Labetalol Hydrochloride
Labetalol is an adrenergic receptor-blocking agent that has both selective alpha 1-adrenergic and nonselective beta-adrenergic receptor-blocking actions. Both the alpha and beta-blocking actions of Labetalol contribute to a decrease in blood pressure in hypertensive patients.Labetalol Hydrochloride is completely absorbed from the gastrointestinal tract with peak plasma levels occurring 1 to 2 hours after oral administration. The plasma half-life of Labetalol following oral administration is about 6 to 8 hours. Approximately 55% to 60% of a dose appears in the urine as conjugates or unchanged Labetalol within the first 24 hours of dosing. Doses of Labetalol Hydrochloride that controlled hypertension did not affect renal function in mildly to severely hypertensive patients with normal renal function.
Oral:Adult: The recommended initial dosage is 100 mg twice daily whether used alone or added to a diuretic regimen. The usual maintenance dosage of Labetalol Hydrochloride is between 200 and 400 mg twice daily.Patients with severe hypertension: May require from 1,200 to 2,400 mg per day, with or without thiazide diuretics. Titration increments should not exceed 200 mg twice daily.Elderly Patients: The majority of elderly patients will require between 100 and 200 mg twice daily.Injection/Infusion:Intravenous Injection: If it is essential to reduce the blood pressure quickly a dose of 50 mg should be given by intravenous injection (over a period of at least one minute) and, if necessary, repeated at five minute intervals until a satisfactory response occurs. The total dose should not exceed 200 mg.Intravenous Infusion: For intravenous infusion the injcetion should be diluted with a suitable intravenous infusion fluid to a concentation of 1 mg/1 ml. Compatible fluids include solution of 5% Dextrose, 0.9% Sodium Chloride and mixture of Sodium Chloride and Dextrose Injection.Hypertension in pregnancy: Initially 20 mg/hour, then doubled every 30 minutes until a satisfactory response is obtained or a dosage of 160 mg/hour is reached.Hypertension following acute myocardial infarction: Initially 15 mg/hour and gradually increased to a maximum of 120 mg/hour depending on the control of blood pressure.Hypertension after stroke: 10-20 mg by intravenous injection over 1 to 2 minutes may repeat or doubled every 10 minutes. (max. dose 300 mg).Hypertension due to other causes: Infuse at a rate of about 2 mg/min until a satisfactory response is obtained, then stop infusion. The effective dose is usually 50-200 mg but larger doses may be needed, especially in patients with phaeochromocytoma.Hypotensive anaesthesia: The recommended starting dose of Labetalol Injection is 10-20 mg intravenously depending on the age and condition of the patient. Patients for whom halothane is contraindicated usually require a higher initial dose of 25-30 mg. If satisfactory hypotension is not achieved after 5 minutes, increments of 5-10 mg should be given until the desired level of blood pressure is attained.
Labecard may enhance the hypotensive effects of halothane. Care should be taken if labetalol is used concomitantly with either Class I antiarrhythmic agents or calcium antagonists of the verapamil type. The hypotensive effect of Labecard may be reduced when used in combination with prostaglandin synthetase inhibitors (NSAIDs). Dosage adjustments may therefore be necessary. Concomitant use of tricyclic antidepressants may increase the incidence of tremor. Cimetidine may increase the bioavailability of Labecard and care is required in oral dosing of the latter.
Labetalol is contraindicated for patients known to have hypersensitivity to the medicine. Labetalol is contraindicated in second or third degree heart block, infranodal A-V block, uncontrolled heart failure, sick-sinus syndrome, cardiogenic shock and other conditions associated with severe and prolonged hypotension or severe bradycardia, and bronchial asthma or other obstructive lung disorders.
Adverse effects reported are postural hypotension (avoid upright position during and for 3 hours after intravenous administration), tiredness, weakness, headache, rashes, scalp tingling, difficulty in micturition, epigastric pain, nausea, vomiting; liver damage.
Teratogenic studies were performed with Labetalol in rats and rabbits at oral doses up to approximately six and four times the maximum recommended human dose (MRHD), respectively. No reproducible evidence of fetal malformations was observed. Labetalol Hydrochloride given to pregnant women with hypertension did not appear to affect the usual course of labor and delivery. Small amounts of Labetalol (approximately 0.004% of the maternal dose) are excreted in human milk. Caution should be exercised when Labetalol tablets are administered to a nursing woman.
There have been rare reports of severe hepatocellular injury with Labecard therapy. The hepatic injury is usually reversible and has occurred after both short and long term treatment. If there is laboratory evidence of liver injury or the patient is jaundiced, Labecard therapy should be stopped and not re-started. Particular care should be taken when Labecard is to be used in patients with hepatic impairment. Labecard should be used with caution in patients with peripheral vascular disease as their symptoms may be exacerbated.
Labecard overdose causes excessive hypotension and sometimes, excessive bradycardia. If overdose with Labecard follows oral ingestion, gastric lavage or pharmacologically induced emesis (using syrup) may be useful for removal of the drug shortly after ingestion. The following additional measures should be employed if necessary: Excessive bradycardia-administer atropine; Cardiac failure-administer digitalis glycoside and diuretic; Hypotension-administer vasopressors (norepinephrine); Bronchospasm-administer epinephrine.
Alpha adrenoceptor blocking drugs, Beta-adrenoceptor blocking drugs
Store in a cool & dry place protected from light. Keep out of reach of children.
{'Indications': 'Labecard Injection is indicated in Hypertension (including hypertension in pregnancy, hypertension after stroke, hypertension with angina, and hypertension following acute myocardial infarction); hypertensive crisis; Anaesthesia when a hypotensive technique is indicated.'}