Intravenous labetalol is available in Australia.
Article Type: Letter to the editor
Subject: Labetalol (Access control)
Labetalol (Dosage and administration)
Preeclampsia (Care and treatment)
Authors: Dennis, A.
Walker, S.
Drinkwater, P.
Crowhurst, J.
Pub Date: 03/01/2010
Publication: Name: Anaesthesia and Intensive Care Publisher: Australian Society of Anaesthetists Audience: Academic Format: Magazine/Journal Subject: Health Copyright: COPYRIGHT 2010 Australian Society of Anaesthetists ISSN: 0310-057X
Issue: Date: March, 2010 Source Volume: 38 Source Issue: 2
Geographic: Geographic Scope: Australia Geographic Code: 8AUST Australia
Accession Number: 225792570
Full Text: In Australia, intravenous labetalol is an orphan drug, with specific application to treatment of pre-eclampsia that clinicians may have thought was not available. However, intravenous labetalol is available. It is manufactured by Phebra (Sydney, NSW), a Therapeutic Goods Administration approved pharmaceutical manufacturing facility and it is provided under Schedule 5A--subregulation 12 (1A) of the Therapeutic Goods Act and Regulations.

Treatment of severe hypertension in pregnancy, defined as a blood pressure [greater than or equal to] 160/110 mmHg, is recommended to reduce maternal morbidity and mortality (1). Oral drugs may be used in women with non-life-threatening hypertension in pregnancy but intravenous agents are frequently required in women with severe hypertension, especially in the setting of pre-eclampsia, and are used to steadily reduce blood pressure over minutes (2).

Intravenous labetalol, a non-selective [beta]-adrenoceptor antagonist with [[alpha].sub.1]-adrenoceptor antagonism, has not been widely available and thus the safest choice of intravenous agents has been limited primarily to hydralazine, with mini-dose diazoxide also used in some settings (3). Other agents such as sodium nitroprusside, glyceryl trinitrate, clonidine and prazosin have been used but their unfavourable side-effect profile limits their clinical usefulness (4,5). Refractory hypertension has been difficult to treat safely and effectively.

Elsewhere in the world, intravenous labetalol has been available for many years and is often the first line of treatment of severe hypertension in pregnancy, mainly because of its favourable side-effect profile of less maternal hypotension and tachycardia compared with hydralazine and other drugs (2). It is generally given as an intravenous bolus of 10 to 20 mg, then 20 to 80 mg every 20 to 30 minutes, to a maximum of 300 mg. It may be given as an intravenous infusion at 1 to 2 mg/minute. Labetalol is contraindicated in women with asthma or cardiac failure.

Used appropriately, with monitoring of the hypertensive woman and foetus and a local drug protocol, we consider that intravenous labetalol represents a major step forward in the treatment of hypertensive emergencies in women with preeclampsia. It gives the clinician another safe, rapidly acting intravenous drug that may be used separately or in combination with other drugs to treat women with severe hypertension in pregnancy.

References

(1.) Lewis G. The Confidential Enquiry into Maternal and Child Health (CEMACH). Saving Mothers' Lives: reviewing maternal deaths to make motherhood safer-2003-2005. London: CEMACH; 2007.

(2.) Podymow T, August P. Update on the use of antihypertensive drugs in pregnancy. Hypertension 2008; 51:960-969.

(3.) Lowe SA, Brown MA, Dekker GA, Gatt S, McLintock CK, McMahon LP et al. Guidelines for the management of hypertensive disorders of pregnancy 2008. Aust N Z J Obstet Gynaecol 2009; 49:242-246.

(4.) Duley L, Henderson-Smart DJ, Meher S. Drugs for treatment of very high blood pressure during pregnancy. Cochrane database of systematic reviews (Online) 2006; 3:CD001449.

(5.) Obstetric Anaesthesia: Scientific Evidence Working Party 2008, ANZCA. From http://www.anzca.edu.au/fellows/sig/ obstetric-anaesthesia-sig/obstetric-anaesthesia-scientific-evidence, Accessed July 2009.

A. Dennis

S. Walker

P. Drinkwater

J. Crowhurst

Heidelberg, Victoria
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