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Labetalol: Wikis


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Systematic (IUPAC) name
CAS number 36894-69-6
ATC code C07AG01
PubChem 3869
DrugBank APRD01062
ChemSpider 3734
Chemical data
Formula C19H24N2O3 
Mol. mass 328.406 g/mol
SMILES eMolecules & PubChem
Pharmacokinetic data
Bioavailability 90-100%
Protein binding 50%
Metabolism hepatic pass metabolism,
Half life Tablet: 6-8 hours; IV: 5.5 hours
Excretion Excreted in urine, not removed by hemodialysis
Therapeutic considerations
Pregnancy cat. C
One of few drugs used for PIH
Legal status Prescription only
Routes oral iv
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Labetalol (Normodyne, Trandate, fixed combination with hydrochlorothiazide: Normozyde) is a mixed alpha/beta Adrenergic antagonist, which is used to treat high blood pressure.[1]



Labetalol has stereoisomers.[2] It is a racemic mixture of four isomers. Two of these isomers, the (S,S)- and (R,S)- forms are inactive. The third, the (S,R)-isomer, is a powerful α1 blocker. The fourth isomer, the (R,R)-isomer, is a mixed nonselective β blocker and selective β2 agonist.

It works by blocking these adrenergic receptors, which decreases peripheral vascular resistance without significantly altering heart rate or cardiac output. The β:α antagonism of Labetalol is approximately 3:1.[3][4]


It has a particular indication in the treatment of pregnancy-induced hypertension which is commonly associated with pre-eclampsia. [5]

It is also used to treat chronic hypertension of pheochromocytoma and hypertensive crisis.[3]


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 twice daily, with a maximum of 2.4 g/day. In cases of emergency dosage might 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:


Labetalol has relative contraindications for use in patients with asthma, congestive heart failure, any degree of heart block, bradycardia, or those in cardiogenic shock.


  1. ^ Fahed S, Grum DF, Papadimos TJ (2008). "Labetalol infusion for refractory hypertension causing severe hypotension and bradycardia: an issue of patient safety". Patient Saf Surg 2: 13. doi:10.1186/1754-9493-2-13. PMID 18505576. PMC 2429901. 
  2. ^ Riva E, Mennini T, Latini R (December 1991). "The alpha- and beta-adrenoceptor blocking activities of labetalol and its RR-SR (50:50) stereoisomers". Br. J. Pharmacol. 104 (4): 823–8. PMID 1687367. 
  3. ^ a b Katzung, Bertram G. (2006). Basic and clinical pharmacology. New York: McGraw-Hill Medical. p. 170. ISBN 0-07-145153-6. 
  4. ^ D A Richards, J Tuckman, and B N Prichard (October 1976). "Assessment of alpha- and beta-adrenoceptor blocking actions of labetalol.". Br J Clin Pharmacol 3 (5): 849–855. PMID PMC1428931. 
  5. ^
  6. ^ Shiohara T, Kano Y (2007). "Lichen planus and lichenoid dermatoses". in Bolognia JL. Dermatology. St. Louis: Mosby. p. 161. ISBN 1-4160-2999-0. 


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