The optimal dosage of ketanserin for patients with severe hypertension in pregnancy

Inadequate safety reporting in pre-eclampsia trials: a systematic evaluation

BACKGROUND

Randomised trials and their syntheses in meta-analyses offer a unique opportunity to assess the frequency and severity of adverse reactions.

OBJECTIVE

To assess safety reporting in pre-eclampsia trials.

SEARCH STRATEGY

Systematic search using bibliographic databases, including Cochrane Central Register of Controlled Trials, Embase, and MEDLINE, from inception to August 2017.

SELECTION CRITERIA

Randomised trials evaluating anticonvulsant or antihypertensive medication for pre-eclampsia.

DATA COLLECTION AND ANALYSIS

Descriptive statistics appraising the adequacy of adverse reaction and toxicity reporting.

MAIN RESULTS

We included 60 randomised trials. Six trials (10%) were registered with the International Clinical Trials Registry Platform, two registry records referred to adverse reactions, stating 'safety and toleration' and 'possible side effects' would be collected. Twenty-six trials (43%) stated the frequency of withdrawals within each study arm, and five trials (8%) adequately reported these withdrawals. Adverse reactions were inconsistently reported across eligible trials: 24 (40%) reported no serious adverse reactions and 36 (60%) reported no mild adverse reactions. The methods of definition or measurement of adverse reactions were infrequently reported within published trial reports.

CONCLUSIONS

Pre-eclampsia trials regularly omit critical information related to safety. Despite the paucity of reporting, randomised trials collect an enormous amount of safety data. Developing and implementing a minimum data set could help to improve safety reporting, permitting a more balanced assessment of interventions by considering the trade-off between the benefits and harms.

FUNDING

National Institute for Health Research (DRF-2014-07-051), UK; Maternity Forum, Royal Society of Medicine, UK.

TWEETABLE ABSTRACT

Developing @coreoutcomes could help to improve safety reporting in #preeclampsia trials. @NIHR_DC.

Bioactive Secondary Metabolites from Acid Mine Waste Extremophiles

The extremophilic microbes of the Berkeley Pit Lake are a valuable source of new and interesting secondary metabolites. It is of particular interest that these acidophilic microbes produce small molecule inhibitors of pathways associated with low pH and high Eh. These same small molecules also inhibit molecular pathways induced by reactive oxygen species (ROS) and inflammation in mammalian cells. Low pH is a hallmark of inflammation and high Eh is one of ROS, so the suitability of this collection as a source of bioactive metabolites is actually quite biorational. Compound isolation was guided by inhibition of caspase-1 and matrix metalloproteinase-3, and active compounds were sent to the National Cancer Institute-Developmental Therapeutics Program and Memorial Sloan Kettering Cancer center for evaluation as either antiproliferative or cytotoxic agents.

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.

Serotonin and blood pressure regulation

5-Hydroxytryptamine (5-HT; serotonin) was discovered more than 60 years ago as a substance isolated from blood. The neural effects of 5-HT have been well investigated and understood, thanks in part to the pharmacological tools available to dissect the serotonergic system and the development of the frequently prescribed selective serotonin-reuptake inhibitors. By contrast, our understanding of the role of 5-HT in the control and modification of blood pressure pales in comparison. Here we focus on the role of 5-HT in systemic blood pressure control. This review provides an in-depth study of the function and pharmacology of 5-HT in those tissues that can modify blood pressure (blood, vasculature, heart, adrenal gland, kidney, brain), with a focus on the autonomic nervous system that includes mechanisms of action and pharmacology of 5-HT within each system. We compare the change in blood pressure produced in different species by short- and long-term administration of 5-HT or selective serotonin receptor agonists. To further our understanding of the mechanisms through which 5-HT modifies blood pressure, we also describe the blood pressure effects of commonly used drugs that modify the actions of 5-HT. The pharmacology and physiological actions of 5-HT in modifying blood pressure are important, given its involvement in circulatory shock, orthostatic hypotension, serotonin syndrome and hypertension.

5-hydroxtryptamine receptors in systemic hypertension: an arterial focus

BACKGROUND

Serotonin (5-hydroxytryptamine [5-HT]) was named for its isolation from blood serum (sero-) and ability to contract smooth muscle (-tonin). Thus, its relationship with the cardiovascular system began with its discovery.

AIMS

This review will focus on the effects of 5-HT and its receptors in the vasculature, with a focus on their involvement in high blood pressure (hypertension). Two seemingly contradictory bodies of evidence exist that make it difficult to assign any one function to 5-HT in vascular control of blood pressure.

RESULTS

 In vitro, 5-HT is an established vasoconstrictor, the effects of which are amplified in hypertension. By contrast, 5-HT (or its precursor 5-hydroxytryptophan) lowers blood pressure when given chronically in vivo. We will discuss ideas that might help us understand these differences, discuss relatively new pharmacology parameters (e.g. biased, inverse agonism) as they pertain to 5-HT receptors, and pose questions that are vital to answer so as to understand the role played by 5-HT in control of blood pressure, especially as it pertains to vascular function.

CONCLUSIONS

Our goal is to understand if the actions of 5-HT in hypertension are physiologically and clinically relevant. The community understands 5-HT has complex cardiovascular effects, and clinical studies have proven equivocal in terms of the involvement of 5-HT. This article provides a balanced view of evidence/literature that illustrates involvement of 5-HT in hypertension as controversial. It contributes new pharmacological knowledge of 5-HT compounds, and poses timely questions as to how this field can move forward. The take home message is that the cardiovascular effects of 5-HT are markedly complex such that we have not yet answered the question of whether 5-HT is beneficial or detrimental to hypertension.

The 5-HT2 antagonist ketanserin is an open channel blocker of human cardiac ether-à-go-go-related gene (hERG) potassium channels

BACKGROUND AND PURPOSE

Ketanserin, a selective 5-HT receptor antagonist, prolongs the QT interval of ECG in patients. The purpose of the present study was to determine whether ketanserin would block human cardiac ether-à-go-go-related gene (hERG) potassium channels.

EXPERIMENTAL APPROACH

Whole-cell patch voltage-clamp technique was used to record membrane currents in HEK 293 cells expressing wild type or mutant hERG channel genes.

KEY RESULTS

Ketanserin blocked hERG current (I(hERG)) in a concentration-dependent manner (IC50=0.11 microM). The drug showed an open channel blocking property, the block increasing significantly at depolarizing voltages between +10 to +60 mV. Voltage-dependence for inactivation of hERG channels was negatively shifted by 0.3 microM ketanserin. A 2.8 fold attenuation of inhibition by elevation of external K+ concentration (from 5.0 to 20 mM) was observed, whereas the inactivation-deficient mutants S620T and S631A had the IC50s of 0.84 +/- 0.2 and 1.7 +/-0.4 microM (7.6 and 15.4 fold attenuation of block). In addition, the hERG mutants in pore helix and S6 also significantly reduced the channel block (2-59 fold) by ketanserin.

CONCLUSIONS AND IMPLICATIONS

These results suggest that ketanserin binds to and blocks the open hERG channels in the pore helix and the S6 domain; channel inactivation is also involved in the blockade of hERG channels. Blockade of hERG channels most likely contributes to the prolongation of QT intervals in ECG observed clinically at therapeutic concentrations of ketanserin.

Insufficient efficacy of intravenous ketanserin in severe early-onset pre-eclampsia

OBJECTIVE

To analyze the efficacy of intravenous ketanserin in controlling blood pressure of severe early-onset pre-eclamptic patients.

STUDY DESIGN

Pre-eclamptic patients (n=47) with a gestational age (GA) between 21 and 32 weeks were treated with intravenous ketanserin in a maximum dosage of 14 mg/h, to obtain a diastolic blood pressure of 90 mmHg or below. The number of patients reaching and maintaining target blood pressure was retrospectively assessed. Patient characteristics associated with an adequate or inadequate response to ketanserin treatment were identified.

RESULTS

With a maximum intravenous dosage of ketanserin, target blood pressure was not achieved in 15 (32%) patients. A high systolic blood pressure at the start of treatment was significantly (p=0.02) associated with failure of ketanserin treatment. The median period of ketanserin treatment in the responding group was 3 days (range 1-10 days). In 26 (55%) of initially successfully treated patients, additional antihypertensive drugs had to be added to maintain adequate blood pressure control.

CONCLUSION

Intravenous ketanserin lacks antihypertensive efficacy in a substantial proportion of severe pre-eclamptic patients, despite high dosages. In patients who initially respond well to ketanserin treatment, additional antihypertensive treatment is often necessary to maintain adequate blood pressure control.

Severe hypertension in pregnancy: Hydralazine or labetalol

OBJECTIVE

The objective was to compare the safety and efficacy of intravenous labetalol and intravenous hydralazine for acutely lowering blood pressure in pregnancy.

STUDY DESIGN

Two hundred women with severe hypertension in pregnancy were randomized to receive hydralazine (5 mg as a slow bolus dose given intravenously, and repeated every 20 min up to a maximum of five doses) or labetalol (20-mg intravenous bolus dose followed by 40 mg if not effective within 20 min, followed by 80 mg every 20 min up to a maximum dose of 300 mg). The primary end point was successful lowering of blood pressure and maternal hypotension.

RESULTS

Women were similar with respect to characteristics at randomization. No significant differences were observed for maternal hypotension or persistent severe hypertension; only two patients in the hydralazine group presented with hypotension. Palpitations (p=0.01) and maternal tachycardia (p=0.05) occurred significantly more often in patients treated with hydralazine. The main neonatal outcomes were very similar per group; however, hypotension and bradycardia were significantly more frequent in the labetalol group. There were two neonatal deaths per antihypertensive drug group.

CONCLUSIONS

This randomized clinical trial shows that labetalol and hydralazine fulfill the criteria required for an antihypertensive drug to treat severe hypertension in pregnancy.

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.

Population pharmacokinetics of ketanserin in pre-eclamptic patients and its association with antihypertensive response

Ketanserin is an antihypertensive drug that is increasingly being used parenterally in the treatment of pre-eclampsia. Because of lack of efficacy in a substantial part of our pre-eclamptic patients, we determined the plasma concentrations of ketanserin in 51 pre-eclamptic patients. Population pharmacokinetic parameters were assessed using the iterative two-stage Bayesian population procedure. The influence of individual pharmacokinetic parameters on antihypertensive response, expressed as the attainment of a diastolic blood pressure <or=90 mmHg using ketanserin treatment, was analysed. Almost all plasma concentrations of ketanserin were in or above the therapeutic range. The individual pharmacokinetics of ketanserin in pre-eclamptic patients showed an accurate fit using a three-compartment model. The pharmacokinetic parameters in our pre-eclamptic population were a metabolic clearance (Cl(m)) of 37.9+/-10.86 L/h and volume of distribution (V1) of 0.544+/- 0.188 L/kg, which is comparable with data from healthy volunteers. Despite a considerable inter-individual variation, no correlation was found between differences in pharmacokinetic parameters and antihypertensive response. We conclude that therapeutic plasma levels can be obtained in pre-eclamptic patients with a fixed dosage schedule of ketanserin and differences in antihypertensive responses within a pre-eclamptic population cannot be attributed to pharmacokinetic differences.

5-HT in systemic hypertension: foe, friend or fantasy?

Since its discovery by Erspamer in the 1930s and identification by Page in the 1950s, 5-HT (5-hydroxytryptamine; serotonin) has been an elusive candidate as a substance that plays a role in the disease of high blood pressure, also known as hypertension. In both animal and human hypertension, arterial contraction to 5-HT is profoundly enhanced. Additionally, 5-HT is a vascular smooth muscle cell mitogen. Because both increased arterial contractility and smooth muscle growth contribute to the disease of hypertension, it is logical to believe that 5-HT is a potential cause of disease, and thus a foe. However, decades of research have produced conflicting results as to the potential role of 5-HT in hypertension. This review will discuss historical findings which both support and refute the involvement of 5-HT in hypertension, and pose some new questions that may reveal novel ways for 5-HT to modify vascular control of blood pressure.

A novel 5-HT receptor ligand and related cytotoxic compounds from an acid mine waste extremophile

Berkeley Pit Lake in Butte, Montana, is an acid mine waste reservoir rich in toxic metals. A Pithomycessp. isolated from the Pit Lake yielded three tyrosine derivatives (1-3), one of which acts as a 5-HT((2a)) receptor ligand. This type of activity has been associated with migraine preventative and antihypertensive drugs. The isolation and characterization of compounds 1-3 and three sesquiterpenes (5-7) that have been isolated previously from higher plants are reported here.

Simultaneous quantitative analysis of ketanserin and ketanserinol in plasma by RP-HPLC with ?uorescence detection

A sensitive and selective high-performance liquid chromatographic assay for the quantification of ketanserin and ketanserinol in human plasma was developed and validated. The procedure involves extraction of ketanserin and ketanserinol from plasma using an Extrelut NT-1 solid-phase extraction column. The chromatograph was equipped with a Hypersil BDS column (100 x 4.5 mm, 3 micro m particle size). Separation was performed with a mixture of acetate buffer 0.01 M, pH 4.9-methanol-acetonitrile (52:40:8, v/v/v). Detection was performed with fluorescence detection (lambda(ex) = 332 nm and lambda(em) = 410 nm). Calibration curves were linear (r(2) = 0.999) in the range 0-400 ng/mL for both ketanserin and ketanserinol. The repeatability coefficient for ketanserin and ketanserinol was 3.1 and 3.0%, respectively. The reproducibility coefficient for ketanserin and ketanserinol was 10.5 and 9.1%, respectively. The limit of quantification for both ketanserin and ketanserinol was 2.0 ng/mL. The mean recovery yield for both ketanserin and ketanserinol was 60%. In an 8 h work day approximately 60 samples, including calibration and reference standards, could be processed.

Drugs for rapid treatment of very high blood pressure during pregnancy

BACKGROUND

Very high blood pressure during pregnancy poses a serious threat to women and their fetuses. The use of drugs to lower blood pressure may reduce this risk.

OBJECTIVES

The objective of this review was to compare different antihypertensive drugs used for rapid treatment of severe hypertension during pregnancy.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group trials register and the Cochrane Controlled Trials Register.

STUDIES

All randomised trials. Quasi random designs were excluded.

PARTICIPANTS

Women with severe hypertension during pregnancy. Women postpartum at trial entry were excluded.

INTERVENTIONS

Comparisons of one antihypertensive agent with another.

OUTCOMES

For the women: blood pressure control, eclampsia, serious maternal morbidity (such as kidney failure and liver failure), Caesarean section, and use of health service resources (such as admission to hospital or intensive care unit). For the baby: death, serious neonatal morbidity, infant and child development, and use of health service resources (such as admission to a special care nursery).

DATA COLLECTION AND ANALYSIS

Data were extracted independently by two reviewers to assess eligibility and describe the trial characteristics, and by one reviewer for the meta-analyses. Discrepancies were resolved by discussion. There was no blinding of authorship or results. Whenever possible, unpublished data were sought from investigators.

MAIN RESULTS

Thirteen of the 14 trials included in this review were small (range 19-627 women). Of the eight comparisons, five included hydralazine. Diazoxide given as 75mg bolus injections appears to be associated with profound hypotension requiring treatment, and ketanserin is less effective than hydralazine at reducing blood pressure. There is no other evidence that any one of the other antihypertensive agents is better than another for women with severe hypertension during pregnancy.

REVIEWER'S CONCLUSIONS

Until better evidence is available, the choice of antihypertensive should depend on the experience and familiarity of an individual clinician with a particular drug, and on what is known about adverse maternal and fetal side-effects. Exceptions are diazoxide and ketanserin, which are probably not good choices.