LABETALOL HYDROCHLORIDE

Clinical safety rating: safe

Other drugs that lower heart rate or blood pressure can have additive effects Can cause liver injury and bronchospasm in susceptible patients.

How it works

Labetalol is a non-selective beta-adrenoceptor blocker and selective alpha-1 adrenoceptor blocker. It reduces myocardial contractility, heart rate, and peripheral vascular resistance.

What the body does with it

Metabolism	Primarily hepatic via glucuronidation; minor CYP2D6 involvement.
Excretion	Primarily hepatic metabolism; ~5% excreted unchanged in urine; ~55-60% as glucuronide conjugates in urine; fecal excretion <5%.
Half-life	Terminal elimination half-life: 6-8 hours. In renal impairment, half-life may be slightly prolonged but not clinically significant; in hepatic impairment, half-life may be significantly prolonged.
Protein binding	~50% bound to albumin.
Volume of Distribution	3-4 L/kg. Moderate distribution into tissues; crosses the placenta; minimal penetration into CNS.
Bioavailability	Oral: ~25% (range 18-45%) due to extensive first-pass metabolism; IV: 100%.
Onset of Action	Oral: 20 minutes to 2 hours; IV: 2-5 minutes.
Duration of Action	Oral: 8-12 hours; IV: 2-4 hours. Duration is dose-dependent and may be prolonged in hepatic impairment.

Classification & Brands

Dosing & administration

Oral: Initial 100 mg twice daily, titrate up to 200-400 mg twice daily; maximum 2400 mg/day. IV: 20 mg slow IV over 2 minutes, then 40-80 mg every 10 minutes as needed up to 300 mg total; or continuous IV infusion at 0.5-2 mg/min.

Dosage form	INJECTABLE
Renal impairment	No dose adjustment required for mild to moderate renal impairment. For severe renal impairment (GFR <30 mL/min), consider starting with lower doses and titrate cautiously due to reduced clearance. Hemodialysis: No supplemental dose needed.
Liver impairment	Caution in hepatic impairment; reduce initial doses and titrate slowly. Child-Pugh Class A: No adjustment. Class B: Reduce dose by 50%. Class C: Contraindicated or use extreme caution.
Pediatric use	Oral: Initial 1-3 mg/kg/day in 2 divided doses, increase gradually; maximum 10-12 mg/kg/day up to 1200 mg/day. IV: 0.2-1 mg/kg/dose every 10 minutes as needed; maximum cumulative dose 3 mg/kg.
Geriatric use	Start at lowest possible dose (oral: 100 mg daily or twice daily; IV: 10-20 mg slow injection). Titrate slowly due to increased risk of hypotension and bradycardia. Monitor renal function.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Other drugs that lower heart rate or blood pressure can have additive effects Can cause liver injury and bronchospasm in susceptible patients.

FDA category	Human
Breastfeeding	Enters breast milk in low amounts (M/P ratio ~0.8-2.6); relative infant dose ~1-3% of maternal weight-adjusted dose. Considered compatible with breastfeeding, but monitor infant for bradycardia, hypotension, and poor feeding. Use lowest effective maternal dose.
Teratogenic Risk

Warnings & precautions

■ FDA Black Box Warning

None

Side Effect Profile

Common Effects	Bradycardia
Serious Effects

Absolute Contraindications

["Sinus bradycardia","Heart block greater than first degree","Cardiogenic shock","Decompensated heart failure","Bronchial asthma","Hypersensitivity to labetalol"]

Clinical Precautions

Precautions

["May exacerbate heart failure; monitor for bronchospasm in asthmatics; may mask hypoglycemia in diabetics; avoid abrupt withdrawal (may precipitate angina or MI); may cause orthostatic hypotension; use caution in hepatic impairment."]

Clinical Tips & Counseling

Drug interactions

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LABETALOL HYDROCHLORIDE

Clinical safety rating: safe

Other drugs that lower heart rate or blood pressure can have additive effects Can cause liver injury and bronchospasm in susceptible patients.

How it works

Labetalol is a non-selective beta-adrenoceptor blocker and selective alpha-1 adrenoceptor blocker. It reduces myocardial contractility, heart rate, and peripheral vascular resistance.

What the body does with it

Metabolism	Primarily hepatic via glucuronidation; minor CYP2D6 involvement.
Excretion	Primarily hepatic metabolism; ~5% excreted unchanged in urine; ~55-60% as glucuronide conjugates in urine; fecal excretion <5%.
Half-life	Terminal elimination half-life: 6-8 hours. In renal impairment, half-life may be slightly prolonged but not clinically significant; in hepatic impairment, half-life may be significantly prolonged.
Protein binding	~50% bound to albumin.
Volume of Distribution	3-4 L/kg. Moderate distribution into tissues; crosses the placenta; minimal penetration into CNS.
Bioavailability	Oral: ~25% (range 18-45%) due to extensive first-pass metabolism; IV: 100%.
Onset of Action	Oral: 20 minutes to 2 hours; IV: 2-5 minutes.
Duration of Action	Oral: 8-12 hours; IV: 2-4 hours. Duration is dose-dependent and may be prolonged in hepatic impairment.

Classification & Brands

Dosing & administration

Dosage form	INJECTABLE
Renal impairment	No dose adjustment required for mild to moderate renal impairment. For severe renal impairment (GFR <30 mL/min), consider starting with lower doses and titrate cautiously due to reduced clearance. Hemodialysis: No supplemental dose needed.
Liver impairment	Caution in hepatic impairment; reduce initial doses and titrate slowly. Child-Pugh Class A: No adjustment. Class B: Reduce dose by 50%. Class C: Contraindicated or use extreme caution.
Pediatric use	Oral: Initial 1-3 mg/kg/day in 2 divided doses, increase gradually; maximum 10-12 mg/kg/day up to 1200 mg/day. IV: 0.2-1 mg/kg/dose every 10 minutes as needed; maximum cumulative dose 3 mg/kg.
Geriatric use	Start at lowest possible dose (oral: 100 mg daily or twice daily; IV: 10-20 mg slow injection). Titrate slowly due to increased risk of hypotension and bradycardia. Monitor renal function.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Other drugs that lower heart rate or blood pressure can have additive effects Can cause liver injury and bronchospasm in susceptible patients.

FDA category	Human
Breastfeeding	Enters breast milk in low amounts (M/P ratio ~0.8-2.6); relative infant dose ~1-3% of maternal weight-adjusted dose. Considered compatible with breastfeeding, but monitor infant for bradycardia, hypotension, and poor feeding. Use lowest effective maternal dose.
Teratogenic Risk

Warnings & precautions

■ FDA Black Box Warning

None

Side Effect Profile

Common Effects	Bradycardia
Serious Effects

Absolute Contraindications

["Sinus bradycardia","Heart block greater than first degree","Cardiogenic shock","Decompensated heart failure","Bronchial asthma","Hypersensitivity to labetalol"]