Recommendation for hypertension
100 mg PO q12hr initially; increased by 100 mg q12hr every 2-3 days
Usual dosage range: 200-400 mg PO q12hr; not to exceed 2400 mg/day
Hypertensive Emergency 20 mg IV over 2 minutes initially, then 40-80 mg IV q10min; total dose not to exceed 300 mg
Alternative: 1-2 mg/min by continuous IV infusion; total dose of 300 mg has been used
A nonselective beta blocker with intrinsic sympathomimetic activity; also alpha blocker
Alternative: 1-2 mg/min by continuous IV infusion; total dose of 300 mg has been used
Bioavailability of 25% orally.
Onset: PO, 20-120 min; IV, 2.5 min
Duration: 100 mg, 8 hr; 300 mg, 12 hr
Peak plasma time: 1-2 hr orally
Peak effect: 15 min (IV); 1-4 hr orally
Protein bound 50%.
Metabolized mainly through conjugation to glucuronide metabolites
Half-life: 6-8 hr orally and 5.5 hr IV.
Excretion: Urine 55-60%, and by feces via bile.
Adverse Effects in greater than 10% of patients.
Dizziness (1-20%)
Lightheadedness (1-20%)
Nausea (≤19%)
Tingling sensation of scalp (4-12%)
Fatigue (1-11%)
Elevated serum blood urea nitrogen (BUN) (≤8%)
Elevated serum creatinine (8%)
Congestion of nasal sinus (1-6%)
Orthostatic hypotension (1-5%)
Absence of ejaculation (<5%)
Paresthesia (<5%)
Elevated liver enzymes (4%)
Diaphoresis (≤4%)
Edema (≤2%)
Bronchospasm (1-2%)
Dyspnea (1-2%)
Pruritus (1%)
Rash (1%)
Altered taste sense (1%)
Ventricular arrhythmia (1%; IV)
Trade names: Normodyne, Trandate
Contraindications to labetalol usuage include: Asthma or chronic obstructive airway disease, severe bradycardia, 2° and 3° heart block, cardiogenic shock, cardiac failure, sinus bradycardia, sick sinus syndrome without pacemaker and prolonged and severe hypotension.
Used with caution with surgery, anesthesia, bronchospasm, cerebrovascular insufficiency, diabetes mellitus, hyperthyroidism, hepatic impairment, renal impairment, peripheral vascular disease, compromised left ventricular function, advanced age, heart failure, and pheochromocytoma.
Associated with increased risk of stroke after surgery.
Liver functions must be monitored as prolonged use may be associated with hepatic injury.
The sudden discontinuance can exacerbate angina and lead to myocardial infarction.
Use with caution in patients taking calcium channel blockers, cardiac glycosides, or inhaled anesthetics
Intraoperative floppy iris syndrome observed during cataract surgery in some patients treated with alpha1 blockers.
Hypotension with or without syncope may occur.