labetalol (Rx)

>10%

Dizziness (1-20%)

Lightheadedness (1-20%)

Nausea (≤19%)

Tingling sensation of scalp (4-12%)

Fatigue (1-11%)

1-10%

Elevated serum blood urea nitrogen (BUN) (≤8%)

Elevated serum creatinine (8%)

Congestion of nasal sinus (1-6%)

Orthostatic hypotension (1-5%)

Absence of ejaculation (<5%)

Paresthesia (<5%)

Elevated liver enzymes (4%)

Diaphoresis (≤4%)

Edema (≤2%)

Bronchospasm (1-2%)

Dyspnea (1-2%)

Pruritus (1%)

Rash (1%)

Altered taste sense (1%)

Ventricular arrhythmia (1%; IV)

Frequency Not Defined

Angioedema

Bradycardia

Alopecia

Cholestatic jaundice

Depression

Diabetes insipidus

Hepatitis

Raynaud syndrome

Toxic myopathy

Urinary retention

Urticaria

Raynaud phenomenon

Contraindications

Asthma or obstructive airway disease, severe bradycardia, 2°/3° heart block (without pacemaker), cardiogenic shock, bronchial asthma, uncompensated cardiac failure, hypersensitivity, sinus bradycardia, sick sinus syndrome without permanent pacemaker; conditions associated with prolonged and severe hypotension

Cautions

Use with caution in anesthesia or surgery (myocardial depression), bronchospastic disease (not recommended), cerebrovascular insufficiency, diabetes mellitus, hyperthyroidism or thyrotoxicosis, hepatic impairment, renal impairment, peripheral vascular disease, compromised left ventricular function, advanced age, heart failure, pheochromocytoma

Increased risk of stroke after surgery

Severe hepatic injury reported with use; with prolonged use, monitor liver function tests

Sudden discontinuance can exacerbate angina and lead to myocardial infarction

Use with caution in patients taking calcium channel blockers, cardiac glycosides, or inhaled anesthetics

Intraoperative floppy iris syndrome observed during cataract surgery in some patients treated with alpha1 blockers (labetalol is both an alpha and a beta blocker)

Hypotension with or without syncope may occur; monitor

Consider pre-existing conditions, such as, sick sinus syndrome before initiating therapy

Use caution in patients with history of severe anaphylaxis to allergens; patients taking beta-blockers may become more sensitive to repeated challenges; treatment with epinephrine in patients taking beta-blockers may be ineffective or promote undesirable effects

Use with caution in patients with myasthenia gravis, psoriasis, or psychiatric illness (may cause or exacerbate CNS depression)

Pregnancy category: C

Lactation: Small amounts excreted; use with caution

Pregnancy Categories

A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

NA: Information not available.

Mechanism of Action

Nonselective beta blocker with intrinsic sympathomimetic activity; also alpha blocker

Absorption

Bioavailability: 25% (PO)

Onset: PO, 20-120 min; IV, 2.5 min

Duration: 100 mg, 8 hr; 300 mg, 12 hr

Peak plasma time: 1-2 hr (PO)

Peak effect: 15 min (IV); 1-4 hr (PO)

Distribution

Protein bound: 50%

Vd: 3-16 L/kg (adults)

Metabolism

Metabolized mainly through conjugation to glucuronide metabolites

Elimination

Half-life: 6-8 hr (PO); 5.5 hr (IV)

Excretion: Urine (55-60%), feces via bile

IV Compatibilities

Solution: Compatible with most common solvents

Y-site: Alcohol 10% in D5W, amikacin, aminophylline, amiodarone, ampicillin, bivalirudin, butorphanol, calcium gluconate, cefazolin, ceftazidime, ceftizoxime, chloramphenicol, cimetidine, clindamycin, dexmedetomidine, diltiazem, dobutamine, dopamine, enalaprilat, epinephrine, erythromycin, esmolol, famotidine, fenoldopam, fentanyl, gatifloxacin, gentamicin, heparin (incompatible at 5 mg/mL), hetastarch, hydromorphone, insulin (?), lidocaine, linezolid, lorazepam, magnesium sulfate, meperidine, metronidazole, midazolam, milrinone, morphine, nicardipine, nitroglycerin, norepinephrine, oxacillin, penicillin G, piperacillin, potassium chloride, potassium phosphates, propofol, ranitidine, sodium acetate, sodium nitroprusside, tobramycin, trimethoprim-sulfamethoxazole, vancomycin, vecuronium

IV Incompatibilities

Solution: Sodium bicarbonate 5%

Y-site: Amphotericin B cholesteryl sulfate, cefoperazone, ceftriaxone, furosemide, nafcillin, thiopental, warfarin

IV Preparation

Standard diluent: 500 mg/250 mL D5W

Minimum volume: 250 mL D5W

IV Administration

Requires infusion pump

Slow direct IV push administered over 2 minutes

Loading infusions (2 mg/min) require close monitoring of HR and BP and are terminated after response occurs or a cumulative dose of 300 mg is reached

Continuous infusions of 2-6 mg/hr have been used in some settings and should not be confused with loading infusions

Storage

Store at room temperature or under refrigeration (2-30°C [36-86°F])

Protect from light and freezing

Solution is clear to slightly yellow