Azithromycin-chloroquine and the intermittent preventive treatment of malaria in pregnancy

Malaria chemoprevention and drug resistance: a review of the literature and policy implications

Chemoprevention strategies reduce malaria disease and death, but the efficacy of anti-malarial drugs used for chemoprevention is perennially threatened by drug resistance. This review examines the current impact of chemoprevention on the emergence and spread of drug resistant malaria, and the impact of drug resistance on the efficacy of each of the chemoprevention strategies currently recommended by the World Health Organization, namely, intermittent preventive treatment in pregnancy (IPTp); intermittent preventive treatment in infants (IPTi); seasonal malaria chemoprevention (SMC); and mass drug administration (MDA) for the reduction of disease burden in emergency situations. While the use of drugs to prevent malaria often results in increased prevalence of genetic mutations associated with resistance, malaria chemoprevention interventions do not inevitably lead to meaningful increases in resistance, and even high rates of resistance do not necessarily impair chemoprevention efficacy. At the same time, it can reasonably be anticipated that, over time, as drugs are widely used, resistance will generally increase and efficacy will eventually be lost. Decisions about whether, where and when chemoprevention strategies should be deployed or changed will continue to need to be made on the basis of imperfect evidence, but practical considerations such as prevalence patterns of resistance markers can help guide policy recommendations.

Use of Azithromycin in Pregnancy: More Doubts than Certainties

Macrolides such as azithromycin are commonly prescribed antibiotics during pregnancy. The good oral bioavailability and transplacental transfer of azithromycin make this drug suitable for the treatment of sexually transmitted diseases, toxoplasmosis, and malaria. Moreover, azithromycin is useful both in the management of preterm pre-labor rupture of membranes and in the adjunctive prophylaxis for cesarean delivery. The aim of this comprehensive narrative review is to critically analyze and summarize the available literature on the main aspects of azithromycin use in pregnant women, with a special focus on adverse offspring outcomes associated with prenatal exposure to the drug. References for this review were identified through searches of MEDLINE, PubMed, and EMBASE. Fetal and neonatal outcomes following prenatal azithromycin exposure have been investigated in several studies, yielding conflicting results. Increased risks of spontaneous miscarriage, major congenital malformations, cardiovascular malformations, digestive system malformations, preterm birth, and low birth weight have been reported in some studies but not in others. Currently, there is no conclusive evidence to support that azithromycin use by pregnant women causes adverse outcomes in their offspring. Therefore, this agent should only be used during pregnancy when clinically indicated, if the benefits of treatment are expected to outweigh the potential risks.

Macrolide and lincosamide antibiotic exposure in the first trimester of pregnancy and risk of congenital anomaly: A European case-control study

This study investigated the risk of congenital heart defects (CHD) and other congenital anomalies (CA) associated with first trimester use of macrolide antibiotics (mainly erythromycin, spiramycin, clarithromycin and azithromycin) and lincosamides (clindamycin) using a case-malformed control design. Data included 145,936 babies with a CA diagnosis (livebirths, stillbirths and terminations of pregnancy for CA) from 15 population-based EUROCAT registries in 13 European countries, covering 9 million births 1995-2012. Cases were babies with CHD, anencephaly, orofacial clefts, genital and limb reduction anomalies associated with antibiotic exposure in the literature. Controls were babies with other CA or genetic conditions. Main outcomes were odds ratios adjusted (AOR) for maternal age and registry, with 95 % Confidence Intervals (95 %CI). Macrolide and lincosamide exposure was recorded for 307 and 28 cases, 72 and 4 non-genetic controls, 57 and 7 genetic controls, respectively. AOR for CHD was not significantly raised (AOR 0.94, 95 %CI: 0.70-1.26 vs non-genetic controls; AOR 1.01, 95 %CI: 0.73-1.41 vs genetic controls), nor significantly raised for any specific macrolide. The risk of atrioventricular septal defect was significantly raised with exposure to any macrolide (AOR 2.98; 95 %CI: 1.48-6.01), erythromycin (AOR 3.68, 95 %CI: 1.28-10.61), and azithromycin (AOR 4.50, 95 %CI: 1.30-15.58). Erythromycin, clarithromycin, azithromycin, and clindamycin were associated with an increased risk of at least one other CA. Further research is needed on the risk of specific CA associated with macrolide and lincosamide use in the first trimester, particularly relevant for the potential use of azithromycin in the treatment of COVID-19.

Repurposing Drugs to Fight Hepatic Malaria Parasites

Malaria remains one of the most prevalent infectious diseases worldwide, primarily affecting some of the most vulnerable populations around the globe. Despite achievements in the treatment of this devastating disease, there is still an urgent need for the discovery of new drugs that tackle infection by Plasmodium parasites. However, de novo drug development is a costly and time-consuming process. An alternative strategy is to evaluate the anti-plasmodial activity of compounds that are already approved for other purposes, an approach known as drug repurposing. Here, we will review efforts to assess the anti-plasmodial activity of existing drugs, with an emphasis on the obligatory and clinically silent liver stage of infection. We will also review the current knowledge on the classes of compounds that might be therapeutically relevant against Plasmodium in the context of other communicable diseases that are prevalent in regions where malaria is endemic. Repositioning existing compounds may constitute a faster solution to the current gap of prophylactic and therapeutic drugs that act on Plasmodium parasites, overall contributing to the global effort of malaria eradication.

A Randomized Open-Label Evaluation of the Antimalarial Prophylactic Efficacy of Azithromycin-Piperaquine versus Sulfadoxine-Pyrimethamine in Pregnant Papua New Guinean Women

Emerging malaria parasite sulfadoxine-pyrimethamine (SP) resistance has prompted assessment of alternatives for intermittent preventive treatment in pregnancy (IPTp). The objective was to evaluate the tolerability and prophylactic efficacy of azithromycin (AZ) plus piperaquine (PQ) in pregnant women in Papua New Guinea. The study was an open-label, randomized, parallel-group trial. A total of 122 women (median gestation, 26 weeks [range, 14 to 32 weeks]) were randomized 1:1 to three daily doses of 1 g AZ plus 960 mg PQ tetraphosphate or single-dose SP (4,500 mg sulfadoxine plus 225 mg pyrimethamine), based on computer-generated block randomization. Tolerability was assessed to day 7, and efficacy was assessed to day 42 (when participants were returned to usual care) and at delivery. Data for 119 participants (AZ-PQ, n = 61; SP, n = 58) were analyzed. Both regimens were well tolerated, but AZ-PQ was associated with more gastrointestinal side effects (31%) and dizziness (21%). Eight women (6.7%) were parasitemic at recruitment but all were aparasitemic by 72 h. There were no differences in blood smear positivity rates between AZ-PQ and SP up to day 42 (0% versus 5.2%; relative risk [RR], 0.14 [95% confidence interval [CI], 0.01 to 2.58] [P = 0.18]; absolute risk reduction [ARR], 5.2% [95% CI, -1.3 to 11.6%]) and at the time of delivery (0% versus 8.7%; RR, 0.11 [95% CI, 0.01 to 2.01] [P = 0.14]; ARR, 8.7% [95% CI, -0.2 to 17.6%]). Of 92 women who were monitored to parturition, 89 (97%) delivered healthy babies; there were 3 stillbirths (SP, n = 1; AZ-PQ, n = 2 [twins]). There was a higher live birth weight (mean ± standard deviation) in the AZ-PQ group (3.13 ± 0.42 versus 2.88 ± 0.55 kg [P = 0.016]; mean difference, 0.25 kg [95% CI, 0.02 to 0.48 kg]). AZ-PQ is a promising candidate for IPTp.

Pharmacotherapy for the prevention of malaria in pregnant women: currently available drugs and challenges

INTRODUCTION

Malaria in pregnancy continues to be a significant public health burden globally, with over 100 million women at risk each year. Sulfadoxine-pyrimethamine (SP) is the only antimalarial recommended for intermittent preventive therapy in pregnancy (IPTp) but increasing parasite resistance threatens its viability. There are few other available antimalarial therapies that currently have sufficient evidence of tolerability, safety, and efficacy to replace SP.

AREAS COVERED

Novel antimalarial combinations are under investigation for potential use as chemoprophylaxis and in IPTp regimens. The present review summarizes currently available therapies, emerging candidate combination therapies, and the potential challenges to integrating these into mainstream policy.

EXPERT OPINION

Alternative drugs or combination therapies to SP for IPTp are desperately required. Dihydroartemisinin-piperaquine and azithromycin-based combinations are showing great promise as potential candidates for IPTp but pharmacokinetic data suggest that dose modification may be required to ensure adequate prophylactic efficacy. If a suitable candidate regimen is not identified in the near future, the success of chemopreventive strategies such as IPTp may be in jeopardy.

Burden, pathology, and costs of malaria in pregnancy: new developments for an old problem

Over the past 10 years, knowledge of the burden, economic costs, and consequences of malaria in pregnancy has improved, and the prevalence of malaria caused by Plasmodium falciparum has declined substantially in some geographical areas. In particular, studies outside of Africa have increased the evidence base of Plasmodium vivax in pregnancy. Rapid diagnostic tests have been poor at detecting malaria in pregnant women, while PCR has shown a high prevalence of low density infection, the clinical importance of which is unknown. Erythrocytes infected with P falciparum that express the surface protein VAR2CSA accumulate in the placenta, and VAR2CSA is an important target of protective immunity. Clinical trials for a VAR2CSA vaccine are ongoing, but sequence variation needs to be carefully studied. Health system and household costs still limit access to prevention and treatment services. Within the context of malaria elimination, pregnant women could be used to monitor malaria transmission. This Series paper summarises recent progress and highlights unresolved issues related to the burden of malaria in pregnancy.

Mass Azithromycin and Malaria Parasitemia in Niger: Results from a Community-Randomized Trial

Studies designed to determine the effects of mass administration of azithromycin on trachoma have suggested that mass azithromycin distributions may also reduce the prevalence of malaria. These studies have typically examined the impact of a small number of treatments over short durations. In this prespecified substudy of a cluster-randomized trial for trachoma, we compared malaria parasitemia prevalence in 24 communities in Niger randomized to receive either annual or biannual mass azithromycin distributions over 3 years. The 12 communities randomized to annual azithromycin received three treatments during the high-transmission season, and the 12 communities randomized to biannual azithromycin received a total of six treatments: three during the high-transmission season and three during the low-transmission season. Blood samples were taken to assess malariometric indices among children in all study communities at a single time point during the high-transmission season after 3 years of the intervention. No significant differences were identified in malaria parasitemia, parasite density, or hemoglobin concentration between the annual and biannual treatment arms. When compared with annual mass azithromycin alone, additional mass azithromycin distributions given during the low-transmission season did not significantly reduce the subsequent prevalence of malaria parasitemia or parasite density after 3 years, as measured during the high-transmission season.

Oral administration of azithromycin ameliorates trypanosomosis in Trypanosoma congolense-infected mice

Animal trypanosomosis is a devastating parasitic disease that is of economic importance to livestock production. The infection includes animal African trypanosomosis, surra, and dourine. The treatment is based solely on few compounds that were discovered decades ago and which are associated with severe toxicity. Furthermore, it is likely that the parasite has developed resistance towards them. Thus, there is an urgent need for new, accessible, and less toxic drugs. Azithromycin is an antibiotic with documented efficacy against Toxoplasma, Babesia, and Plasmodium. The current study investigated its effects against animal trypanosomes. An in vitro system was used to determine the trypanocidal effects of azithromycin against Trypanosoma congolense, Trypanosoma brucei brucei, and Trypanosoma evansi, and cytotoxicity in Madin-Darby bovine kidney (MDBK) and NIH 3T3 cells. Furthermore, the trypanocidal effects of azithromycin were investigated in T. congolense-infected mice. In vitro, azithromycin had an IC₅₀ of 0.19 ± 0.17; 3.69 ± 2.26; 1.81 ± 1.82 μg/mL against T. congolense, T. b. brucei, and T. evansi, respectively. No cytotoxic effects were observed in MDBK and NIH 3T3 cells. The efficacy of orally administered azithromycin was investigated in short-term and long-term treatment protocols. Although the short-term treatment protocol showed no curative effects, the survival rate of the mice was significantly prolonged (p < 0.001) in comparison to the control group. The long-term treatment yielded satisfying curative effects with doses of 300 and 400 mg/kg achieving 80 and 100% survival, respectively. In conclusion, long-term oral azithromycin treatment has trypanocidal effects against T. congolense.

Optimal antimalarial dose regimens for chloroquine in pregnancy based on population pharmacokinetic modelling

Despite extensive use and accumulated evidence of safety, there have been few pharmacokinetic studies from which appropriate chloroquine (CQ) dosing regimens could be developed specifically for pregnant women. Such optimised CQ-based regimens, used as treatment for acute malaria or as intermittent preventive treatment in pregnancy (IPTp), may have a valuable role if parasite CQ sensitivity returns following reduced drug pressure. In this study, population pharmacokinetic/pharmacodynamic modelling was used to simultaneously analyse plasma concentration-time data for CQ and its active metabolite desethylchloroquine (DCQ) in 44 non-pregnant and 45 pregnant Papua New Guinean women treated with CQ and sulfadoxine/pyrimethamine or azithromycin (AZM). Pregnancy was associated with 16% and 49% increases in CQ and DCQ clearance, respectively, as well as a 24% reduction in CQ relative bioavailability. Clearance of DCQ was 22% lower in those who received AZM in both groups. Simulations based on the final multicompartmental model demonstrated that a 33% CQ dose increase may be suitable for acute treatment for malaria in pregnancy as it resulted in equivalent exposure to that in non-pregnant women receiving recommended doses, whilst a double dose would likely be required for an effective duration of post-treatment prophylaxis when used as IPTp especially in areas of CQ resistance. The impact of co-administered AZM was clinically insignificant in simulations. The results of past/ongoing trials employing recommended adult doses of CQ-based regimens in pregnant women should be interpreted in light of these findings, and consideration should be given to using increased doses in future trials.

Parasitological Clearance Rates and Drug Concentrations of a Fixed Dose Combination of Azithromycin-Chloroquine in Asymptomatic Pregnant Women with Plasmodium Falciparum Parasitemia: An Open-Label, Non-Comparative Study in Sub-Saharan Africa

Background

Malaria remains one of the most important causes of morbidity and mortality in pregnant women and their newborn babies in sub-Saharan Africa. Intermittent preventive treatment in pregnancy (IPTp) is recommended by the World Health Organization (WHO) to reduce the burden of disease and improve maternal and neonatal survival and general health. Due to the growing resistance to sulfadoxine-pyrimethamine (SP), the current WHO-recommended drug for IPTp, identification of new and effective drugs is an urgent priority.

Methods and Findings

This was an open-label, non-comparative study (NCT01103713) in 5 countries in East and sub-Saharan Africa (Benin, Kenya, Malawi, Tanzania, and Uganda) to assess parasitological response and drug concentrations of a single, 3-day course of four tablets of a fixed-dose combination of azithromycin-chloroquine (AZCQ) 250/155 mg given during the second or third trimester to women with asymptomatic Plasmodium falciparum parasitemia in their first or second pregnancy. Parasitemia was determined by microscopy and molecular genotyping was performed to characterize parasites relative to the baseline infection. Weekly follow-up visits took place until day 42 after first dose and additional follow-up occurred after delivery. Systemic concentrations of azithromycin (AZ), chloroquine (CQ), and the CQ metabolite, desethyl CQ (DECQ) were evaluated at Day 0 (pre-dose), at Day 2 (pre-dose, 2 and 8 hours) and randomly at Days 7 and 14. Systemic concentrations of CQ and DECQ were also measured randomly at Day 21 and Day 28. In total, 404 women were screened for eligibility and 168 were treated, 155 of whom completed the study. PCR-adjusted parasitological response in the modified intent-to-treat population at day 28 (the primary efficacy endpoint) was estimated by the Kaplan-Meier method as 99.35% (95% confidence interval [CI]: 97.76, 100.00). PCR-adjusted parasitological response remained high at day 42 (95.19%; 95% CI: 91.35, 99.03). In general, the mean concentrations of serum AZ, plasma CQ, and plasma DECQ showed large CV% values (ranges of 33–156%, 42–228%, and 57–109%, respectively). There were 157 live births, three stillbirths, and eight pregnancies of unknown outcome: 7 due to withdrawal of participant consent and 1 lost to follow-up. The most frequent treatment-emergent adverse events were vomiting (20.8%) and dizziness (19.6%).

Conclusions

These results suggest that a 3-day course of AZCQ can lead to an adequate 28-day parasitological response.

Malarial Infection and Curable Sexually Transmitted and Reproductive Tract Infections Among Pregnant Women in a Rural District of Zambia

Malarial infection and curable sexually transmitted and reproductive tract infections (STIs/RTIs) are important causes of adverse birth outcomes. Reducing the burden of these infections in pregnancy requires interventions that can be easily integrated into the antenatal care (ANC) package. However, efforts to integrate the control of malarial infection and curable STIs/RTIs in pregnancy have been hampered by a lack of evidence related to their coinfection. Thus, we investigated the prevalence of coinfection among pregnant women of rural Zambia. A prospective cohort study was conducted in Nchelenge District, Zambia, involving 1,086 first ANC attendees. We screened participants for peripheral malarial infection and curable STIs/RTIs (syphilis, Chlamydia, gonorrhea, trichomoniasis, and bacterial vaginosis), and collected relevant sociodemographic data at booking. Factors associated with malarial and STI/RTI coinfection were explored using univariate and multivariate regression models. Among participants with complete results (N = 1,071), 38.7% (95% confidence interval [CI] = 35.7-41.6) were coinfected with malaria parasites and at least one STI/RTI; 18.9% (95% CI = 16.5-21.2) were infected with malaria parasites only; 26.0% (95% CI = 23.5-28.8) were infected with at least one STI/RTI but no malaria parasites, and 16.4% (95% CI = 14.1-18.6) had no infection. Human immunodeficiency virus (HIV)-infected women had a higher risk of being coinfected than HIV-uninfected women (odds ratio [OR] = 3.59 [95% CI = 1.73-7.48], P < 0.001). The prevalence of malarial and STI/RTI coinfection was high in this population. An integrated approach to control malarial infection and STIs/RTIs is needed to reduce this dual burden in pregnancy.

Underreporting and Missed Opportunities for Uptake of Intermittent Preventative Treatment of Malaria in Pregnancy (IPTp) in Mali

Objectives

To identify factors contributing to low uptake of intermittent preventive treatment of malaria in pregnancy with sulfadoxine-pyrimethamine (IPTp-SP) in rural Mali.

Methods

We conducted secondary data analysis on Mali’s 2012–2013 Demographic and Health Survey (DHS) to determine the proportion of women who failed to take IPTp-SP due to ineligibility or non-attendance at antenatal care (ANC). We also identified the proportion who reported taking other or unknown medications to prevent malaria in pregnancy and those who did not know if they took any medication to prevent malaria in pregnancy. We conducted qualitative interviews, focus groups and ANC observations in six rural sites in Mali’s Sikasso and Koulikoro regions to identify reasons for missed opportunities.

Results

Our secondary data analysis found that reported IPTp-SP coverage estimates are misleading due to their dependence on a variable (“source of IPTp”) that is missing 62% of its data points. Among all women who gave birth in the two years prior to the survey, 56.2% reported taking at least one dose of IPTp-SP. Another 5.2% reported taking chloroquine, 1.9% taking another drug to prevent malaria in pregnancy, 4.4% not knowing what drug they took to prevent malaria, and 1.1% not knowing if they took any drug to prevent malaria. The majority of women who did not receive IPTp-SP were women who also did not attend ANC. Our qualitative data revealed that many health centers neither administer IPTp-SP by directly observed therapy, nor give IPTp-SP at one month intervals through the second and third trimesters, nor provide IPTp-SP free of charge. Women generally reported IPTp-SP as available and tolerable, but frequently could not identify its name or purpose, potentially affecting accuracy of responses in household surveys.

Conclusion

We estimate IPTp-SP uptake to be significantly higher than stated in Mali’s 2012–13 DHS report. Increasing ANC attendance should be the first priority for increasing IPTp-SP coverage. Reducing cost and access barriers, ensuring that providers follow up-to-date guidelines, and improving patient counseling on IPTp-SP would also facilitate optimal uptake.

Efficacy and Safety of Azithromycin-Chloroquine versus Sulfadoxine-Pyrimethamine for Intermittent Preventive Treatment of Plasmodium falciparum Malaria Infection in Pregnant Women in Africa: An Open-Label, Randomized Trial

BACKGROUND

The World Health Organization recommends intermittent preventive treatment in pregnancy (IPTp) with sulfadoxine-pyrimethamine (SP) in African regions with moderate to high malaria transmission. However, growing resistance to SP threatens the effectiveness of IPTp-SP, and alternative drugs are needed. This study tested the efficacy, tolerability, and safety of a fixed-dose combination azithromycin-chloroquine (AZCQ; 250 mg AZ/155 mg CQ base) for IPTp relative to IPTp-SP.

METHODS AND FINDINGS

A randomized, Phase 3, open-label, multi-center study was conducted in sub-Saharan Africa (Benin, Kenya, Malawi, Tanzania, and Uganda) between October 2010 and November 2013. Pregnant women received 3 IPTp courses with AZCQ (each course: 1,000/620 mg AZCQ QD for 3 days) or SP (each course 1,500/75 mg SP QD for 1 day) at 4- to 8-week intervals during the second and third trimester. Long-lasting insecticide-treated bednets were also provided at enrollment. Study participants were followed up until day 28 post delivery (time window: day 28-42). The primary endpoint was the proportion of participants with sub-optimal pregnancy outcomes (a composite endpoint comprising live-borne neonates with low birth weight [LBW, <2,500 g], premature birth [<37 weeks], still birth [>28 weeks], abortion [≤28 weeks], lost to follow-up prior to observation of pregnancy outcome, or missing birth weight). The study was terminated early after recruitment of 2,891 of the planned 5,044 participants, due to futility observed in a pre-specified 35% interim analysis. In the final intent-to-treat dataset, 378/1,445 (26.2%) participants in the AZCQ and 342/1,445 (23.7%) in the SP group had sub-optimal pregnancy outcomes, with an estimated risk ratio (RR) of 1.11 (95% CI: 0.97, 1.25; p = 0.12). There was no significant difference in the incidence of LBW between treatment groups (57/1138 [5.0%] in the AZCQ group, 68/1188 [5.7%] in the SP group, RR 0.87 [95% CI: 0.62, 1.23]; p = 0.44). IPTp-AZCQ was less well-tolerated in mothers than IPTp-SP. Occurrences of congenital anomalies, deaths, and serious adverse events were comparable in neonates for both groups. Limitations included the open-label design and early study termination.

CONCLUSIONS

IPTp-AZCQ was not superior to IPTp-SP in this study and alternatives for IPTp-SP remain to be identified. The proportions of sub-optimal pregnancy outcomes and LBW were lower than expected, which may be linked to insecticide-treated bednet use throughout the study. Reduced incidences of symptomatic malaria infection and peripheral parasitemia in the AZCQ group relative to SP suggest that AZCQ warrants further investigation as an alternative treatment of uncomplicated malaria.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT01103063).

Macrolides and associated antibiotics based on similar mechanism of action like lincosamides in malaria

Malaria, a parasite vector-borne disease, is one of the biggest health threats in tropical regions, despite the availability of malaria chemoprophylaxis. The emergence and rapid extension of Plasmodium falciparum resistance to various anti-malarial drugs has gradually limited the potential malaria therapeutics available to clinicians. In this context, macrolides and associated antibiotics based on similar mechanism of action like lincosamides constitute an interesting alternative in the treatment of malaria. These molecules, whose action spectrum is similar to that of tetracyclines, are typically administered to children and pregnant women. Recent studies have examined the effects of azithromycin and the lincosamide clindamycin, on isolates from different continents. Azithromycin and clindamycin are effective and well tolerated in the treatment of uncomplicated malaria in combination with quinine. This literature review assesses the roles of macrolides and lincosamides in the prophylaxis and treatment of malaria.

Population pharmacokinetics, tolerability, and safety of dihydroartemisinin-piperaquine and sulfadoxine-pyrimethamine-piperaquine in pregnant and nonpregnant Papua New Guinean women

The tolerability, safety, and disposition of dihydroartemisinin (DHA) and piperaquine (PQ) were assessed in 32 pregnant (second/third trimester) and 33 nonpregnant Papua New Guinean women randomized to adult treatment courses of DHA-PQ (three daily doses) or sulfadoxine-pyrimethamine (SP)-PQ (three daily PQ doses, single dose of SP). All dose adminstrations were observed, and subjects fasted for 2 h postdose. Plasma PQ was assayed by using high-performance liquid chromatography, and DHA was assessed by using liquid chromatography-mass spectrometry. Compartmental pharmacokinetic models were developed using a population-based approach. Both regimens were well tolerated. There was an expected increase in the rate-corrected electrocardiographic QT interval which was independent of pregnancy and treatment. Two pregnant and two nonpregnant women had Plasmodium falciparum parasitemia which cleared within 48 h, and no other subject became slide positive for malaria during 42 days of follow-up. Of 30 pregnant women followed to delivery, 27 (90%) delivered healthy babies and 3 (10%) had stillbirths; these obstetric outcomes are consistent with those in the general population. The area under the plasma PQ concentration-time curve (AUC0-∞) was lower in the pregnant patients (median [interquartile range], 23,721 μg · h/liter [21,481 to 27,951 μg · h/liter] versus 35,644 μg · h/liter [29,546 to 39,541 μg · h/liter]; P < 0.001) in association with a greater clearance relative to bioavailability (73.5 liters/h [69.4 to 78.4] versus 53.8 liters/h [49.7 to 58.2]; P < 0.001), but pregnancy did not influence the pharmacokinetics of DHA. The apparent pharmacokinetic differences between the present study and results from other studies of women with uncomplicated malaria that showed no effect of pregnancy on the AUC0-∞ of PQ and greater bioavailability may reflect differences in postdose fat intake, proportions of women with malaria, and/or racial differences in drug disposition.

Impact of intermittent preventive treatment in pregnancy with azithromycin-containing regimens on maternal nasopharyngeal carriage and antibiotic sensitivity of Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus: a cross-sectional survey at delivery

Sulfadoxine-pyrimethamine (SP) plus azithromycin (AZ) (SPAZ) has the potential for intermittent preventive treatment of malaria in pregnancy (IPTp), but its use could increase circulation of antibiotic-resistant bacteria associated with severe pediatric infections. We evaluated the effect of monthly SPAZ-IPTp compared to a single course of SP plus chloroquine (SPCQ) on maternal nasopharyngeal carriage and antibiotic susceptibility of Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus at delivery among 854 women participating in a randomized controlled trial in Papua New Guinea. Serotyping was performed, and antibiotic susceptibility was evaluated by disk diffusion and Etest. Potential risk factors for carriage were examined. Nasopharyngeal carriage at delivery of S. pneumoniae (SPAZ, 7.2% [30/418], versus SPCQ, 19.3% [84/436]; P<0.001) and H. influenzae (2.9% [12/418] versus 6.0% [26/436], P=0.028), but not S. aureus, was significantly reduced among women who had received SPAZ-IPTp. The number of macrolide-resistant pneumococcal isolates was small but increased in the SPAZ group (13.3% [4/30], versus SPCQ, 2.2% [2/91]; P=0.033). The proportions of isolates with serotypes covered by the 13-valent pneumococcal conjugate vaccine were similar (SPAZ, 10.3% [3/29], versus SPCQ, 17.6% [16/91]; P=0.352). Although macrolide-resistant isolates were rare, they were more commonly detected in women who had received SPAZ-IPTp, despite the significant reduction of maternal carriage of S. pneumoniae and H. influenzae observed in this group. Future studies on SPAZ-IPTp should evaluate carriage and persistence of macrolide-resistant S. pneumoniae and other pathogenic bacteria in both mothers and infants and assess the clinical significance of their circulation.

Efficacy and safety of a combination of azithromycin and chloroquine for the treatment of uncomplicated Plasmodium falciparum malaria in two multi-country randomised clinical trials in African adults

BACKGROUND

Given increasing rates of resistance to existing therapy, new options for treatment and prophylaxis of malaria are needed.

METHODS

Two randomised, comparative, non-inferiority studies were conducted in Africa, one double-blinded and one open-label. Adults with fever, a positive peripheral blood smear, and a positive rapid diagnostic test for Plasmodium falciparum were randomised in both studies to either azithromycin (AZ) 1,000 mg plus chloroquine (CQ) 600-mg base (AZCQ 1,000 mg) once daily for three days or mefloquine hydrochloride (MQ) 1,250 mg (split dose). In the first study, an additional regimen of AZ 500 mg plus CQ 600-mg base (AZCQ 500 mg) once daily for three days was included. All study participants were hospitalised until three consecutive daily blood smears were negative for asexual P. falciparum parasitaemia. Study participants were evaluated weekly for 42 days, with Day 28 polymerase chain reaction (PCR)-corrected parasitological clearance rate as primary endpoint.

RESULTS

A total of 467 subjects were randomised in the two studies. At 28 days' follow-up, PCR-corrected parasitological clearance rates in the per protocol population in the first study were 101/103 (98%) with AZCQ 1,000 mg compared with 102/103 (99%) with MQ (95% confidence interval [CI]: -5.2, 3.3). The AZCQ 500-mg regimen was stopped during an interim study review (six [86%] clearance of seven evaluable; two lost to follow-up). In the second study, clearance rates were similar: AZCQ 1,000 mg 107/107 (100%) vs MQ 111/112 (99%; 95% CI: -1.8, 3.6). Among the participating countries, in vitro CQ resistance based on pfcrt mutation frequency in the baseline isolates across both studies ranged from 20.8% (Zambia) to 96.1% (Uganda). Serious adverse events (AEs; all causality) were observed more frequently with MQ compared with AZCQ (four vs one, respectively), though discontinuations for AEs were similar (four vs three, respectively). Common AEs in the AZ-containing arms included pruritus, vomiting, dizziness, and headache.

CONCLUSIONS

Among adults with symptomatic uncomplicated falciparum malaria in Africa, the combination of AZ 1,000 mg and CQ 600-mg base once daily for three days resulted in Day 28 PCR-corrected parasitological clearance rates of ≥98% and was non-inferior to treatment with MQ. AZCQ was well tolerated.

TRIAL REGISTRATION

ClinicalTrials.gov identifiers NCT00082576 and NCT00367653.

Collateral benefits arising from mass administration of azithromycin in the control of active trachoma in resource limited settings

Introduction

The benefits of the use of antibiotics in the mass treatment for active trachoma and other diseases have been documented, but the secondary effects arising from such a programme have not been fully elucidated. The purpose of this study was to investigate the potential secondary benefits arising from the use of azithromycin in mass treatment of active trachoma in an economically challenged Kenyan nomadic community.

Methods

Health information reports for January 2005 to December 2010 were reviewed to determine the annual trends of infectious diseases in the two districts, Narok and Transmara. The year 2007 was considered as the baseline for mass drug administration (MDA). Odds ratios (OR) were used to describe the association.

Results

The mass distribution coverage in Narok was 83% in 2008, 74% in 2009 and 63% in 2010. The odds for malaria (OR = 1.13; 95% CI 1.12-1.14), diarrhoeal diseases (OR = 1.04; 95% CI 1.01-1.06), urinary tract infections (UTIs) (OR = 1.21; 95% CI 1.17-1.26), intestinal worms (OR, 4.98; 95% CI 4.68-5.3), and respiratory diseases other than pneumonia (OR, 1.15; 95% CI 1.13-1.16) were higher after three rounds of mass treatment, indicating a better outcome. Before the intervention, there was a reducing trend in the odds for respiratory diseases. In Transmara (control), there was an increase in odds for malaria, respiratory infections, UTIs and intestinal worms. The odds for diarrhoeal diseases, skin diseases and pneumonia decreased throughout the study period.

Conclusion

Mass distribution of azithromycin may have contributed to the decrease in the prevalence of the respiratory infections in Narok District.

Azithromycin is able to control Toxoplasma gondii infection in human villous explants

Background

Although Toxoplasma gondii infection is normally asymptomatic, severe cases of toxoplasmosis may occur in immunosuppressed patients or congenitally infected newborns. When a fetal infection is established, the recommended treatment is a combination of pyrimethamine, sulfadiazine and folinic acid (PSA). The aim of the present study was to evaluate the efficacy of azithromycin to control T. gondii infection in human villous explants.

Methods

Cultures of third trimester human villous explants were infected with T. gondii and simultaneously treated with either PSA or azithromycin. Proliferation of T. gondii, as well as production of cytokines and hormones by chorionic villous explants, was analyzed.

Results

Treatment with either azithromycin or PSA was able to control T. gondii infection in villous explants. After azithromycin or PSA treatment, TNF-α, IL-17A or TGF-β1 levels secreted by infected villous explants did not present significant differences. However, PSA-treated villous explants had decreased levels of IL-10 and increased IL-12 levels, while treatment with azithromycin increased production of IL-6. Additionally, T. gondii-infected villous explants increased secretion of estradiol, progesterone and HCG + β, while treatments with azithromycin or PSA reduced secretion of these hormones concurrently with decrease of parasite load.

Conclusions

In conclusion, these results suggest that azithromycin may be defined as an effective alternative drug to control T. gondii infection at the fetal-maternal interface.

Impact of mass azithromycin distribution on malaria parasitemia during the low-transmission season in Niger: a cluster-randomized trial

We assessed the effect of mass azithromycin treatment on malaria parasitemia in a trachoma trial in Niger. Twenty-four study communities received treatment during the wet, high-transmission season. Twelve of the 24 communities were randomized to receive an additional treatment during the dry, low-transmission season. Outcome measurements were conducted at the community-level in children < 1-72 months of age in May-June 2011. Parasitemia was higher in the 12 once-treated communities (29.8%, 95% confidence interval [CI] = 21.5-40.0%) than in the 12 twice-treated communities (19.5%, 95% CI = 13.0-26.5%, P = 0.03). Parasite density was higher in once-treated communities (354 parasites/μL, 95% CI = 117-528 parasites/μL) than in twice-treated communities (74 parasites/μL, 95% CI = 41-202 parasites/μL, P = 0.03). Mass distribution of azithromycin reduced malaria parasitemia 4-5 months after the intervention. The results suggest that drugs with antimalaria activity can have long-lasting impacts on malaria during periods of low transmission.

Chloroquine-azithromycin combination antimalarial treatment decreases risk of respiratory- and gastrointestinal-tract infections in Malawian children

BACKGROUND

Chloroquine-azithromycin is being evaluated as combination therapy for malaria. It may provide added benefit in treating or preventing bacterial infections that occur in children with malaria.

OBJECTIVE

We aim to evaluate the effect of treating clinical malaria with chloroquine-azithromycin on the incidence of respiratory-tract and gastrointestinal-tract infections compared to treatment with chloroquine monotherapy.

METHODS

We compared the incidence density and time to first events of respiratory-tract and gastrointestinal-tract infections among children assigned to receive chloroquine-azithromycin or chloroquine for all symptomatic malaria episodes over the course of 1 year in a randomized longitudinal trial in Blantyre, Malawi.

RESULTS

The incidence density ratios of total respiratory-tract infections and gastrointestinal-tract infections comparing chloroquine-azithromycin to chloroquine monotherapy were 0.67 (95% confidence interval [CI], .48, .94) and 0.74 (95% CI, .55, .99), respectively. The time to first lower-respiratory-tract and gastrointestinal-tract infections were significantly longer in the chloroquine-azithromycin arm compared to the chloroquine arm (P = .04 and P = .02, respectively).

CONCLUSIONS

Children treated routinely with chloroquine-azithromycin had fewer respiratory and gastrointestinal-tract infections than those treated with chloroquine alone. This antimalarial combination has the potential to reduce the burden of bacterial infections among children in malaria-endemic countries.

On the pathway to better birth outcomes? A systematic review of azithromycin and curable sexually transmitted infections

The WHO recommends the administration of sulfadoxine-pyrimethamine (SP) to all pregnant women living in areas of moderate (stable) to high malaria transmission during scheduled antenatal visits, beginning in the second trimester and continuing to delivery. Malaria parasites have lost sensitivity to SP in many endemic areas, prompting the investigation of alternatives that include azithromycin-based combination (ABC) therapies. Use of ABC therapies may also confer protection against curable sexually transmitted infections and reproductive tract infections (STIs/RTIs). The magnitude of protection at the population level would depend on the efficacy of the azithromycin-based regimen used and the underlying prevalence of curable STIs/RTIs among pregnant women who receive preventive treatment. This systematic review summarizes the efficacy data of azithromycin against curable STIs/RTIs.

Trends in chloroquine resistance marker, Pfcrt-K76T mutation ten years after chloroquine withdrawal in Tanzania

Background

Plasmodium falciparum resistance to anti-malarial drugs remains a major obstacle to the control of malaria. In 2001 Tanzania replaced chloroquine (CQ) with sulphadoxine-pyrimethamine (SP) as first-line drug, which in turn was replaced by artemisinin combination therapy in 2006. SP has however, continued to be used in intermittent preventive treatment of malaria in pregnancy (IPTp) despite reports of high levels of resistance to SP due to the lack of alternatives to SP for IPTp. Recent reports have indicated recovery of CQ-susceptibility in Malawi, Kenya, Mozambique, and Tanzania based on the prevalence of wild types at codon 76 of the Pfcrt gene in indigenous P. falciparum populations. The current prevalence of this Pfcrt-76 CQ resistance marker from six regions of Tanzania mainland is hereby reported.

Methods

DNA extracted from filter-paper dried blood spots and rapid diagnostics kit strips collected from finger-prick blood were used to genotype the Pfcrt-76 resistance marker using PCR-RFLP. Data from previously published studies were used to generate CQ susceptibility recovery trends using logistic regression model.

Results

Seven hundred and forty one (741) samples were genotyped. The current frequency of the CQ-susceptible Pfcrt-K76 was above 92% and did not differ between regions in Tanzania (χ2 = 2.37; p = 0.795). The K76 allelic prevalence was between 85.7 and 93% in regions (χ2 = 7.88, p = 0.163). The CQ resistance recovery trends showed regional variability that may be caused by differences in malaria transmission intensity, but overall the trends converge as the susceptibility levels in all regions approach >90%.

Conclusions

CQ withdrawal in Tanzania has resulted into >90% recovery of susceptibility in ten years of withdrawal. These findings are in support of the search for CQ-based combination drugs as a possible future alternative to SP for IPTp in places where full recovery of CQ-susceptibility will be evident.

Antimalarial drug discovery - the path towards eradication

Malaria is a disease that still affects a significant proportion of the global human population. Whilst advances have been made in lowering the numbers of cases and deaths, it is clear that a strategy based solely on disease control year on year, without reducing transmission and ultimately eradicating the parasite, is unsustainable. This article highlights the current mainstay treatments alongside a selection of emerging new clinical molecules from the portfolio of Medicines for Malaria Venture (MMV) and our partners. In each case, the key highlights from each research phase are described to demonstrate how these new potential medicines were discovered. Given the increased focus of the community on eradicating the disease, the strategy for next generation combination medicines that will provide such potential is explained.

Creative solutions to extraordinary challenges in clinical trials: methodology of a phase III trial of azithromycin and chloroquine fixed-dose combination in pregnant women in Africa

Background

Malaria in pregnancy is one of the most common preventable causes of maternal and neonatal morbidity and mortality in sub-Saharan Africa. To prevent its adverse effects, such as maternal anaemia, placental parasitaemia and low birth weight (LBW) neonates, the World Health Organization recommends effective malaria case management, use of insecticide-treated bed nets and intermittent preventive therapy in pregnancy (IPTp). Sulphadoxine-pyrimethamine (SP) has been the standard for IPTp in several countries, but parasite resistance to SP is growing. Therefore, new IPTp therapies are urgently needed. One candidate being evaluated for IPTp is a fixed-dose combination of azithromycin and chloroquine (AZCQ). This paper describes the challenges and the innovative solutions implemented in designing and conducting a pivotal AZCQ-IPTp trial, sponsored by Pfizer Inc and co-funded by Pfizer Inc and the Medicines for Malaria Venture.

Methods

The AZCQ-IPTp pivotal trial is a multicentre, multicountry, phase III, open-label, randomized superiority study of AZCQ-IPTp versus SP-IPTp in pregnant women of sub-Saharan Africa. The trial was designed to meet stringent regulatory agency scientific advice and IPTp policy makers’ recommendations, and incorporates an innovative adaptive design to manage programme risk, maintain the operating characteristics of the study and optimize resources. The trial’s novel composite primary endpoint is the proportion of participants with a suboptimal pregnancy outcome (abortion [≤28 weeks], stillbirths [>28 weeks], premature [<37 weeks] deliveries, LBW [<2,500 g] live neonates, missing neonatal birth weight data or loss to follow-up). The study employs a prospective group sequential design with three unblinded analyses when 50%, 70% and 100% of participants achieve the primary endpoint; the study team will remain blinded to the analyses until after the completion of the study. The number of participants randomized will be adaptive, based on the blinded review of the observed pooled primary endpoint data across the two treatment arms, when approximately 1,000 participants complete the primary endpoint assessments.

Results

This study is ongoing and expected to complete in 2014.

Conclusion

This report describes the unique challenges and innovative solutions implemented in designing and conducting this pivotal AZCQ-IPTp trial, which may serve as a prototype for future IPTp and other studies involving similar conditions.

In vitro activity of Pheroid vesicles containing antibiotics against Plasmodium falciparum

The macrolide antibiotics, erythromycin and azithromycin, have been studied for their potential antimalarial activity, but only modest activity has been demonstrated. In this study, we investigated the enhancement of the efficacy of these antibiotics in combination with a patented lipid-based drug delivery system, Pheroid technology. A chloroquine resistant strain of Plasmodium falciparum (RSA11) was incubated with the formulations for a prolonged incubation time (144 h). Drug efficacy assays were conducted by analyzing the histidine-rich protein II levels of the parasites. The effects of azithromycin and erythromycin were compared with other antibiotics and standard antimalarial drugs. The poor water soluble nature of the drugs led to the formation of micro scale Pheroid vesicles with average particle sizes of 72.76±10.73 μm for azithromycin and 100.62±29.27 μm for erythromycin. The IC(50) values of erythromycin and azithromycin alone and entrapped in Pheroid vesicles decreased statistically significant (P0.05). Prolonged exposure was also statistically meaningful (P0.05), although it seems that exposure need not exceed 96 h. Pheroid vesicles also proved successful in decreasing the IC(50) values of doxycycline, tetracycline and triclosan. Pheroid vesicles containing antibiotics could prove successful as a malaria treatment option.

The global pipeline of new medicines for the control and elimination of malaria

Over the past decade, there has been a transformation in the portfolio of medicines to combat malaria. New fixed-dose artemisinin combination therapy is available, with four different types having received approval from Stringent Regulatory Authorities or the World Health Organization (WHO). However, there is still scope for improvement. The Malaria Eradication Research agenda identified several gaps in the current portfolio. Simpler regimens, such as a single-dose cure are needed, compared with the current three-day treatment. In addition, new medicines that prevent transmission and also relapse are needed, but with better safety profiles than current medicines. There is also a big opportunity for new medicines to prevent reinfection and to provide chemoprotection. This study reviews the global portfolio of new medicines in development against malaria, as of the summer of 2012. Cell-based phenotypic screening, and 'fast followers' of clinically validated classes, mean that there are now many new classes of molecules starting in clinical development, especially for the blood stages of malaria. There remain significant gaps for medicines blocking transmission, preventing relapse, and long-duration molecules for chemoprotection. The nascent pipeline of new medicines is significantly stronger than five years ago. However, there are still risks ahead in clinical development and sustainable funding of clinical studies is vital if this early promise is going to be delivered.

The effect of monthly sulfadoxine-pyrimethamine, alone or with azithromycin, on PCR-diagnosed malaria at delivery: a randomized controlled trial

BACKGROUND

New regimens for intermittent preventive treatment in pregnancy (IPTp) against malaria are needed as the effectiveness of the standard two-dose sulfadoxine-pyrimethamine (SP) regimen is under threat. Previous trials have shown that IPTp with monthly SP benefits HIV-positive primi- and secundigravidae, but there is no conclusive evidence of the possible benefits of this regimen to HIV-negative women, or to a population comprising of both HIV-positive and -negative women of different gravidities.

METHODS

This study analyzed 484 samples collected at delivery as part of a randomized, partially placebo controlled clinical trial, conducted in rural Malawi between 2003 and 2007. The study included pregnant women regardless of their gravidity or HIV-infection status. The participants received SP twice (controls), monthly SP, or monthly SP and two doses of azithromycin (AZI-SP). The main outcome was the prevalence of peripheral Plasmodium falciparum malaria at delivery diagnosed with a real-time polymerase chain reaction (PCR) assay.

FINDINGS

Overall prevalence of PCR-diagnosed peripheral P. falciparum malaria at delivery was 10.5%. Compared with the controls, participants in the monthly SP group had a risk ratio (95% CI) of 0.33 (0.17 to 0.64, P<0.001) and those in the AZI-SP group 0.23 (0.11 to 0.48, P<0.001) for malaria at delivery. When only HIV-negative participants were analyzed, the corresponding figures were 0.26 (0.12 to 0.57, P<0.001) for women in the monthly SP group, and 0.24 (0.11 to 0.53, P<0.001) for those in the AZI-SP group.

CONCLUSIONS

Our results suggest that increasing the frequency of SP administration during pregnancy improves the efficacy against malaria at delivery among HIV-negative women, as well as a population consisting of both HIV-positive and -negative pregnant women of all gravidities, in a setting of relatively low but holoendemic malaria transmission, frequent use of bed nets and high SP resistance.

Antimalarial activity of 9a-N substituted 15-membered azalides with improved in vitro and in vivo activity over azithromycin

Novel classes of antimalarial drugs are needed due to emerging drug resistance. Azithromycin, the first macrolide investigated for malaria treatment and prophylaxis, failed as a single agent and thus novel analogues were envisaged as the next generation with improved activity. We synthesized 42 new 9a-N substituted 15-membered azalides with amide and amine functionalities via simple and inexpensive chemical procedures using easily available building blocks. These compounds exhibited marked advances over azithromycin in vitro in terms of potency against Plasmodium falciparum (over 100-fold) and high selectivity for the parasite and were characterized by moderate oral bioavailability in vivo. Two amines and one amide derivative showed improved in vivo potency in comparison to azithromycin when tested in a mouse efficacy model. Results obtained for compound 6u, including improved in vitro potency, good pharmacokinetic parameters, and in vivo efficacy higher than azithromycin and comparable to chloroquine, warrant its further development for malaria treatment and prophylaxis.

Drug repositioning in the treatment of malaria and TB

The emergence and spread of drug resistance in the malaria parasite Plasmodium falciparum as well as multi- and extremely drug-resistant forms of Mycobacterium tuberculosis, the causative agent of TB, could hamper the control of these diseases. For instance, there are indications that the malaria parasite is becoming resistant to artemisinin derivatives, drugs that form the backbone of antimalarial combination therapy. Likewise, Mycobacterium tuberculosis strains that are multidrug-resistant or extremely drug-resistant to first- and second-line drugs have been associated with increased mortality. Thus, more than ever, new antimalarials and anti-TB drugs are needed. One of the strategies to discover new drugs is to reposition or repurpose existing drugs, thus reducing the cost and time of drug development. In this review, we discuss how this concept has been used in the past to discover antimalarial and anti-TB drugs, and summarize strategies that can lead to the discovery and development of new drugs.

Azithromycin in periodontal treatment: more than an antibiotic

Azithromycin is a macrolide antibiotic used extensively in medicine for the treatment of a wide range of infections such as upper respiratory tract infections, middle ear infections, sexually transmitted infections and trachoma. It is also effective against the most common periodontopathogens. The versatility of the macrolides extends beyond their antibiotic properties as a result of their well-documented immune-modulating/anti-inflammatory effects. Macrolides, including azithromycin, are therefore used to treat diseases not associated with bacteria, such as severe asthma, chronic obstructive pulmonary diseases and, more recently, cystic fibrosis. Azithromycin is concentrated in neutrophils, macrophages and particularly fibroblasts; all of these cells are central players in the pathogenesis of most periodontal diseases. This paper reviews the diverse properties of azithromycin and the clinical periodontal studies of its effects in both the treatment of periodontitis and in resolving drug-related gingival overgrowth. Evidence exists to support the use of a single course of azithromycin in the treatment of advanced periodontal diseases. Azithromycin could have a triple role in the treatment and resolution of periodontal diseases: suppressing periodontopathogens, anti-inflammatory activity and healing through persistence at low levels in macrophages and fibroblasts in periodontal tissues, even after a single course of three tablets. If future periodontal research confirms these properties, it could become a valuable host-modulator in periodontal treatment.

Drugs for malaria: something old, something new, something borrowed

Malaria was estimated to cause 800,000 deaths and 225 million cases worldwide in 2010. Worryingly, the first-line treatment currently relies on a single drug class called artemisinins, and there are signs that the parasite is becoming resistant to these drugs. The good news is that new technology has given us new approaches to drug discovery. New drugs generated this way are probably 10-15 years away from the clinic. Other antimalarials that may offer hope include those rehabilitated after not being used for some time, those that act as inhibitors of resistance mechanisms, those that limit infection while allowing protective immunity to develop, and those which are drugs borrowed from other disease treatments. All of these offer new hope of turning the tables on malaria. In parallel with the effort to develop vaccines that interrupt malaria transmission, drugs that target the parasite during transmission to the mosquito or during its pre-erythrocytic development in the liver, may allow us to terminate the parasite's spread.

Intermittent preventive treatment regimens for malaria in HIV-positive pregnant women

BACKGROUND

Intermittent preventive treatment is recommended for pregnant women living in malaria endemic countries due to benefits for both mother and baby. However, the impact may not be the same in HIV-positive pregnant women, as HIV infection impairs a woman's immunity.

OBJECTIVES

To compare intermittent preventive treatment regimens for malaria in HIV-positive pregnant women living in malaria-endemic areas.

SEARCH STRATEGY

In June 2011, we searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL, MEDLINE; EMBASE; LILACS, the metaRegister of Controlled Trials (mRCT), reference lists and conference abstracts. We also contacted researchers and organizations for information on relevant trials.

SELECTION CRITERIA

Randomized controlled trials comparing different intermittent preventive treatment regimens for preventing malaria in HIV-positive pregnant women in malaria-endemic areas.

DATA COLLECTION AND ANALYSIS

Two authors extracted data and assessed risk bias. Dichotomous variables were combined using risk ratios (RR) and mean differences (MD) for continuous outcomes, both with 95% confidence intervals (CI).

MAIN RESULTS

Two randomized trials with 722 HIV-positive pregnant women were included, comparing monthly regimens of sulfadoxine-pyrimethamine (SP) to the standard 2-dose regimen in the second and third trimesters. There were no statistically significant differences between monthly SP and 2-dose SP in rates of maternal anaemia, low birth weight, and neonatal mortality. In primigravidae and secondigravidiae, the monthly regimen was associated with less placental parasitaemia (RR 0.38, 95% CI 0.21 to 0.70, two trials) and less peripheral parasitaemia (RR 0.25, 95% CI 0.14 to 0.43, two trials), but no effect was demonstrated in multigravid women. Babies born to primigravidae and secundigravida women on monthly SP had a higher mean birth weight (weighted mean difference (WMD) 130 g; 95% CI 120 g to 150 g, two trials) than babies born to mothers on 2-dose SP. Multigravidae women treated with monthly SP had significant higher haemoglobin level than those treated with treated 2 dose SP (WMD 0.21 g/dL, 95% CI 0.15 g/dL to 0.27 g/dL, one trial). There were no trials that assessed other treatment regimens for intermittent preventive treatment in HIV-positive pregnant women.

AUTHORS' CONCLUSIONS

Three or more doses of SP is superior to the standard two doses in HIV-positive pregnant women. However, since SP cannot be administered concurrently with co-trimoxazole - a drug often recommended for infection prophylaxis in HIV-positive pregnant women, new drugs and research is needed to address needs of HIV-positive pregnant women.

Identifying apicoplast-targeting antimalarials using high-throughput compatible approaches

Malarial parasites have evolved resistance to all previously used therapies, and recent evidence suggests emerging resistance to the first-line artemisinins. To identify antimalarials with novel mechanisms of action, we have developed a high-throughput screen targeting the apicoplast organelle of Plasmodium falciparum. Antibiotics known to interfere with this organelle, such as azithromycin, exhibit an unusual phenotype whereby the progeny of drug-treated parasites die. Our screen exploits this phenomenon by assaying for "delayed death" compounds that exhibit a higher potency after two cycles of intraerythrocytic development compared to one. We report a primary assay employing parasites with an integrated copy of a firefly luciferase reporter gene and a secondary flow cytometry-based assay using a nucleic acid stain paired with a mitochondrial vital dye. Screening of the U.S. National Institutes of Health Clinical Collection identified known and novel antimalarials including kitasamycin. This inexpensive macrolide, used for agricultural applications, exhibited an in vitro IC(50) in the 50 nM range, comparable to the 30 nM activity of our control drug, azithromycin. Imaging and pharmacologic studies confirmed kitasamycin action against the apicoplast, and in vivo activity was observed in a murine malaria model. These assays provide the foundation for high-throughput campaigns to identify novel chemotypes for combination therapies to treat multidrug-resistant malaria.

Newer approaches to malaria control

Malaria is the third leading cause of death due to infectious diseases affecting around 243 million people, causing 863,000 deaths each year, and is a major public health problem. Most of the malarial deaths occur in children below 5 years and is a major contributor of under-five mortality. As a result of environmental and climatic changes, there is a change in vector population and distribution, leading to resurgence of malaria at numerous foci. Resistance to antimalarials is a major challenge to malaria control and there are new drug developments, new approaches to treatment strategies, combination therapy to overcome resistance and progress in vaccine development. Now, artemisinin-based combination therapy is the first-line therapy as the malarial parasite has developed resistance to other antimalarials. Reports of artemisinin resistance are appearing and identification of new drug targets gains utmost importance. As there is a shift from malaria control to malaria eradication, more research is focused on malaria vaccine development. A malaria vaccine, RTS,S, is in phase III of development and may become the first successful one. Due to resistance to insecticides and lack of environmental sanitation, the conventional methods of vector control are turning out to be futile. To overcome this, novel strategies like sterile insect technique and transgenic mosquitoes are pursued for effective vector control. As a result of the global organizations stepping up their efforts with continued research, eradication of malaria can turn out to be a reality.

Chemoprophylaxis in malaria: drugs, evidence of efficacy and costs

This review concentrates on different aspects of malaria chemoprophylaxis, namely drug combinations, resistance, impact of malaria prevention in pregnancy and cost effectiveness. A MEDLINE search was performed for all articles with the key word 'Malaria' in the title field and 'Prophylaxis' in any field. The search was restricted to articles published in English within the last decade (1999-2009). Data sources included review articles published in core clinical journals, cohort studies, interventional studies, case control studies and cross sectional analyses. The mechanism of action, trial evidence of efficacy, side effects and geographical distribution of resistance is discussed for each prophylactic drug regimen. Impact of prophylaxis in pregnancy and the cost considerations are discussed under two separate sub topics.

Intermittent preventive treatment of malaria in pregnancy: at the crossroads of public health policy

The intermittent preventive treatment of malaria in pregnancy (IPTp) with sulphadoxine-pyrimethamine (SP) has been a key component of the focused antenatal care package for nearly a decade, reducing the burden of low birthweight attributable to malaria in sub-Saharan Africa. However, SP has lost parasite sensitivity in many sub-Saharan locations during the same period, rendering its beneficial effect in IPTp debatable. Malaria transmission has also declined in some epidemiological settings. There is no evidence to suggest, however, that the risk of malaria in pregnancy without preventive measures has declined in the same locations. Thus, the urgency to identify efficacious drugs and/or new strategies to prevent malaria in pregnancy remains as great as ever. We summarise the results of recently published SP-IPTp studies from areas of high drug resistance and/or low malaria transmission. We also present the evidence for mefloquine and azithromycin-based combinations (ABCs), two leading drug options to replace SP in IPTp. We discuss optimal dosing for ABCs and their likely protection against several sexually transmitted and reproductive tract infections. We also summarise data from a diagnosis-based alternative to IPTp known as the intermittent screening and treatment (IST) for malaria. Clinical and operational research is urgently needed to compare birth outcomes achieved by IPTp with ABCs vs. IST using an efficacious antimalarial therapy.

In vivo and in vitro antimalarial properties of azithromycin-chloroquine combinations that include the resistance reversal agent amlodipine

Evidence of emerging Plasmodium falciparum resistance to artemisinin-based combination therapies, documented in western Cambodia, underscores the continuing need to identify new antimalarial combinations. Given recent reports of the resurgence of chloroquine-sensitive P. falciparum parasites in Malawi, after the enforced and prolonged withdrawal of this drug, and indications of a possible synergistic interaction with the macrolide azithromycin, we sought to further characterize chloroquine-azithromycin combinations for their in vitro and in vivo antimalarial properties. In vitro 96-h susceptibility testing of chloroquine-azithromycin combinations showed mostly additive interactions against freshly cultured P. falciparum field isolates obtained from Mali. Some evidence of synergy, however, was apparent at the fractional 90% inhibitory concentration level. Additional in vitro testing highlighted the resistance reversal properties of amlodipine for both chloroquine and quinine. In vivo experiments, using the Peters 4-day suppressive test in a P. yoelii mouse model, revealed up to 99.9% suppression of parasitemia following treatment with chloroquine-azithromycin plus the R enantiomer of amlodipine. This enantiomer was chosen because it does not manifest the cardiac toxicities observed with the racemic mixture. Pharmacokinetic/pharmacodynamic analyses in this rodent model and subsequent extrapolation to a 65-kg adult led to the estimation that 1.8 g daily of R-amlodipine would be required to achieve similar efficacy in humans, for whom this is likely an unsafe dose. While these data discount amlodipine as an additional partner for chloroquine-based combination therapy, our studies continue to support azithromycin as a safe and effective addition to antimalarial combination therapies.

Azithromycin for treating uncomplicated malaria

BACKGROUND

To prevent the development of drug resistance, the World Health Organization (WHO) recommends treating malaria with combination therapy. Azithromycin, an antibiotic with antimalarial properties, may be a useful additional option for antimalarial therapy.

OBJECTIVES

To compare the use of azithromycin alone or in combination with other antimalarial drugs with the use of alternative antimalarial drugs for treating uncomplicated malaria caused by Plasmodium falciparum or Plasmodium vivax.

SEARCH STRATEGY

We searched the Cochrane Infectious Diseases Group Specialized Register (August 2010); CENTRAL (The Cochrane Library Issue 3, 2010); MEDLINE (1966 to August 2010); EMBASE (1974 to August 2010); LILACS (August 2010); the metaRegister of Controlled Trials (mRCT, August 2010); conference proceedings; and reference lists. We also contacted researchers and a pharmaceutical company.

SELECTION CRITERIA

Randomized controlled trials comparing azithromycin, either alone or combined with another antimalarial drug, with another antimalarial drug used alone or combined with another antimalarial drug, or with azithromycin combined with another antimalarial drug if different combinations or doses of azithromycin were used. The primary outcome was treatment failure by day 28, defined as parasitological or clinical evidence of treatment failure between the start of treatment and day 28. Secondary outcomes included treatment failure by day 28 corrected for new infections confirmed by polymerase chain reaction (PCR), fever and parasite clearance time, and adverse events.

DATA COLLECTION AND ANALYSIS

Two people independently applied the inclusion criteria, extracted data and assessed methodological quality. We used risk ratio (RR) and 95% confidence intervals (CI).

MAIN RESULTS

Fifteen trials met the inclusion criteria (2284 participants, 69% males, 16% children). They were conducted in disparate malaria endemic areas, with the earlier studies conducted in Thailand (five) and India (two), and the more recent studies (eight) spread across three continents (South America, Africa, Asia). The 15 studies involved 41 treatment arms, 12 different drugs, and 28 different treatment regimens. Two studies examined P. vivax.Three-day azithromycin (AZ) monotherapy did not perform well for P. vivax or P. falciparum (Thailand: P. vivax failure rate 0.5 g daily, 56%, 95% CI 31 to 78. India: P. vivax failure rate 1 g daily,12%, 95% CI 7 to 21; P. falciparum failure rate 1 g daily, 64%, 95% CI 36 to 86.) A 1 g azithromycin and 0.6 g chloroquine combination daily for three days for uncomplicated P. falciparum infections was associated with increased treatment failure in India and Indonesia compared with the combination of sulphadoxine-pyrimethamine and chloroquine (pooled RR 2.66, 95% CI 1.25 to 5.67), and compared with the combination atovaquone-proguanil in a multicentre trial in Columbia and Surinam (RR 24.72, 95% CI 6.16 to 99.20). No increased risk of treatment failure was seen in two studies in Africa with mefloquine as the comparator drug (pooled RR 2.02, 95% CI 0.51 to 7.96, P = 0.3); the pooled RR for PCR-corrected data for the combination versus mefloquine was 1.01, 95% CI 0.18 to 5.84 (P = 1.0). An increased treatment failure risk was seen when comparing azithromycin in a dose of 1.2 to 1.5 mg in combination with artesunate (200 mg per day for three days) with artemether-lumefantrine (pooled RR 3.08, 95% CI 2.09 to 4.55; PCR-corrected pooled RR 3.63, 95% CI 2.02 to 6.52).Serious adverse events and treatment discontinuation were similar across treatment arms. More adverse events were reported when comparing the 1 g azithromycin/ 0.6 g chloroquine combination with mefloquine (pooled RR 1.20, 95% CI 1.06 to 1.36) or atovaquone-proguanil (RR 1.41, 95% CI 1.09 to1.83).

AUTHORS' CONCLUSIONS

Currently, there is no evidence for the superiority or equivalence of azithromycin monotherapy or combination therapy for the treatment of P. falciparum or P. vivax compared with other antimalarials or with the current first-line antimalarial combinations. The available evidence suggests that azithromycin is a weak antimalarial with some appealing safety characteristics. Unless the ongoing dose, formulation and product optimisation process results in a universally efficacious product, or a specific niche application is identified that is complementary to the current scala of more efficacious antimalarial combinations, azithromycin's future for the treatment of malaria does not look promising.

Anti-malarial drugs and the prevention of malaria in the population of malaria endemic areas

Anti-malarial drugs can make a significant contribution to the control of malaria in endemic areas when used for prevention as well as for treatment. Chemoprophylaxis is effective in preventing deaths and morbidity from malaria, but it is difficult to sustain for prolonged periods, may interfere with the development of naturally acquired immunity and will facilitate the emergence and spread of drug resistant strains if applied to a whole community. However, chemoprophylaxis targeted to groups at high risk, such as pregnant women, or to periods of the year when the risk from malaria is greatest, can be an effective and cost effective malaria control tool and has fewer drawbacks. Intermittent preventive treatment, which involves administration of anti-malarials at fixed time points, usually when a subject is already in contact with the health services, for example attendance at an antenatal or vaccination clinic, is less demanding of resources than chemoprophylaxis and is now recommended for the prevention of malaria in pregnant women and infants resident in areas with medium or high levels of malaria transmission. Intermittent preventive treatment in older children, probably equivalent to targeted chemoprophylaxis, is also highly effective but requires the establishment of a specific delivery system. Recent studies have shown that community volunteers can effectively fill this role. Mass drug administration probably has little role to play in control of mortality and morbidity from malaria but may have an important role in the final stages of an elimination campaign.

Natural immunization against malaria: causal prophylaxis with antibiotics

Malaria remains the most prevalent vector-borne infectious disease and has the highest rates of fatality. Current antimalarial drug strategies cure malaria or prevent infections but lack a sustained public health impact because they fail to expedite the acquisition of protective immunity. We show that antibiotic administration during transmission of the parasite Plasmodium berghei results in swift acquisition of long-lived, life cycle-specific protection against reinfection with live sporozoites in mice. Antibiotic treatment specifically inhibits the biogenesis and inheritance of the apicoplast in Plasmodium liver stages, resulting in continued liver-stage maturation but subsequent failure to establish blood-stage infection. Exponential expansion of these attenuated liver-stage merozoites from a single sporozoite induces potent immune protection against malaria. If confirmed in residents of malaria-endemic areas, periodic prophylaxis with safe and affordable antibiotics may offer a powerful shortcut toward a needle-free surrogate malaria immunization strategy.

Anti-bacterial activity of intermittent preventive treatment of malaria in pregnancy: comparative in vitro study of sulphadoxine-pyrimethamine, mefloquine, and azithromycin

BACKGROUND

Intermittent preventive treatment of malaria with sulphadoxine-pyrimethamine (SP) is recommended for the prevention of malaria in pregnancy in sub-Saharan Africa. Increasing drug resistance necessitates the urgent evaluation of alternative drugs. Currently, the most promising candidates in clinical development are mefloquine and azithromycin. Besides the anti-malarial activity, SP is also a potent antibiotic and incurs significant anti-microbial activity when given as IPTp - though systematic clinical evaluation of this action is still lacking.

METHODS

In this study, the intrinsic anti-bacterial activity of mefloquine and azithromycin was assessed in comparison to sulphadoxine-pyrimethamine against bacterial pathogens with clinical importance in pregnancy in a standard microdilution assay.

RESULTS

SP was highly active against Staphylococcus aureus and Streptococcus pneumoniae. All tested Gram-positive bacteria, except Enterococcus faecalis, were sensitive to azithromycin. Additionally, azithromycin was active against Neisseria gonorrhoeae. Mefloquine showed good activity against pneumococci but lower in vitro action against all other tested pathogens.

CONCLUSION

These data indicate important differences in the spectrum of anti-bacterial activity for the evaluated anti-malarial drugs. Given the large scale use of IPTp in Africa, the need for prospective clinical trials evaluating the impact of antibiotic activity of anti-malarials on maternal and foetal health and on the risk of promoting specific drug resistance of bacterial pathogens is discussed.