Labetalol


Concise Prescribing Info
Indications/Uses
Listed in Dosage.
Dosage/Direction for Use
Adult : PO HTN Initial: 100 mg bid, may increase gradually according to patients response to 200-400 mg bid. Max: 2.4 g/day in 2-4 divided doses. IV Emergency treatment of HTN 20 mg injected slowly for at least 2 min; followed by 40-80 mg every 10 min. Max: 200 mg. Patient should remain supine during and 3 hr after the procedure. HTN in pregnancy Start infusion at a rate of 20 mg/hr, then doubled every 30 min until a satisfactory response is achieved or a dose of 160 mg/hr is reached. HTN after MI Initiate infusion at a rate of 15 mg/hr, then increase gradually until a favourable response is obtained or a dose of 120 mg/hr is reached. Hypotensive anaesth Initial: 10-20 mg, increase at 5-10 mg increments if satisfactory hypotension is not achieved after 5 min. Administer higher initial doses if halothane anaesth is not used.
Dosage Details
Intravenous
Emergency treatment of hypertension
Adult: 20 mg injected slowly for at least 2 min, followed by 40-80 mg dose every 10 min, if necessary up to 300 mg. Patient should remain supine during and 3 hr after the procedure.

Intravenous
Hypotensive anaesthesia
Adult: Initially, 10-20 mg, increase at 5-10 mg increments if satisfactory hypotension is not achieved after 5 min. Administer higher initial doses if halothane anaesth is not used.

Intravenous
Hypertension after myocardial infarction
Adult: Initiate infusion at a rate of 15 mg/hr, then increase gradually until a favourable response is obtained or a dose of 120 mg/hr is reached.

Intravenous
Hypertension in pregnancy
Adult: Start infusion at a rate of 20 mg/hr, doubled every 30 min until a satisfactory response is achieved or a dose of 160 mg/hr is reached.

Oral
Hypertension
Adult: Initially, 100 mg bid, may increase gradually according to patients response to 200-400 mg bid. Max: 2.4 g/day in 2-4 divided doses.
Elderly: Initially, 50-100 mg bid. Maintenance: 100-200 mg bid.
Administration
Should be taken with food. Take immediately after meals.
Incompatibility
Na bicarbonate 5% and alkaline solutions.
Contraindications
Obstructive airway disease (e.g. bronchial asthma), 2nd and 3rd degree heart block, cardiogenic shock, conditions w/ severe or prolonged hypotension, uncompensated heart failure, severe bradycardia.
Special Precautions
Patients w/ phaeochromocytoma, inadequate cardiac function and well-compensated heart failure, DM, nonallergic bronchospasm. Patients undergoing major surgery involving general anaesth. May mask symptoms of hypoglycaemia. Avoid abrupt withdrawal as it may exacerbate angina. Hepatic impairment. Elderly, pregnancy and lactation.
Adverse Reactions
Intraoperative floppy iris syndrome, orthostatic hypotension, bradycardia, syncope, paraesthesia, dizziness, dyspnoea, fatigue, vertigo, headache, nasal stuffiness, diarrhoea, abdominal pain, male sexual dysfunction, dyspepsia, nausea, vomiting, flatulence, constipation, taste disturbances, scalp tingling, tremor, muscle weakness, urinary retention, hepatitis, jaundice, rash, increased transaminases, nightmares, claudication.
Potentially Fatal: Hepatic injury.
IV/Parenteral/PO: C
MonitoringParameters
Monitor LFT periodically and BP.
Overdosage
Symptoms: Hypotension, bradycardia, cardiac failure, bronchospasm. Management: Symptomatic and supportive treatment. Admin activated charcoal after emesis or gastric lavage. Atropine or epinephrine may be given for bradycardia. For severe hypotension, a vasopressor (e.g. dopamine, norepinephrine) may be administered and for heart failure, a cardiac glycoside and diuretic. Glucagon may be beneficial for the management of myocardial depression and hypotension. A β2-adrenergic agonist and/or a theophylline derivative may be used for bronchospasm. Diazepam may be used for seizures.
Drug Interactions
Synergistic hypotensive effect w/ halothane. Increased absolute bioavailability w/ cimetidine. Decreased absolute bioavailability w/ glutethimide. Additive hypotensive effect w/ nitroglycerin. Increased incidence of tremor w/ TCAs. Increased risk of bradycardia and heart block w/ Ca channel blocker (e.g. verapamil, diltiazem).
Lab Interference
False-positive results in fluorometric or photometric analysis of urinary catecholamines.
Action
Description: Labetalol competitively inhibits the adrenergic stimulation of β-receptors w/in the myocardium, bronchial and vascular smooth muscle, and α1-receptors w/in vascular smooth muscle. It also has some intrinsic β2-agonist and membrane-stabilising activity.
Onset: 20 min to 2 hr (oral); 2-5 min (IV).
Duration: Dose dependent: 8-12 hr (oral); 2-18 hr (IV).
Pharmacokinetics:
Absorption: Absorbed readily from the GI tract. Bioavailability increased by food. Time to peak plasma concentration: Approx 1-2 hr (oral); 5-15 min (IV).
Distribution: Crosses the placenta, enters breast milk. Volume of distribution: 3-16 L/kg. Plasma protein binding: Approx 50%.
Metabolism: Extensive first-pass metabolism primarily via glucuronide conjugation.
Excretion: Via urine (55-60% as glucuronide conjugates; <5% as unchanged drug). Elimination half-life: Approx 6-8 hr (oral); approx 5.5 hr (IV).
Storage
Store between 2-30°C.
MIMS Class
Disclaimer: This information is independently developed by MIMS based on Labetalol from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2020 MIMS. All rights reserved. Powered by MIMS.com
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