Labetalol: Uses Action Administration Side Effect Nursing Consideration by Nurses Note

 Labetalol

Uses of Labetalol

Management of hypertension. IV for severe hypertension. OFF-LABEL: Management of preeclampsia, severe hypertension in pregnancy, hypertension during acute ischemic stroke, pediatric hypertension. 

Administration Precautions of Labetalol

Contraindications: Hypersensitivity to labetalol. Bronchial asthma, history of obstructive airway disease, cardiogenic shock, uncompensated HF, second or third-degree heart block (except in pts with functioning pacemaker), severe bradycardia, conditions associated with severe, prolonged hypotension. Cautions: Compensated HF, severe anaphylaxis to allergens, myasthenia gravis, psychiatric disease, hepatic impairment, pheochromocytoma, diabetes; concurrent use with digoxin, verapamil, or diltiaZEM; arterial obstruction, elderly. Pts with peripheral vascular disease, Raynaud’s disease.

Action of Labetalol

Blocks alpha1 -, beta1 -, beta2 - (large doses) adrenergic receptor sites. Therapeutic Effect: Slows sinus heart rate; decreases peripheral vascular resistance, B/P.

Pharmacokinetics of Labetalol

Route: PO

  Onset: 0.5–2 hrs

  Peak: 2–4 hrs

  Duration:  8–12 hrs

Route: IV

  Onset: 2–5 min

  Peak: 5–15 min

  Duration: 2–4 hrs

Incompletely absorbed from GI tract. Bioavailability: 25%. Protein binding: 50%. Metabolized in liver. Primarily excreted in urine. Not removed by hemodialysis. Half-life: 6–8 hrs.

Lifespan considerations of Labetalol

 Pregnancy/Lactation: Drug crosses placenta. Small amount distributed in breast milk. Children: Safety and efficacy not established. Elderly: Age-related peripheral vascular disease may increase susceptibility to decreased peripheral circulation. May have increased risk of orthostatic hypotension.

DHA/MOH/HAAD/ PROMETRIC PRACTICE QUESTIONS

Interactions of Labetalol

DRUG: May decrease effects of beta2 -adrenergic agonists (e.g., arformoterol, salmeterol), theophylline. Beta-blockers (e.g., carvedilol, metoprolol), calcium channel blockers (e.g., diltiazem, verapamil), digoxin may increase risk of bradycardia. HERBAL: Ephedra, ginseng, yohimbe may worsen hypertension. Garlic may increase the antihypertensive effect. Licorice may cause water retention, increased serum sodium, decreased serum potassium. FOOD: None known. LAB VALUES: May increase serum antinuclear antibody titer (ANA), BUN, LDH, alkaline phosphatase, bilirubin, creatinine, potassium, triglycerides, lipoprotein, uric acid, ALT, AST

Availability (Rx) Injection Solution: 5 mg/mL. Tablets: 100 mg, 200 mg, 300 mg

Administration/handling of Labetalol

IV:  Prolonged duration of action: Monitor several hrs after administration. Excessive administration may result in prolonged hypotension and/or bradycardia.

Reconstitution • For IV infusion, dilute in D5W to provide concentration of 1–2 mg/mL.

 Rate of Administration of Labetalol

• For IV push, administer at a rate of 10 mg/min. 

• For IV infusion, administer at rate of 2 mg/min initially. Rate is adjusted according to B/P.

 • Monitor B/P immediately before and q5–10min during IV administration (maximum effect occurs within 5 min).

Storage 

• Store at room temperature. 

• After dilution, IV solution is stable for 72 hrs.

 • Solution appears clear, colorless to light yellow. 

• Discard if discolored or precipitate forms

PO

 • Give without regard to food. 

• Tablets may be crushed.

IV incompatibilities of Labetalol

 Amphotericin B complex (Abelcet, AmBisome, Amphotec), ceftaroline (Teflaro), cefTRIAXone (Rocephin), furosemide (Lasix), heparin, nafcillin (Nafcil).

IV Compatibilities of Labetalol

 Amiodarone (Cordarone), calcium gluconate, dexmedetomidine (Precedex), diltiaZEM (Cardizem), DOBUTamine (Dobutrex), DOPamine (Intropin), enalapril (Vasotec), fentaNYL (Sublimaze), HYDROmorphone (Dilaudid), lidocaine, LORazepam (Ativan), magnesium sulfate, midazolam (Versed), milrinone (Primacor), morphine, nitroglycerin, norepinephrine (Levophed), potassium chloride, potassium phosphate, propofol (Diprivan).

Indications/routes/dosage of Labetalol

Hypertension

PO: ADULTS, ELDERLY: Initially, 100 mg twice daily. Adjust in increments of 100 mg twice daily q2–3days. Usual dose: 100–300 mg twice daily. May require up to 2,400 mg/day. CHILDREN: 1–3 mg/kg/day in 2 divided doses. Maximum: 10–12 mg/kg/day up to 1,200 mg/day. 

Severe Hypertension, Hypertensive Crisis

IV: ADULTS: Initially, 10–20 mg (bolus over 2 min). Additional doses of 40– 80 mg may be given at 10-min intervals, up to total dose of 300 mg. CHILDREN: 0.2–1 mg/kg/dose. Maximum: 40 mg/dose. IV Infusion: ADULTS: Initially, 2 mg/min up to total dose of 300 mg. CHILDREN: 0.2–1 mg/kg/hr. Maximum: 3 mg/kg/hr or 40 mg/dose.

Dosage in Renal Impairment: No dose adjustment. 

Dosage in Hepatic Impairment: Use caution.

Kidney Anatomy: Function, Shape, Location, Measurement 

Side effects of Labetalol

Frequent (20%–11%): Drowsiness, dizziness, excessive fatigue. Occasional (10% or less): Dyspnea, peripheral oedema, depression, anxiety, constipation, diarrhoea, nasal congestion, weakness, diminished sexual function, transient scalp tingling, insomnia, nausea, vomiting, abdominal discomfort. Rare: Altered taste, dry eyes, increased urination, paresthesia.

Adverse effects/toxic reactions of Labetalol

May precipitate, aggravate HF due to decreased myocardial stimulation. Abrupt withdrawal may precipitate myocardial ischemia, producing chest pain, diaphoresis, palpitations, headache, tremor. May mask signs, symptoms of acute hypoglycemia (tachycardia, B/P changes) in diabetic pts. Rapid reduction of blood pressure may cause CVA, optic nerve infarction, ischemic changes on EKG. May cause severe orthostatic hypotension.

Nursing considerations of Labetalol

Assess baseline renal function, LFT. Assess B/P, apical pulse immediately before drug administration (if pulse is 60/min or less or systolic B/P is lower than 90 mm Hg, withhold medication, contact physician). Question history of bradycardia, HF, second or third-degree heart block, myasthenia gravis. 

Intervention/evaluation of Labetalol

 Monitor B/P for hypotension. Assess pulse for quality, irregular rate, bradycardia. Monitor EKG for cardiac arrhythmias. Assist with ambulation if dizziness occurs. Assess for evidence of HF: dyspnea (particularly on exertion or lying down), night cough, peripheral oedema, distended neck veins. Monitor I&O (increase in weight, decrease in urine output may indicate HF).