Labetalol

# Labetalol ## Overview - **Classification**: Non-selective beta-adrenergic blocker with alpha-1 adrenergic blocking activity. - **Mechanism**: Blocks beta-1, beta-2, and alpha-1 receptors. Beta-blockade reduces heart rate and contractility; alpha-1 blockade leads to vasodilation, reducing peripheral vascular resistance. ## Primary Indications 1. **Hypertension (oral)** - Management of essential hypertension. 2. **Hypertensive Emergencies (IV)** - Rapid reduction of blood pressure in acute severe hypertension. 3. **Hypertension in pregnancy/Preeclampsia (IV/oral)** - Control of blood pressure during pregnancy. ## Adult Dosing ### Standard Dosing **Hypertensive Emergencies (IV)** - **Dose**: Initial **20 mg IV** over 2 minutes. - **Frequency**: May repeat **40-80 mg IV** every 10 minutes. - **Route**: Intravenous (IV). - **Maximum dose**: Cumulative dose **300 mg**. - **Alternative**: Continuous infusion **2 mg/min**, titrated up to **300 mg** total. **Hypertension (Oral)** - **Dose**: Initial **100 mg PO**. - **Frequency**: Twice daily (BID). - **Route**: Oral (PO). - **Duration**: Chronic treatment. - **Titration**: Titrate every 2-3 days in **100 mg BID** increments. - **Maximum dose**: Typically **1200-2400 mg/day** in 2-3 divided doses. **Hypertension in Pregnancy (Oral)** - **Dose**: Initial **100 mg PO**. - **Frequency**: Twice daily (BID). - **Route**: Oral (PO). - **Maximum dose**: Up to **2400 mg/day** as needed. ### Dose Adjustments - **Renal Impairment**: No specific dose adjustment needed. Use with caution. - **Hepatic Impairment**: Reduce initial doses. Titrate slowly as metabolism may be impaired. - **Elderly Patients**: Start with lower doses (e.g., **50 mg PO BID**). Titrate slowly due to increased sensitivity. ## Pediatric Dosing ### Neonates (0-28 days) - **Dose**: IV: **0.2-0.5 mg/kg/dose** IV. - **Frequency**: Over 10-15 minutes; may repeat in 30-60 minutes. - **Maximum**: Not well established; careful titration. - **Special Notes**: Limited data; closely monitor for bradycardia and hypotension. ### Infants (1-12 months) - **Dose**: IV: **0.2-1 mg/kg/dose** IV. - **Frequency**: Over 10-15 minutes; may repeat every 4-6 hours. - **Maximum**: **4 mg/kg/day**. ### Children (1-12 years) - **Dose**: IV: **0.2-1 mg/kg/dose** IV. Max **40 mg/dose**. - **Frequency**: Over 10-15 minutes; may repeat every 4-6 hours. - **Maximum**: **4 mg/kg/day** or **300 mg/day** (whichever is less). - **Oral**: **1-3 mg/kg/day** in 2 divided doses. Max **400 mg/day**. ### Adolescents (13-18 years) - **Dose**: Adult dosing guidelines generally apply. - **Maximum**: Adult maximum doses apply (**300 mg IV**, **2400 mg PO/day**). ## Safety Information ### Contraindications - **Absolute**: Severe bradycardia, heart block (2nd or 3rd degree), cardiogenic shock. - **Absolute**: Decompensated heart failure, severe asthma/COPD. - **Relative**: Known hypersensitivity to labetalol. ### Common Adverse Effects - **Very Common (>10%)**: Dizziness, orthostatic hypotension, fatigue, nausea. - **Common (1-10%)**: Headache, vertigo, tingling sensation (scalp), dyspepsia, dyspnea. - **Serious but Rare**: Bronchospasm, heart failure exacerbation, liver injury, profound hypotension. ### Key Drug Interactions - **PDE-5 inhibitors (e.g., sildenafil)**: Potentiates hypotensive effects. Avoid concomitant use. - **Calcium Channel Blockers (non-dihydropyridine, e.g., verapamil, diltiazem)**: Increased risk of bradycardia, heart block, heart failure. Monitor closely. - **Beta-agonists (e.g., albuterol)**: Labetalol may antagonize bronchodilatory effects. - **Tricyclic Antidepressants (TCAs)**: May increase tremor. ## Monitoring & Follow-up - **Before Treatment**: Baseline blood pressure (BP), heart rate (HR), ECG, liver function tests (LFTs). - **During Treatment**: Monitor BP and HR regularly (frequently with IV, periodically with oral). - **During Treatment**: Monitor for signs of heart failure (edema, dyspnea). - **Clinical Signs**: Watch for dizziness, syncope, severe bradycardia, worsening respiratory symptoms. ## Clinical Pearls - 💡 **Dual Action**: Offers both alpha-1 and beta-blockade, often leading to effective BP reduction without significant reflex tachycardia. - 💡 **Pregnancy**: A first-line option for hypertension in pregnancy due to its established safety profile. - 💡 **IV Administration**: Administer IV boluses slowly (over at least 2 minutes) to minimize risk of profound hypotension. - 💡 **Orthostasis**: Counsel patients on potential for orthostatic hypotension, especially with initial doses or dose increases. - 💡 **Pheochromocytoma**: Do NOT use as monotherapy; ensure adequate alpha-blockade is established first. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.