Intermittent Preventive Treatment of Malaria in Pregnancy with Mefloquine in HIV-Negative Women: A Multicentre Randomized Controlled Trial

Background Intermittent preventive treatment in pregnancy (IPTp) with sulfadoxine-pyrimethamine (SP) is recommended by WHO to prevent malaria in African pregnant women. The spread of SP parasite resistance has raised concerns regarding long-term use for IPT. Mefloquine (MQ) is the most promising of available alternatives to SP based on safety profile, long half-life, and high efficacy in Africa. We evaluated the safety and efficacy of MQ for IPTp compared to those of SP in HIV-negative women. Methods and Findings A total of 4,749 pregnant women were enrolled in an open-label randomized clinical trial conducted in Benin, Gabon, Mozambique, and Tanzania comparing two-dose MQ or SP for IPTp and MQ tolerability of two different regimens. The study arms were: (1) SP, (2) single dose MQ (15 mg/kg), and (3) split-dose MQ in the context of long lasting insecticide treated nets. There was no difference on low birth weight prevalence (primary study outcome) between groups (360/2,778 [13.0%]) for MQ group and 177/1,398 (12.7%) for SP group; risk ratio [RR], 1.02 (95% CI 0.86-1.22; p=0.80 in the ITT analysis). Women receiving MQ had reduced risks of parasitemia (63/1,372 [4.6%] in the SP group and 88/2,737 [3.2%] in the MQ group; RR, 0.70 [95% CI 0.51-0.96]; p=0.03) and anemia at delivery (609/1,380 [44.1%] in the SP group and 1,110/2743 [40.5%] in the MQ group; RR, 0.92 [95% CI 0.85-0.99]; p=0.03), and reduced incidence of clinical malaria (96/551.8 malaria episodes person/year [PYAR] in the SP group and 130/1,103.2 episodes PYAR in the MQ group; RR, 0.67 [95% CI 0.52-0.88]; p=0.004) and all-cause outpatient attendances during pregnancy (850/557.8 outpatients visits PYAR in the SP group and 1,480/1,110.1 visits PYAR in the MQ group; RR, 0.86 [0.78-0.95]; p=0.003). There were no differences in the prevalence of placental infection and adverse pregnancy outcomes between groups. Tolerability was poorer in the two MQ groups compared to SP. The most frequently reported related adverse events were dizziness (ranging from 33.9% to 35.5% after dose 1; and 16.0% to 20.8% after dose 2) and vomiting (30.2% to 31.7%, after dose 1 and 15.3% to 17.4% after dose 2) with similar proportions in the full and split MQ arms. The open-label design is a limitation of the study that affects mainly the safety assessment. Conclusions Women taking MQ IPTp (15 mg/kg) in the context of long lasting insecticide treated nets had similar prevalence rates of low birth weight as those taking SP IPTp. MQ recipients had less clinical malaria than SP recipients, and the pregnancy outcomes and safety profile were similar. MQ had poorer tolerability even when splitting the dose over two days. These results do not support a change in the current IPTp policy. Trial registration ClinicalTrials.gov NCT 00811421; Pan African Clinical Trials Registry PACTR 2010020001429343Please see later in the article for the Editors' Summary Editors' Summary Background Half the world's population is at risk of malaria, a mosquito-borne parasitic disease that kills about 600,000 people every year. Most of these deaths occur among young children in sub-Saharan Africa but pregnant women and their unborn children living in Africa are also very vulnerable to malaria. Infection with malaria during pregnancy can cause severe maternal anemia (reduced red blood cell numbers), stillbirths, and pre-term and low-birthweight babies, and is responsible for the deaths of many African babies and women. To prevent this loss of life, the World Health Organization (WHO) recommends a three-pronged approachthe delivery to pregnant women of the antimalarial drug sulfadoxine-pyrimethamine (SP) at each scheduled antenatal care visit given at least one month apart (intermittent preventive treatment in pregnancy; IPTp), the use of insecticide treated bed nets to protect pregnant women from the bites of infected mosquitoes, and effective case management of pregnant women with malarial illness. Why Was This Study Done? IPTp with SP reduces the delivery of low-birth-weight babies and neonatal deaths but malaria parasites are becoming resistant to SP. Thus, other antimalarial drugs need to be evaluated for use in IPTp. Suitable drugs need to remain in the body for a long time to maximize their prophylactic (preventative) effect, they need to be given as a single dose at antenatal clinic visits to ensure compliance, and they must not harm the unborn child. In this open-label, randomized controlled trial (RCT), the researchers compare the efficacy and safety of IPTp with SP and mefloquine (MQ, an antimalarial drug that matches these criteria) in HIV-negative women living in Africa. The study also compares the tolerability of two MQ regimens. RCTs compare outcomes in groups of people chosen to receive different interventions through the play of chance; in open-label RCTs, both the researchers and the study participants know which treatment is being administered. IPTp with SP is only recommended for HIV-negative women because SP interacts with cotrimoxazole, which is routinely given to HIV-positive individuals to prevent infections. What Did the Researchers Do and Find? The researchers assigned 4,749 pregnant women in Benin, Gabon, Mozambique, and Tanzania to one of three study groups. Participants in the SP and MQ groups received two doses of SP or MQ, respectively, administered at least one month apart. Participants in the split-dose MQ group received each MQ dose as half doses given on consecutive days. The prevalence of low-birth-weight deliveries (the study's primary outcome; the prevalence of a condition is the proportion of a population with that condition) was similar in the SP group and in the combined MQ groups. However, compared to women who received SP, women who received MQ had a lower risk of parasitemia (parasites in the blood), a lower risk of anemia at delivery, fewer episodes of clinical malaria, and fewer outpatient attendances. The prevalence of placental infection with malaria parasites and of adverse pregnancy outcomes such as stillbirth was similar in all the study groups. Finally, the tolerability of IPTp was poorer in the two MQ intervention groups than in the SP group, but similar proportions of adverse events (mainly dizziness and vomiting) were reported for the two MQ dosing regimens. What Do These Findings Mean? These findings indicate that HIV-negative African women taking MQ for IPTp had a similar risk of a low-birth-weight delivery (the study's primary outcome) and lower risk of malaria illness during pregnancy than women taking SP for IPTp. Because the study did not have a no-IPTp arm (for ethical reasons), these findings provide no information about the efficacy or safety or either MQ or SP per se; these findings only indicate that MQ is no more efficacious than SP in the prevention of low-birth-weight babies. Moreover, because the study was open-label, the accuracy of the findings related to the tolerability and safety of MQ compared to SP may be limited because of biases in the assessment of safety outcomes. Given that the MQ dose used here for IPTp was associated with poorer tolerability than that of SP, these findings do not support the use of MQ instead of SP for IPTp. Additional Information Please access these websites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001733. A related PLOS MedicineResearch Article by Raquel Gonzalez and colleagues examines IPTp-MQ in HIV-infected women receiving cotrimoxazole prophylaxis This study is further discussed in a PLOS MedicinePerspective by Richard Steketee. Information is available from the World Health Organization on malaria (in several languages) and on malaria in pregnancy; information on IPTp and the updated WHO policy recommendation on IPTp with SP are available; the 2013 World Malaria Report provides details of the current global malaria situation The US Centers for Disease Control and Prevention also provides information on malaria; a personal story about malaria in pregnancy is available Information is available from the Roll Back Malaria Partnership on all aspects of global malaria control, including information on malaria in pregnancy The Malaria in Pregnancy Consortium is undertaking research into the prevention and treatment of malaria in pregnancy MedlinePlus provides links to additional information on malaria (in English and Spanish)