A Comparison of Hydralazine and Labetalol in the Management of Se
Journal of Women's Health Care

Journal of Women's Health Care
Open Access

ISSN: 2167-0420


Research Article - (2014) Volume 3, Issue 6

A Comparison of Hydralazine and Labetalol in the Management of Severe Preeclampsia

Lahaga Isaac Nombur*, Eyaofun Teddy Agida, Aliyu Yabaji Isah and Bissallah Ahmed Ekele
University of Abuja Teaching Hospital, Abuja, Nigeria
*Corresponding Author: Lahaga Isaac Nombur, Consultant, University of Abuja Teaching Hospital Obstetrics and Gynaecology, Gwagwalada, Federal Capital Territory, Abuja, Federal Capital Territrory +234, Nigeria, Tel: +2347068834712 Email:


The burden of pre-eclampsia and eclampsia is the rationale behind the research. There is paucity of prospective study on this subject in Nigeria. Therefore there was a need for a prospective study that may provide concrete data and firm conclusion on this subject. Furthermore, there was also a need for a study among pregnant women in the Federal capital territory, with a rapidly increasing heterogeneous population. Recently Labetalol was introduced in the obstetrics unit, of the University of Abuja Teaching Hospital but hydralazine has been in use for the management of severe pre-eclampsia in the hospital. Therefore, there was a need to compare the safety and efficacy of these drugs for acutely lowering blood pressure in severe pre-eclampsia in this unit.

Keywords: Hydralazine; Labetalol; Severe pre-eclampsia


Pre-eclampsia is a common complication of pregnancy. Preeclampsia and eclampsia are hypertensive disorders of pregnancy that cause significant morbidity and mortality in the mother and fetus both in developed and developing countries [1]. In Nigeria, they are listed as one of the top three causes of maternal mortality [2-6]. The ultimate cure for pre-eclampsia and eclampsia is the delivery of the baby. However, maternal and perinatal deaths are significantly reduced with appropriate treatment [1].

The most commonly used threshold for treatment of hypertension in pregnancy is severe hypertension (Systolic Blood Pressure ≥ 160 mmHg or Diastolic Blood Pressure ≥ 110 mmHg) as recommended by the National High Blood Pressure Education Program [7,8]. Various antihypertensive agents have been used for lowering blood pressure in severe pre-eclampsia.

Hydralazine is a peripheral vasodilator, and the most frequently used intravenous antihypertensive for women with severe hypertension in pregnancy [8]. However, its side effects are common and mimic symptoms of deteriorating pre-eclampsia for example headache, nausea and vomiting [9].

Labetalol is a non-selective beta-blocker and a post-synaptic alpha-1 blocking agent. Intravenous Labetalol is also used for treatment of severe hypertension in pregnancy as a first line drug and has a better side effect profile but specific concerns have been raised about the risk of neonatal bradycardia [10].

Intravenous hydralazine, oral nifedipine and oral or intravenous Labetalol are the drugs most commonly used to control acute severe hypertension in women with pre-eclampsia [8,11-13]. Nifedipine is not currently recommended for acute severe hypertension in pregnancy by the American College of Obstetricians and Gynaecologists [14]. The reason for this may be uncertainty that exists about how safe it is for the mother [10].

Recently, a Cochrane systematic review considered the effectiveness of antihypertensives for treatment of severe hypertension during pregnancy and concluded that there is no evidence that one antihypertensive agent is preferable to the others for improving outcome for women with very high blood pressure during pregnancy, and their babies [15]. The purpose of this study was to compare the efficacy and safety of intravenous hydralazine and intravenous Labetalol for management of severe pre-eclampsia.

Materials and Methods

This was a randomised clinical trial to compare the efficacy and safety of intravenous hydralazine and labetalol for the management of severe preeclampsia.

Entry criteria were pregnancy more than 20weeks and severe hypertension (systolic blood pressure of 160mmHg or more and /or diastolic blood pressure of 110mmHg or more) and Proteinuria of at least 1+ as measured by dipstick in a catheter specimen urine sample.

Those who did not consent, contraindication or known allergy to hydralazine or labetalol were excluded.

Standard mercury sphygmomanometer with appropriately sized cuff was used. The first and fifth Korotkoff sounds were recorded for systolic and diastolic blood pressure respectively. The blood pressure was measured with patient in left lateral recumbent position with the patient’s arm at the level of the heart for all measurements.

The sample size for comparison groups was calculated using the formula [16] n= 2Z2 PQ/D2

n= minimum sample size, Z= 95% confidence interval using 1.96

P= Prevalence of severe preeclampsia (2.0) [17], Q= 1.0-P

D = degree of accuracy desired, usually set at 0.05.

n = 60. Adding 5% attrition rate, anticipated response rate 95%.

The selected sample size was 60/0.95 = 63. Then each trial group was allocated 63 participants. The minimum sample size was 126 participants.

Enrolled patients were randomly allocated to one of the two therapeutic regimens. Randomisation was performed using computergenerated list by means of sequentially numbered, opaque, sealed envelopes indicating their medication. One group of patients received hydralazine and the other group received labetalol (Table 1) [8,18,19].

Drug Treatment
Hydralazine 5mg as a slow bolus dose administered intravenously and repeated 10mg every 20-minutes until the desired effect was achieved up to a maximum of 5 doses
Labetalol 20mg intravenous bolus dose followed by 40mg if not effective within 10-minutes followed by 80mg every 10-minutes up to a maximum dose of 300mg (5 doses)

Table 1: Treatment of severe preeclampsia [8,18,19].

Parameter Hydralazine Labetalol P – value
No  (%) No  (%)
Maternal age (Years)          
<20 5 (7.9) 8 (12.7)  
20-24 13 (20.6) 8 (12.7)  
25-29 26 (41.3) 21 (33.3)  
30-34 16 (25.4) 22 (34.9) 0.61
35-39 1 (1.6) 1 (1.6)  
>40 2 (3.2) 3 (4.8)  
Total 63 (100.0) 63 (100.0)  
Nulliparous 33 (52.4) 37 (58.7)  
Multiparous 30 (47.6) 26 (41.3) 0.47
Total 63 (100.0) 63 (100.0)  
Gestational Age          
<37weeks (Preterm) 27 (42.9) 24 (38.1)  
> 37weeks (Term) 36 (57.1) 39 (61.9) 0.58
Total 63 (100.0) 63 (100.0)  
Booking status          
Unbooked 15 (23.8) 21 (33.3)  
Booked 48 (76.2) 42 (66.7) 0.23
Total 63 (100.0) 63 (100.0)  
Over 80% of women in each group were in the age bracket of 20 – 34 years and more than half were Nulliparous in both groups. Majority delivered at term and were booked patients.

Table 2: Demographic characteristic of women enrolled.

The desired end point Systolic Blood Pressure 130-140 mmHg and Diastolic Blood Pressure 80-100 mmHg

Management of severe preeclampsia included preventing seizures, all women initially received magnesium sulphate as a 4 g intravenous loading dose over 10 minutes and 10 g intramuscularly (5g in each buttocks). Maintenance dose 5 g intramuscularly in alternate buttocks was administered every 4 hours until 24 hours after delivery.

Data was analysed using SPSS (Statistical package software for social sciences) version 16.0. Chi-square test was used to analyse categorical variables and differences in continuous variables were analysed using Mann-Witney test. P-value of less than 0.05 was accepted as indicating statistical significance.

The ethical clearance was obtained from the Research Ethics Committee of the University of Abuja Teaching Hospital and informed consent for participation was obtained for all patients.


A total of 126women met the inclusion criteria, agreed to participate and were randomized. The demographic variables were similar between women in both arm of the study (Table 3).

Variables Hydralazine Labetalol p- value
Time to BP control (mins)      
Median (IQR) 40 (30, 50) 40 (30, 60) 0.17
No. of Doses to BP Control No  (%) No (%)  
Single  30 (47.6) 33 (52.4)  
2 – 3 19 (30.1) 18 (28.6)  
4 – 5 11 (17.5) 10 (15.8) 0.94
severe hypertension
  3  (4.8) 2 (3.2)  
Total 63  (100.0) 63 (100.0)  
The Blood pressure control was achieved within 40 minutes in both groups. There was no significant difference between the numbers of doses required to achieve control in both groups. Interquartile range (IQR).

Table 3: Time to achieve blood pressure control and Number of doses required.

The time to achieve blood pressure control and the number of doses of each drug needed to achieve such control is presented in Table 3. An average of 40 minutes was required in both groups to achieve blood pressure control while 77.7% and 81.0% of women in Hydralazine and Labetalol group respectively needed a maximum of 3 doses of their respective drugs to achieve control. The timing to achieve control and the required number of doses was not statistically different between the 2 groups (Table 3). A combination of hydralazine and Labetalol were used in 3 (4.8%) and 2 (3.2%) patients for Hydralazine and Labetalol groups respectively, because of persistent severe hypertension (P=0.94).

Table 4 showed number of repeat courses of administrations to achieve blood pressure control. There was no significant difference observed in rebound hypertension and need for subsequent repeat administration of the Hydralazine and Labetalol in either group (P=1.0).

Repeats Hydralazine (%) Labetalol (%) P value
None 57 (90.5) 58 (92.1)  
1 5 (7.9) 4 (6.3) 1.0
2 or more 1 (1.6) 1 (1.6)  
Total 63 (100.0) 63 (100.0)  
Majority of women had control with the loading doses of Hydralazine and Labetalol.

Table 4: Repeat courses of administration to achieve blood pressure control.

Maternal complications and outcome were summarised in Table 5. Headache was significantly more frequent in patients given hydralazine than following Labetalol use. The difference was statistically significant (25.4% vs. 3.2% respectively, p = 0.01). Eclampsia occurred after the loading dose of magnesium sulphate and 2 doses of hydralazine while none in the labetalol group. There was no difference demonstrated in the maternal outcome between the 2 groups, as over 90% in each group delivered without complication. There were no maternal deaths in any of the women studied.

Complication Hydralazine
No  (%)
P – value
Headache 16  (25.4) 2 (3.2) 0.01
Nausea / Vomiting 1  (1.6) 1 (1.6)  
Epigastric Pain 2 (3.2) 1  (1.6)  
Visual disturbances 3  (4.8) 4(6.4)  
Dizziness 2 (3.2) 2(3.2)  
Normal delivery 57  (90.5) 60 (95.2)  
Placenta Abruptio 5  (7.9) 2(3.2)  
Eclampsia 1  (1.6) 0  (0.0) 0.35
HELLP Syndrome 0  (0.0) 1 (1.6)  
Total 63 (100.0) 63  (100.0)  
Headache was significantly more frequent in patients given hydralazine. Over 90% of the women in both groups had normal delivery without complications.

Table 5: Maternal complications and Outcome.

The fetal outcome is shown in Table 6. The respective fresh stillbirth of 4 and 2 among the Hydralazine and Labetalol groups were those women that had Abruptio placentae. Three and 2 of the stillbirths occurred before commencement of treatment in hydralazine and labetalol group respectively. A woman that had abruptio placenta during the treatment with 3 doses of hydralazine had a stillbirth while none had stillbirth during treatment with labetalol. There were no significant differences observed in fetal outcome between the 2 arms of the study.

Fetal outcome Hydralazine
No  (%)
No (%)
P – value
Fresh stillbirth 4 (6.3) 2(3.2)  
Fetal distress 4 (6.3) 5(7.9)  
1 min APGAR < 7 3 (4.8) 2 (3.2) 0.91
5 min APGAR < 7 2  (3.2) 4(6.3)  
Admission into SCBU 10  (15.9) 11 (17.5)  
No Admission to SCBU 40  (63.5) 39 (61.9)  
Fetal Birth weight      
Very low birth weight (1.0-1.4kg) 6  (9.5) 8 (12.7)  
Low birth weight (1.5–2.4kg) 26  (41.3) 21 (33.3) 0.62
Normal birth weight (2.5–3.9kg) 31  (49.2) 34  (54.0)  
Total 63  (100.0) 63  (100.0)  
Most of the babies were discharge to their mothers at delivery, without admission to Special Care Baby Unit (SCBU) in both groups of women. The Apgar scores were similar in both arm of the study. The recorded very low and Low birth weight were not statistically different between both groups.

Table 6: Fetal outcome.

Figures 1 and 2 shows median systolic and diastolic blood pressure control with respect to Hydralazine and Labetalol. There was a similar control in both groups.


Figure 1: Median Systolic Blood Pressure control in Hydralazine and Labetalol Groups.


Figure 2: Median Diastolic Blood Pressure control in Hydralazine and Labetalol Groups.


This randomized clinical trial for the treatment of severe preeclampsia using either Hydralazine or Labetalol demonstrated that both drugs remain effective rapid antihypertensive agents in such hypertensive emergencies as severe preeclampsia. This finding collaborate earlier studies including Cochrane review on the efficacy of either drugs in hypertensive crisis in pregnancy [10,15,20].Majority of the patients in both arms of the study were nulliparous. This supported the fact that Preeclampsia is more common among primigravidae [17].The preponderance of preeclampsia at advanced maternal age of greater than 35 year [21] was however not supported in this research work where over 80% of women in both group were aged between 20 – 34years. It is probable that recruitment with majority of participants in the lower age group may have bias the outcome of this study in contrast to previous workers [21]. A community based study where a wider age distribution of the participants may be feasible may corroborate the earlier reports of previous study [21]. It has also been shown in previous report that severe preeclampsia was more likely to occur among unbooked patient who may not have had the benefit of early diagnosis and monitoring in antenatal clinic [17]. The finding from this study runs contrary to this assertion as more patients in both arms of the study were booked. Perhaps, the fact that majority of women attending this institution are from urban area and are likely to utilise the facility for antenatal care may be responsible for this finding.

The average time taken to achieve desired blood pressure control was similar for both drugs. Also similar doses were required for blood pressure control in both groups. This finding perhaps forms the basis of accepting the null hypothesis in this study that demonstrated no superiority of one over the other in achieving fast blood pressure control. This finding was in keeping with previous studies [10,20]. The difference in the number of women in both groups that had persistent hypertension was however not statistically significant just as was earlier reported by previous workers [10,20]. There was no maternal hypotension in both groups. The absence of maternal hypotension and the relative success and safety profile observed in this study has earlier been reported by other workers using the same agents [10,15,20,22-24].

Those who had fresh stillbirths in Hydralazine and Labetalol group were patients managed for abruptio placentae. These deaths were more likely to be the complication from the abruptio placenta than from the effect of either the Hydralazine or Labetalol administration. This is because 3 and 2 of the stillbirths occurred before commencement of treatment in hydralazine and labetalol group respectively. There were no significant differences in the fetal outcome in both groups, further collaborating the finding of non-superiority of these drugs over one another.

Headache was significantly more frequent in patients given hydralazine compared to Labetalol. Vigil-De Gracia et al reported a rather higher frequency of maternal tachycardia and palpitations with the use of hydralazine compared to the use of labetalol, but no statistically significant difference in frequency of headache among their study groups [10]. Other researchers had reported similar adverse maternal side effects with either hydralazine or Labetalol [20].

In a meta-analysis conducted by Duley et al. [15] they found insufficient data for reliable conclusions about the comparative effects of these two antihypertensive agents. They concluded that until better evidence is available, the choice of antihypertensive should depend on what is known about adverse drug effects and how familiar the clinician is with a particular drug. Our findings in this study may have added to the existing knowledge on the subject matter.


  1. Ekele BA (2009) Use of magnesium sulfate to manage pre-eclampsia and eclampsia in Nigeria: overcoming the odds. Ann Afr Med 8: 73-75.
  2. Audu LR, Ekele BA (2002) A ten year review of maternal mortality in Sokoto, northern Nigeria. West Afr J Med 21: 74-76.
  3. El-Nafaty AU, Melah GS, Massa AA, Audu BM, Nelda M (2004) The analysis of eclamptic morbidity and mortality in the Specialist Hospital Gombe, Nigeria. J Obstet Gynaecol 24: 142-147.
  4. Ekele BA, Bello SO, Adamu AN (2007) Clusters of eclampsia in a Nigerian teaching hospital. Int J Gynaecol Obstet 96: 62-66.
  5. Tukur J, Umar BA, Rabi'u A (2007) Pattern of eclampsia in a tertiary health facility situated in a semi-rural town in Northern Nigeria. Ann Afr Med 6: 164-167.
  6. SOGON (2004) Status of emergency Obstetric Services in six States of Nigeria- A needs assessment report.
  7. Bolte AC, van Geijn HP, Dekker GA (2001) Management and monitoring of severe preeclampsia. Eur J Obstet Gynecol Reprod Biol 96: 8-20.
  8. [No authors listed] (2000) Report of the National High Blood Pressure Education Program Working Group on High Blood Pressure in Pregnancy. Am J Obstet Gynecol 183: S1-1S22.
  9. Magee LA, Cham C, Waterman EJ, Ohlsson A, von Dadelszen P (2003) Hydralazine for treatment of severe hypertension in pregnancy: meta-analysis. BMJ 327: 955-960.
  10. Vigil-De Gracia P, Lasso M, Ruiz E, Vega-Malek JC, de Mena FT, et al. (2006) Severe hypertension in pregnancy: hydralazine or labetalol. A randomized clinical trial. Eur J Obstet Gynecol Reprod Biol 128: 157-162.
  11. RCOG (2006) Guideline 10A. Management of severe preeclampsia and eclampsia.
  12. Cunningham FG (2005) Hypertensive disorders in pregnancy. In Williams Obstetrics 22nd edition. McGraw-Hill, New York.
  13. Frias AE Jr, Belfort MA (2003) Post Magpie: how should we be managing severe preeclampsia? Curr Opin Obstet Gynecol 15: 489-495.
  14. ACOG (2002) Diagnosis and Management of preeclampsia and eclampsia. ACOG Practice Bulletin No.33January 2002. American College of Obstetricians and Gynaecologists. Int J Gynaecol Obstet 77: 67-75.
  15. Duley L, Henderson-Smart DJ, Meher S (2013) Drugs for treatment of very high blood pressure during pregnancy. Cochrane Database Syst Rev.
  16. Araoye MO (2003) Research Methodology with Statistics for Health and Social Sciences. Nathadex Publishers Ilorin 115-129.
  17. Omole-Ohonsi A, Ashimi AO (2008) Preeclampsia- A Study of Risk Factors Nigerian Medical Practitioner AJOL 53: 99-102.
  18. Committee on Obstetric Practice (2011) Committee Opinion no. 514: emergent therapy for acute-onset, severe hypertension with preeclampsia or eclampsia. Obstet Gynecol 118: 1465-1468.
  19. Quan A (2006) Fetopathy associated with exposure to angiotensin converting enzyme inhibitors and angiotensin receptor antagonists. Early Hum Dev 82: 23-28.
  20. Delgado De Pasquale S, Velarde R, Reyes O, De la Ossa K (2013) Hydralazine vs Labetalol for treatment of severe hypertensive disorders of pregnancy. A randomized, controlled trial. Preg Hyper: An Int J Women’s Card Health 4:19-22
  21. Lamminpää R, Vehviläinen-Julkunen K, Gissler M, Heinonen S (2012) Preeclampsia complicated by advanced maternal age: a registry-based study on primiparous women in Finland 1997-2008. BMC Pregnancy Childbirth 12: 47.
  22. Mabie WC, Gonzalez AR, Sibai BM, Amon E (1987) A comparative trial of labetalol and hydralazine in the acute management of severe hypertension complicating pregnancy. Obstet Gynecol 70: 328-333.
  23. Bhorat IE, Naidoo DP, Rout CC, Moodley J (1993) Malignant ventricular arrhythmias in eclampsia: a comparison of labetalol with dihydralazine. Am J Obstet Gynecol 168: 1292-1296.
  24. Unuigbe JA, Ebomwonyi IO, Sule Z, Agbon-Ojeme GE, Uwaifo JO, et al. (2011) Management of Severe Preeclampsia, eclampsia, and severe hypertensive crises in Benin City, Nigeria, using a combination of magnesium sulphate and Labet (Labetalol)
Citation: Nombur LI, Agida ET, Isah AY, Ekele BA (2014) A Comparison of Hydralazine and Labetalol in the Management of Severe Preeclampsia. J Women’s Health Care 3:200.

Copyright: © 2014 Nombur LI, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.