Labetalol

Labetalol

Clinical data
Pregnancy category	C One of few drugs used for PIH
Routes of administration	oral iv
ATC code	C07AG01 (WHO)
Legal status
Legal status	In general: ℞ (Prescription only)
Pharmacokinetic data
Bioavailability	90-100%
Protein binding	50%
Metabolism	hepatic pass metabolism,
Elimination half-life	Tablet: 6-8 hours; IV: 5.5 hours
Excretion	Excreted in urine, not removed by hemodialysis
Identifiers
IUPAC name 2-hydroxy-5-[1-hydroxy-2- (4-phenylbutan-2-ylamino)-ethyl]-benzamide
CAS Number	36894-69-6
PubChem CID	3869
DrugBank	APRD01062
E number	{{#property:P628}}
ECHA InfoCard	{{#property:P2566}}
Chemical and physical data
Formula	C19H24N2O3
Molar mass	328.406 g/mol

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Labetalol (Normodyne, Trandate, fixed combination with hydrochlorothiazide: Normozyde) is an alpha-1 and beta adrenergic blocker used to treat high blood pressure. It works by blocking these adrenergic receptors, which slows sinus heart rate, decreases peripheral vascular resistance.

It has a particular indication in the treatment of pregnancy-induced hypertension.

Administration

Labetalol is available in 100, 200, and 300 mg tablets and intravenously (only as Trandate) in 5 mg/ml solution. Adults taking tablets usually start with 100 mg two times a day, with a maximum of 2.4 g/day. In an emergency situation, this may be higher. IV doses are usually started at 20mg over 2 minutes. Additional doses of 40mg, then 80mg may be administered every ten minutes as needed. Additional 80mg doses can be given to a total maximum dose of 300 mg. Additionally, Labetalol can be administered by IV infusion at a rate of 2mg/minute, with a maximum dose of 300mg.

Side effects

Side effects may include:

• Drowsiness
• Fatigue
• Weakness
• Difficulty sleeping
• Diminished sexual function
• Scalp tingling which passes after time.
• A rare but potentially lethal side effect is respiratory distress. If respiratory distress occurs after starting this drug, do not take additional dose; go to the emergency room and tell the clinician that you are having respiratory distress that you think may be due to the labetalol. Nurses: If your hospitalized patient on labetalol begins to have respiratory distress (may have no decrease in oximetry readings), stop the drug, initiate oxygen at 1-2 liters, and call the physician. Closely monitor the patient until all signs of respiratory distress are relieved.

Contraindications

Labetalol should not be used in patients that have asthma, congestive heart failure, any degree of heart blocks, slow heart rates or those in cardiogenic shock

References

• Hodgson, Barbara B., and Kizior, Robert J. Saunders Nursing Drug Handbook 2006. St. Louis, MO: Elsevier, Saunders, 2006. bledsoe "prehospital emergency pharmacology" upper Saddle River, New Jersey: Pearson 2005

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