Contraindications for Intravenous Labetalol
Intravenous labetalol is absolutely contraindicated in bronchial asthma, overt cardiac failure, greater than first-degree heart block, cardiogenic shock, severe bradycardia, severe and prolonged hypotension, and hypersensitivity to any component of the product. 1
Absolute Contraindications
The FDA drug label explicitly lists the following as absolute contraindications for IV labetalol 1:
- Bronchial asthma - Beta-blockers, even those with apparent cardioselectivity, should not be used in patients with obstructive airway disease 1
- Overt cardiac failure - Sympathetic stimulation is vital for circulatory function in congestive heart failure, and beta-blockade carries the risk of further depressing myocardial contractility 1
- Greater than first-degree heart block 1
- Cardiogenic shock 1
- Severe bradycardia 1
- Conditions associated with severe and prolonged hypotension 1
- Hypersensitivity to any component 1
Relative Contraindications and High-Risk Situations
Acute Pulmonary Edema
Beta blockers are contraindicated in acute pulmonary edema. 2 The ACC/AHA guidelines specifically list clevidipine, nitroglycerin, and nitroprusside as preferred agents, explicitly noting that beta blockers are contraindicated in this setting 2
Acute Coronary Syndromes with Specific Features
Labetalol should be avoided in acute coronary syndromes when the following are present 2:
- Moderate-to-severe left ventricular failure with pulmonary edema
- Bradycardia (<60 bpm)
- Hypotension (SBP <100 mm Hg)
- Poor peripheral perfusion
- Second- or third-degree heart block
- Reactive airways disease
Pheochromocytoma
Use with extreme caution in pheochromocytoma, as paradoxical hypertensive responses have been reported in a few patients with this tumor 1. While labetalol can be effective in lowering blood pressure in pheochromocytoma (often requiring higher than usual doses), the risk of paradoxical hypertension makes this a relative contraindication requiring careful monitoring 3, 4, 1
Pregnancy-Related Considerations
In pregnancy, the cumulative dose should not exceed 800 mg/24h to prevent fetal bradycardia 3. The European Heart Journal recommends a maximum cumulative dose of 300 mg in 24 hours for postpartum patients 5
Perioperative Setting
Several deaths have occurred when labetalol was used during surgery, including cases to control bleeding. 1 A synergism between labetalol and halothane anesthesia has been demonstrated 1. Protracted severe hypotension and difficulty in restarting or maintaining a heartbeat have been reported with beta-blockers during major surgery 1
Hepatic Dysfunction
Labetalol should be stopped and not restarted if the patient develops jaundice or laboratory evidence of liver injury 1. Periodic determination of hepatic laboratory tests is appropriate for patients taking labetalol 1
Clinical Context Matters
When Labetalol IS Preferred
Despite the contraindications above, labetalol remains a first-line agent for 2, 3:
- Acute aortic dissection (with esmolol)
- Severe pre-eclampsia and eclampsia
- Acute coronary syndromes (when contraindications listed above are absent)
- Hypertensive emergencies with hyperadrenergic states
Common Pitfall to Avoid
The most critical error is using labetalol in patients with any history of obstructive airway disease, including asthma 1. Even in patients without active bronchospasm, the FDA label is unequivocal that beta-blockers should not be used in patients with a history of obstructive airway disease 1. This is an absolute contraindication, not a relative one.