Efficacy of rectal artesunate compared with parenteral quinine in initial treatment of moderately severe malaria in African children and adults: a randomised study

Artesunate Inhibits Neointimal Hyperplasia by Promoting IRF4 Associated Macrophage Polarization

Vascular restenosis is a serious clinical issue initiated and aggravated by macrophage inflammation, with no effective treatments available, in cardiovascular and autoimmune diseases. However, the untapped mechanisms and new targets that can regulate macrophage polarization and vascular restenosis remain elusive. The research identifies interferon regulatory factor 4 (IRF4) expression as crucial in macrophage polarization during arterial restenosis. Myeloid-specific Irf4 deficiency and overexpression experiments showed that IRF4 promoted M2 macrophage polarization, inhibited M1 macrophage transitions, and disrupted the interaction between macrophages and vascular smooth muscle cells to reduce neointimal hyperplasia by directly upregulating krüppel like factor 4 (KLF4) expression. Artesunate, an FDA-approved drug, is screened as a potent activator of IRF4 expression in M2 polarization, and its treatment attenuated arterial restenosis in rodents and non-human primates. The findings reveal a significant protective role of IRF4 in the development of neointimal hyperplasia by regulating macrophage polarization, and artesunate may be proposed as a novel therapy for vascular restenosis.

Artesunate Inhibits Metastatic Potential in Cisplatin-Resistant Bladder Cancer Cells by Altering Integrins

The survival of patients with locally advanced and metastatic bladder cancer (BCa) is persistently low. Hence, new treatment options are urgently needed. Artesunate (ART) a derivative of artemisinin, used in Traditional Chinese Medicine, shows anti-tumor activity extending over a broad spectrum of human cancers. As we have previously shown, ART inhibits growth in cisplatin-sensitive (parental) and cisplatin-resistant BCa cells. However, how ART acts on the metastatic potential of BCa remained unclear. To clarify, we applied ART to parental and cisplatin-resistant RT4, RT112, T24, and TCCSup BCa cell lines. We examined tumor cell adhesion to vascular endothelium and immobilized collagen and evaluated chemotactic activity, migration, and invasive activity of the BCa cells. Adhesion receptors, integrin α and β subtypes, integrin-linked kinase (ILK), and focal adhesion kinase (FAK) were investigated. The functional relevance of integrin expression altered by ART was determined by blocking studies. ART significantly reduced tumor cell adhesion to vascular endothelium and immobilized collagen in parental as well as in cisplatin-resistant BCa cells. Depending on cell type, ART suppressed tumor cell motility and diminished integrin expression (surface and total). Functional blocking of integrins altered by ART reduced cell adhesion and invasion of the BCa cells. Thus, the metastatic potential of parental and cisplatin-resistant BCa cells was significantly inhibited by ART, making it a promising treatment option for patients with advanced or therapy-resistant BCa.

Defining the next generation of severe malaria treatment: a target product profile

BACKGROUND

Severe malaria is a life-threatening infection, particularly affecting children under the age of 5 years in Africa. Current treatment with parenteral artemisinin derivatives is highly efficacious. However, artemisinin partial resistance is widespread in Southeast Asia, resulting in delayed parasite clearance after therapy, and has emerged independently in South America, Oceania, and Africa. Hence, new treatments for severe malaria are needed, and it is prudent to define their characteristics now. This manuscript focuses on the target product profile (TPP) for new treatments for severe malaria. It also highlights preparedness when considering ways of protecting the utility of artemisinin-based therapies.

TARGET PRODUCT PROFILE

Severe malaria treatments must be highly potent, with rapid onset of antiparasitic activity to clear the infection as quickly as possible to prevent complications. They should also have a low potential for drug resistance selection, given the high parasite burden in patients with severe malaria. Combination therapies are needed to deter resistance selection and dissemination. Partner drugs which are approved for uncomplicated malaria treatment would provide the most rapid development pathway for combinations, though new candidate molecules should be considered. Artemisinin combination approaches to severe malaria would extend the lifespan of current therapy, but ideally, completely novel, non-artemisinin-based combination therapies for severe malaria should be developed. These should be advanced to at least phase 2 clinical trials, enabling rapid progression to patient use should current treatment fail clinically. New drug combinations for severe malaria should be available as injectable formulations for rapid and effective treatment, or as rectal formulations for pre-referral intervention in resource-limited settings.

CONCLUSION

Defining the TPP is a key step to align responses across the community to proactively address the potential for clinical failure of artesunate in severe malaria. In the shorter term, artemisinin-based combination therapies should be developed using approved or novel drugs. In the longer term, novel combination treatments should be pursued. Thus, this TPP aims to direct efforts to preserve the efficacy of existing treatments while improving care and outcomes for individuals affected by this life-threatening disease.

The wrongful indictment of pre-referral rectal artesunate further delays the roll-out of this lifesaving drug

Administering rectal artesunate suppositories to patients with severe malaria before they receive parenteral and oral consolidation therapy was found to reduce mortality more than a decade ago. The roll-out of rectal artesunate could combat the current global increase in malaria deaths. Instead, on Jan 27, 2022, WHO recommended a moratorium on the deployment of rectal artesunate and in doing so stopped the roll-out of a lifesaving intervention. This decision was based mainly on the results from an observational study that is part of a larger project being conducted in Nigeria, Uganda, and DR Congo. The Community Access to Rectal Artesunate for Malaria (CARAMAL) project was not set up to provide patient transport to referral health-care centres for parenteral artesunate administration or logistic support to assure the availability of parenteral and oral antimalarial consolidation therapy. Using a before-after study design, which is known to be prone to bias, the study found that case fatality rates of severe malaria increased instead of decreased after the roll-out of rectal artesunate. However, the study and its analysis have methodological flaws that provide an alternative explanation for study findings. Instead of further delaying the roll-out of rectal artesunate, there is an urgent need for a concerted effort to provide rectal artesunate as originally intended, where and when it is needed.

Guardians and research staff experiences and views about the consent process in hospital-based paediatric research studies in urban Malawi: A qualitative study

BACKGROUND

Obtaining consent has become a standard way of respecting the patient's rights and autonomy in clinical research. Ethical guidelines recommend that the child's parent/s or authorised legal guardian provides informed consent for their child's participation. However, obtaining informed consent in paediatric research is challenging. Parents become vulnerable because of stress related to their child's illness. Understanding the views held by guardians and researchers about the consent process in Malawi, where there are limitations in health care access and research literacy will assist in developing appropriate consent guidelines.

METHODS

We conducted 20 in-depth interviews with guardians of children and research staff who had participated in paediatric clinical trial and observational studies in acute and non-acute settings in the Southern Region of Malawi. Interviews were audio-recorded, transcribed verbatim, and thematically analysed. Interviews were compared across studies and settings to identify differences and similarities in participants' views about informed consent processes. Data analysis was facilitated by NVIVO 11 software.

RESULTS

All participants across study types and settings reported that they associated participating in research with therapeutic benefits. Substantial differences were noted in the decision-making process across study settings. Guardians from acute studies felt that the role of their spouses was neglected during consenting, while staff reported that they had problems obtaining consent from guardians when their partners were not present. Across all study types and settings, research staff reported that they emphasised the benefits more than the risks of the study to participants, due to pressure to recruit. Participants from non-acute settings were more likely to recall information shared during the consent process than participants in the acute setting.

CONCLUSION

The health care context, culture and research process influenced participants' understanding of study information across study types and settings. We advise research managers or principal investigators to define minimum requirements that would not compromise the consent process and conduct study specific training for staff. The use of one size fits all consent process may not be ideal. More guidance is needed on how these differences can be incorporated during the consent process to improve understanding and delivery of consent. Trial registration Not applicable.

Effectiveness of rectal artesunate as pre-referral treatment for severe malaria in children under 5 years of age: a multi-country observational study

BACKGROUND

To prevent child deaths from severe malaria, early parenteral treatment is essential. Yet, in remote rural areas, accessing facilities offering parenteral antimalarials may be difficult. A randomised controlled trial found pre-referral treatment with rectal artesunate (RAS) to reduce deaths and disability in children who arrived at a referral facility with delay. This study examined the effectiveness of pre-referral RAS treatment implemented through routine procedures of established community-based health care systems.

METHODS

An observational study accompanied the roll-out of RAS in the Democratic Republic of the Congo (DRC), Nigeria and Uganda. Children <5 years of age presenting to a community-based health provider with a positive malaria test and signs of severe malaria were enrolled and followed up during admission and after 28 days to assess their health status and treatment history. The primary outcome was death; covariates of interest included RAS use, referral completion, and post-referral treatment.

RESULTS

Post-roll-out, RAS was administered to 88% of patients in DRC, 52% in Nigeria, and 70% in Uganda. The overall case fatality rate (CFR) was 6.7% (135/2011) in DRC, 11.7% (69/589) in Nigeria, and 0.5% (19/3686) in Uganda; 13.8% (865/6286) of patients were sick on day 28. The CFR was higher after RAS roll-out in Nigeria (16.1 vs. 4.2%) and stable in DRC (6.7 vs. 6.6%) and Uganda (0.7 vs. 0.3%). In DRC and Nigeria, children receiving RAS were more likely to die than those not receiving RAS (aOR=3.06, 95% CI 1.35-6.92 and aOR=2.16, 95% CI 1.11-4.21, respectively). Only in Uganda, RAS users were less likely to be dead or sick at follow-up (aOR=0.60, 95% CI 0.45-0.79). Post-referral parenteral antimalarials plus oral artemisinin-based combination therapy (ACT), a proxy for appropriate post-referral treatment, was protective. However, in referral health facilities, ACT was not consistently administered after parenteral treatment (DRC 68.4%, Nigeria 0%, Uganda 70.9%).

CONCLUSIONS

Implemented at scale to the recommended target group, pre-referral RAS had no beneficial effect on child survival in three highly malaria-endemic settings. RAS is unlikely to reduce malaria deaths unless health system issues such as referral and quality of care at all levels are addressed.

TRIAL REGISTRATION

The study is registered on ClinicalTrials.gov : NCT03568344.

Community access to rectal artesunate for malaria (CARAMAL): A large-scale observational implementation study in the Democratic Republic of the Congo, Nigeria and Uganda

The key to reducing malaria deaths in highly endemic areas is prompt access to quality case management. Given that many severe cases occur at peripheral level, rectal artesunate (RAS) in the form of suppositories was developed in the 1990s, allowing for rapid initiation of life-saving antimalarial treatment before referral to a health facility with full case management capabilities. One randomized controlled trial published in 2009 showed a protective effect of RAS pre-referral treatment against overall mortality of 26%, but with significant differences according to study sites and length of referral. Two important issues remained unaddressed: (1) whether the mortality impact of RAS observed under controlled trial conditions could be replicated under real-world circumstances; and (2) clear operational guidance for the wide-scale implementation of RAS, including essential health system determinants for optimal impact. From 2018 to 2020, the Community Access to Rectal Artesunate for Malaria (CARAMAL) project was conducted as a large-scale observational implementation study in the Democratic Republic of the Congo (DRC), Nigeria, and Uganda (registered on ClinicalTrials.gov as NCT03568344). CARAMAL aimed to provide high-quality field evidence on the two issues above, in three remote settings with high malaria endemicity. A number of complementary study components were implemented. The core of the CARAMAL study was the Patient Surveillance System (PSS), which allowed tracking of cases of severe febrile illness from first contact at the periphery to a referral health facility, and then on to a Day 28 visit at the home of the patient. Community and provider cross-sectional surveys complemented the PSS. Here we describe in some detail RAS implementation, as well as the key CARAMAL study components and basic implementation experience. This manuscript does not intend to present key study results, but provides an extensive reference document for the companion papers describing the impact, referral process, post-referral treatment and costing of the RAS intervention.

Efficacy of Topically Administered Dihydroartemisinin in Treating Papillomavirus-Induced Anogenital Dysplasia in Preclinical Mouse Models

The artemisinin family of compounds is cytopathic in certain cancer cell lines that are positive for human papillomaviruses (HPV) and can potentially drive the regression of dysplastic lesions. We evaluated the efficacy of topical dihydroartemisinin (DHA) on cervical dysplasia and anal dysplasia in two papillomavirus mouse models: K14E6/E7 transgenic mice, which express HPV16 oncogenes; and immunodeficient NOD/SCID gamma (NSG) mice infected with Mus musculus papillomavirus (MmuPV1). Mice started treatment with DHA at 25 weeks of age (K14E6/E7) or 20 weeks post infection (MmuPV1-infected), when the majority of mice are known to have papillomavirus-induced low- to high-grade dysplasia. Mice were treated with or without topical DHA at the cervix or anus and with or without topical treatment with the chemical carcinogen 7,12 dimethylbenz(a)anthracene (DMBA) at the anus of in transgenic mice to induce neoplastic progression. Mice were monitored for overt tumor growth, and tissue was harvested after 20 weeks of treatment and scored for severity of histological disease. For MmuPV1-infected mice, anogenital lavages were taken to monitor for viral clearance. Tissues were also evaluated for viral gene expression at the RNA and/or protein levels. Treatment with topical DHA did not reduce dysplasia in the anogenital tract in either papillomavirus-induced mouse model and did not prevent progression to anal cancer in the DMBA-treated K14E6/E7 mice.

Prereferral rectal artesunate and referral completion among children with suspected severe malaria in the Democratic Republic of the Congo, Nigeria and Uganda

INTRODUCTION

Children who receive prereferral rectal artesunate (RAS) require urgent referral to a health facility where appropriate treatment for severe malaria can be provided. However, the rapid improvement of a child's condition after RAS administration may influence a caregiver's decision to follow this recommendation. Currently, the evidence on the effect of RAS on referral completion is limited.

METHODS

An observational study accompanied the roll-out of RAS in three malaria endemic settings in the Democratic Republic of the Congo (DRC), Nigeria and Uganda. Community health workers and primary health centres enrolled children under 5 years with suspected severe malaria before and after the roll-out of RAS. All children were followed up 28 days after enrolment to assess their treatment-seeking pathways.

RESULTS

Referral completion was 67% (1408/2104) in DRC, 48% (287/600) in Nigeria and 58% (2170/3745) in Uganda. In DRC and Uganda, RAS users were less likely to complete referral than RAS non-users in the pre-roll-out phase (adjusted OR (aOR)=0.48, 95% CI 0.30 to 0.77 and aOR=0.72, 95% CI 0.58 to 0.88, respectively). Among children seeking care from a primary health centre in Nigeria, RAS users were less likely to complete referral compared with RAS non-users in the post-roll-out phase (aOR=0.18, 95% CI 0.05 to 0.71). In Uganda, among children who completed referral, RAS users were significantly more likely to complete referral on time than RAS non-users enrolled in the pre-roll-out phase (aOR=1.81, 95% CI 1.17 to 2.79).

CONCLUSIONS

The findings of this study raise legitimate concerns that the roll-out of RAS may lead to lower referral completion in children who were administered prereferral RAS. To ensure that community-based programmes are effectively implemented, barriers to referral completion need to be addressed at all levels. Alternative effective treatment options should be provided to children unable to complete referral.

TRIAL REGISTRSTION NUMBER

NCT03568344; ClinicalTrials.gov.

Anti-parasitic drugs modulate the non-selective channels formed by connexins or pannexins

The proteins connexins, innexins, and pannexins are the subunits of non-selective channels present in the cell membrane in vertebrates (connexins and pannexins) and invertebrates (innexins). These channels allow the transfer of ions and molecules across the cell membrane or, and in many cases, between the cytoplasm of neighboring cells. These channels participate in various physiological processes, particularly under pathophysiological conditions, such as bacterial, viral, and parasitic infections. Interestingly, some anti-parasitic drugs also block connexin- or pannexin-formed channels. Their effects on host channels permeable to molecules that favor parasitic infection can further explain the anti-parasitic effects of some of these compounds. In this review, the effects of drugs with known anti-parasitic activity that modulate non-selective channels formed by connexins or pannexins are discussed. Previous studies that have reported the presence of these proteins in worms, ectoparasites, and protozoa that cause parasitic infections have also been reviewed.

Pharmacokinetic Study of Rectal Artesunate in Children with Severe Malaria in Africa

When severe malaria is suspected in children, the WHO recommends pretreatment with a single rectal dose of artesunate before referral to an appropriate facility. This was an individually randomized, open-label, 2-arm, crossover clinical trial in 82 Congolese children with severe falciparum malaria to characterize the pharmacokinetics of rectal artesunate. At admission, children received a single dose of rectal artesunate (10 mg/kg of body weight) followed 12 h later by intravenous artesunate (2.4 mg/kg) or the reverse order. All children also received standard doses of intravenous quinine. Artesunate and dihydroartemisinin were measured at 11 fixed intervals, following 0- and 12-h drug administrations. Clinical, laboratory, and parasitological parameters were measured. After rectal artesunate, artesunate and dihydroartemisinin showed large interindividual variability (peak concentrations of dihydroartemisinin ranged from 5.63 to 8,090 nM). The majority of patients, however, reached previously suggested in vivo IC50 and IC90 values (98.7% and 92.5%, respectively) of combined concentrations of artesunate and dihydroartemisinin between 15 and 30 min after drug administration. The median (interquartile range [IQR]) time above IC50 and IC90 was 5.68 h (2.90 to 6.08) and 2.74 h (1.52 to 3.75), respectively. The absolute rectal bioavailability (IQR) was 25.6% (11.7 to 54.5) for artesunate and 19.8% (10.3 to 35.3) for dihydroartemisinin. The initial 12-h parasite reduction ratio was comparable between rectal and intravenous artesunate: median (IQR), 84.3% (50.0 to 95.4) versus 69.2% (45.7 to 93.6), respectively (P = 0.49). Despite large interindividual variability, rectal artesunate can initiate and sustain rapid parasiticidal activity in most children with severe falciparum malaria while they are transferred to a facility where parenteral artesunate is available. (This study has been registered at ClinicalTrials.gov under identifier NCT02492178.).

The preclinical discovery and development of rectal artesunate for the treatment of malaria in young children: a review of the evidence

INTRODUCTION

Plasmodium falciparum, the deadliest malaria parasite, kills hundreds of thousands of people per year, mainly young children in Sub-Saharan Africa. Artesunate suppositories are recommended as pre-referral malaria treatment in remote endemic areas for severely ill children to prevent progression of the disease and to provide extra time for patients until the definitive severe malaria treatment can be administered.

AREAS COVERED

The authors provide an overview of the discovery of artesunate and its different formulations focusing on rectal administration, summarizing key studies concerning the pharmacokinetic, pharmacodynamic, safety, tolerability and efficacy of rectal artesunate leading to WHO recommendation and market authorization in Africa. In addition, studies on acceptance and adherence to rectal artesunate administration and the post-launch status are also covered.

EXPERT OPINION

Efforts by ministries of health in malaria endemic countries together with international health organizations should establish and enforce guidelines to ensure the correct use of artesunate suppositories only as pre-referral medication in presumed severe malaria cases to minimize the risk of abuse as a monotherapy for treatment of uncomplicated malaria. The priority is to not jeopardize the efficacy of artesunate and to prevent resistance development against this valuable drug class in Africa.

Enhancing the antimalarial activity of artesunate

The global challenge to the treatment of malaria is mainly the occurrence of resistance of malaria parasites to conventionally used antimalarials. Artesunate, a semisynthetic artemisinin compound, and other artemisinin derivatives are currently used in combination with selected active antimalarial drugs in order to prevent or delay the emergence of resistance to artemisinin derivatives. Several methods, such as preparation of hybrid compounds, combination therapy, chemical modification and the use of synthetic materials to enhance solubility and delivery of artesunate, have been employed over the years to improve the antimalarial activity of artesunate. Each of these methods has advantages it bestows on the efficacy of artesunate. This review discussed the various methods employed in enhancing the antimalarial activity of artesunate and delaying the emergence of resistance of parasite to it.

Barriers and Facilitators to Obtaining Informed Consent in a Critical Care Pediatric Research Ward in Southern Malawi

Informed consent is an ethical requirement in clinical research. Obtaining informed consent is challenging in resource-constrained settings. We report results of a formative qualitative study that examined factors that facilitate and hinder informed consent for clinical research among critically ill children in Malawi. We argue that truly informed consent in a pediatric intensive care unit (PICU) is challenged by parental distress, time constraints when balancing care for critically ill patients with research-related tasks, and social hierarchies and community mistrust toward certain research procedures. We interviewed health care providers and parents of children attending a critical care unit to identify potential challenges and solicit strategies for addressing them. Providers and caregivers suggested practical solutions to enhance research participant understanding of clinical trial research, including the use of visual materials, community engagement strategies, and using patients as advocates in promoting understanding of research procedures.

An evaluation of rectal artesunate for the pre-hospital management of severe malaria

INTRODUCTION

Severe falciparum malaria stills accounts for around half a million childhood deaths per year in sub-Saharan Africa. Prompt treatment of sick children close to home starting with artesunate given rectally by appropriately trained people can be lifesaving.

AREAS COVERED

Rectal artesunate (RAS) has been developed for use in the WHO approved strategy of pre-referral intervention. This review covers the formulation, pharmacokinetics, safety, efficacy, and implementation of this drug. There is little RCT evidence and the only RCT has been controversial. It is unlikely that there will be further randomized studies in the field. There is a concern that the administration of a single dose of artesunate without adequate follow up therapy may encourage the emergence of artemisinin resistance.

EXPERT OPINION

Artesunate is an essential drug and RAS is a very useful, potentially lifesaving formulation designed to be quickly administered in remote areas to severely unwell children by non-medical personnel. However, its use needs to be monitored and onward referral for definitive antimalarial treatment ensured.

Cost effectiveness of pre-referral antimalarial treatment in severe malaria among children in sub-Saharan Africa

BACKGROUND

In 2013, 78% of malaria deaths occurred in children aged 5 years and below, in sub-Saharan Africa. Treatment of severe malaria requires a health facility with inpatient care. However, in most sub-Sahara African countries, access to health facilities is a major problem. Pre-referral antimalarial treatments aim to delay the progress of severe malaria as patients seek to access health facilities. Rectal artesunate can be administered in the community as a pre-referral treatment in rural hard-to-reach areas. In Kenya, though pre-referral rectal artesunate has been included in the National Guidelines for pre-referral treatment, it is yet to be implemented in the public healthcare system. It is important, therefore, to establish its cost-utility compared to current parenteral treatments. This study evaluated the cost-utility of provision of pre-referral treatments by community health workers compared to similar services at a primary health facility.

METHODS

This was a decision model-based cost-utility analysis, comparing pre-referral antimalarial treatments provided by: community health workers (CHWs), primary health facility, direct access to a tertiary health facility and no access to treatment. A theoretical cohort, of 1000 children, who were below 5 years old; residing in rural hard-to-reach areas, was taken as the reference population. Data was collected through key informant interviews, to assess the costs, while key measures of effectiveness, were obtained from existing studies. The key measure of outcomes was Disability Adjusted Life Years (DALYS) averted. Probabilistic sensitivity analysis was carried out to assess the robustness of the model.

RESULTS

Provision of rectal pre-referral treatment by community health workers was estimated to avert 13,276 DALYs, at a cost of $68,428 for a cohort of 1000 children. Provision of rectal pre-referral treatment at a primary health facility was estimated to avert 9993 DALYs, at a cost of $73,826 for a cohort of 1000 children, while going directly to a tertiary health facility was estimated to avert 15,801 DALYs, at a cost of $114,903 for a cohort of 1000 children. The incremental cost effectiveness ratios for provision of pre-referral treatment by community health care and primary health workers were $5.11 and $7.30 per DALYs averted respectively.

CONCLUSION

Use of CHWs was more cost effective than provision of pre-referral treatments at a primary health facility especially, with high referral compliance. Rectal artesunate can easily be administered by community health workers, unlike parenteral pre-referral interventions.

Rectal route in the 21st Century to treat children

The rectal route can be considered a good alternative to the oral route for the paediatric population because these dosage forms are neither to be swallowed nor need to be taste-masked. Rectal forms can also be administered in an emergency to unconscious or vomiting children. Their manufacturing cost is low with excipients generally regarded as safe. Some new formulation strategies, including mucoadhesive gels and suppositories, were introduced to increase patient acceptability. Even if recent paediatric clinical studies have demonstrated the equivalence of the rectal route with others, in order to enable the use of this promising route for the treatment of children in the 21st Century, some effort should be focused on informing and educating parents and care givers. This review is the first ever to address all the aforementioned items, and to list all drugs used in paediatric rectal forms in literature and marketed products in developed countries.

Pre-referral rectal artesunate for severe malaria

BACKGROUND

Severe or complicated malaria is a medical emergency and people die as a result of delays in starting treatment. Most patients need parenteral treatment, and in primary healthcare facilities, where intravenous therapy is not available but intramuscular injections can be given, intramuscular quinine, artesunate, and artemether have been used before transporting patients to hospital.However, in rural settings with limited access to health care, intramuscular injections may also be unavailable. In these situations, rectal artesunate given prior to transfer to hospital by volunteers with little medical training, may be a feasible option.

OBJECTIVES

To evaluate the effects of pre-referral treatment with rectal artesunate on mortality and morbidity in people with severe malaria.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) published in The Cochrane Library; MEDLINE; EMBASE and LILACS up to 21 May 2014. We also searched the WHO clinical trial registry platform and the metaRegister of Controlled Trials (mRCT) for ongoing trials.

SELECTION CRITERIA

Individual or cluster-randomized controlled trials comparing pre-referral rectal artesunate with placebo or injectable antimalarials in children and children with severe malaria.

DATA COLLECTION AND ANALYSIS

Two authors independently screened titles and abstracts for potentially eligible trials, and extracted data from the included trials. Dichotomous outcomes were summarized using risk ratios (RR) and presented with 95% confidence intervals (95% CI). Where data allowed, we conducted subgroup analyses by age, trial region and whether participants were included in the trial analysis. We assessed the quality of evidence for the most important outcomes using the GRADE approach.

MAIN RESULTS

One trial met the inclusion criteria; a placebo-controlled trial of 17,826 children and adults living in rural villages in Ghana and Tanzania (Africa) and Bangladesh (Asia). Villagers with no previous medical training were trained to recognize the symptoms of severe malaria, administer rectal artesunate and refer patients to hospital. The trained villagers were supervised during the trial period. In the African sites only children aged 6 to 72 months were enrolled, whereas in Bangladesh, older children and adults were also enrolled.In young children (aged 6 to 72 months) there were fewer deaths following rectal artesunate than with placebo (RR 0.74; 95% CI 0.59 to 0.93; one trial; 8050 participants; moderate quality evidence), while in older children and adults there were more deaths in those given rectal artesunate (RR 2.21; 95% CI 1.18 to 4.15; one trial; 4018 participants; low quality evidence).In Africa, only 56% of participants reached a secondary healthcare facility within six hours compared to over 90% in Asia. There were no differences between the intervention and control groups in the proportion of participants reaching a healthcare facility within six hours (RR 0.99; 95% CI 0.98 to 1.01; 12,068 participants), or in the proportion with parasitaemia (RR 1.00; 95% CI 0.98 to 1.02; 17,826 participants), or with coma or convulsions on arrival (RR 1.01; 95% CI 0.90 to 1.14; 12,068 participants).There are no existing trials that compare rectal versus intramuscular artesunate.

AUTHORS' CONCLUSIONS

In rural areas without access to injectable antimalarials rectal artesunate provided before transfer to a referral facility probably reduces mortality in severely ill young children compared to referral without treatment. However, the unexpected finding of possible higher mortality in older children and adults has to be taken into account in forming any national or local policies about pre-referral rectal artesunate.

Comparative study of the effectiveness and pharmacokinetics of two rectal artesunate/oral mefloquine combination regimens for the treatment of uncomplicated childhood falciparum malaria

BACKGROUND

Rectal artesunate has been shown to be an effective treatment for falciparum malaria and is useful in patients who cannot take medicine orally or when parenteral medication is inconvenient. A combination with mefloquine can decrease the duration of treatment, increase compliance and delay development of resistance. There are no clear data on whether a higher dosage of rectal artesunate results in a better clinical response.

AIM

To assess two rectal artesunate/oral mefloquine regimens for treating uncomplicated multi-drug-resistant childhood falciparum malaria.

METHODS

Seventy children aged 1-14 years with uncomplicated falciparum malaria were randomly assigned to receive either 10 (range 8-12) or 20 (range 16-24) mg/kg/day rectal artesunate for 3 days followed by 25 mg/kg oral mefloquine. The study endpoints were fever clearance time, parasite clearance time and proportion of patients with recrudescence. Serum levels of artesunate and dihydro-artemisinin were measured after the first dose of rectal artesunate in 16 subjects.

RESULTS

Both regimens were safe and effective. The cure rate was 100% in the 53 patients who completed 28-day follow-up. All of the study endpoints were comparable between both treatment groups.

CONCLUSION

A regimen of rectal artesunate 10 mg/kg/day for 3 days followed by mefloquine 25 mg/kg is optimal for the treatment of uncomplicated falciparum malaria. There was no definite benefit from increasing the dosage of rectal artesunate from 10 to 20 mg/kg/day.

Antimalarial Drug Therapy: The Role of Parasite Biology and Drug Resistance

Malaria continues to affect public health and economic growth in many regions of the world. The number of infections continues to rise and is associated with increased mortality, despite basic science and public health efforts. Drug therapy remains the mainstay of treatment and prevention of this disease. Plasmodium has a complex life cycle involving an arthropod vector and distinct stages within the human host. Each parasite stage plays a unique role in transmission, disease, and latency. These different stages may vary in their response to the various antimalarial compounds. This article will review antimalarial therapies and drug resistance in the context of the parasites' biology.

Antimalarial drug resistance: a review of the biology and strategies to delay emergence and spread

The emergence of resistance to former first-line antimalarial drugs has been an unmitigated disaster. In recent years, artemisinin class drugs have become standard and they are considered an essential tool for helping to eradicate the disease. However, their ability to reduce morbidity and mortality and to slow transmission requires the maintenance of effectiveness. Recently, an artemisinin delayed-clearance phenotype was described. This is believed to be the precursor to resistance and threatens local elimination and global eradication plans. Understanding how resistance emerges and spreads is important for developing strategies to contain its spread. Resistance is the result of two processes: (i) drug selection of resistant parasites; and (ii) the spread of resistance. In this review, we examine the factors that lead to both drug selection and the spread of resistance. We then examine strategies for controlling the spread of resistance, pointing out the complexities and deficiencies in predicting how resistance will spread.

Pharmacodynamics of antimalarial chemotherapy

Malaria chemotherapy is under constant threat from the emergence and spread of multidrug resistance of Plasmodium falciparum. Resistance has been observed to almost all currently used antimalarials. Some drugs are also limited by toxicity. A fundamental component of the strategy for malaria chemotherapy is based on prompt, effective and safe antimalarial drugs. To counter the threat of resistance of P. falciparum to existing monotherapeutic regimens, current malaria treatment is based principally on the artemisinin group of compounds, either as monotherapy or artemisinin-based combination therapies for treatment of both uncomplicated and severe falciparum malaria. Key advantages of artemisinins over the conventional antimalarials include their rapid and potent action, with good tolerability profiles. Their action also covers transmissible gametocytes, resulting in decreased disease transmission. Up to now there has been no prominent report of drug resistance to this group of compounds. Treatment of malaria in pregnant women requires special attention in light of limited treatment options caused by potential teratogenicity coupled with a paucity of safety data for the mother and fetus. Treatment of other malaria species is less problematic and chloroquine is still the drug of choice, although resistance of P. vivax to chloroquine has been reported. Multiple approaches to the identification of new antimalarial targets and promising antimalarial drugs are being pursued in order to cope with drug resistance.

Artesunate versus quinine for treating severe malaria

BACKGROUND

Severe malaria results in over a million deaths every year, most of them in children aged under five years and living in sub-Saharan Africa. This review examines whether treatment with artesunate, instead of the standard treatment quinine, would result in fewer deaths and better treatment outcomes.

OBJECTIVES

To compare artesunate with quinine for treating severe malaria.

SEARCH METHODS

We searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL (The Cochrane Library), MEDLINE, EMBASE, LILACS, ISI Web of Science, the metaRegister of Controlled trials (mRCT), conference proceedings, and reference lists of articles to November 2010.

SELECTION CRITERIA

Randomized controlled trials comparing intravenous, intramuscular, or rectal artesunate with intravenous or intramuscular quinine for treating adults and children with severe malaria who are unable to take medication by mouth.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the eligibility and risk of bias of trials, and extracted and analysed data. The primary outcome was all-cause death. Dichotomous outcomes were summarized using risk ratios (RR) and continuous outcomes by mean differences (MD). Where appropriate, we combined data in meta-analyses.

MAIN RESULTS

Eight trials enrolling 1664 adults and 5765 children are included in this review.Treatment with artesunate significantly reduced the risk of death both in adults (RR 0.61, 95% Confidence Interval (CI) 0.50 to 0.75; 1664 participants, five trials) and children (RR 0.76, 95% CI 0.65 to 0.90; 5765 participants, four trials)In children, treatment with artesunate increased the incidence of neurological sequelae at the time of hospital discharge. The majority of these sequelae were transient and no significant difference between treatments was seen at later follow up.

AUTHORS' CONCLUSIONS

The evidence clearly supports the superiority of parenteral artesunate over quinine for the treatment of severe malaria in both adults and children and in different regions of the world.

Novel formulation and drug delivery strategies for the treatment of pediatric poverty-related diseases

INTRODUCTION

Due to a lack of approved drugs and formulations, children represent the most vulnerable patients. Magistral, unlicensed formulations obtained by the manipulation of solid forms should undergo clinical evaluation to ensure bioequivalence. The development of new pediatric medicines is complex and faces technological, economic and ethical challenges. This phenomenon has contributed to the emergence of an adult-children gap. To improve the situation, the World Health Organization launched the global campaign 'Make medicines child size' and a number of international initiatives have been established. The situation is more critical in the case of poverty-related diseases (PRDs) that mainly affect poor countries.

AREAS COVERED

This review critically discusses different strategies to develop pediatric formulations and drug delivery systems (DDS) in PRDs and their potential implementation in the current market. Readers will gain an updated perspective on the development of pediatric medicines for the treatment of PRDs and the proximate challenges and opportunities faced to ensure an effective pharmacotherapy.

EXPERT OPINION

There is an urgent need for the development of innovative, scalable and cost-viable formulations to ensure pediatric patients have access to appropriate medications for PRDs. The guidelines of the International Conference on Harmonisation constitute a very good orientation tool, as they emphasize physiological and developmental aspects that need to be considered in pediatric research. It is important to consider cultural, economic and ethical aspects that make developing nations facing PRDs different from the developed world. Thus, the best strategy would probably be to conceive and engage similar initiatives in the developing world, to address unattended therapeutic niches.

Artesunate versus quinine for treating severe malaria

BACKGROUND

Severe malaria results in over a million deaths every year, most of them in children aged under five years and living in sub-Saharan Africa. This review examines whether treatment with artesunate, instead of the standard treatment quinine, would result in fewer deaths and better treatment outcomes.

OBJECTIVES

To compare artesunate with quinine for treating severe malaria.

SEARCH STRATEGY

We searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL (The Cochrane Library), MEDLINE, EMBASE, LILACS, ISI Web of Science, the metaRegister of Controlled trials (mRCT), conference proceedings, and reference lists of articles to November 2010.

SELECTION CRITERIA

Randomized controlled trials comparing intravenous, intramuscular, or rectal artesunate with intravenous or intramuscular quinine for treating adults and children with severe malaria who are unable to take medication by mouth.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the eligibility and risk of bias of trials, and extracted and analysed data. The primary outcome was all-cause death. Dichotomous outcomes were summarized using risk ratios (RR) and continuous outcomes by mean differences (MD). Where appropriate, we combined data in meta-analyses.

MAIN RESULTS

Eight trials enrolling 1664 adults and 5765 children are included in this review.Treatment with artesunate significantly reduced the risk of death both in adults (RR 0.61, 95% Confidence Interval (CI) 0.50 to 0.75; 1664 participants, five trials) and children (RR 0.76, 95% CI 0.65 to 0.90; 5765 participants, four trials)In children, treatment with artesunate increased the incidence of neurological sequelae at the time of hospital discharge. The majority of these sequelae were transient and no significant difference between treatments was seen at later follow up.

AUTHORS' CONCLUSIONS

The evidence clearly supports the superiority of parenteral artesunate over quinine for the treatment of severe malaria in both adults and children and in different regions of the world.

Pitfalls in new artemisinin-containing antimalarial drug development

Artemisinin combination therapy (ACT) paves the way for new opportunities to eliminate malaria in the tropics. However, the huge increase of ACT consumption raises major concerns about their availability over the next few years. At the same time a decrease in their efficacy has already been reported. Alongside the deployment of multifocal control programs, the process ranging from artemisia crop production to accreditation of new ACT combinations urgently needs to be strengthened to supply sufficient quantities of high-quality drugs. New suppliers will have the opportunity to enter this market to develop new formulations, and bioequivalence studies are required to validate these new formulations. It is thus crucial for national malaria control teams to be able to better scrutinize the dossier of these new formulations.

Artesunate: The Best Drug in the Treatment of Severe and Complicated Malaria

This review summarizes progress in treating severe and complicated malaria, which are global problems, claiming at least one million lives annually, and have been accompanied by advances in our understanding of the pathogenesis of severe malaria complications. New drugs such as intravenous artesunate (AS) and intramuscular artemether (AM) are improving outcomes and decreasing malaria deaths. Trials comparing AM to the traditional parenteral drug, quinine, have not demonstrated however convincing evidence of a mortality advantage for AM. The South East Asian Quinine Artesunate Malaria Trials (SEAQUAMAT), a multicenter, randomized, open-label study comparing AS with quinine showed that parenteral AS was shown to be associated with a 35% reduction in the risk of mortality compare to quinine, and is now the recommended treatment by the WHO for severe and complicated malaria in low-transmission areas and in the second and third trimesters of pregnancy, with almost all the benefit reported in those with high parasite counts. Artesunate is a semisynthetic derivative of artemisinin whose water solubility facilitates absorption and provides an advantage over other artemisinins because it can be formulated as oral, rectal, intramuscular, and intravenous preparations. Artesunate is rapidly hydrolyzed to dihydroartemisinin, which is the most active schizonticidal metabolite. Injectable AS results in a more rapid systemic availability of AS compared with intramuscular AM. This pharmacokinetic advantage may provide a clinical advantage in the treatments of severe and complicated malaria.

Understanding caretakers' dilemma in deciding whether or not to adhere with referral advice after pre-referral treatment with rectal artesunate

BACKGROUND

Malaria kills. A single rectal dose of artesunate before referral can reduce mortality and prevent permanent disability. However, the success of this intervention depends on caretakers' adherence to referral advice for follow-up care. This paper explores the dilemma facing caretakers when they are in the process of deciding whether or not to transit their child to a health facility after pre-referral treatment with rectal artesunate.

METHODS

Four focus group discussions were held in each of three purposively selected villages in Mtwara rural district of Tanzania. Data were analysed manually using latent qualitative content analysis.

RESULTS

The theme "Caretakers dilemma in deciding whether or not to adhere with referral advice after pre-referral treatment with rectal artesunate" depicts the challenge they face. Caretakers' understanding of the rationale for going to hospital after treatment--when and why they should adhere--influenced adherence. Caretakers, whose children did not improve, usually adhered to referral advice. If a child had noticeably improved with pre-referral treatment however, caretakers weighed whether they should proceed to the facility, balancing the child's improved condition against other competing priorities, difficulties in reaching the health facilities, and the perceived quality of care at the health facility. Some misinterpretation were found regarding the urgency and rationale for adherence among some caretakers of children who improved which were attributed to be possibly due to their prior understanding.

CONCLUSION

Some caretakers did not adhere when their children improved and some who adhered did so without understanding why they should proceed to the facility. Successful implementation of the rectal artesunate strategy depends upon effective communication regarding referral to clinic.

Early rectal artesunate administration: a life-saver in remote areas?

Evaluation of: Gomes MF, Faiz MA, Gyapong GO et al.: Pre-referral rectal artesunate to prevent death and disability in severe malaria: a placebo-controlled trial. Lancet 373, 557–566 (2009). Malaria remains a major cause of morbidity and mortality in endemic areas, particularly in children under 5 years of age in sub-Saharan Africa. Distance to healthcare facilities is a key determinant of outcome. Gomes and colleagues report that pre-referral rectal artesunate administration significantly reduced permanent disability or death in patients still not receiving inpatient treatment after more than 6 h. In contrast, no significant effect was noted if treatment was administered within less than 6 h. With some questions remaining, this strategy appears to be an important, probably highly cost-effective additional tool urgently needed to help reducing the burden of disease.

Pre-referral rectal artesunate to prevent death and disability in severe malaria: a placebo-controlled trial

BACKGROUND

Most malaria deaths occur in rural areas. Rapid progression from illness to death can be interrupted by prompt, effective medication. Antimalarial treatment cannot rescue terminally ill patients but could be effective if given earlier. If patients who cannot be treated orally are several hours from facilities for injections, rectal artesunate can be given before referral and acts rapidly on parasites. We investigated whether this intervention reduced mortality and permanent disability.

METHODS

In Bangladesh, Ghana, and Tanzania, patients with suspected severe malaria who could not be treated orally were allocated randomly to a single artesunate (n=8954) or placebo (n=8872) suppository by taking the next numbered box, then referred to clinics at which injections could be given. Those with antimalarial injections or negative blood smears before randomisation were excluded, leaving 12 068 patients (6072 artesunate, 5996 placebo) for analysis. Primary endpoints were mortality, assessed 7-30 days later, and permanent disability, reassessed periodically. All investigators were masked to group assignment. Analysis was by intention to treat. This study is registered in all three countries, numbers ISRCTN83979018, 46343627, and 76987662.

RESULTS

Mortality was 154 of 6072 artesunate versus 177 of 5996 placebo (2.5%vs 3.0%, p=0.1). Two versus 13 (0.03%vs 0.22%, p=0.0020) were permanently disabled; total dead or disabled: 156 versus 190 (2.6%vs 3.2%, p=0.0484). There was no reduction in early mortality (56 vs 51 deaths within 6 h; median 2 h). In patients reaching clinic within 6 h (median 3 h), pre-referral artesunate had no significant effect on death after 6 h or permanent disability (71/4450 [1.6%] vs 82/4426 [1.9%], risk ratio 0.86 [95% CI 0.63-1.18], p=0.35). In patients still not in clinic after more than 6 h, however, half were still not there after more than 15 h, and pre-referral rectal artesunate significantly reduced death or permanent disability (29/1566 [1.9%] vs 57/1519 [3.8%], risk ratio 0.49 [95% CI 0.32-0.77], p=0.0013).

INTERPRETATION

If patients with severe malaria cannot be treated orally and access to injections will take several hours, a single inexpensive artesunate suppository at the time of referral substantially reduces the risk of death or permanent disability.

FUNDING

UNICEF/UNDP/World Bank Special Programme for Research and Training in Tropical Diseases (WHO/TDR); WHO Global Malaria Programme (WHO/GMP); Sall Family Foundation; the European Union (QLRT-2000-01430); the UK Medical Research Council; USAID; Irish Aid; the Karolinska Institute; and the University of Oxford Clinical Trial Service Unit (CTSU).

What does it take to control malaria?

More than 125 years after the discovery of the causative parasites, human malaria remains a major global-health problem. Despite many important discoveries in the epidemiology and pathogenesis of the disease, and the availability of effective treatment and control measures, there was no decline in global malarial mortality from 1954 to 1997. The economic prospects of the countries in which malaria is endemic are closely related to the burden of the disease, a situation that calls for an enhanced, concerted effort from the global community in the fight against the disease. This review explains the effects and limitations of the available control tools, summarises the extent to which they are currently employed, describes how their use could be improved, and discusses the particular importance of a vaccine in controlling the disease.

Rectal artemisinins for malaria: a review of efficacy and safety from individual patient data in clinical studies

BACKGROUND

Rectal administration of artemisinin derivatives has potential for early treatment for severe malaria in remote settings where injectable antimalarial therapy may not be feasible. Preparations available include artesunate, artemisinin, artemether and dihydroartemisinin. However each may have different pharmacokinetic properties and more information is needed to determine optimal dose and comparative efficacy with each another and with conventional parenteral treatments for severe malaria.

METHODS

Individual patient data from 1167 patients in 15 clinical trials of rectal artemisinin derivative therapy (artesunate, artemisinin and artemether) were pooled in order to compare the rapidity of clearance of Plasmodium falciparum parasitaemia and the incidence of reported adverse events with each treatment. Data from patients who received comparator treatment (parenteral artemisinin derivative or quinine) were also included. Primary endpoints included percentage reductions in parasitaemia at 12 and 24 hours. A parasite reduction of >90% at 24 hours was defined as parasitological success.

RESULTS

Artemisinin and artesunate treatment cleared parasites more rapidly than parenteral quinine during the first 24 hours of treatment. A single higher dose of rectal artesunate treatment was five times more likely to achieve >90% parasite reductions at 24 hours than were multiple lower doses of rectal artesunate, or a single lower dose administration of rectal artemether.

CONCLUSION

Artemisinin and artesunate suppositories rapidly eliminate parasites and appear to be safe. There are less data on artemether and dihydroartemisinin suppositories. The more rapid parasite clearance of single high-dose regimens suggests that achieving immediate high drug concentrations may be the optimal strategy.

Artesunate versus quinine for treating severe malaria

BACKGROUND

Severe malaria kills over a million people every year. We sought evidence of superiority of artesunate compared with the standard treatment quinine.

OBJECTIVES

To compare artesunate with quinine for treating severe malaria.

SEARCH STRATEGY

We searched the Cochrane Infectious Diseases Group Specialized Register (January 2007), CENTRAL (The Cochrane Library 2006, Issue 4), MEDLINE (1966 to January 2007), EMBASE (1974 to January 2007), LILACS (1982 to January 2007), ISI Web of Science (1945 to January 2007), the metaRegister of Controlled trials (mRCT), conference proceedings, and reference lists of articles. We contacted researchers and the World Health Organization.

SELECTION CRITERIA

Randomized controlled trials comparing intravenous, intramuscular, or rectal artesunate with intravenous or intramuscular quinine for treating adults and children with severe malaria who are unable to take medication by mouth.

DATA COLLECTION AND ANALYSIS

Two authors assessed the eligibility and methodological quality of trials, extracted and analysed data, and drafted the review. The third author contributed to the design and writing of the review. Death was the primary outcome. Dichotomous outcomes were summarized using relative risks and continuous outcomes by mean differences. Where appropriate, we combined data in meta-analyses. Heterogeneity was investigated for the primary outcome using subgroup analyses.

MAIN RESULTS

Six trials enrolling 1938 participants (1664 adults and 274 children) met our inclusion criteria. All six trials were conducted in Asia, and only one small trial enrolled only children. Five trials used intravenous artesunate and one trial intramuscular artesunate; all six used intravenous quinine. Treatment with artesunate significantly reduced the risk of death (RR 0.62, 95% CI 0.51 to 0.75; 1938 participants, 6 trials), reduced parasite clearance time (WMD 8.14 h, 95% CI 11.55 to 4.73; 292 participants, 3 trials), and hypoglycaemia detected by routine monitoring (RR 0.46, 95% CI 0.25 to 0.87; 185 participants, 2 trials). There was no evidence of a difference in neurological sequelae, coma recovery time, time to hospital discharge, fever clearance time, or adverse effects other than hypoglycaemia.

AUTHORS' CONCLUSIONS

Intravenous artesunate is the drug of choice for adults with severe malaria, particularly if acquired in Asia. This review did not identify sufficient data to make firm conclusions about the treatment of children or the effectiveness of intramuscular artesunate. There is an urgent need to compare the effects of artesunate with quinine in African children with severe malaria. The applicability of these results to Asian children and the ethics of further research are points of debate.

The treatment of severe malaria

In the SEAQUAMAT trial, parenteral artesunate was shown to be associated with a considerably lower mortality than quinine, and is now the recommended treatment for severe malaria in low-transmission areas and in the second and third trimesters of pregnancy. A trial is underway to establish its role in African children. The development of artesunate suppositories may provide the means to treat patients with severe disease in remote rural settings, potentially buying the time needed to reach a health care facility. The increasing availability of basic intensive care facilities in developing countries also has the potential to further reduce mortality.

Artesunate, artemether or quinine in severe Plasmodium falciparum malaria?

Quinine and the artemisinin-derivative drugs artesunate and artemether are effective treatments for severe falciparum malaria. Trials comparing artemether with quinine have not demonstrated convincing evidence of a mortality advantage for artemether. The South East Asian Quinine Artesunate Malaria Trial (SEAQUAMAT), a multicenter, randomized, open-label trial in 1461 adults with severe malaria in Asia compared artesunate with quinine. Mortality was 15% in the artesunate group and 22% in the quinine group, a reduction of 34.7% (95% confidence interval: 18.5-47.6%) in the artesunate group, with almost all the benefit reported in those with high parasite counts. Artesunate should constitute first-line treatment for severe malaria in Asia. These results can probably be generalized to the treatment of severe malaria in adults from all areas, especially in those with hyperparasitemia. However, it is unclear whether these results can be generalized to children in Africa, who constitute the majority of those who die from severe malaria worldwide.

Treatment of childhood Plasmodium falciparum malaria: current challenges

Malaria continues to be a major cause of mortality and morbidity in tropical countries. Infection with Plasmodium falciparum may be asymptomatic, cause an uncomplicated febrile illness or give rise to severe disease complicated by coma, acidosis or severe anemia. Treatment of the febrile illness with two drugs--preferably in the form of an artemisinin-containing combination therapy--is now widely recommended, both for greater efficacy and in order to delay the evolution of drug resistance. The clinical picture of severe malaria differs according to the age and immune status of the individual; treatment requires a range of supportive measures, as well as an efficacious antimalarial drug. Insecticide-treated bednets and presumptive treatment programs are increasingly deployed in malaria control programs, while vaccines are showing promise.

Malaria chemotherapy

Most malaria control strategies today depend on safe and effective drugs, as they have done for decades. But sensitivity to chloroquine, hitherto the workhorse of malaria chemotherapy, has rapidly declined throughout the tropics since the 1980s, and this drug is now useless in many high-transmission areas. New options for resource-constrained governments are few, and there is growing evidence that the burden from malaria has been increasing, as has malaria mortality in Africa. In this chapter, we have tried to outline the main pharmacological properties of current drugs, and their therapeutic uses and limitations. We have summarised the ways in which these drugs are employed, both in the formal health sector and in self-medication. We have briefly touched on the limitations of current drug development, but have tried to pick out a few promising drugs that are under development. Given that Plasmodium falciparum is the organism that kills, and that has developed multi-drug resistance, we have tended to focus upon it. Similarly, given that around 90% of global mortality from malaria occurs in Africa, there is the tendency to dwell on this continent. We give no apology for placing our emphasis upon the use of antimalarial drugs in endemic populations rather than their use for prophylaxis in travellers.

Safety and efficacy of rectal compared with intramuscular quinine for the early treatment of moderately severe malaria in children: randomised clinical trial

OBJECTIVE

To compare the safety and efficacy of quinine given by the rectal route with quinine given by the intramuscular route in children with moderately severe Plasmodium falciparum malaria.

DESIGN

Randomised, open, clinical trial.

SETTING

Health centre in Burkina Faso.

PARTICIPANTS

898 children with moderately severe P falciparum malaria who were unable to take oral treatment.

INTERVENTION

Rectal quinine (20 mg/kg diluted to 30 mg/ml in water solution) or intramuscular quinine (12.5 mg/kg) every 12 hours until oral quinine could be taken.

MAIN OUTCOME MEASURES

Primary safety outcome was the presence of blood in stools and secondary safety outcome was diarrhoea. Primary efficacy outcome was early treatment failure and secondary efficacy outcomes were late clinical and parasitological failures, fever clearance time, and time to oral intake.

RESULTS

Blood in stools and diarrhoea were more common in children given quinine by the rectal route than by the intramuscular route (blood in stools: 5% v 1%, absolute difference 3.9%, 95% confidence interval 1.8% to 6.1%; diarrhoea: 5% v 1%, 3.5%, 1.3% to 5.7%). On anoscopy, inflammatory lesions (9/248, 3%) were associated with bloody striations in stools. Side effects of rectal quinine were rare and transitory. Local pain (90%), inflammation (79%), and transient impairment of mobility (15%) were observed with intramuscular quinine. Early treatment failure was higher in the rectal group (6% v 3%, absolute difference 3.0%, 95% confidence interval 0.2% to 5.9%). All except two children in each group had negative blood slide results at day 5. Fever recurrence at day 7 was higher in the intramuscular group (37/375 v 18/395, absolute difference 5.3%, 1.6% to 8.9%). Other efficacy outcomes (late clinical failure, late parasitological failure, fever clearance time, time to starting oral intake and rate of deterioration to severe malaria) did not differ.

CONCLUSION

Quinine given by the rectal route has an acceptable safety profile and could be used in the early management of moderately severe malaria in children in sub-Saharan Africa, halting progression to severe disease.

Artesunate suppositories versus intramuscular artemether for treatment of severe malaria in children in Papua New Guinea

Drug treatment of severe malaria must be rapidly effective. Suppositories may be valuable for childhood malaria when circumstances prevent oral or parenteral therapy. We compared artesunate suppositories (n = 41; 8 to 16 mg/kg of body weight at 0 and 12 h and then daily) with intramuscular (i.m.) artemether (n = 38; 3.2 mg/kg at 0 h and then 1.6 mg/kg daily) in an open-label, randomized trial with children with severe Plasmodium falciparum malaria in Papua New Guinea (PNG). Parasite density and temperature were measured every 6 h for > or = 72 h. Primary endpoints included times to 50% and 90% parasite clearance (PCT50 and PCT90) and the time to per os status. In a subset of 29 patients, plasma levels of artemether, artesunate, and their common active metabolite dihydroartemisinin were measured during the first 12 h. One suppository-treated patient with multiple complications died within 2 h of admission, but the remaining 78 recovered uneventfully. Compared to the artemether-treated children, those receiving artesunate suppositories had a significantly earlier mean PCT50 (9.1 versus 13.8 h; P = 0.008) and PCT90 (15.6 versus 20.4 h; P = 0.011). Mean time to per os status was similar for each group. Plasma concentrations of primary drug plus active metabolite were significantly higher in the artesunate suppository group at 2 h postdose. The earlier initial fall in parasitemia with artesunate is clinically advantageous and mirrors higher initial plasma concentrations of active drug/metabolite. In severely ill children with malaria in PNG, artesunate suppositories were at least as effective as i.m. artemether and may, therefore, be useful in settings where parenteral therapy cannot be given.

Ethical perspective on malaria research for Africa

Malaria is a leading cause of death and illness in Africa, afflicting mainly young children, infants and young pregnant women, especially in rural areas where access to health services is often limited. Resistance to the safest and most affordable antimalarials, the threat of insecticide resistance, demand for research and development of new malaria treatment, prevention and control tools in the form of new antimalarials, vaccines, diagnostics, insecticides and devices. New antimalarial tools must be tested on the most afflicted groups (young children, infants and pregnant women) whose autonomy especially in tradition African rural settings is severely impaired or diminished. They, therefore, deserve special protection by the researcher; thorough ethical review ensuring genuine informed consent is therefore crucial. The testing of new products, particularly with novel vaccine formulations and new adjuvants in the vulnerable groups, age de-escalation, trial of transmission blocking vaccines, the initial testing (Phases Ia and IIa) of vaccines and drugs in non-endemic populations all pose ethical dilemmas, as do bioprospecting (biopiracy) and the standard of care during and after the research. Besides these concerns, ethical issues relating to epidemiological research are also addressed.

Pediatric malaria in the developing world

Hundreds of millions of people suffer from malaria, and more than a million children die of malaria each year. Malaria typically presents with fever and headache, but the presentation often is nonspecific. The diagnosis should be based on blood tests, and thick and thin smears are the standard means of identifying parasites. In some areas, chloroquine still is effective as treatment, but other medications are needed in most parts of the world. Patients with severe disease (altered consciousness, marked anemia, and/or respiratory distress) should begin therapy parenterally. Control measures depend on the use of insecticide-treated bednets, early identification and treatment of symptomatic individuals, and intermittent preventive therapy. Progress continues toward the development of a useful vaccine.