Labetalol

1. Introduction

Labetalol is a combined alpha- and beta-adrenergic receptor blocker primarily used to manage hypertension, including in pregnancy and hypertensive emergencies. It reduces blood pressure by relaxing blood vessels (alpha-blockade) and slowing the heart rate (beta-blockade).

2. Indications

  • Approved Indications:
    • Hypertension (mild to severe).
    • Hypertensive emergencies, including those in pregnancy (e.g., pre-eclampsia).
    • Chronic hypertension during pregnancy.
  • Off-Label Uses:
    • Aortic dissection (to reduce blood pressure and shear stress).

3. Dosage

  • Adults:
    • Oral Hypertension:
      • Initial: 100 mg twice daily.
      • Maintenance: 200–400 mg twice daily.
      • Maximum: 2400 mg/day in divided doses.
    • Hypertensive Emergency (IV):
      • Bolus: 20 mg IV over 2 minutes, followed by 40–80 mg every 10 minutes (maximum 300 mg).
      • Infusion: 0.5–2 mg/min titrated to response.
  • Elderly:
    • Start with 50 mg twice daily and titrate slowly due to increased sensitivity to hypotension.
  • Paediatric Use (rarely used):
    • 0.5–1 mg/kg IV bolus, repeated every 10 minutes (maximum: 3 mg/kg).

4. Administration

  • Oral Tablets: Take with food to enhance absorption and reduce gastrointestinal side effects.
  • IV Administration: Administer in a controlled setting, such as a hospital, where blood pressure and heart rate can be closely monitored.

5. Forms Available

  • Tablets: 100 mg, 200 mg, 300 mg.
  • Injectable: 5 mg/mL for IV use.

6. Side Effects

6.1. Common Side Effects

  • Fatigue.
  • Dizziness or light-headedness (due to hypotension).
  • Nausea.
  • Nasal congestion.

6.2. Less Common Side Effects

  • Tingling of the scalp.
  • Indigestion.
  • Sweating.

6.3. Rare but Serious Side Effects

  • Bradycardia (slow heart rate).
  • Heart block or heart failure.
  • Severe hypotension or syncope.
  • Bronchospasm (especially in patients with asthma).

7. Warnings

  • Asthma: Use cautiously in patients with reactive airway diseases, as beta-blockade may worsen bronchospasm.
  • Heart Failure: May worsen symptoms in patients with decompensated heart failure.
  • Hepatotoxicity: Rare cases of liver damage have been reported with labetalol use.
  • Hypoglycaemia: Can mask signs of low blood sugar in diabetic patients.

8. Precautions

  • Avoid abrupt withdrawal to prevent rebound hypertension or angina.
  • Use cautiously in patients with:
    • Severe bradycardia or heart block.
    • Pheochromocytoma (without concurrent alpha-blockade).
    • Peripheral vascular disease.

9. Interactions

  • Drug-Drug Interactions:
    • Other antihypertensives: Additive hypotensive effects.
    • Beta-agonists (e.g., salbutamol): May reduce efficacy of beta-agonists.
    • Calcium channel blockers (e.g., verapamil): Increased risk of heart block or bradycardia.
    • Anaesthetics: Increased risk of severe hypotension.
  • Drug-Food Interactions:
    • No significant interactions, but taking with food enhances tolerability.

10. Monitoring Parameters

  • Blood pressure and heart rate (for effectiveness and safety).
  • Liver function tests (during prolonged therapy).
  • Signs of heart failure (e.g., swelling, shortness of breath).

11. Use in Children

  • Rarely used in paediatrics; dosing is based on weight. Use under specialist guidance.

12. Use in Pregnancy

  • Category C: Commonly used to manage hypertension in pregnancy and pre-eclampsia. It is generally safe and effective but should be monitored carefully.

13. Use in Elderly

  • Start at lower doses due to increased risk of orthostatic hypotension and bradycardia.

14. Use in Kidney Disease

  • No specific dose adjustments are required, but monitor blood pressure closely.

15. Use in Liver Disease

  • Use cautiously in patients with liver impairment, as labetalol is metabolised in the liver. Monitor liver function regularly.

16. Patient Counselling Points

  • Take labetalol exactly as prescribed, preferably with food to reduce stomach upset.
  • Do not stop taking labetalol suddenly; taper off gradually under medical supervision.
  • Avoid activities requiring alertness (e.g., driving) if you experience dizziness or fatigue.
  • Inform your doctor if you experience symptoms such as severe dizziness, slow heartbeat, or difficulty breathing.
  • For diabetic patients, monitor blood sugar levels closely, as labetalol may mask symptoms of hypoglycaemia.

17. Table of Brand Names, Manufacturers, and Prices

Brand NameManufacturerPrice (USD)
TrandatePfizer$30–50 (30 tablets, 100 mg)
NormodyneAkorn Pharmaceuticals$25–45 (30 tablets, 100 mg)
Generic LabetalolVarious manufacturers$10–20 (30 tablets, 100 mg)

18. FAQs (15 Questions)

  1. What is labetalol used for?
    It is used to treat high blood pressure, hypertensive emergencies, and pregnancy-induced hypertension.
  2. How does labetalol work?
    It blocks alpha- and beta-receptors, reducing blood pressure by relaxing blood vessels and slowing the heart rate.
  3. Can labetalol be used during pregnancy?
    Yes, it is commonly used to manage hypertension in pregnancy and pre-eclampsia.
  4. What is the usual dose of labetalol?
    The typical starting dose is 100 mg twice daily, adjusted based on blood pressure response.
  5. Can labetalol cause side effects?
    Yes, common side effects include dizziness, fatigue, nausea, and nasal congestion.
  6. How should labetalol be taken?
    Take it with food to improve absorption and reduce side effects.
  7. Can labetalol cause low blood pressure?
    Yes, it may cause hypotension, especially if the dose is too high or in dehydrated patients.
  8. Is labetalol safe for asthma patients?
    Use cautiously, as it may worsen bronchospasm in patients with reactive airway diseases.
  9. Can I stop taking labetalol suddenly?
    No, sudden withdrawal can lead to rebound hypertension or angina. Taper off gradually.
  10. Does labetalol interact with other medications?
    Yes, it interacts with antihypertensives, calcium channel blockers, and beta-agonists, among others.
  11. Can labetalol be used in children?
    It is rarely used in children and should only be administered under specialist guidance.
  12. What should I do if I miss a dose of labetalol?
    Take it as soon as you remember, unless it’s close to the next dose. Do not double the dose.
  13. Does labetalol affect blood sugar levels?
    Yes, it may mask symptoms of low blood sugar in diabetic patients.
  14. Can labetalol cause liver damage?
    Rarely, labetalol can cause hepatotoxicity. Monitor liver function during prolonged therapy.
  15. How should labetalol be stored?
    Store at room temperature, away from moisture and heat.