The hemodynamic effects of intravenous digoxin-binding fab immunoglobulin in severe preeclampsia: a double-blind, randomized, clinical trial

Sensational site: the sodium pump ouabain-binding site and its ligands

Cardiotonic steroids (CTS), used by certain insects, toads, and rats for protection from predators, became, thanks to Withering's trailblazing 1785 monograph, the mainstay of heart failure (HF) therapy. In the 1950s and 1960s, we learned that the CTS receptor was part of the sodium pump (NKA) and that the Na+/Ca2+ exchanger was critical for the acute cardiotonic effect of digoxin- and ouabain-related CTS. This "settled" view was upended by seven revolutionary observations. First, subnanomolar ouabain sometimes stimulates NKA while higher concentrations are invariably inhibitory. Second, endogenous ouabain (EO) was discovered in the human circulation. Third, in the DIG clinical trial, digoxin only marginally improved outcomes in patients with HF. Fourth, cloning of NKA in 1985 revealed multiple NKA α and β subunit isoforms that, in the rodent, differ in their sensitivities to CTS. Fifth, the NKA is a cation pump and a hormone receptor/signal transducer. EO binding to NKA activates, in a ligand- and cell-specific manner, several protein kinase and Ca2+-dependent signaling cascades that have widespread physiological effects and can contribute to hypertension and HF pathogenesis. Sixth, all CTS are not equivalent, e.g., ouabain induces hypertension in rodents while digoxin is antihypertensinogenic ("biased signaling"). Seventh, most common rodent hypertension models require a highly ouabain-sensitive α2 NKA and the elevated blood pressure is alleviated by EO immunoneutralization. These numerous phenomena are enabled by NKA's intricate structure. We have just begun to understand the endocrine role of the endogenous ligands and the broad impact of the ouabain-binding site on physiology and pathophysiology.

Endogenous Digitalis-like Factors as a Key Molecule in the Pathophysiology of Pregnancy-Induced Hypertension and a Potential Therapeutic Target in Preeclampsia

Preeclampsia (PE), the most severe presentation of hypertensive disorders of pregnancy, is the major cause of morbidity and mortality linked to pregnancy, affecting both mother and fetus. Despite advances in prophylaxis and managing PE, delivery of the fetus remains the only causative treatment available. Focus on complex pathophysiology brought the potential for new treatment options, and more conservative options allowing reduction of feto-maternal complications and sequelae are being investigated. Endogenous digitalis-like factors, which have been linked to the pathogenesis of preeclampsia since the mid-1980s, have been shown to play a role in the pathogenesis of various cardiovascular diseases, including congestive heart failure and chronic renal disease. Elevated levels of EDLF have been described in pregnancy complicated by hypertensive disorders and are currently being investigated as a therapeutic target in the context of a possible breakthrough in managing preeclampsia. This review summarizes mechanisms implicating EDLFs in the pathogenesis of preeclampsia and evidence for their potential role in treating this doubly life-threatening disease.

Whither digitalis? What we can still learn from cardiotonic steroids about heart failure and hypertension

Cloning of the "Na⁺ pump" (Na⁺,K⁺-ATPase or NKA) and identification of a circulating ligand, endogenous ouabain (EO), a cardiotonic steroid (CTS), triggered seminal discoveries regarding EO and its NKA receptor in cardiovascular function and the pathophysiology of heart failure (HF) and hypertension. Cardiotonic digitalis preparations were a preferred treatment for HF for two centuries, but digoxin was only marginally effective in a large clinical trial (1997). This led to diminished digoxin use. Missing from the trial, however, was any consideration that endogenous CTS might influence digitalis' efficacy. Digoxin, at therapeutic concentrations, acutely inhibits NKA but, remarkably, antagonizes ouabain's action. Prolonged treatment with ouabain, but not digoxin, causes hypertension in rodents; in this model, digoxin lowers blood pressure (BP). Furthermore, NKA-bound ouabain and digoxin modulate different protein kinase signaling pathways and have disparate long-term cardiovascular effects. Reports of "brain ouabain" led to the elucidation of a new, slow neuromodulatory pathway in the brain; locally generated EO and the α2 NKA isoform help regulate sympathetic drive to the heart and vasculature. The roles of EO and α2 NKA have been studied by EO assay, ouabain-resistant mutation of α2 NKA, and immunoneutralization of EO with ouabain-binding Fab fragments. The NKA α2 CTS binding site and its endogenous ligand are required for BP elevation in many common hypertension models and full expression of cardiac remodeling and dysfunction following pressure overload or myocardial infarction. Understanding how endogenous CTS impact hypertension and HF pathophysiology and therapy should foster reconsideration of digoxin's therapeutic utility.

Preeclampsia: Cardiotonic Steroids, Fibrosis, Fli1 and Hint to Carcinogenesis

Despite prophylaxis and attempts to select a therapy, the frequency of preeclampsia does not decrease and it still takes the leading position in the structure of maternal mortality and morbidity worldwide. In this review, we present a new theory of the etiology and pathogenesis of preeclampsia that is based on the interaction of Na/K-ATPase and its endogenous ligands including marinobufagenin. The signaling pathway of marinobufagenin involves an inhibition of transcriptional factor Fli1, a negative regulator of collagen synthesis, followed by the deposition of collagen in the vascular tissues and altered vascular functions. Moreover, in vitro and in vivo neutralization of marinobufagenin is associated with the restoration of Fli1. The inverse relationship between marinobufagenin and Fli1 opens new possibilities in the treatment of cancer; as Fli1 is a proto-oncogene, a hypothesis on the suppression of Fli1 by cardiotonic steroids as a potential anti-tumor therapeutic strategy is discussed as well. We propose a novel therapy of preeclampsia that is based on immunoneutralization of the marinobufagenin by monoclonal antibodies, which is capable of impairing marinobufagenin-Na/K-ATPase interactions.

Role of endogenous digitalis-like factors in the clinical manifestations of severe preeclampsia: a sytematic review

Endogenous digitalis-like factor(s), originally proposed as a vasoconstrictor natriuretic hormone, was discovered in fetal and neonatal blood accidentally because it cross-reacts with antidigoxin antibodies (ADAs). Early studies using immunoassays with ADA identified the digoxin-like immuno-reactive factor(s) (EDLF) in maternal blood as well, and suggested it originated in the feto-placental unit. Mammalian digoxin-like factors have recently been identified as at least two classes of steroid compounds, plant derived ouabain (O), and several toad derived bufodienolides, most prominent being marinobufagenin (MBG). A synthetic pathway for MBG has been identified in mammalian placental tissue. Elevated maternal and fetal EDLF, O and MBG have been demonstrated in preeclampsia (PE), and inhibition of red cell membrane sodium, potassium ATPase (Na, K ATPase (NKA)) by EDLF is reversed by ADA fragments (ADA-FAB). Accordingly, maternal administration of a commercial ADA-antibody fragment (FAB) was tested in several anecdotal cases of PE, and two, small randomized, prospective, double-blind clinical trials. In the first randomized trial, ADA-FAB was administered post-partum, in the second antepartum. In the post-partum trial, ADA-FAB reduced use of antihypertensive drugs. In the second trial, there was no effect of ADA-FAB on blood pressure, but the fall in maternal creatinine clearance (CrCl) was prevented. In a secondary analysis using the pre-treatment maternal level of circulating Na, K ATPase (NKA) inhibitory activity (NKAI), ADA-FAB reduced the incidence of pulmonary edema and, unexpectedly, that of severe neonatal intraventricular hemorrhage (IVH). The fall in CrCl in patients given placebo was proportional to the circulating level of NKAI. The implications of these findings on the pathophysiology of the clinical manifestations PE are discussed, and a new model of the respective roles of placenta derived anti-angiogenic (AAG) factors (AAGFs) and EDLF is proposed.

Increased serum heme oxygenase-1 levels as a diagnostic marker of oxidative stress in preeclampsia

OBJECTIVE

To evaluate the utility of serum biomarkers in the diagnosis of preeclampsia (PE) and also investigate possible correlation with pathogenesis of PE.

METHODS

Maternal serum concentrations of heme oxygenase-1 (HO1) and N-myc downstream-regulated gene 1 (NDRG1) were measured at 27-34 weeks of gestation in a case-control study of 33 pregnant women diagnosed with PE and in 43 normotensive pregnant women without proteinuria. The Mann-Whitney U test and Spearman's correlation were used for statistical analysis.

RESULTS

The median serum HO1 level was found to be significantly higher in the PE group [76.7 ng/ml (23.4-445.7)] than control group [55.9 ng/ml (3.7-354.3)] (p = 0.006). Positive correlation was found between HO1 levels with presence of PE (r = 0.316, p = 0.005). There was no significant difference in NDRG1 values between the two groups (p = 0.226).

CONCLUSIONS

Serum HO1 levels were found to be increased in patients with PE compared with normotensive pregnant women.

Ouabain inhibits placental sFlt1 production by repressing HSP27-dependent HIF-1α pathway

Up-regulation of placental soluble fms-like tyrosine kinase 1 (sFlt1) contributes to the pathogenesis of preeclampsia. To evaluate novel upstream pathways that regulate placental sFlt1 production, we screened a library of natural compounds (n=502) in human placental cell lines. Here, we report 3 compounds in the cardiac glycoside family, ouabain, gitoxigenin, and digitoxin, that inhibit placental sFlt1 production at nanomolar concentrations in vitro. We further characterized ouabain and demonstrated that it inhibits sFlt1 mRNA and protein expression in human placental cytotrophoblasts and explant cultures in a dose- and time-dependent manner. Ouabain down-regulated sFlt1 production by inhibiting hypoxia-inducible factor 1 (HIF-1α) protein expression in the placenta. Furthermore, we found that phosphorylation of heat-shock protein 27 (HSP27) was necessary for ouabain to inhibit HIF-1α translation. In a rat model of pregnancy-induced hypertension, ouabain reduced mean arterial pressure and enhanced placental HSP27 phosphorylation without any adverse effects on pups. Further studies are needed to explore the usefulness of targeting HIF-1α/HSP27 pathway in preeclampsia.

Digoxin antibody fragment, antigen binding (Fab), treatment of preeclampsia in women with endogenous digitalis-like factor: a secondary analysis of the DEEP Trial

OBJECTIVE

Endogenous digitalis-like factors (EDLFs) are elevated in women with preeclampsia, and the use of an anti-digoxin antibody Fab (DIF) in women with preeclampsia who were remote from term reduced maternal blood pressure and preserved renal function. The objective was to determine whether DIF treatment in women with severe preeclampsia in association with positive EDLFs in maternal serum improves maternal-perinatal outcomes.

STUDY DESIGN

This was a planned secondary analysis from a randomized, placebo-controlled, double-blind study of DIF in women with severe preeclampsia with positive EDLF status that was managed expectantly between 23 weeks 5 days and 34 weeks' gestation (19 women received placebo, and 17 women received DIF). Primary outcome variables were a change in creatinine clearance and the use of antihypertensives. Secondary outcomes were maternal and perinatal complications.

RESULTS

Women with positive EDLFs who received DIF had an attenuated decline in creatinine clearance from baseline compared with placebo (-4.5 ± 12.9 vs -53.2 ± 12.6 mL/min; P = .005). In this same group, the use of antihypertensives (the other primary outcome) was lower but not significantly so (41% vs 63%; P = .12). However, women who were treated with DIF had a lower rate of pulmonary edema (1/17 vs 6/19 women; P = .035) and lower rates of neonatal intraventricular hemorrhage (DIF: 0/17 women vs placebo: 5/19 women; P = .015).

CONCLUSION

In women with severe preeclampsia who were remote from term who were EDLF positive, the use of DIF was associated with improved maternal and neonatal outcome. These findings suggest the need for a large multicenter trial that would evaluate the benefits of DIF in the treatment of women with severe preeclampsia who are remote from term and with positive EDLF status.

Drugs for treatment of very high blood pressure during pregnancy

BACKGROUND

Very high blood pressure during pregnancy poses a serious threat to women and their babies. The aim of antihypertensive therapy is to lower blood pressure quickly but safety, to avoid complications. Antihypertensive drugs lower blood pressure but their comparative effectiveness and safety, and impact on other substantive outcomes is uncertain.

OBJECTIVES

To compare different antihypertensive drugs for very high blood pressure during pregnancy.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group Trials Register (9 January 2013).

SELECTION CRITERIA

Studies were randomised trials. Participants were women with severe hypertension during pregnancy. Interventions were comparisons of one antihypertensive drug with another.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and assessed trial quality. Two review authors extracted data and checked them for accuracy.

MAIN RESULTS

Thirty-five trials (3573 women) with 15 comparisons were included. Women allocated calcium channel blockers were less likely to have persistent high blood pressure compared to those allocated hydralazine (six trials, 313 women; 8% versus 22%; risk ratio (RR) 0.37, 95% confidence interval (CI) 0.21 to 0.66). Ketanserin was associated with more persistent high blood pressure than hydralazine (three trials, 180 women; 27% versus 6%; RR 4.79, 95% CI 1.95 to 11.73), but fewer side-effects (three trials, 120 women; RR 0.32, 95% CI 0.19 to 0.53) and a lower risk of HELLP (haemolysis, elevated liver enzymes and lowered platelets) syndrome (one trial, 44 women; RR 0.20, 95% CI 0.05 to 0.81).Labetalol was associated with a lower risk of hypotension compared to diazoxide (one trial 90 women; RR 0.06, 95% CI 0.00 to 0.99) and a lower risk of caesarean section (RR 0.43, 95% CI 0.18 to 1.02), although both were borderline for statistical significance.Both nimodipine and magnesium sulphate were associated with a high incidence of persistent high blood pressure, but this risk was lower for nimodipine compared to magnesium sulphate (one trial, 1650 women; 47% versus 65%; RR 0.84, 95% CI 0.76 to 0.93). Nimodipine was associated with a lower risk of respiratory difficulties (RR 0.28, 95% CI 0.08 to 0.99), fewer side-effects (RR 0.68, 95% CI 0.55 to 0.85) and less postpartum haemorrhage (RR 0.41, 95% CI 0.18 to 0.92) than magnesium sulphate. Stillbirths and neonatal deaths were not reported.There are insufficient data for reliable conclusions about the comparative effects of any other drugs.

AUTHORS' CONCLUSIONS

Until better evidence is available the choice of antihypertensive should depend on the clinician's experience and familiarity with a particular drug; on what is known about adverse effects; and on women's preferences. Exceptions are nimodipine, magnesium sulphate (although this is indicated for women who require an anticonvulsant for prevention or treatment of eclampsia), diazoxide and ketanserin, which are probably best avoided.

DigiFab interacts with endogenous cardiotonic steroids and reverses preeclampsia-induced Na/K-ATPase inhibition

Elevated levels of endogenous Na/K-ATPase (NKA) inhibitors, cardiotonic steroids (CTSs) including marinobufagenin (MBG), contribute to pathogenesis of preeclampsia (PE) and represent a target for immunoneutralization by Digibind (Ovine Digoxin Immune Antibody, Glaxo-Smith Kline). Because Digibind is no longer commercially available, we studied whether DigiFab (BTG International Ltd, UK) can substitute Digibind for immunoneutralization of CTS in patients with PE. We compared DigiFab, Digibind, and anti-MBG monoclonal antibody (mAb) with respect to their ability to interact with CTS in PE plasma and to restore NKA activity in erythrocytes from patients with PE. Using immunoassays based on DigiFab, Digibind, and anti-MBG mAb, we studied the elution profile of CTS following high-performance liquid chromatography (HPLC) fractionation of PE plasma. Totally, 7 patients with mild PE (28 ± 2 years; gestational age, 39 ± 0.5 weeks; blood pressure 156 ± 5/94 ± 2 mm Hg) and 6 normotensive pregnant participants (28 ± 1 years; gestational age, 39 ± 0.4 weeks; blood pressure 111 ± 2/73 ± 2 mm Hg) were enrolled. Preeclampsia was associated with a substantial inhibition of erythrocyte NKA (1.47 ± 0.17 vs 2.65 ± 0.16 µmol Pi/mL per h in control group, P < .001). Ex vivo, at 10 µg/mL concentration, which is consistent with the clinical dosing of Digibind administered previously in PE, DigiFab and Digibind as well as anti-MBG mAb (0.5 µg/mL) restored erythrocyte NKA activity. Following HPLC fractionation of pooled PE and control plasma, PE-associated increase in CTS material was detected by Digibind (176 vs 75 pmoles), DigiFab (221 vs 70 pmoles), and anti-MBG mAb (1056 vs 421 pmoles). Therefore, because DigiFab interacts with CTS from PE plasma and reverses PE-induced NKA inhibition, it can substitute Digibind for immunoneutralization of CTS in patients with PE.

In preeclampsia endogenous cardiotonic steroids induce vascular fibrosis and impair relaxation of umbilical arteries

BACKGROUND

Marinobufagenin (MBG), a bufadienolide cardiotonic steroid, induces cardiovascular fibrosis. Because levels of MBG in preeclampsia are increased, and anti-MBG monoclonal antibody reduces blood pressure (BP) in a rat model of preeclampsia, we hypothesized that in preeclampsia, elevated MBG levels would be associated with the development of fibrosis in feto-placental circulation and with impairment of vascular relaxation.

METHOD

We studied 16 patients with preeclampsia (systolic BP=150±4 mmHg; 28±2 years, 37±1 weeks gestational age) and 14 gestational age-matched normal pregnant women (systolic BP=112±2 mmHg).

RESULTS

Preeclampsia was associated with a rise in plasma and placental levels of MBG. In preeclamptic umbilical arteries, the expression of Fli-1, a transcription factor and a negative regulator of fibrosis, was significantly reduced (P<0.001), whereas procollagen-1 expression was increased (P<0.01). As compared to control vessels, isolated rings of umbilical arteries from patients with preeclampsia demonstrated unaltered responsiveness to endothelin-1 (EC50=2.2 and 3.2 nmol/l, respectively), but exhibited an impaired response to the relaxant effect of sodium nitroprusside (EC50=1.5 vs. 32.4 nmol/l, P<.001) following endothelin-1-induced constriction. Ex-vivo treatment of normal umbilical arteries explants with 1 and 10 nmol/l MBG for 24 h mimicked the effects of preeclampsia, specifically suppressed Fli-1 and increased collagen-1 expression while impairing vasorelaxation.

CONCLUSION

Our results indicate that in preeclampsia, elevated levels of MBG induce vascular fibrosis via a Fli-1-dependent mechanism which leads to an impairment of vasorelaxation, and suggest that MBG represents a potential target for therapy of this syndrome.

Both high and low maternal salt intake in pregnancy alter kidney development in the offspring

In humans, low glomerular numbers are related to hypertension, cardiovascular, and renal disease in adult life. The present study was designed 1) to explore whether above- or below-normal dietary salt intake during pregnancy influences nephron number and blood pressure in the offspring and 2) to identify potential mechanisms in kidney development modified by maternal sodium intake. Sprague-Dawley rats were fed low (0.07%)-, intermediate (0.51%)-, or high (3.0%)-sodium diets during pregnancy and lactation. The offspring were weaned at 4 wk and subsequently kept on a 0.51% sodium diet. The kidney structure was assessed at postnatal weeks 1 and 12 and the expression of proteins of interest at term and at week 1. Blood pressure was measured in male offspring by telemetry from postnatal month 2 to postnatal month 9. The numbers of glomeruli at weeks 1 and 12 were significantly lower and, in males, telemetrically measured mean arterial blood pressure after month 5 was higher in offspring of dams on a high- or low- compared with intermediate-sodium diet. A high-salt diet was paralleled by higher concentrations of marinobufagenin in the amniotic fluid and an increase in the expression of both sprouty-1 and glial cell-derived neutrophic factor in the offspring's kidney. The expression of FGF-10 was lower in offspring of dams on a low-sodium diet, and the expression of Pax-2 and FGF-2 was lower in offspring of dams on a high-sodium diet. Both excessively high and excessively low sodium intakes during pregnancy modify protein expression in offspring kidneys and reduce the final number of glomeruli, predisposing the risk of hypertension later in life.

Endogenous cardiotonic steroids in chronic renal failure

BACKGROUND

Previous reports demonstrated that digitalis-like cardiotonic steroids (CTS) contribute to the pathogenesis of end-stage renal disease. The goal of the present study was to define the nature of CTS in patients with chronic kidney disease (CKD) and in partially nephrectomized (PNx) rats.

METHODS

In patients with CKD and in healthy controls, we determined plasma levels of marinobufagenin (MBG) and endogenous ouabain (EO) and erythrocyte Na/K-ATPase activity in the absence and in the presence of 3E9 anti-MBG monoclonal antibody (mAb) and Digibind. Levels of MBG and EO were also determined in sham-operated Sprague-Dawley rats and in rats following 4 weeks of PNx.

RESULTS

In 25 patients with CKD plasma, MBG but not EO was increased (0.86 ± 0.07 versus 0.28 ± 0.02 nmol/L, P < 0.01) and erythrocyte Na/K-ATPase was inhibited (1.24 ± 0.10 versus 2.80 ± 0.09 μmol Pi/mL/h, P < 0.01) as compared to that in 19 healthy subjects. Ex vivo, 3E9 mAb restored Na/K-ATPase in erythrocytes from patients with CKD but did not affect Na/K-ATPase from control subjects. Following chromatographic fractionation of uremic versus normal plasma, a competitive immunoassay based on anti-MBG mAb detected a 3-fold increase in the level of endogenous material having retention time similar to that seen with MBG. A similar pattern of CTS changes was observed in uremic rats. As compared to sham-operated animals, PNx rats exhibited 3-fold elevated levels of MBG but not that of EO.

CONCLUSIONS

In chronic renal failure, elevated levels of a bufadienolide CTS, MBG, contribute to Na/K-ATPase inhibition and may represent a potential target for therapy.

Interaction of Digibind with endogenous cardiotonic steroids from preeclamptic placentae

BACKGROUND

Preeclampsia is a major cause of maternal and fetal mortality, and its pathogenesis is not fully understood. Endogenous digitalis-like cardiotonic steroids (CTS) have been implicated in the pathophysiology of preeclampsia; this is illustrated by clinical observations that Digibind, a therapeutic digoxin antibody fragment which binds CTS, lowers blood pressure and reverses Na/K-ATPase inhibition in patients with preeclampsia. Recently we reported that plasma levels of marinobufagenin (MBG), a bufadienolide vasoconstrictor CTS, are increased four-fold in patients with severe preeclampsia.

METHODS

In the present study, we compared levels of MBG in normal and preeclamptic placentae, as well as the interactions of Digibind and antibodies against MBG and ouabain with material purified from preeclamptic placentae using high-performance liquid chromatography (HPLC).

RESULTS

Levels of endogenous MBG, but not that of endogenous ouabain, exhibited a four-fold elevation in preeclamptic placentae vs. normal placentae (13.6 +/- 2.5 and 48.6 +/- 7.0 nmoles/g tissue; P < 0.01). The elution time of endogenous placental MBG-like immunoreactive material from reverse-phase HPLC column was identical to that of authentic MBG. A competitive immunoassay based on Digibind exhibited reactivity to HPLC fractions having retention times similar to that seen with MBG and other bufadienolides, but not to ouabain-like immunoreactive material.

CONCLUSIONS

Our results suggest that elevated levels of endogenous bufadienolide CTS represent a potential target for immunoneutralization in patients with preeclampsia.

Endogenous cardiotonic steroids: physiology, pharmacology, and novel therapeutic targets

Endogenous cardiotonic steroids (CTS), also called digitalis-like factors, have been postulated to play important roles in health and disease for nearly half a century. Recent discoveries, which include the specific identification of endogenous cardenolide (endogenous ouabain) and bufadienolide (marinobufagenin) CTS in humans along with the delineation of an alternative mechanism by which CTS can signal through the Na(+)/K(+)-ATPase, have increased the interest in this field substantially. Although CTS were first considered important in the regulation of renal sodium transport and arterial pressure, more recent work implicates these hormones in the regulation of cell growth, differentiation, apoptosis, and fibrosis, the modulation of immunity and of carbohydrate metabolism, and the control of various central nervous functions and even behavior. This review focuses on the physiological interactions between CTS and other regulatory systems that may be important in the pathophysiology of essential hypertension, preeclampsia, end-stage renal disease, congestive heart failure, and diabetes mellitus. Based on our increasing understanding of the regulation of CTS as well as the molecular mechanisms of these hormone increases, we also discuss potential therapeutic strategies.

Drugs for treatment of very high blood pressure during pregnancy

BACKGROUND

Very high blood pressure during pregnancy poses a serious threat to women and their babies. Antihypertensive drugs lower blood pressure. Their comparative effects on other substantive outcomes, however, is uncertain.

OBJECTIVES

To compare different antihypertensive drugs for very high blood pressure during pregnancy.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group Trials Register (28 February 2006) and CENTRAL (The Cochrane Library 2006, Issue 2).

SELECTION CRITERIA

Studies were randomised trials. Participants were women with severe hypertension during pregnancy. Interventions were comparisons of one antihypertensive drug with another.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data.

MAIN RESULTS

Twenty-four trials (2949 women) with 12 comparisons were included. Women allocated calcium channel blockers rather than hydralazine were less likely to have persistent high blood (five trials, 263 women; 6% versus 18%; relative risk (RR) 0.33, 95% confidence interval (CI) 0.15 to 0.70). Ketanserin was associated with more persistent high blood pressure than hydralazine (four trials, 200 women; 27% versus 6%; RR 4.79, 95% CI 1.95 to 11.73), but fewer side-effects (three trials, 120 women; RR 0.32, 95% CI 0.19 to 0.53) and a lower risk of HELLP (Haemolysis, Elevated Liver enzymes and Lowered Platelets) syndrome (one trial, 44 women, RR 0.20, 95% CI 0.05 to 0.81). Labetalol was associated with a higher risk of hypotension (one trial 90 women; RR 0.06, 95% CI 0.00 to 0.99) and caesarean section (RR 0.43, 95% CI 0.18 to 1.02) than diazoxide. Data were insufficient for reliable conclusions about other outcomes. The risk of persistent high blood pressure was greater for nimodipine compared to magnesium sulphate (two trials 1683 women; 47% versus 65%; RR 0.84, 95% CI 0.76 to 0.93). Nimodipine was also associated with a higher risk of eclampsia (RR 2.24, 95% CI 1.06 to 4.73) and respiratory difficulties (RR 0.28, 95% CI 0.08 to 0.99), but fewer side-effects (RR 0.68, 95% CI 0.54 to 0.86) and less postpartum haemorrhage (RR 0.41, 95% CI 0.18 to 0.92) than magnesium sulphate. Stillbirths and neonatal deaths were not reported. There are insufficient data for reliable conclusions about the comparative effects of any other drugs.

AUTHORS' CONCLUSIONS

Until better evidence is available, the choice of antihypertensive should depend on the clinician's experience and familiarity with a particular drug, and on what is known about adverse effects. Exceptions are diazoxide, ketanserin, nimodipine and magnesium sulphate, which are probably best avoided.