Labetalol iv dose in bp -258
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Here is the complete, textbook-sourced answer on Labetalol IV dosing in hypertensive emergencies (BP crisis):
Labetalol IV Dose - Hypertensive Emergency
Mechanism
Labetalol is a combined non-selective α₁- and β-blocker (α:β ratio of 1:7 for the IV formulation). It reduces peripheral vascular resistance without reflex tachycardia, while maintaining cerebral, renal, and coronary blood flow.
IV Dosing - Two Methods
Method 1: Intermittent IV Bolus (most common)
| Step | Dose | Timing |
|---|---|---|
| Initial dose | 20 mg IV over 2 min | - |
| Repeat doses | 20-80 mg IV every 10 min | As needed |
| Maximum cumulative dose | 300 mg total | - |
Method 2: Continuous IV Infusion
- 0.5-2 mg/min IV infusion, titrated to effect
Onset and Duration
- Onset of action: 2-5 minutes after IV administration
- Peak effect: 5-15 minutes
- Duration: 2-4 hours
Special Situations
| Situation | Notes |
|---|---|
| Aortic dissection | Preferred agent - 20 mg IV bolus over 2 min, then 20-80 mg every 10 min, then 0.5-2 mg/min infusion |
| Pregnancy / Preeclampsia | Safe to use - starting dose 10-20 mg IV, may double every 10 min up to 80 mg/dose, max 300 mg total |
| Hypertensive encephalopathy | Suitable choice |
| Acute coronary syndrome | Suitable choice |
| Pheochromocytoma | Suitable (combined α + β block) |
IV-to-Oral Conversion
Once BP is controlled with IV labetalol, initiate 200 mg orally, followed by 200-400 mg in 6-12 hours, then 400-2400 mg/day in divided doses based on response.
Contraindications
- Asthma / active bronchospasm
- Decompensated heart failure
- Significant bradycardia or heart block
Sources: Goldman-Cecil Medicine (Table 63-3), Creasy & Resnik's Maternal-Fetal Medicine, Tintinalli's Emergency Medicine, Goodman & Gilman's Pharmacological Basis of Therapeutics
Contra indication
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Here is the complete list of Labetalol Contraindications, sourced directly from multiple textbooks:
Labetalol - Contraindications
Absolute Contraindications
| Contraindication | Reason |
|---|---|
| Bronchial Asthma | Non-selective β-blockade causes bronchoconstriction and bronchospasm |
| COPD (with asthmatic component) | Same mechanism - bronchospasm risk |
| Bradycardia | β-blockade further slows the heart rate |
| Heart Block (2nd/3rd degree AV block) | Worsens conduction delay; risk of complete block |
| Decompensated / Congestive Heart Failure | Negative inotropy can worsen cardiac output |
| Cardiogenic Shock | Reduces cardiac output, worsens hemodynamic collapse |
Relative Contraindications
| Contraindication | Notes |
|---|---|
| Hepatic impairment | Labetalol is extensively metabolised by the liver; impaired clearance increases toxicity risk |
| Reactive airway disease | Even without frank asthma, any reactive airway component warrants caution |
| Bradycardia from raised ICP | Bradycardia secondary to increased intracranial pressure is a relative contraindication |
| Peripheral vascular disease | β-blockade can worsen limb ischemia |
Quick Memory Tip
"ABCHH" - Asthma, Bradycardia, Congestive heart failure, Heart block, Hepatic impairment
Sources: Tintinalli's Emergency Medicine (Table 57-6), Comprehensive Clinical Nephrology 7th Ed, Creasy & Resnik's Maternal-Fetal Medicine, Harrison's Principles of Internal Medicine 22E, Lippincott Pharmacology
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