Indications
Hypertension (see Hypertension)
- Aortic Dissection (see Aortic Dissection)
- Hypertensive Emergency (see Hypertension)
Contraindications
Sinus Bradycardia (Sinus Bradycardia)
- Labetalol May Exacerbate Bradycardia
Atrioventricular Heart Blocks
- Labetalol May Exacerbate Atrioventricular Heart Blocks
- Types of Atrioventricular Heart Blocks
- First Degree Atrioventricular Block (First Degree Heart Block) (see First Degree Atrioventricular Block)
- Second Degree Atrioventricular Block-Mobitz Type I (Wenckebach) (see Second Degree Atrioventricular Block-Mobitz Type I)
- Second Degree Atrioventricular Block-Mobitz Type II (see Second Degree Atrioventricular Block-Mobitz Type II)
- Third Degree Atrioventricular Block (Third Degree Heart Block, Complete Heart Block) (see Third Degree Atrioventricular Block)
Hypotension (see Hypotension)
- Labetalol May Exacerbate Hypotension
Cocaine Intoxication (see Cocaine)
- Labetalol Has an Alpha/Beta Antagonism Ratio of 1:7 (Br Heart J, 1977) [MEDLINE]
- For this Reason, Labetalol Used in the Setting of Cocaine Intoxication Has Not Been Demonstrated to Reverse Cocaine-Induced Coronary Artery Vasospasm (and Can Result in Unopposed α1-Adrenergic Receptor Stimulation)
Pharmacology
Combined β-Adrenergic Receptor Antagonist (Beta Blocker) + α1-Adrenergic Receptor Antagonist (Alpha Blocker)
- Labetalol has an α/β Antagonism Ratio of 1:7 (Br Heart J, 1977) [MEDLINE]
Metabolism
- Hepatic: extensive (via CYP450)
Half-Life
- Half-Life: 5-8 hrs
Excretion
- Feces: 50%
- Renal: 50%
Administration
Oral (PO)
- Dose
- Start 100 mg BID
- May Divide Dose TID Instead
- Escalate in Increments of 200 mg Per Day q2-3 days (Max: 2400 mg/Day)
- Start 100 mg BID
Intravenous (IV)
- Dose: 10-80 mg IV q6 hrs
Intravenous Continuous Infusion
- Dose: 2 mg/min (max dose: 300 mg)
Dose Adjustment
- Hepatic: use with caution in liver disease
- Renal: none
Use in Pregnancy (see Pregnancy)
- xxx
Use During Breast Feeding
- xxxx
Adverse Effects
Allergic Adverse Effects
- Anaphylactoid Reaction (see Anaphylaxis)
Cardiovascular Adverse Effects
Atrioventricular Heart Blocks
- First Degree Atrioventricular Block (First Degree Heart Block) (see First Degree Atrioventricular Block)
- Second Degree Atrioventricular Block-Mobitz Type I (Wenckebach) (see Second Degree Atrioventricular Block-Mobitz Type I)
- Second Degree Atrioventricular Block-Mobitz Type II (see Second Degree Atrioventricular Block-Mobitz Type II, [[Second Degree Atrioventricular Block-Mobitz Type II]])
- Third Degree Atrioventricular Block (Third Degree Heart Block, Complete Heart Block) (see Third Degree Atrioventricular Block)
Sinus Bradycardia (see Sinus Bradycardia)
- xxx
Congestive Heart Failure (CHF) (see Congestive Heart Failure)
- xxx
Hypotension (see Hypotension)
- xxxx
Syncope (see Syncope)
- xxx
Gastrointestinal/Hepatic Adverse Effects
- Dyspepsia
- Hepatotoxicity (see xxxx)
- Nausea/Vomiting (see Nausea and Vomiting)
Neurologic Adverse Effects
- Dizziness (see Dizziness)
- Fatigue (see Fatigue)
- Headache (see Headache)
- Parasthesias (see Parasthesias)
Otolaryngologic Adverse Effetcts
- Rhinitis (see Rhinitis)
Pulmonary Adverse Effects
- Bronchospasm/Exacerbation of Obstructive Airways Disease (see Obstructive Lung Disease)
- Dyspnea (see Dyspnea)
- Interstitial Pneumonitis (see Interstitial Lung Disease)
Renal Adverse Effects
- Elevated Blood Urea Nitrogen (BUN) and Creatinine (Cr)
Rheumatologic Adverse Effects
- Drug-Induced Systemic Lupus Erythematosus (SLE) (see Systemic Lupus Erythematosus)
- Epidemiology: moderate-low risk of developing drug-induced SLE
- Peripheral Edema (see Peripheral Edema)
- Raynaud’s Pnenomenon (see Raynaud’s Phenomenon)
Other Adverse Effects
- Ejaculatory Dysfunction
- Intraoperative Floppy Iris Syndrome
Adverse Effects with Abrupt Discontinuation
- Angina/Myocardial Infarction (MI) (see Coronary Artery Disease)
- Ventricular Arrhythmia (see Ventricular Tachycardia
References
- Pharmacological basis for antihypertensive effects of intravenous labetalol. Br Heart J. 1977;39(1):99 [MEDLINE]