LABETALOL HYDROCHLORIDE IN SODIUM CHLORIDE
Clinical safety rating
safeNo significant drug interactions Can cause hypernatremia and fluid overload.
Labetalol is a competitive antagonist at both beta-adrenoceptors (beta1 and beta2) and alpha1-adrenoceptors, leading to decreased cardiac output, peripheral vascular resistance, and reduced blood pressure.
| Metabolism | Extensively metabolized in the liver via glucuronidation (direct conjugation) and also via CYP2D6 (minor pathway). |
| Excretion | Primarily renal (90-95% as unchanged drug and glucuronide conjugates) and a small amount in feces (<5%). |
| Half-life | Terminal elimination half-life is 6-8 hours; may be prolonged in elderly, hepatic impairment, or renal impairment (up to 16 hours). |
| Protein binding | Approximately 50% bound to albumin. |
| Volume of Distribution | Vd is 0.5-1.2 L/kg; distributes extensively into tissues, including crossing the placenta and entering breast milk. |
| Bioavailability | Oral: 25-40% due to extensive first-pass metabolism; Intravenous: 100%. |
| Onset of Action | Intravenous: 5-10 minutes; Oral: 20-40 minutes. |
| Duration of Action | Intravenous: 2-6 hours; Oral: 8-12 hours (dose dependent). |
| Molecular Weight | 364.87 |
Intravenous: Initially 20 mg (0.25 mg/kg for 70 kg) over 2 minutes, then 40-80 mg every 10 minutes until desired response or total 300 mg; or continuous infusion at 0.5-2 mg/min titrated to blood pressure. Switch to oral when stable.
| Dosage form | SOLUTION |
| Renal impairment | No specific dose adjustment required for GFR >15 mL/min; for GFR <15 mL/min or dialysis, use with caution and consider reducing dose. Monitor for hypotension and bradycardia. |
| Liver impairment | Child-Pugh A: No adjustment required. Child-Pugh B: Reduce dose by 50% and titrate slowly. Child-Pugh C: Contraindicated due to extensive hepatic metabolism. |
| Pediatric use | Intravenous: 0.2-0.5 mg/kg/dose every 10 minutes as needed, up to 1 mg/kg total. Continuous infusion: 0.25-3 mg/kg/hour. Maximum single dose: 1 mg/kg. |
| Geriatric use | Start with low end of dosing range (e.g., 10-20 mg IV initial), titrate cautiously due to increased sensitivity and risk of hypotension, bradycardia, and bronchospasm. |
| 1st trimester | Use only if potential benefit justifies potential risk to fetus. May cause intrauterine growth restriction; avoid in women with preeclampsia or hypertension due to risk of fetal bradycardia, hypotension, or hypoglycemia. |
| 2nd trimester | Use only if clearly needed. Monitor fetal growth and heart rate. Associated with reduced placental perfusion and fetal bradycardia. |
| 3rd trimester | Avoid near term due to risk of neonatal hypotension, bradycardia, respiratory depression, and hypoglycemia. May inhibit uterine contractions. |
Clinical note
No significant drug interactions Can cause hypernatremia and fluid overload.
| FDA category | Animal |
| Placental transfer | Crosses placenta with fetal concentrations approximately 40-50% of maternal serum levels. |
| Breastfeeding | Labetalol is excreted into breast milk in low amounts (less than 1% of maternal dose). Monitor infant for bradycardia and hypotension. American Academy of Pediatrics considers it compatible with breastfeeding. |
| Lactation Rating | L2 (Safer) |
| Teratogenic Risk | First trimester: Limited human data; animal studies show no major teratogenic effects at clinically relevant doses. Second and third trimesters: Associated with fetal bradycardia, hypotension, hypoglycemia, and intrauterine growth restriction due to beta-blockade. Risk of preterm delivery and respiratory depression at birth. |
| Fetal Monitoring | Monitor maternal blood pressure, heart rate, and signs of heart failure. Fetal monitoring includes ultrasound for growth, amniotic fluid index, and nonstress test or biophysical profile in third trimester. Neonatal monitoring for bradycardia, hypoglycemia, and respiratory depression for 24-48 hours after delivery. |
| Fertility Effects | No specific studies in humans; animal studies show no impairment of fertility. Beta-blockers may affect male and female fertility by altering hemodynamics, but clinical significance is unknown. |
■ FDA Black Box Warning
No FDA boxed warning.
| Common Effects | fluid replacement |
| Serious Effects |
Bronchial asthmaCardiogenic shockSinus bradycardiaSecond- or third-degree AV blockOvert cardiac failureSevere hepatic impairmentHypersensitivity to labetalol or any component
| Precautions | May cause bronchospasm in patients with asthma/COPD; may mask symptoms of hypoglycemia or thyrotoxicosis; may cause severe bradycardia; discontinue if signs of hepatic injury occur; use caution in patients with heart failure or diabetes. |
| Food/Dietary | Avoid alcohol, which can enhance hypotensive and sedative effects. No significant food interactions are documented, but a balanced diet is recommended. Maintain adequate fluid intake to prevent dehydration-induced hypotension. |
| Clinical Pearls | Labetalol combines alpha-1 and non-selective beta-blockade, causing less reflex tachycardia than pure beta-blockers. It is a pregnancy category C drug but is commonly used for hypertensive emergencies in pregnancy (e.g., preeclampsia). Monitor for orthostatic hypotension, especially during IV administration. Avoid in patients with bronchial asthma, heart block, or severe bradycardia. May mask symptoms of hypoglycemia and thyrotoxicosis. |
| Patient Advice | Do not stop taking this medication suddenly; abrupt withdrawal may worsen chest pain or cause a heart attack. · This drug may cause dizziness or lightheadedness, especially when standing up quickly; rise slowly from sitting or lying down. · Avoid alcohol, as it may increase dizziness and drowsiness. · Inform all healthcare providers that you are taking labetalol, especially before surgery or dental procedures. · If you have diabetes, monitor blood sugar closely, as labetalol can mask signs of low blood sugar. |
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