labetalol

Contraindicated in:

Decompensated HF;
Pulmonary edema;
Cardiogenic shock;
Bradycardia or heart block.

Use Cautiously in:

Renal impairment;
Hepatic impairment;
Pulmonary disease (including asthma);
Diabetes mellitus (may mask signs of hypoglycemia);
Thyrotoxicosis (may mask symptoms);
History of severe allergic reactions (intensity of reactions may be ↑);
OB: Recommended for treatment of chronic hypertension (PO) or hypertensive emergency in pregnancy (IV); may cause fetal/neonatal bradycardia, hypotension, hypoglycemia, or respiratory depression;
Pedi: Safety and effectiveness not established in children;
Geri: Older adults may have ↑ sensitivity (↑ risk of orthostatic hypotension); initial dosage ↓ recommended.

Adv. Reactions/Side Effects ⬆ ⬇

CV: orthostatic hypotension, ARRHYTHMIAS, BRADYCARDIA, HF

Derm: rash

EENT: blurred vision, dry eyes, intraoperative floppy iris syndrome, nasal stuffiness

Endo: hyperglycemia, hypoglycemia

GI: constipation, diarrhea, nausea

GU: erectile dysfunction, ↓libido

MS: arthralgia, back pain, muscle cramps

Neuro: fatigue, weakness, anxiety, depression, dizziness, drowsiness, insomnia, memory loss, mental status changes, nightmares, paresthesia

Resp: bronchospasm, PULMONARY EDEMA, wheezing

Interactions ⬆ ⬇

Drug-drug:

General anesthesia and verapamil may cause additive myocardial depression.
Additive bradycardia may occur with digoxin, verapamil, diltiazem, clonidine, or ivabradine.
Additive hypotension may occur with other antihypertensives, acute ingestion of alcohol, or nitrates.
Concurrent thyroid administration may ↓ effectiveness.
May alter the effectiveness of insulin or oral hypoglycemic agents (dose adjustments may be necessary).
May ↓ the effectiveness of adrenergic bronchodilators and theophylline.
May ↓ beneficial beta cardiovascular effects of dopamine or dobutamine.
Use cautiously within 14 days of MAO inhibitor therapy (may result in hypertension).
Effects may be ↑ by propranolol or cimetidine.
Concurrent NSAIDs may ↓ antihypertensive action.

Availability ⬆ ⬇

(Generic available)

Tablets: 100 mg; 200 mg; 300 mg
Premixed infusion: 100 mg/100 mL 0.72% NaCl; 200 mg/200 mL D5W; 200 mg/200 mL 0.72% NaCl; 300 mg/300 mL 0.72% NaCl
Solution for injection: 5 mg/mL

Route/Dosage ⬆ ⬇

PO (Adults ): 100 mg twice daily initially, may ↑ by 100 mg twice daily every 2–3 days as needed (usual range 400–800 mg/day in 2–3 divided doses; doses up to 1.2–2.4 g/day have been used).
IV (Adults ): 20 mg (0.25 mg/kg) initially, additional doses of 40–80 mg may be given every 10 min as needed (not to exceed 300 mg total dose) or 2 mg/min infusion (range 50–300 mg total dose required).

Action ⬆ ⬇

Blocks stimulation of beta₁ (myocardial)- and beta₂ (pulmonary, vascular, and uterine)-adrenergic receptor sites.
Also has alpha₁-adrenergic blocking activity, which may result in more orthostatic hypotension.

Therapeutic effects:

Decreased BP.

Classifications ⬆ ⬇

Therapeutic Classification: antianginals, antihypertensives

Pharmacologic Classification: beta blockers

Pharmacokinetics ⬆ ⬇

Absorption: Well absorbed but rapidly undergoes extensive first-pass hepatic metabolism, resulting in 25% bioavailability.

Distribution: Widely distributed to tissues.

Metabolism/Excretion: Undergoes extensive hepatic metabolism.

Half-Life: 3–8 hr.

Canadian Brand Names ⬆ ⬇

Time/Action Profile ⬆ ⬇

(cardiovascular effects)

ROUTE	ONSET	PEAK	DURATION
PO	20 min–2 hr	1–4 hr	8–12 hr
IV	2–5 min	5 min	16–18 hr

Patient/Family Teaching ⬆ ⬇

Instruct patient to take medication as directed, at the same time each day, even if feeling well; do not skip or double up on missed doses. Take missed doses as soon as possible up to 8 hr before next dose. Abrupt withdrawal may precipitate life-threatening arrhythmias, hypertension, or myocardial ischemia.
Advise patient to make sure enough medication is available for weekends, holidays, and vacations. A written prescription may be kept in wallet in case of emergency.
Teach patient and family how to check pulse and BP. Instruct them to check pulse daily and BP biweekly. Advise patient to hold dose and contact health care professional if pulse is <50 bpm or BP changes significantly.
May cause drowsiness or dizziness. Caution patients to avoid driving or other activities that require alertness until response to the drug is known. Caution patients receiving labetalol IV to call for assistance during ambulation or transfer.
Advise patients to make position changes slowly to minimize orthostatic hypotension, especially during initiation of therapy or when dose is increased. Patients taking oral labetalol should be especially cautious when drinking alcohol, standing for long periods, or exercising, and during hot weather, because orthostatic hypotension is enhanced.
Caution patient that this medication may increase sensitivity to cold.
Instruct patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and to consult health care professional before taking any Rx, OTC, or herbal products, especially NSAIDs and cold preparations, concurrently with this medication. Patients on antihypertensive therapy should also avoid excessive amounts of coffee, tea, and cola.
Advise patients with diabetes to closely monitor blood glucose, especially if weakness, malaise, irritability, or fatigue occurs. Medication may mask tachycardia and increased BP as signs of hypoglycemia, but dizziness and sweating may still occur.
Advise patient to notify health care professional if slow pulse, difficulty breathing, wheezing, cold hands and feet, dizziness, light-headedness, confusion, depression, rash, fever, sore throat, unusual bleeding, or bruising occurs.
Instruct patient to inform health care professional of medication regimen prior to treatment or surgery.
Rep: Advise females of reproductive potential to notify health care professional if pregnancy is planned or suspected, or if breastfeeding. Appropriate for treatment of chronic hypertension in pregnancy and breastfeeding. Monitor fetal growth during pregnancy and the newborn should be monitored for 48 hr after delivery for bradycardia, hypoglycemia, and respiratory depression.
Advise patient to carry identification describing disease process and medication regimen at all times.
Hypertension: Reinforce the need to continue additional therapies for hypertension (weight loss, sodium restriction, stress reduction, regular exercise, moderation of alcohol consumption, and smoking cessation). Medication controls but does not cure hypertension.

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Indications ⬇

Contraind./Precautions ⬆ ⬇