Randomized comparison of mefloquine-artesunate versus quinine in the treatment of multidrug-resistant falciparum malaria in pregnancy

Efficacy and Safety of Artemisinin-Based Combination Therapy for the Treatment of Uncomplicated Malaria in Pregnant Women: A Systematic Review and Meta-Analysis

Introduction

Malaria is one of the infectious diseases with substantial risks for pregnant women, the fetus and the newborn child. Thus, prevention and treatment of malaria with safe and effective drugs is of paramount importance. Pregnant women are mostly excluded from clinical trials, and systematic approaches of pharmacovigilance in pregnancy are limited. This means the safety and efficacy of antimalarial agents during pregnancy are unclear.

Purpose

This study was designed to carry out a systematic review and aggregate data meta-analysis of literature published on efficacy and safety of artemisinin-based combination therapy (ACT) for uncomplicated malaria in pregnant women.

Methods

A search of literature published between 1998 to 2020 on efficacy and safety of artemisinin-based combination therapy (ACT) in pregnant women was made using Cochrane Library, Medline and the Malaria in Pregnancy Consortium Library. Data were extracted independently by two reviewers, and any discrepancies were resolved by consensus. Meta-analysis was carried out using Open Meta-Analyst software. Random effects model was applied, and the heterogeneity of studies was evaluated using Higgins I².

Results

Twenty-four studies that fulfilled the inclusion criteria were included in the final assessment. Overall, days 28 to 63 malaria treatment success rate was 96.1%. Overall days 28 to 63 cure rates for AL, AS+AQ, AS+MQ, DHA+PQ, AS+ATQ+PG and AS+SP were 95.1%, 92.2%, 97.0%,94.3%, 96.5% and 97.4%, respectively. Comparison of ACTs with non-ACTs revealed that the risk of treatment failure was substantially lower in patients treated with ACTs than with non-ACTs (risk ratio 0.20, 95% C.I. 0.09–0.43). The overall prevalences of miscarriage, stillbirth and congenital anomalies were 0.3%, 2.1% and 1.0%, respectively, and found to be comparable among various ACTs. There was comparable tolerability across ACTs during pregnancy.

Conclusion

ACTs demonstrated a high cure rate, safety and tolerability against Plasmodium falciparum infection in pregnant women. The higher treatment success and comparable tolerability could be used as an input for decision makers to support the continued usage of ACTs for treatment of uncomplicated falciparum malaria in pregnant women.

Deleterious effects of malaria in pregnancy on the developing fetus: a review on prevention and treatment with antimalarial drugs

All malaria infections are harmful to both the pregnant mother and the developing fetus. One in ten maternal deaths in malaria endemic countries are estimated to result from Plasmodium falciparum infection. Malaria is associated with a 3-4 times increased risk of miscarriage and a substantially increased risk of stillbirth. Current treatment and prevention strategies reduce, but do not eliminate, malaria's damaging effects on pregnancy outcomes. Reviewing evidence generated from meta-analyses, systematic reviews, and observational data, the first paper in this Series aims to summarise the adverse effects of malaria in pregnancy on the fetus and how the current drug treatment and prevention strategies can alleviate these effects. Although evidence supports the safety and treatment efficacy of artemisinin-based combination therapies in the first trimester, these therapies have not been recommended by WHO for the treatment of malaria at this stage of pregnancy. Intermittent preventive treatment of malaria in pregnancy with sulfadoxine-pyrimethamine is contraindicated in the first trimester and provides imperfect chemoprevention because of inadequate dosing, poor (few and late) antenatal clinic attendance, increasing antimalarial drug resistance, and decreasing naturally acquired maternal immunity due to the decreased incidence of malaria. Alternative strategies to prevent malaria in pregnancy are needed. The prevention of all malaria infections by providing sustained exposure to effective concentrations of antimalarial drugs is key to reducing the adverse effects of malaria in pregnancy.

Efficacy and tolerability of artemisinin-based and quinine-based treatments for uncomplicated falciparum malaria in pregnancy: a systematic review and individual patient data meta-analysis

BACKGROUND

Malaria in pregnancy affects both the mother and the fetus. However, evidence supporting treatment guidelines for uncomplicated (including asymptomatic) falciparum malaria in pregnant women is scarce and assessed in varied ways. We did a systematic literature review and individual patient data (IPD) meta-analysis to compare the efficacy and tolerability of different artemisinin-based or quinine-based treatments for malaria in pregnant women.

METHODS

We did a systematic review of interventional or observational cohort studies assessing the efficacy of artemisinin-based or quinine-based treatments in pregnancy. Seven databases (MEDLINE, Embase, Global Health, Cochrane Library, Scopus, Web of Science, and Literatura Latino Americana em Ciencias da Saude) and two clinical trial registries (International Clinical Trials Registry Platform and ClinicalTrials.gov) were searched. The final search was done on April 26, 2019. Studies that assessed PCR-corrected treatment efficacy in pregnancy with follow-up of 28 days or more were included. Investigators of identified studies were invited to share data from individual patients. The outcomes assessed included PCR-corrected efficacy, PCR-uncorrected efficacy, parasite clearance, fever clearance, gametocyte development, and acute adverse events. One-stage IPD meta-analysis using Cox and logistic regression with random-effects was done to estimate the risk factors associated with PCR-corrected treatment failure, using artemether-lumefantrine as the reference. This study is registered with PROSPERO, CRD42018104013.

FINDINGS

Of the 30 studies assessed, 19 were included, representing 92% of patients in the literature (4968 of 5360 episodes). Risk of PCR-corrected treatment failure was higher for the quinine monotherapy (n=244, adjusted hazard ratio [aHR] 6·11, 95% CI 2·57-14·54, p<0·0001) but lower for artesunate-amodiaquine (n=840, 0·27, 95% 0·14-0·52, p<0·0001), artesunate-mefloquine (n=1028, 0·56, 95% 0·34-0·94, p=0·03), and dihydroartemisinin-piperaquine (n=872, 0·35, 95% CI 0·18-0·68, p=0·002) than artemether-lumefantrine (n=1278) after adjustment for baseline asexual parasitaemia and parity. The risk of gametocyte carriage on day 7 was higher after quinine-based therapy than artemisinin-based treatment (adjusted odds ratio [OR] 7·38, 95% CI 2·29-23·82).

INTERPRETATION

Efficacy and tolerability of artemisinin-based combination therapies (ACTs) in pregnant women are better than quinine. The lower efficacy of artemether-lumefantrine compared with other ACTs might require dose optimisation.

FUNDING

The Bill & Melinda Gates Foundation, ExxonMobil Foundation, and the University of Oxford Clarendon Fund.

Delivering infectious disease interventions to women and children in conflict settings: a systematic reviefw

BACKGROUND

Conflict has played a role in the large-scale deterioration of health systems in low-income and middle-income countries (LMICs) and increased risk of infections and outbreaks. This systematic review aimed to synthesise the literature on mechanisms of delivery for a range of infectious disease-related interventions provided to conflict-affected women, children and adolescents.

METHODS

We searched Medline, Embase, CINAHL and PsychINFO databases for literature published in English from January 1990 to March 2018. Eligible publications reported on conflict-affected neonates, children, adolescents or women in LMICs who received an infectious disease intervention. We extracted and synthesised information on delivery characteristics, including delivery site and personnel involved, as well as barriers and facilitators, and we tabulated reported intervention coverage and effectiveness data.

RESULTS

A majority of the 194 eligible publications reported on intervention delivery in sub-Saharan Africa. Vaccines for measles and polio were the most commonly reported interventions, followed by malaria treatment. Over two-thirds of reported interventions were delivered in camp settings for displaced families. The use of clinics as a delivery site was reported across all intervention types, but outreach and community-based delivery were also reported for many interventions. Key barriers to service delivery included restricted access to target populations; conversely, adopting social mobilisation strategies and collaborating with community figures were reported as facilitating intervention delivery. Few publications reported on intervention coverage, mostly reporting variable coverage for vaccines, and fewer reported on intervention effectiveness, mostly for malaria treatment regimens.

CONCLUSIONS

Despite an increased focus on health outcomes in humanitarian crises, our review highlights important gaps in the literature on intervention delivery among specific subpopulations and geographies. This indicates a need for more rigorous research and reporting on effective strategies for delivering infectious disease interventions in different conflict contexts.

PROSPERO REGISTRATION NUMBER

CRD42019125221.

Optimal Duration of Follow-up for Assessing Antimalarial Efficacy in Pregnancy: A Retrospective Analysis of a Cohort Followed Up Until Delivery on the Thailand-Myanmar Border

Background

Follow-up for 28–42 days is recommended by the World Health Organization to assess antimalarial drug efficacy for nonpregnant populations. This study aimed to determine the optimal duration for pregnant women, as no specific guidance currently exists.

Methods

The distributions of time to recrudescence (treatment failure), confirmed by polymerase chain reaction genotyping for different antimalarial drugs in pregnancy, were analyzed by accelerated failure time models using secondary data on microscopically confirmed recurrent falciparum malaria collected in prospective studies on the Thailand–Myanmar border between 1994 and 2010.

Results

Of 946 paired isolates from 703 women, the median duration of follow-up for each genotyped recurrence (interquartile range) was 129 (83–174) days, with 429 polymerase chain reaction–confirmed recrudescent. Five different treatments were evaluated, and 382 Plasmodium falciparum recrudescences were identified as eligible. With log-logistic models adjusted for baseline parasitemia, the predicted cumulative proportions of all the recrudescences that were detected by 28 days were 70% (95% confidence interval [CI], 65%–74%) for quinine monotherapy (n = 295), 66% (95% CI, 53%–76%) for artesunate monotherapy (n = 43), 62% (95% CI, 42%–79%) for artemether–lumefantrine (AL; n = 19), 46% (95% CI, 26%–67%) for artesunate with clindamycin (n = 19), and 34% (95% CI, 11%–67%) for dihydroartemisinin–piperaquine (DP; n = 6). Corresponding figures by day 42 were 89% (95% CI, 77%–95%) for AL and 71% (95% CI, 38%–91%) for DP. Follow-up for 63 days was predicted to detect ≥95% of all recrudescence, except for DP.

Conclusions

In low-transmission settings, antimalarial drug efficacy assessments in pregnancy require longer follow-up than for nonpregnant populations.

Artemisinin-based combination therapy during pregnancy: outcome of pregnancy and infant mortality: a cohort study

BACKGROUND

The World Health Organization (WHO) recommendation of treating uncomplicated malaria during the second and third trimester of pregnancy with an artemisinin-based combination therapy (ACT) has already been implemented by all sub-Saharan African countries. However, there is limited knowledge on the effect of ACT on pregnancy outcomes, and on newborn and infant's health.

METHODS

Pregnant women with malaria in four countries (Burkina Faso, Ghana, Malawi and Zambia) were treated with either artemether-lumefantrine (AL), amodiaquine-artesunate (ASAQ), mefloquine-artesunate (MQAS), or dihydroartemisinin-piperaquine (DHA-PQ); 3127 live new-borns (822 in the AL, 775 in the ASAQ, 765 in the MQAS and 765 in the DHAPQ arms) were followed-up until their first birthday.

RESULTS

Prevalence of placental malaria and low birth weight were 28.0% (738/2646) and 16.0% (480/2999), respectively, with no significant differences between treatment arms. No differences in congenital malformations (p = 0.35), perinatal mortality (p = 0.77), neonatal mortality (p = 0.21), and infant mortality (p = 0.96) were found.

CONCLUSIONS

Outcome of pregnancy and infant survival were similar between treatment arms indicating that any of the four artemisinin-based combinations could be safely used during the second and third trimester of pregnancy without any adverse effect on the baby. Nevertheless, smaller safety differences between artemisinin-based combinations cannot be excluded; country-wide post-marketing surveillance would be very helpful to confirm such findings. Trial registration ClinicalTrials.gov, NCT00852423, Registered on 27 February 2009, https://clinicaltrials.gov/ct2/show/NCT00852423.

Antimalarial drugs for treating and preventing malaria in pregnant and lactating women

INTRODUCTION

Malaria in pregnancy and postpartum cause maternal mortality and adverse fetal outcomes. Efficacious and safe antimalarials are needed to treat and prevent such serious consequences. However, because of the lack of evidence on fetal safety, quinine, an old and less efficacious drug has long been recommended for pregnant women. Uncertainty about safety in relation to breastfeeding leads to withholding of efficacious treatments postpartum or cessation of breastfeeding. Areas covered: A search identified literature on humans in three databases (MEDLINE, Embase and Global health) using pregnancy or lactation, and the names of antimalarial drugs as search terms. Adverse reactions to the mother, fetus or breastfed infant were summarized together with efficacies. Expert opinion: Artemisinins are more efficacious and well-tolerated than quinine in pregnancy. Furthermore, the risks of miscarriage, stillbirth or congenital abnormality were not higher in pregnancies exposed to artemisinin derivatives for treatment of malaria than in pregnancies exposed to quinine or in the comparable background population unexposed to any antimalarials, and this was true for treatment in any trimester. Assessment of safety and efficacy of antimalarials including dose optimization for pregnant women is incomplete. Resistance to sulfadoxine-pyrimethamine in Plasmodium falciparum and long unprotected intervals between intermittent treatment doses begs reconsideration of current preventative recommendations in pregnancy. Data remain limited on antimalarials during breastfeeding; while most first-line drugs appear safe, further research is needed.

Updated CDC Recommendations for Using Artemether-Lumefantrine for the Treatment of Uncomplicated Malaria in Pregnant Women in the United States

Malaria infection during pregnancy is associated with an increased risk for maternal and fetal complications. In the United States, treatment options for uncomplicated, chloroquine-resistant Plasmodium falciparum and P. vivax malaria in pregnant women are limited to mefloquine or quinine plus clindamycin (1). However, limited availability of quinine and increasing resistance to mefloquine restrict these options. Strong evidence now demonstrates that artemether-lumefantrine (AL) (Coartem) is effective and safe in the treatment of malaria in pregnancy. The World Health Organization (WHO) has endorsed artemisinin-based combination therapies (ACTs), such as AL, for treatment of uncomplicated malaria during the second and third trimesters of pregnancy and is currently considering whether to add ACTs, including AL, as an option for malaria treatment during the first trimester (2,3). This policy note reviews the evidence and updates CDC recommendations to include AL as a treatment option for uncomplicated malaria during the second and third trimesters of pregnancy and during the first trimester of pregnancy when other treatment options are unavailable. These updated recommendations reflect current evidence and are consistent with WHO treatment guidelines.

Treatment of uncomplicated and severe malaria during pregnancy

Over the past 10 years, the available evidence on the treatment of malaria during pregnancy has increased substantially. Owing to their relative ease of use, good sensitivity and specificity, histidine rich protein 2 based rapid diagnostic tests are appropriate for symptomatic pregnant women; however, such tests are less appropriate for systematic screening because they will not detect an important proportion of infections among asymptomatic women. The effect of pregnancy on the pharmacokinetics of antimalarial drugs varies greatly between studies and class of antimalarial drugs, emphasising the need for prospective studies in pregnant and non-pregnant women. For the treatment of malaria during the first trimester, international guidelines are being reviewed by WHO. For the second and third trimester of pregnancy, results from several trials have confirmed that artemisinin-based combination treatments are safe and efficacious, although tolerability and efficacy might vary by treatment. It is now essential to translate such evidence into policies and clinical practice that benefit pregnant women in countries where malaria is endemic. Access to parasitological diagnosis or appropriate antimalarial treatment remains low in many countries and regions. Therefore, there is a pressing need for research to identify quality improvement interventions targeting pregnant women and health providers. In addition, efficient and practical systems for pharmacovigilance are needed to further expand knowledge on the safety of antimalarial drugs, particularly in the first trimester of pregnancy.

A brief review on features of falciparum malaria during pregnancy

Malaria in pregnancy is a serious public health problem in tropical areas. Frequently, the placenta is infected by accumulation of Plasmodium falciparum-infected erythrocytes in the intervillous space. Falciparum malaria acts during pregnancy by a range of mechanisms, and chronic or repeated infection and co-infections have insidious effects. The susceptibility of pregnant women to malaria is due to both immunological and humoral changes. Until a malaria vaccine becomes available, the deleterious effects of malaria in pregnancy can be avoided by protection against infection and prompt treatment with safe, effective antimalarial agents; however, concurrent infections such as with HIV and helminths during pregnancy are jeopardizing malaria control in sub-Saharan Africa.

Methodology of assessment and reporting of safety in anti-malarial treatment efficacy studies of uncomplicated falciparum malaria in pregnancy: a systematic literature review

Background

Considering the uncertainty of safety of anti-malarial drugs in pregnancy, efficacy studies are one of the few sources of clinical safety data. Complete safety evaluation is not usually incorporated in efficacy studies due to financial and human resource constraints. This review reports the methods used for the assessment of safety of artemisinin-based and quinine-based treatments in efficacy studies in pregnancy.

Methods

Methodology of assessment and reporting of safety in efficacy studies of artemisinin-based and quinine-based treatment in pregnancy was reviewed using seven databases and two clinical trial registries. The protocol was registered to PROSPERO (CRD42017054808).

Results

Of 48 eligible efficacy studies the method of estimation of gestational age was reported in only 32 studies (67%, 32/48) and ultrasound was used in 18 studies (38%, 18/48). Seventeen studies (35%, 17/48) reported parity, 9 (19%, 9/48) reported gravidity and 13 (27%, 13/48) reported both. Thirty-eight studies (79%, 38/48) followed participants through to pregnancy outcome. Fetal loss was assessed in 34 studies (89%, 34/38), but the definition of miscarriage and stillbirth were defined only in 11 (32%, 11/34) and 7 (21%, 7/34) studies, respectively. Preterm birth was assessed in 26 studies (68%, 26/38) but was defined in 16 studies (62%, 16/26). Newborn weight was assessed in 30 studies (79%, 30/38) and length in 10 studies (26%, 10/38). Assessment of birth weight took gestational age into account in four studies (13%, 4/30). Congenital abnormalities were reported in 32 studies (84%, 32/38). Other common risk factors for adverse pregnancy outcomes were not well-reported.

Conclusion

Incomplete reporting and varied methodological assessment of pregnancy outcomes in anti-malarial drug efficacy studies limits comparison across studies. A standard list of minimal necessary parameters to assess and report the safety component of efficacy studies of anti-malarials in pregnancy is proposed.

Electronic supplementary material

The online version of this article (10.1186/s12936-017-2136-x) contains supplementary material, which is available to authorized users.

Systematic literature review and meta-analysis of the efficacy of artemisinin-based and quinine-based treatments for uncomplicated falciparum malaria in pregnancy: methodological challenges

Background

There is no agreed standard method to assess the efficacy of anti-malarials for uncomplicated falciparum in pregnancy despite an increased risk of adverse outcomes for the mother and the fetus. The aim of this review is to present the currently available evidence from both observational and interventional cohort studies on anti-malarial efficacy in pregnancy and summarize the variability of assessment and reporting found in the review process.

Methods

Efficacy methodology and assessment of artemisinin-based treatments (ABT) and quinine-based treatments (QBT) were reviewed systematically using seven databases and two clinical trial registries (protocol registration—PROSPERO: CRD42017054808). Pregnant women in all trimesters with parasitologically confirmed uncomplicated falciparum malaria were included irrespective of symptoms. This review attempted to re-calculate proportions of treatment success applying the same definition as the standard WHO methodology for non-pregnant populations. Aggregated data meta-analyses using data from randomized control trials (RCTs) comparing different treatments were performed by random effects model.

Results

A total of 48 eligible efficacy studies were identified including 7279 treated Plasmodium falciparum episodes. While polymerase chain reaction (PCR) was used in 24 studies for differentiating recurrence, the assessment and reporting of treatment efficacy was heterogeneous. When the same definition could be applied, PCR-corrected treatment failure of ≥ 10% at any time points was observed in 3/30 ABT and 3/7 QBT arms. Ten RCTs compared different combinations of ABT but there was a maximum of two published RCTs with PCR-corrected outcomes for each comparison. Five RCTs compared ABT and QBT. Overall, the risk of treatment failure was significantly lower in ABT than in QBT (risk ratio 0.22, 95% confidence interval 0.07–0.63), although the actual drug combinations and outcome endpoints were different. First trimester women were included in 12 studies none of which were RCTs of ABT.

Conclusions

Efficacy studies in pregnancy are not only limited in number but use varied methodological assessments. In five RCTs with comparable methodology, ABT resulted in higher efficacy than QBT in the second and third trimester of pregnancy. Individual patient data meta-analysis can include data from observational cohort studies and could overcome some of the limitations of the current assessment given the paucity of data in this vulnerable group.

Electronic supplementary material

The online version of this article (10.1186/s12936-017-2135-y) contains supplementary material, which is available to authorized users.

The Safety of Artemisinin Derivatives for the Treatment of Malaria in the 2nd or 3rd Trimester of Pregnancy: A Systematic Review and Meta-Analysis

Given the high morbidity for mother and fetus associated with malaria in pregnancy, safe and efficacious drugs are needed for treatment. Artemisinin derivatives are the most effective antimalarials, but are associated with teratogenic and embryotoxic effects in animal models when used in early pregnancy. However, several organ systems are still under development later in pregnancy. We conducted a systematic review and meta-analysis of the occurrence of adverse pregnancy outcomes among women treated with artemisinins monotherapy or as artemisinin-based combination therapy during the 2nd or 3rd trimesters relative to pregnant women who received non-artemisinin antimalarials or none at all. Pooled odds ratio (POR) were calculated using Mantel-Haenszel fixed effects model with a 0.5 continuity correction for zero events. Eligible studies were identified through Medline, Embase, and the Malaria in Pregnancy Consortium Library. Twenty studies (11 cohort studies and 9 randomized controlled trials) contributed to the analysis, with 3,707 women receiving an artemisinin, 1,951 a non-artemisinin antimalarial, and 13,714 no antimalarial. The PORs (95% confidence interval (CI)) for stillbirth, fetal loss, and congenital anomalies when comparing artemisinin versus quinine were 0.49 (95% CI 0.24-0.97, I2 = 0%, 3 studies); 0.58 (95% CI 0.31-1.16, I2 = 0%, 6 studies); and 1.00 (95% CI 0.27-3.75, I2 = 0%, 3 studies), respectively. The PORs comparing artemisinin users to pregnant women who received no antimalarial were 1.13 (95% CI 0.77-1.66, I2 = 86.7%, 3 studies); 1.10 (95% CI 0.79-1.54, I2 = 0%, 4 studies); and 0.79 (95% CI 0.37-1.67, I2 = 0%, 3 studies) for miscarriage, stillbirth and congenital anomalies respectively. Treatment with artemisinin in 2nd and 3rd trimester was not associated with increased risks of congenital malformations or miscarriage and may be was associated with a reduced risk of stillbirths compared to quinine. This study updates the reviews conducted by the WHO in 2002 and 2006 and supports the current WHO malaria treatment guidelines malaria in pregnancy.

Treatment regimens for pregnant women with falciparum malaria

INTRODUCTION

With increasing parasite drug resistance, the WHO has updated treatment recommendations for falciparum malaria including in pregnancy. This review assesses the evidence for choice of treatment for pregnant women.

AREAS COVERED

Relevant studies, primarily those published since 2010, were identified from reference databases and were used to identify secondary data sources. Expert commentary: WHO recommends use of intravenous artesunate for severe malaria, quinine-clindamycin for uncomplicated malaria in first trimester, and artemisinin combination therapy for uncomplicated malaria in second/third trimesters. Because fear of adverse outcomes has often excluded pregnant women from conventional drug development, available data for novel therapies are usually based on preclinical studies and cases of inadvertent exposure. Changes in antimalarial drug disposition in pregnancy have been observed but are yet to be translated into specific treatment recommendations. Such targeted regimens may become important as parasite resistance demands that drug exposure is optimized.

The influence of pregnancy on the pharmacokinetic properties of artemisinin combination therapy (ACT): a systematic review

Background

Pregnancy has been reported to alter the pharmacokinetic properties of anti-malarial drugs, including the different components of artemisinin-based combination therapy (ACT). However, small sample sizes make it difficult to draw strong conclusions based on individual pharmacokinetic studies. The aim of this review is to summarize the evidence of the influence of pregnancy on the pharmacokinetic properties of different artemisinin-based combinations.

Methods

A PROSPERO-registered systematic review to identify clinical trials that investigated the influence of pregnancy on the pharmacokinetic properties of different forms of ACT was conducted, following PRISMA guidelines. Without language restrictions, Medline/PubMed, Embase, Cochrane Central Register of Controlled Trials, Web of Science, LILACS, Biosis Previews and the African Index Medicus were searched for studies published up to November 2015. The following components of ACT that are currently recommend by the World Health Organization as first-line treatment of malaria in pregnancy were reviewed: artemisinin, artesunate, dihydroartemisinin, lumefantrine, amodiaquine, mefloquine, sulfadoxine, pyrimethamine, piperaquine, atovaquone and proguanil.

Results

The literature search identified 121 reports, 27 original studies were included. 829 pregnant women were included in the analysis. Comparison of the available studies showed lower maximum concentrations (C_max) and exposure (AUC) of dihydroartemisinin, the active metabolite of all artemisinin derivatives, after oral administration of artemether, artesunate and dihydroartemisinin in pregnant women. Low day 7 concentrations were commonly seen in lumefantrine studies, indicating a low exposure and possibly reduced efficacy. The influence of pregnancy on amodiaquine and piperaquine seemed not to be clinically relevant. Sulfadoxine plasma concentration was significantly reduced and clearance rates were higher in pregnancy, while pyrimethamine and mefloquine need more research as no general conclusion can be drawn based on the available evidence. For atovaquone, the available data showed a lower maximum concentration and exposure. Finally, the maximum concentration of cycloguanil, the active metabolite of proguanil, was significantly lower, possibly compromising the efficacy.

Conclusion

These findings suggest that reassessment of the dose of the artemisinin derivate and some components of ACT are necessary to ensure the highest possible efficacy of malaria treatment in pregnant women. However, for most components of ACT, data were insufficient and extensive research with larger sample sizes will be necessary to identify the exact influences of pregnancy on the pharmacokinetic properties of different artemisinin-based combinations. In addition, different clinical studies used diverse study designs with various reported relevant outcomes. Future pharmacokinetic studies could benefit from more uniform designs, in order to increase quality, robustness and effectiveness.

Study registration: CRD42015023756 (PROSPERO)

Electronic supplementary material

The online version of this article (doi:10.1186/s12936-016-1160-6) contains supplementary material, which is available to authorized users.

Artemisinin-Based Combination Therapy Versus Quinine or Other Combinations for Treatment of Uncomplicated Plasmodium falciparum Malaria in the Second and Third Trimester of Pregnancy: A Systematic Review and Meta-Analysis

The World Health Organization recommends artemisinin-based combination therapies (ACTs) for the treatment of uncomplicated falciparum malaria in the second and third trimesters of pregnancy. We conducted a meta-analysis to compare efficacy, safety and tolerability of ACTs versus quinine and other non-ACT antimalarials. The median PCR-adjusted failure rate by days 28 to 63 in the non-ACT group was 6 (range 0–37) per 100 women, lower in the ACT group overall (pooled risk ratio [PRR] random effects, 0.41; 95% confidence interval [CI], 0.16–1.05; 6 trials), and significantly lower compared with oral quinine (PRR, 0.20; 95% CI, 0.08–0.49; 4 trials). There were no differences in fetal deaths and congenital abnormalities. Compared with quinine, artemisinin-based combinations therapies were associated with less tinnitus (PRR, 0.19; 95% CI, 0.03–1.11; 4 studies), dizziness (PRR, 0.64; 95% CI, 0.44–0.93; 3 trials), and vomiting (PRR, 0.33; 95% CI, 0.15–0.73; 3 trials). Artemisinin-based combination therapies are better than quinine in the second and third trimesters; their use should be encouraged among health workers.

Treating severe malaria in pregnancy: a review of the evidence

Severe malaria in pregnancy is a large contributor to maternal morbidity and mortality. Intravenous quinine has traditionally been the treatment drug of choice for severe malaria in pregnancy. However, recent randomized clinical trials (RCTs) indicate that intravenous artesunate is more efficacious for treating severe malaria, resulting in changes to the World Health Organization (WHO) treatment guidelines. Artemisinins, including artesunate, are embryo-lethal in animal studies and there is limited experience with their use in the first trimester. This review summarizes the current literature supporting 2010 WHO treatment guidelines for severe malaria in pregnancy and the efficacy, pharmacokinetics, and adverse event data for currently used antimalarials available for severe malaria in pregnancy. We identified ten studies on the treatment of severe malaria in pregnancy that reported clinical outcomes. In two studies comparing intravenous quinine with intravenous artesunate, intravenous artesunate was more efficacious and safe for use in pregnant women. No studies detected an increased risk of miscarriage, stillbirth, or congenital anomalies associated with first trimester exposure to artesunate. Although the WHO recommends using either quinine or artesunate for the treatment of severe malaria in first trimester pregnancies, our findings suggest that artesunate should be the preferred treatment option for severe malaria in all trimesters.

Intervals to Plasmodium falciparum recurrence after anti-malarial treatment in pregnancy: a longitudinal prospective cohort

Background

Plasmodium falciparum infections adversely affect pregnancy. Anti-malarial treatment failure is common. The objective of this study was to examine the duration of persistent parasite carriage following anti-malarial treatment in pregnancy.

Methods

The data presented here are a collation from previous studies carried out since 1994 in the Shoklo Malaria Research Unit (SMRU) on the Thailand-Myanmar border and performed using the same unique methodology detailed in the Materials and Methods section. Screening for malaria by microscopy is a routine part of weekly antenatal care (ANC) visits and therapeutic responses to anti-malarials were assessed in P. falciparum malaria cases. Women with microscopy confirmed P. falciparum malaria had a PCR blood spot from a finger-prick sample collected. Parasite DNA was extracted from the blood-spot samples using saponin lysis/Chelex extraction method and genotyped using polymorphic segments of MSP1, MSP2 and GLURP. Recurrent infections were classified by genotyping as novel, recrudescent or indeterminate. Factors associated with time to microscopy-detected recrudescence were analysed using multivariable regression techniques.

Results

From December 1994 to November 2009, 700 women were treated for P. falciparum and there were 909 recurrent episodes (481 novel and 428 recrudescent) confirmed by PCR genotyping. Most of the recurrences, 85 % (770/909), occurred after treatment with quinine monotherapy, artesunate monotherapy or artesunate-clindamycin. The geometric mean number of days to recurrence was significantly shorter in women with recrudescent infection, 24.5 (95 %: 23.4-25.8), compared to re-infection, 49.7 (95 %: 46.9-52.7), P <0.001. The proportion of recrudescent P. falciparum infections that occurred after days 28, 42 and 63 from the start of treatment was 29.1 % (124/428), 13.3 % (57/428) and 5.6 % (24/428). Recrudescent infections ≥100 days after treatment occurred with quinine and mefloquine monotherapy, and quinine + clindamycin and artesunate + atovaquone-proguanil combination therapy. Treatments containing an artemisinin derivative or an intercalated Plasmodium vivax infection increased the geometric mean interval to recrudescence by 1.28-fold (95 % CI: 1.09-1.51) and 2.19-fold (1.77-2.72), respectively. Intervals to recrudescence were decreased 0.83-fold (0.73-0.95) if treatment was not fully supervised (suggesting incomplete adherence) and 0.98-fold (0.96-0.99) for each doubling in baseline parasitaemia.

Conclusions

Prolonged time to recrudescence may occur in pregnancy, regardless of anti-malarial treatment. Long intervals to recrudescence are more likely with the use of artemisinin-containing treatments and also observed with intercalated P. vivax infections treated with chloroquine. Accurate determination of drug efficacy in pregnancy requires longer duration of follow-up, preferably until delivery or day 63, whichever occurs last.

Malaria: an update on current chemotherapy

INTRODUCTION

Chemotherapy of malaria has become a rapidly changing field. Less than two decades ago, treatment regimens were increasingly bound to fail due to emerging drug resistance against 4-aminoquinolines and sulfa compounds. By now, artemisinin-based combination therapies (ACTs) constitute the standard of care for uncomplicated falciparum malaria and are increasingly also taken into consideration for the treatment of non-falciparum malaria.

AREAS COVERED

This narrative review provides an overview of the state-of-art antimalarial drug therapy, highlights the global portfolio of current Phase III/IV clinical trials and summarizes current developments.

EXPERT OPINION

Malaria chemotherapy remains a dynamic field, with novel drugs and drug combinations continuing to emerge in order to outpace the development of large-scale drug resistance against the currently most important drug class, the artemisinin derivatives. More randomized controlled studies are urgently needed especially for the treatment of malaria in first trimester pregnant women. ACTs should be used for the treatment of imported malaria more consequently. Gaining sufficient efficacy and safety information on ACT use for non-falciparum species including Plasmodium ovale and malariae should be a research priority. Continuous investment into malaria drug development is a vital factor to combat artemisinin resistance and successfully improve malaria control toward the ultimate goal of elimination.

Mefloquine safety and tolerability in pregnancy: a systematic literature review

Background

Control of malaria in pregnant women is still a major challenge as it constitutes an important cause of maternal and neonatal mortality. Mefloquine (MQ) has been used for malaria chemoprophylaxis in non-immune travellers for several decades and it constitutes a potential candidate for intermittent preventive treatment in pregnant women (IPTp).

Methods

The safety of MQ, including its safety in pregnancy, is controversial and a continuing subject of debate. Published studies which evaluated the use of MQ for malaria prevention or treatment in pregnant women and which reported data on drug tolerability and/or pregnancy outcomes have been reviewed systematically.

Results

Eighteen articles fitted the inclusion criteria, only one study was double-blind and placebo controlled. No differences were found in the risk of adverse pregnancy outcomes in women exposed to MQ compared to those exposed to other anti-malarials or to the general population. MQ combined with artesunate seems to be better tolerated than standard quinine therapy for treatment of non-severe falciparum malaria, but a MQ loading dose (10 mg/kg) is associated with more dizziness compared with placebo. When used for IPTp, MQ (15 mg/kg) may have more side effects than sulphadoxine- pyrimethamine.

Conclusions

In the published literature there are no indications that MQ use during pregnancy carries an increased risk for the foetus. Ideally, the use of MQ to prevent malaria should be based on a risk-benefit analysis of adverse effects against the risk of acquiring the infection. For this purpose double-blinded randomized controlled trials in African pregnant women are much needed.

Clinical audit to enhance safe practice of skilled birth attendants for the fetus with nuchal cord: evidence from a refugee and migrant cohort

BACKGROUND

Current evidence for optimal management of fetal nuchal cord detected after the head has birthed supports techniques that avoid ligation of the umbilical cord circulation. Routine audit found frequent unsafe management of nuchal cord by skilled birth attendants (SBAs) in migrant and refugee birth centres on the Thai-Burmese border.

METHOD

The audit cycle was used to enhance safe practice by SBA for the fetus with nuchal cord. In the three birth centres the action phase of the audit cycle was initially carried out by the doctor responsible for the site. Six months later a registered midwife, present six days per week for three months in one birth facility, encouraged SBAs to facilitate birth with an intact umbilical circulation for nuchal cord. Rates of cord ligation before birth were recorded over a 24 month period (1-July-2011 to 30-June-2013) and in-depth interviews and a knowledge survey of the SBAs took place three months after the registered midwife departure.

RESULTS

The proportion of births with nuchal cord ligation declined significantly over the four six monthly quarters from 15.9% (178/1123) before the action phase of the audit cycle; to 11.1% (107/966) during the action phase of the audit cycle with the doctors; to 2.4% (28/1182) with the registered midwife; to 0.9% (9/999) from three to nine months after the departure of the registered midwife, (p < 0.001, linear trend). Significant improvements in safe practice were observed at all three SMRU birth facilities. Knowledge of fetal nuchal cord amongst SBAs was sub-optimal and associated with fear and worry despite improved practice. The support of a registered midwife increased confidence of SBAs.

CONCLUSION

The audit cycle and registered midwife interprofessional learning for SBAs led to a significant improvement in safe practice for the fetus with nuchal cord. The authors would encourage this type of learning in organizations with birth facilities on the Thai-Burmese border and in other similar resource limited settings with SBAs.

Malaria in pregnancy

Pregnant women have a higher risk of malaria compared to non-pregnant women. This review provides an update on knowledge acquired since 2000 on P. falciparum and P.vivax infections in pregnancy. Maternal risk factors for malaria in pregnancy (MiP) include low maternal age, low parity, and low gestational age. The main effects of MIP include maternal anaemia, low birth weight (LBW), preterm delivery and increased infant and maternal mortality.

P. falciparum infected erythrocytes sequester in the placenta by expressing surface antigens, mainly variant surface antigen (VAR2CSA), that bind to specific receptors, mainly chondroitin sulphate A. In stable transmission settings, the higher malaria risk in primigravidae can be explained by the non-recognition of these surface antigens by the immune system. Recently, placental sequestration has been described also for P.vivax infections. The mechanism of preterm delivery and intrauterine growth retardation is not completely understood, but fever (preterm delivery), anaemia, and high cytokines levels have been implicated.

Clinical suspicion of MiP should be confirmed by parasitological diagnosis. The sensitivity of microscopy, with placenta histology as the gold standard, is 60% and 45% for peripheral and placental falciparum infections in African women, respectively. Compared to microscopy, RDTs have a lower sensitivity though when the quality of microscopy is low RDTs may be more reliable. Insecticide treated nets (ITN) and intermittent preventive treatment in pregnancy (IPTp) are recommended for the prevention of MiP in stable transmission settings. ITNs have been shown to reduce malaria infection and adverse pregnancy outcomes by 28–47%. Although resistance is a concern, SP has been shown to be equivalent to MQ and AQ for IPTp. For the treatment of uncomplicated malaria during the first trimester, quinine plus clindamycin for 7 days is the first line treatment and artesunate plus clindamycin for 7 days is indicated if this treatment fails; in the 2^nd and 3^rd trimester first line treatment is an artemisinin-based combination therapy (ACT) known to be effective in the region or artesunate and clindamycin for 7 days or quinine and clindamycin. For severe malaria, in the second and third trimester parenteral artesunate is preferred over quinine. In the first trimester, both artesunate and quinine (parenteral) may be considered as options. Nevertheless, treatment should not be delayed and should be started immediately with the most readily available drug.

Plasmodium falciparum Na+/H+ exchanger (pfnhe-1) genetic polymorphism in Indian Ocean malaria-endemic areas

To date, 11 studies conducted in different countries to test the association between Plasmodium falciparum Na(+)/H(+) exchanger gene (pfnhe-1; PF13_0019) polymorphisms and in vitro susceptibility to quinine have generated conflicting data. In this context and to extend our knowledge of the genetic polymorphism of Pfnhe gene, we have sequenced the ms4760 locus from 595 isolates collected in the Comoros (N = 250; an area with a high prevalence of chloroquine and sulfadoxine-pyrimethamine resistance) and Madagascar (N = 345; a low drug-resistance area). Among them, 29 different alleles were observed, including 8 (27%) alleles not previously described. Isolates from the Comoros showed more repeats in block II (DNNND), which some studies have found to be positively associated with in vitro resistance to quinine, compared with isolates from Madagascar. Additional studies are required to better define the mechanisms underlying quinine resistance, which involve multiple gene interactions.

Global analysis of Plasmodium falciparum Na(+)/H(+) exchanger (pfnhe-1) allele polymorphism and its usefulness as a marker of in vitro resistance to quinine

The aim of this study was to provide a comprehensive analysis of the worldwide genetic polymorphism of ms4760 alleles of the pfnhe-1 gene and to discuss their usefulness as molecular marker of quinine resistance (QNR). A new numbering of ms4760 allele, classification grouping ms4760 alleles according to the number of DNNND and DDNHNDNHNND repeat motifs in blocks II and V was also proposed. A total of 1508 ms4760 sequences from isolates, culture-adapted parasites or reference strains from various geographical regions were retrieved from GenBank (last update on 15th June 2012) or from publications and were used for genetic analyses. The association of different alleles of pfnhe-1 with resistance to quinoline antimalarial drugs showed marked geographic disparities. The validity and reliability of candidate polymorphisms in pfnhe-1 gene as molecular markers of QNR appeared restricted to endemic areas from South Asia or possibly East African countries and needs to be confirmed.

Study on the developmental toxicity of combined artesunate and mefloquine antimalarial drugs on rats

Antimalarial drug combinations containing artemisinins (ACTs) have become first choice therapies for Plasmodium falciparum malaria. Data on safety of ACTs in pregnancy are limited and no previous study has been conducted on the developmental toxicity of artesunate-mefloquine combinations on the first trimester of gestation. To evaluate the developmental toxicity of an artesunate/mefloquine combination, pregnant rats were treated orally with artesunate (15 and 40 mg/kg bwt/day), mefloquine (30 and 80 mg/kg bwt/day) and artesunate/mefloquine (15/30 and 40/80 mg/kg bwt/day) on gestation days 9-11. Dams were C-sectioned on day 20, and their uteri and fetuses removed and examined for soft tissue and skeleton abnormalities. Artesunate increased embryolethality and the incidence of limb long bone malformations on the absence of overt maternal toxicity. Mefloquine (80 mg/kg bwt/day) was maternally toxic and enhanced fetal variations. Combination of artesunate and mefloquine did not enhance their toxicity compared to the toxicity observed after its separate administration. Embryotoxicity of artesunate was apparently attenuated when it is co-administered with mefloquine.

Artemether-lumefantrine to treat malaria in pregnancy is associated with reduced placental haemozoin deposition compared to quinine in a randomized controlled trial

Background

Data on efficacy of artemisinin-based combination therapy (ACT) to treat Plasmodium falciparum during pregnancy in sub-Saharan Africa is scarce. A recent open label, randomized controlled trial in Mbarara, Uganda demonstrated that artemether-lumefantrine (AL) is not inferior to quinine to treat uncomplicated malaria in pregnancy. Haemozoin can persist in the placenta following clearance of parasites, however there is no data whether ACT can influence the amount of haemozoin or the dynamics of haemozoin clearance.

Methods

Women attending antenatal clinics with weekly screening and positive blood smears by microscopy were eligible to participate in the trial and were followed to delivery. Placental haemozoin deposition and inflammation were assessed by histology. To determine whether AL was associated with increased haemozoin clearance, population haemozoin clearance curves were calculated based on the longitudinal data.

Results

Of 152 women enrolled in each arm, there were 97 and 98 placental biopsies obtained in the AL and quinine arms, respectively. AL was associated with decreased rates of moderate to high grade haemozoin deposition (13.3% versus 25.8%), which remained significant after correcting for gravidity, time of infection, re-infection, and parasitaemia. The amount of haemozoin proportionately decreased with the duration of time between treatment and delivery and this decline was greater in the AL arm. Haemozoin was not detected in one third of biopsies and the prevalence of inflammation was low, reflecting the efficacy of antenatal care with early detection and prompt treatment of malaria.

Conclusions

Placental haemozoin deposition was decreased in the AL arm demonstrating a relationship between pharmacological properties of drug to treat antenatal malaria and placental pathology at delivery. Histology may be considered an informative outcome for clinical trials to evaluate malaria control in pregnancy.

Trial registration

REGISTRY: http://clinicaltrials.gov/ct2/show/NCT00495508

Malaria in pregnancy in the Asia-Pacific region

Most pregnant women at risk of for infection with Plasmodium vivax live in the Asia-Pacific region. However, malaria in pregnancy is not recognised as a priority by many governments, policy makers, and donors in this region. Robust data for the true burden of malaria throughout pregnancy are scarce. Nevertheless, when women have little immunity, each infection is potentially fatal to the mother, fetus, or both. WHO recommendations for the control of malaria in pregnancy are largely based on the situation in Africa, but strategies in the Asia-Pacific region are complicated by heterogeneous transmission settings, coexistence of multidrug-resistant Plasmodium falciparum and Plasmodium vivax parasites, and different vectors. Most knowledge of the epidemiology, effect, treatment, and prevention of malaria in pregnancy in the Asia-Pacific region comes from India, Papua New Guinea, and Thailand. Improved estimates of the morbidity and mortality of malaria in pregnancy are urgently needed. When malaria in pregnancy cannot be prevented, accurate diagnosis and prompt treatment are needed to avert dangerous symptomatic disease and to reduce effects on fetuses.

Effects of artemisinins on reticulocyte count and relationship to possible embryotoxicity in confirmed and unconfirmed malarial patients

Rat studies suggest that artemisinin-induced decreases in reticulocyte count are a marker for embryotoxicity (in one study, r = 0.82; p < 0.05). In clinical studies, therapeutic doses of artemisinins induced decreases in reticulocyte count that were larger in five of six groups of healthy volunteers (mean decreases of 47-75%) than in 12 groups of patients with malaria (mean decreases of 0-34% and incidences of low reticulocyte count of 0.6-18%). Malaria causes hypoferremia and drug concentrates in infected red cells so, among the explanations for the lesser decreases in patients, is that malaria protects against artemisinin-induced decreases in reticulocyte count by reducing the target tissue levels of active drug and/or ferrous iron which activates the drug to toxic free radicals. The disease could also protect against embryotoxicity in which case pregnant women without malaria would be at greater risk of artemisinin-induced embryotoxicity. Malaria protection against artesunate toxicity has been observed in rats. No artemisinin-induced embryotoxicity has been identified in limited numbers of women with confirmed malaria in the first trimester. However, in large parts of tropical Africa, malaria treatment is based on fever rather than confirmation of parasitemia and many pregnant women without malaria are exposed to antimalarials. No clinical studies have been conducted on uninfected women for whom pregnancy was identified and then an artemisinin was administered subsequently. Testing in rats and/or humans is needed to determine if malaria protects against reticulocytopenia and embryotoxicity and whether the parasite is a more or less sensitive target than the embryo and reticulocyte.

Quinine, an old anti-malarial drug in a modern world: role in the treatment of malaria

Quinine remains an important anti-malarial drug almost 400 years after its effectiveness was first documented. However, its continued use is challenged by its poor tolerability, poor compliance with complex dosing regimens, and the availability of more efficacious anti-malarial drugs. This article reviews the historical role of quinine, considers its current usage and provides insight into its appropriate future use in the treatment of malaria. In light of recent research findings intravenous artesunate should be the first-line drug for severe malaria, with quinine as an alternative. The role of rectal quinine as pre-referral treatment for severe malaria has not been fully explored, but it remains a promising intervention. In pregnancy, quinine continues to play a critical role in the management of malaria, especially in the first trimester, and it will remain a mainstay of treatment until safer alternatives become available. For uncomplicated malaria, artemisinin-based combination therapy (ACT) offers a better option than quinine though the difficulty of maintaining a steady supply of ACT in resource-limited settings renders the rapid withdrawal of quinine for uncomplicated malaria cases risky. The best approach would be to identify solutions to ACT stock-outs, maintain quinine in case of ACT stock-outs, and evaluate strategies for improving quinine treatment outcomes by combining it with antibiotics. In HIV and TB infected populations, concerns about potential interactions between quinine and antiretroviral and anti-tuberculosis drugs exist, and these will need further research and pharmacovigilance.

Efficacy and safety of artemether-lumefantrine compared with quinine in pregnant women with uncomplicated Plasmodium falciparum malaria: an open-label, randomised, non-inferiority trial

BACKGROUND

Malaria in pregnancy is associated with maternal and fetal morbidity and mortality. In 2006, WHO recommended use of artemisinin-based combination treatments during the second or third trimesters, but data on efficacy and safety in Africa were scarce. We aimed to assess whether artemether-lumefantrine was at least as efficacious as oral quinine for the treatment of uncomplicated falciparum malaria during the second and third trimesters of pregnancy in Mbarara, Uganda.

METHODS

We did an open-label, randomised, non-inferiority trial between October, 2006, and May, 2009, at the antenatal clinics of the Mbarara University of Science and Technology Hospital in Uganda. Pregnant women were randomly assigned (1:1) by computer generated sequence to receive either quinine hydrochloride or artemether-lumefantrine, and were followed up weekly until delivery. Our primary endpoint was cure rate at day 42, confirmed by PCR. The non-inferiority margin was a difference in cure rate of 5%. Analysis of efficacy was for all randomised patients without study deviations that could have affected the efficacy outcome. This study was registered with ClinicalTrials.gov, number NCT00495508.

FINDINGS

304 women were randomly assigned, 152 to each treatment group. By day 42, 16 patients were lost to follow-up and 25 were excluded from the analysis. At day 42, 137 (99.3%) of 138 patients taking artemether-lumefantrine and 122 (97.6%) of 125 taking quinine were cured-difference 1.7% (lower limit of 95% CI -0.9). There were 290 adverse events in the quinine group and 141 in the artemether-lumefantrine group.

INTERPRETATION

Artemisinin derivatives are not inferior to oral quinine for the treatment of uncomplicated malaria in pregnancy and might be preferable on the basis of safety and efficacy.

FUNDING

Médecins Sans Frontières and the European Commission.

Current knowledge and challenges of antimalarial drugs for treatment and prevention in pregnancy

IMPORTANCE OF THE FIELD

Malaria infection during pregnancy is a major public health problem worldwide, with 50 million pregnancies exposed to the infection every year. Approximately 25,000 maternal deaths and between 75,000 and 200,000 infant deaths could be prevented each year by effective malaria control in pregnancy. Antimalarial drug treatment and prevention has been hampered by the appearance of drug resistance, which has been a particular problem in pregnancy due to the inherent safety issues.

AREAS COVERED IN THIS REVIEW

New antimalarial drugs and combinations are being studied but there is not yet sufficient information on their efficacy or, more importantly, on their safety in pregnancy. This article provides an overview of the relevance of the topic and reviews the current antimalarial drugs recommended for pregnancy, as well as the guidelines for both treatment and prevention in women living in endemic areas and for travellers.

WHAT THE READER WILL GAIN

Updated information on the drugs currently used for malaria treatment and prevention in pregnancy, including new drugs under development, is provided. The gaps on efficacy and safety information for use during pregnancy are also discussed.

TAKE HOME MESSAGE

Prevention and case management of malaria during pregnancy is based on risk-benefit criteria and poses one of the greatest challenges to current malaria control.

Compliance with a three-day course of artesunate-mefloquine combination and baseline anti-malarial treatment in an area of Thailand with highly multidrug resistant falciparum malaria

Background

Artemisinin-based combination therapy (ACT) is presently recommended by the World Health Organization as first-line treatment for uncomplicated Plasmodium falciparum malaria in several countries, as a mean of prolonging the effectiveness of first-line malaria treatment regimens. A three-day course of artesunate-mefloquine (4 mg/kg body weight once daily for three consecutive days, plus 15 and 10 mg/kg body weight mefloquine on the first and second days) has been adopted by Malaria Control Programme of Thailand as first-line treatment for uncomplicated falciparum malaria all over the country since 2008. The gametocytocydal anti-malarial drug primaquine is administered at the dose of 30 mg (0.6 mg/kg) on the last day. The aim of the present study was to assess patient compliance of this combination regimen when applied to field condition.

Methods

A total of 240 patients (196 males and 44 females) who were attending the malaria clinics in Mae-Sot, Tak Province and presenting with symptomatic acute uncomplicated falciparum malaria, with no reappearance of Plasmodium vivax parasitaemia during follow-up were included into the study. The first dose of the treatment was given to the patients under direct supervision. All patients were given the medication for self-treatment at home and were requested to come back for follow-up on day 3 of the initial treatment. Baseline (day 0) and day 3 whole blood mefloquine and plasma primaquine concentrations were determined by high performance liquid chromatography.

Results

Two patients had recrudescence on days 28 and 35. The Kaplan-Meier estimate of the 42-day efficacy rate of this combination regimen was 99.2% (238/240). Based on whole blood mefloquine and plasma primaquine concentrations on day 3 of the initial treatment, compliance with mefloquine and primaquine in this three-day artesunate-mefloquine combination regimen were 96.3% (207/215), and 98.5% (197/200), respectively. Baseline mefloquine and primaquine levels were observed in 24 and 16% of the patients.

Conclusion

The current first-line treatment and a three-day combination regimen of artesunate-mefloquine provides excellent patient compliance with good efficacy and tolerability in the treatment of highly multidrug resistance falciparum malaria. Previous treatment with mefloquine and primaquine were common in this area.

Severe embryotoxicity of artemisinin derivatives in experimental animals, but possibly safe in pregnant women

Preclinical studies in rodents have demonstrated that artemisinins, especially injectable artesunate, can induce fetal death and congenital malformations at a low dose range. The embryotoxicity can be induced in those animals only within a narrow window in early embryogenesis. Evidence was presented that the mechanism by which embryotoxicity of artemisinins occurs seems to be limited to fetal erythropoiesis and vasculogenesis/ angiogenesis on the very earliest developing red blood cells, causing severe anemia in the embryos with higher drug peak concentrations. However, this embryotoxicity has not been convincingly observed in clinical trials from 1,837 pregnant women, including 176 patients in the first trimester exposed to an artemisinin agent or artemisinin-based combination therapy (ACT) from 1989 to 2009. In the rodent, the sensitive early red cells are produced synchronously over one day with single or multiple exposures to the drug can result in a high proportion of cell deaths. In contrast, primates required a longer period of treatment of 12 days to induce such embryonic loss. In humans only limited information is available about this stage of red cell development; however, it is known to take place over a longer time period, and it may well be that a limited period of treatment of 2 to 3 days for malaria would not produce serious toxic effects. In addition, current oral intake, the most commonly used route of administration in pregnant women with an ACT, results in lower peak concentration and shorter exposure time of artemisinins that demonstrated that such a concentration–course profile is unlikely to induce the embryotoxicity. When relating the animal and human toxicity of artemisinins, the different drug sensitive period and pharmacokinetic profiles as reviewed in the present report may provide a great margin of safety in the pregnant women.

Drug resistance and in vitro susceptibility of Plasmodium falciparum in Thailand during 1988-2003

The aim of the present study was to investigate antimalarial drug pressure resulting from the clinical use of different antimalarials in Thailand. The phenotypic diversity of the susceptibility profiles of antimalarials, i.e., chloroquine (CQ), quinine (QN), mefloquine (MQ), and artesunate (ARS) in Plasmodium falciparum isolates collected during the period from 1988 to 2003 were studied. P. falciparum isolates from infected patients were collected from the Thai-Cambodian border area at different time periods (1988-1989, 1991-1992, and 2003), during which 3 different patterns of drug use had been implemented: MQ + sulphadoxine (S) + pyrimethamine (P), MQ alone and MQ + ARS, respectively. The in vitro drug susceptibilities were investigated using a method based on the incorporation of [(3)H] hypoxanthine. A total of 50 isolates were tested for susceptibilities to CQ, QN, MQ, and ARS. Of these isolates, 19, 16, and 15 were adapted during the periods 1988-1989, 1991-1993, and 2003, respectively. P. falciparum isolates collected during the 3 periods were resistant to CQ. Sensitivities to MQ declined from 1988 to 2003. In contrast, the parasite was sensitive to QN, and similar sensitivity profile patterns were observed during the 3 time periods. There was a significantly positive but weak correlation between the IC(50) values of CQ and QN, as well as between the IC(50) values of QN and MQ. Drug pressure has impact on sensitivity of P. falciparum to MQ. A combination therapy of MQ and ARS is being applied to reduce the parasite resistance, and also increasing the efficacy of the drug.

Sensitive periods for developmental toxicity of orally administered artesunate in the rat

BACKGROUND

Artesunate has been reported to cause embryolethality and malformations when administered orally to rats during organogenesis. The purpose of this study was to determine the most sensitive period(s) for the induction of these effects in order to provide clues about possible mechanisms and to identify a short treatment regimen for further studies.

METHODS

Pregnant rats were orally administered artesunate (10, 17 or 30 mg/kg/day) on single or multiple days of gestation. Cesarean sections and fetal evaluations were conducted on Day 21 postcoitum (pc).

RESULTS

Embryolethality, cardiovascular malformations and a syndrome of skeletal defects were observed after single doses on days 10 to 14 pc, while no developmental effects were observed before (day 9 pc) or after (days 16 or 17 pc) that period. The most sensitive day for embryo lethality was day 11 pc, where lethality occurred with a very steep dose response (postimplantation loss was approximately 15% at 10 mg/kg and 100% at 17 mg/kg/day). The most sensitive day for the induction of malformations was day 10 pc. Malformations tended to occur in partially resorbed litters and included cardiovascular defects and bent and misshapen long bones and scapulae.

CONCLUSIONS

The sensitive window for developmental toxicity of artesunate in the rat was identified as days 10 to 14 pc. Single oral doses produced embryolethality and similar cardiovascular and skeletal malformations as previously reported in longer term dosing experiments. These single dose treatment regimens could be useful to further investigate the mechanistic basis for artesunate-induced developmental toxicity.

Artesunate: developmental toxicity and toxicokinetics in monkeys

BACKGROUND

The developmental toxicity, toxicokinetics, and hematological effects of the antimalarial drug, artesunate, were previously studied in rats and rabbits and have now been studied in cynomolgus monkeys.

METHODS

Groups of up to 15 pregnant females were dosed on Gestation Days (GD) 20-50 or for 3-7-day intervals.

RESULTS

At 30 mg/kg/day, 6 embryos died between GD30 and GD40. Histologic examination of 3 live embryos (GD26-GD36) revealed a marked reduction in embryonic erythroblasts and cardiomyopathy. At 12 mg/kg/day, 6 embryos died between GD30 and GD45. Four surviving fetuses examined on GD100 had no malformations, but long bone lengths were slightly decreased. At the developmental no-adverse-effect-level (4 mg/kg/day), maternal plasma AUC was 3.68 ng.h/mL for artesunate and 6.93 ng.h/ml for its active metabolite, dihydroartemisinin (DHA). No developmental toxicity occurred with administration of 12 mg/kg/day for 3 or 7 days, GD29-31 or GD27-33 (maternal plasma AUC of 9.84 ng.h/mL artesunate and 16.4 ng.h/mL DHA). Exposures at embryotoxic doses were substantially lower than human therapeutic exposures. However, differences in monkey and human Vss for artesunate (0.5 L/kg vs. 0.18 L/kg) confound relying solely on AUC for assessing human risk. Decreases in reticulocyte count occur at therapeutic doses in humans. Changes to reticulocyte counts at embryotoxic doses in monkeys (> or =12 mg/kg/day) were variable and generally minor.

CONCLUSIONS

Artesunate was embryolethal at > or =12 mg/kg/day when dosed for at least 12 days at the beginning of organogenesis, but not when dosed for 3 or 7 days, indicating that developmental toxicity of artesunate is dependent upon duration of dosing in cynomologus monkeys.

Sub-microscopic infections and long-term recrudescence of Plasmodium falciparum in Mozambican pregnant women

Background

Control of malaria in pregnancy remains a public health challenge. Improvements in its correct diagnosis and the adequacy of protocols to evaluate anti-malarial drug efficacy in pregnancy, are essential to achieve this goal.

Methods

The presence of Plasmodium falciparum was assessed by real-time (RT) PCR in 284 blood samples from pregnant women with clinical complaints suggestive of malaria, attending the maternity clinic of a Mozambican rural hospital. Parasite recrudescences in 33 consecutive paired episodes during the same pregnancy were identified by msp1 and msp2 genotyping.

Results

Prevalence of parasitaemia by microscopy was 5.3% (15/284) and 23.2% (66/284) by RT-PCR. Sensitivity of microscopy, compared to RT-PCR detection, was 22.7%. Risk of maternal anaemia was higher in PCR-positive women than in PCR-negative women (odds ratio [OR] = 1.92, 95% confidence interval [CI] 1.09–3.36). Genotyping confirmed that recrudescence after malaria treatment occurred in 7 (21%) out of 33 pregnant women with consecutive episodes during the same pregnancy (time range between recrudescent episodes: 14 to 187 days).

Conclusion

More accurate and sensitive diagnostic indicators of malaria infection in pregnancy are needed to improve malaria control. Longer follow-up periods than the standard in vivo drug efficacy protocol should be used to assess anti-malarial drug efficacy in pregnancy.

A randomised controlled trial of artemether-lumefantrine versus artesunate for uncomplicated plasmodium falciparum treatment in pregnancy

BACKGROUND

To date no comparative trials have been done, to our knowledge, of fixed-dose artemisinin combination therapies (ACTs) for the treatment of Plasmodium falciparum malaria in pregnancy. Evidence on the safety and efficacy of ACTs in pregnancy is needed as these drugs are being used increasingly throughout the malaria-affected world. The objective of this study was to compare the efficacy, tolerability, and safety of artemether-lumefantrine, the most widely used fixed ACT, with 7 d artesunate monotherapy in the second and third trimesters of pregnancy.

METHODS AND FINDINGS

An open-label randomised controlled trial comparing directly observed treatment with artemether-lumefantrine 3 d (AL) or artesunate monotherapy 7 d (AS7) was conducted in Karen women in the border area of northwestern Thailand who had uncomplicated P. falciparum malaria in the second and third trimesters of pregnancy. The primary endpoint was efficacy defined as the P. falciparum PCR-adjusted cure rates assessed at delivery or by day 42 if this occurred later than delivery, as estimated by Kaplan-Meier survival analysis. Infants were assessed at birth and followed until 1 y of life. Blood sampling was performed to characterise the pharmacokinetics of lumefantrine in pregnancy. Both regimens were very well tolerated. The cure rates (95% confidence interval) for the intention to treat (ITT) population were: AS7 89.2% (82.3%-96.1%) and AL 82.0% (74.8%-89.3%), p = 0.054 (ITT); and AS7 89.7% (82.6%-96.8%) and AL 81.2% (73.6%-88.8%), p = 0.031 (per-protocol population). One-third of the PCR-confirmed recrudescent cases occurred after 42 d of follow-up. Birth outcomes and infant (up to age 1 y) outcomes did not differ significantly between the two groups. The pharmacokinetic study indicated that low concentrations of artemether and lumefantrine were the main contributors to the poor efficacy of AL.

CONCLUSION

The current standard six-dose artemether-lumefantrine regimen was well tolerated and safe in pregnant Karen women with uncomplicated falciparum malaria, but efficacy was inferior to 7 d artesunate monotherapy and was unsatisfactory for general deployment in this geographic area. Reduced efficacy probably results from low drug concentrations in later pregnancy. A longer or more frequent AL dose regimen may be needed to treat pregnant women effectively and should now be evaluated. Parasitological endpoints in clinical trials of any antimalarial drug treatment in pregnancy should be extended to delivery or day 42 if it comes later.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN86353884.

Drugs for treating uncomplicated malaria in pregnant women

BACKGROUND

Women are more vulnerable to malaria during pregnancy, and malaria infection may have adverse consequences for the fetus. Identifying safe and effective treatments is important.

OBJECTIVES

To compare the effects of drug regimens for treating uncomplicated falciparum malaria in pregnant women.

SEARCH STRATEGY

We searched the Cochrane Infectious Diseases Group Specialized Register (February 2008), CENTRAL (The Cochrane Library 2008, Issue 1), MEDLINE (1966 to February 2008), EMBASE (1974 to February 2008), LILACS (February 2008), mRCT (February 2008), reference lists, and conference abstracts. We also contacted researchers in the field, organizations, and pharmaceutical companies.

SELECTION CRITERIA

Randomized and quasi-randomized controlled trials of antimalarial drugs for treating uncomplicated malaria in pregnant women.

DATA COLLECTION AND ANALYSIS

Two authors assessed trial eligibility and risk of bias, and extracted data. We performed a quantitative analysis only where we could combine the data. We combined dichotomous data using the risk ratio (RR) and presented each result with a 95% confidence interval (CI).

MAIN RESULTS

Ten trials (1805 participants) met the inclusion criteria. Two were quasi-randomized, seven did not describe allocation concealment, and all adjusted treatment failure to exclude new infections. One trial reported fewer treatment failures at day 63 with artesunate plus mefloquine compared with quinine (RR 0.09, 95% CI 0.02 to 0.38; 106 participants). One trial reported fewer treatment failures at day 63 with artesunate plus atovaquone-proguanil compared with quinine (RR 0.14, 95% CI 0.03 to 0.57; 80 participants). One trial reported fewer treatment failures at day 28 when amodiaquine was compared with chloroquine (RR 0.20, 95% CI 0.08 to 0.46; 420 participants) and when amodiaquine plus sulfadoxine-pyrimethamine was compared with chloroquine (RR 0.02, 95% CI 0.00 to 0.26; 418 participants). Compared with sulfadoxine-pyrimethamine given alone, one trial reported fewer treatment failures at delivery (or day 40) with artesunate plus sulfadoxine-pyrimethamine (RR 0.15, 95% CI 0.04 to 0.59; 79 participants) and azithromycin plus sulfadoxine-pyrimethamine (RR 0.27, 95% CI 0.10 to 0.76; 82 participants).

AUTHORS' CONCLUSIONS

Data are scant. Some combination treatments appear to be effective at treating malaria in pregnancy; however, safety data are limited.