Labetalol
Labetalol (Normodyne, Trandate, fixed combination with hydrochlorothiazide: Normozyde) is a mixed alpha/beta Adrenergic antagonist, which is used to treat high blood pressure.
Chemistry
Labetalol has stereoisomers. It 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.
Indications
It has a particular indication in the treatment of pregnancy-induced hypertension which is commonly associated with pre-eclampsia. <Ref> http://www.bnf.org/bnf/bnf/56/2488.htm?q=%22labetalol%22 </ref>
It is also used to treat chronic hypertension of pheochromocytoma and hypertensive crisis.
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 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: Drowsiness
Fatigue
Weakness
Difficulty sleeping
Diminished sexual function
Scalp tingling which passes after time.
A rare but potentially lethal side effect is respiratory distress.
Contraindications
Labetalol has relative contraindications for use in patients with asthma, congestive heart failure, any degree of heart block, bradycardia, or those in cardiogenic shock.
Translation
The word "Labetalol" occurs as such in the following languages: English, Dutch, Polish, Portuguese.
Translation(s) in other languages: Italian: Labetalolo, Chinese: 拉贝洛尔.
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