Labetalol

Labetalol
Adult Indications & Dosage
Pediatric Indications & Dosage
Contraindications
Warnings & Precautions
Adverse Reactions
Drug Interactions
Use in Specific Populations
Administration & Monitoring
Overdosage
Pharmacology
Clinical Studies
How Supplied
Images
Patient Counseling Information
Precautions with Alcohol
Brand Names
Look-Alike Names

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Alonso Alvarado, M.D. [2]

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Overview

Labetalol is a beta-adrenergic blocker, alpha-adrenergic blocker that is FDA approved for the treatment of hypertension. Common adverse reactions include orthostatic hypotension, tingling sensation, nausea, dizziness, nasal congestion, fatigue.

Adult Indications and Dosage

FDA-Labeled Indications and Dosage (Adult)

• Dosage must be individualized.
• The recommended initial dosage is 100 mg twice daily whether used alone or added to a diuretic regimen. After 2 or 3 days, using standing blood pressure as an indicator, dosage may be titrated in increments of 100 mg b.i.d. every 2 or 3 days. The usual maintenance dosage of labetalol HCl is between 200 and 400 mg twice daily.
• Since the full antihypertensive effect of labetalol HCl is usually seen within the first 1 to 3 hours of the initial dose or dose increment, the assurance of a lack of an exaggerated hypotensive response can be clinically established in the office setting. The antihypertensive effects of continued dosing can be measured at subsequent visits, approximately 12 hours after a dose, to determine whether further titration is necessary.
• Patients with severe hypertension may require from 1,200 to 2,400 mg per day, with or without thiazide diuretics. * Should side effects (principally nausea or dizziness) occur with these doses administered twice daily, the same total daily dose administered three times daily may improve tolerability and facilitate further titration. Titration increments should not exceed 200 mg twice daily.
• I When a diuretic is added, an additive antihypertensive effect can be expected. In some cases this may necessitate a labetalol HCl dosage adjustment. As with most antihypertensive drugs, optimal dosages of labetalol hydrochloride tablets are usually lower in patients also receiving a diuretic.
• When transferring patients from other antihypertensive drugs, labetalol hydrochloride tablets should be introduced as recommended and the dosage of the existing therapy progressively decreased.

Elderly Patients

As in the general patient population, labetalol therapy may be initiated at 100 mg twice daily and titrated upwards in increments of 100 mg b.i.d. as required for control of blood pressure. Since some elderly patients eliminate labetalol more slowly, however, adequate control of blood pressure may be achieved at a lower maintenance dosage compared to the general population. The majority of elderly patients will require between 100 and 200 mg b.i.d.

Off-Label Use and Dosage (Adult)

Guideline-Supported Use

Acute Myocardial Infarction

• Developed by: ACC/AHA

• Class of Recommendation: Class IIb

• Strength of Evidence: Level of Evidence C

• Dosing Information/Recommendation

• 200 to 600 mg bid for the treatment of cocaine induced ACS.

Non–Guideline-Supported Use

Angina

• Dosing Information

• 100 mg bid.

Cardiac Dysrrhythmia

• Dosing Information

• Oral: 800 mg/day (hypertension + premature ventricular beats)
• IV: 1 mg/min (sinus rhythm restoration in patients resenting: sinus tachycardia, paroxysmal SVT, paroxysmal AFib, chronic AFib or VT

Electroshock Therapy Complication

• Dosing Information

• 5 mg/mL (treatment of hypertension and arrhythmias).

Postoperative Hypertension

• Dosing Information

• Initial dose of 10 mg IV over 2 minutes, 10 to 20 mg doses every 10 minutes to a maximum of 300 mg/day may be administered if required.

Hypertensive Urgency

• Dosing Information

• 200 mg PO.

Hypertensive Encephalopathy

• Dosing Information

• 1 to 2 mg/kg IV bolus.

Middle Ear Microsurgery

• Dosing Information

• Initial dose of 0.3 mg/kg IV, then 0.05 to 0.07 mg/kg administered every 30 minutes.

Central Nervous System Surgery

• Dosing Information

• Continuous infusion 0.05 to 0.75 mg/kg/hour or 10 to 20 mg IV boluses with 60 to 120 minute intervals.

Pediatric Indications and Dosage

FDA-Labeled Indications and Dosage (Pediatric)

There is limited information regarding Labetalol FDA-Labeled Indications and Dosage (Pediatric) in the drug label.

Off-Label Use and Dosage (Pediatric)

Guideline-Supported Use

There is limited information regarding Off-Label Guideline-Supported Use of Labetalol in pediatric patients.

Non–Guideline-Supported Use

Ventricular Arrhythmias

• Dosing Information

• 75 mg PO q12h.

Condition 2

• Dosing Information

• (Dosage)

Condition 3

• Dosing Information

• (Dosage)

Contraindications

• Bronchial asthma
• Overt cardiac failure
• Second degree heart block
• Third degree heart block
• Cardiogenic shock
• Severe bradycardia
• Hypotension
• Hypersensitivity

Beta-blockers, even those with apparent cardioselectivity, should not be used in patients with a history of obstructive airway disease, including asthma.

Warnings

Conidition 1

(Description)

Adverse Reactions

Clinical Trials Experience

Central Nervous System

(list/description of adverse reactions)

Cardiovascular

(list/description of adverse reactions)

Respiratory

(list/description of adverse reactions)

Gastrointestinal

(list/description of adverse reactions)

Hypersensitive Reactions

(list/description of adverse reactions)

Miscellaneous

(list/description of adverse reactions)

Condition 2

Central Nervous System

(list/description of adverse reactions)

Cardiovascular

(list/description of adverse reactions)

Respiratory

(list/description of adverse reactions)

Gastrointestinal

(list/description of adverse reactions)

Hypersensitive Reactions

(list/description of adverse reactions)

Miscellaneous

(list/description of adverse reactions)

Postmarketing Experience

(Description)

Drug Interactions

• Drug 1
• Drug 2
• Drug 3
• Drug 4
• Drug 5

Drug 1

(Description)

Drug 2

(Description)

Drug 3

(Description)

Drug 4

(Description)

Drug 5

(Description)

Use in Specific Populations

Pregnancy

Pregnancy Category (FDA): (Description)
Pregnancy Category (AUS): (Description)

Labor and Delivery

(Description)

Nursing Mothers

(Description)

Pediatric Use

(Description)

Geriatic Use

(Description)

Gender

(Description)

Race

(Description)

Renal Impairment

(Description)

Hepatic Impairment

(Description)

Females of Reproductive Potential and Males

(Description)

Immunocompromised Patients

(Description)

Others

(Description)

Administration and Monitoring

Administration

(Oral/Intravenous/etc)

Monitoring

Condition 1

(Description regarding monitoring, from Warnings section)

Condition 2

(Description regarding monitoring, from Warnings section)

Condition 3

(Description regarding monitoring, from Warnings section)

IV Compatibility

Solution

Compatible

• Solution 1
• Solution 2
• Solution 3

Not Tested

• Solution 1
• Solution 2
• Solution 3

Variable

• Solution 1
• Solution 2
• Solution 3

Incompatible

• Solution 1
• Solution 2
• Solution 3

Y-Site

Compatible

• Solution 1
• Solution 2
• Solution 3

Not Tested

• Solution 1
• Solution 2
• Solution 3

Variable

• Solution 1
• Solution 2
• Solution 3

Incompatible

• Solution 1
• Solution 2
• Solution 3

Admixture

Compatible

• Solution 1
• Solution 2
• Solution 3

Not Tested

• Solution 1
• Solution 2
• Solution 3

Variable

• Solution 1
• Solution 2
• Solution 3

Incompatible

• Solution 1
• Solution 2
• Solution 3

Syringe

Compatible

• Solution 1
• Solution 2
• Solution 3

Not Tested

• Solution 1
• Solution 2
• Solution 3

Variable

• Solution 1
• Solution 2
• Solution 3

Incompatible

• Solution 1
• Solution 2
• Solution 3

TPN/TNA

Compatible

• Solution 1
• Solution 2
• Solution 3

Not Tested

• Solution 1
• Solution 2
• Solution 3

Variable

• Solution 1
• Solution 2
• Solution 3

Incompatible

• Solution 1
• Solution 2
• Solution 3

Overdosage

Acute Overdose

Signs and Symptoms

(Description)

Management

(Description)

Chronic Overdose

Signs and Symptoms

(Description)

Management

(Description)

Pharmacology

Labetalol
Systematic (IUPAC) name
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Mechanism of Action

Labetalol combines both selective, competitive, alpha1-adrenergic blocking and nonselective, competitive, beta-adrenergic blocking activity in a single substance. In man, the ratios of alpha- to beta-blockade have been estimated to be approximately 1:3 and 1:7 following oral and intravenous (IV) administration, respectively. Beta2-agonist activity has been demonstrated in animals with minimal beta1-agonist (ISA) activity detected. In animals, at doses greater than those required for alpha- or beta-adrenergic blockade, a membrane stabilizing effect has been demonstrated.

Structure

Labetalol hydrochloride tablets, USP are adrenergic receptor blocking agents that have both selective alpha1-adrenergic and nonselective beta-adrenergic receptor blocking actions in a single substance.

Labetalol hydrochloride (HCl) is a racemate chemically designated as 2-hydroxy-5-[1-hydroxy-2-[(1-methyl-3-phenylpropyl) amino] ethyl] benzamide monohydrochloride, and it has the following structure:

This image is provided by the National Library of Medicine.

Labetalol HCl has the molecular formula C19H24N2O3•HCl and a molecular weight of 364.9. It has two asymmetric centers and therefore exists as a molecular complex of two diastereoisomeric pairs. Dilevalol, the R, R´stereoisomer, makes up 25% of racemic labetalol.

Labetalol HCl is a white or off-white crystalline powder, soluble in water.

Labetalol hydrochloride tablets contain 100, 200, or 300 mg of labetalol HCl and are taken orally. The tablets also contain the inactive ingredients lactose monohydrate, corn starch, crospovidone, colloidal silicon dioxide, magnesium stearate, polyvinyl alcohol, polyethylene glycol, titanium dioxide and talc.

Pharmacodynamics

The capacity of Labetalol to block alpha receptors in man has been demonstrated by attenuation of the pressor effect of phenylephrine and by a significant reduction of the pressor response caused by immersing the hand in ice-cold water ("cold-pressor test"). Labetalol 's beta1-receptor blockade in man was demonstrated by a small decrease in the resting heart rate, attenuation of tachycardia produced by isoproterenol or exercise, and by attenuation of the reflex tachycardia to the hypotension produced by amyl nitrite. Beta2-receptor blockade was demonstrated by inhibition of the isoproterenol-induced fall in diastolic blood pressure. Both the alpha- and beta-blocking actions of orally administered Labetalol contribute to a decrease in blood pressure in hypertensive patients. Labetalol consistently, in dose-related fashion, blunted increases in exercise-induced blood pressure and heart rate, and in their double product. The pulmonary circulation during exercise was not affected by Labetalol dosing.

Single oral doses of Labetalol administered to patients with coronary artery disease had no significant effect on sinus rate, intraventricular conduction, or QRS duration. The atrioventricular (A-V) conduction time was modestly prolonged in two of seven patients. In another study, IV Labetalol slightly prolonged A-V nodal conduction time and atrial effective refractory period with only small changes in heart rate. The effects on A-V nodal refractoriness were inconsistent.

Labetalol produces dose-related falls in blood pressure without reflex tachycardia and without significant reduction in heart rate, presumably through a mixture of its alpha- and beta-blocking effects. Hemodynamic effects are variable, with small, nonsignificant changes in cardiac output seen in some studies but not others, and small decreases in total peripheral resistance. Elevated plasma renins are reduced.

Doses of Labetalol that controlled hypertension did not affect renal function in mildly to severely hypertensive patients with normal renal function.

Due to the alpha1-receptor blocking activity of Labetalol , blood pressure is lowered more in the standing than in the supine position, and symptoms of postural hypotension (2%), including rare instances of syncope, can occur. Following oral administration, when postural hypotension has occurred, it has been transient and is uncommon when the recommended starting dose and titration increments are closely followed. Symptomatic postural hypotension is most likely to occur 2 to 4 hours after a dose, especially following the use of large initial doses or upon large changes in dose.

The peak effects of single oral doses of Labetalol occur within 2 to 4 hours. The duration of effect depends upon dose, lasting at least 8 hours following single oral doses of 100 mg and more than 12 hours following single oral doses of 300 mg. The maximum, steady-state blood pressure response upon oral, twice-a-day dosing occurs within 24 to 72 hours.

The antihypertensive effect of labetalol has a linear correlation with the logarithm of labetalol plasma concentration, and there is also a linear correlation between the reduction in exercise-induced tachycardia occurring at 2 hours after oral administration of Labetalol and the logarithm of the plasma concentration.

About 70% of the maximum beta-blocking effect is present for 5 hours after the administration of a single oral dose of 400 mg with suggestion that about 40% remains at 8 hours.

The antianginal efficacy of Labetalol has not been studied. In 37 patients with hypertension and coronary artery disease, Labetalol did not increase the incidence or severity of angina attacks.

Exacerbation of angina and, in some cases, myocardial infarction and ventricular dysrhythmias have been reported after abrupt discontinuation of therapy with beta-adrenergic blocking agents in patients with coronary artery disease. Abrupt withdrawal of these agents in patients without coronary artery disease has resulted in transient symptoms, including tremulousness, sweating, palpitation, headache, and malaise. Several mechanisms have been proposed to explain these phenomena, among them increased sensitivity to catecholamines because of increased numbers of beta receptors.

Although beta-adrenergic receptor blockade is useful in the treatment of angina and hypertension, there are also situations in which sympathetic stimulation is vital. For example, in patients with severely damaged hearts, adequate ventricular function may depend on sympathetic drive. Beta-adrenergic blockade may worsen A-V block by preventing the necessary facilitating effects of sympathetic activity on conduction. Beta2-adrenergic blockade results in passive bronchial constriction by interfering with endogenous adrenergic bronchodilator activity in patients subject to bronchospasm, and it may also interfere with exogenous bronchodilators in such patients.

Pharmacokinetics

Labetalol is completely absorbed from the gastrointestinal tract with peak plasma levels occurring 1 to 2 hours after oral administration. The relative bioavailability of Labetalol tablets compared to an oral solution is 100%. The absolute bioavailability (fraction of drug reaching systemic circulation) of labetalol when compared to an IV infusion is 25%; this is due to extensive "first-pass" metabolism. Despite "first-pass" metabolism, there is a linear relationship between oral doses of 100 to 3,000 mg and peak plasma levels. The absolute bioavailability of labetalol is increased when administered with food.

The plasma half-life of labetalol following oral administration is about 6 to 8 hours. Steady-state plasma levels of labetalol during repetitive dosing are reached by about the third day of dosing. In patients with decreased hepatic or renal function, the elimination half-life of labetalol is not altered; however, the relative bioavailability in hepatically impaired patients is increased due to decreased "first-pass" metabolism.

The metabolism of labetalol is mainly through conjugation to glucuronide metabolites. These metabolites are present in plasma and are excreted in the urine and, via the bile, into the feces. Approximately 55% to 60% of a dose appears in the urine as conjugates or unchanged labetalol within the first 24 hours of dosing.

Labetalol has been shown to cross the placental barrier in humans. Only negligible amounts of the drug crossed the blood-brain barrier in animal studies. Labetalol is approximately 50% protein bound. Neither hemodialysis nor peritoneal dialysis removes a significant amount of Labetalol from the general circulation (<1%).

Elderly Patients

Some pharmacokinetic studies indicate that the elimination of labetalol is reduced in elderly patients. Therefore, although elderly patients may initiate therapy at the currently recommended dosage of 100 mg b.i.d., elderly patients will generally require lower maintenance dosages than nonelderly patients.

Nonclinical Toxicology

Long-term oral dosing studies with labetalol HCl for 18 months in mice and for 2 years in rats showed no evidence of carcinogenesis. Studies with labetalol HCl using dominant lethal assays in rats and mice and exposing microorganisms according to modified Ames tests showed no evidence of mutagenesis.

Clinical Studies

Condition 1

(Description)

Condition 2

(Description)

Condition 3

(Description)

How Supplied

(Description)

Storage

There is limited information regarding Labetalol Storage in the drug label.

Images

Drug Images

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Package and Label Display Panel

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Patient Counseling Information

(Patient Counseling Information)

Precautions with Alcohol

Alcohol-Labetalol interaction has not been established. Talk to your doctor about the effects of taking alcohol with this medication.

Brand Names

There is limited information regarding Labetalol Brand Names in the drug label.

Look-Alike Drug Names

• (Paired Confused Name 1a) — (Paired Confused Name 1b)
• (Paired Confused Name 2a) — (Paired Confused Name 2b)
• (Paired Confused Name 3a) — (Paired Confused Name 3b)

Drug Shortage Status

Drug Shortage

Price

References

The contents of this FDA label are provided by the National Library of Medicine.