Intermittent presumptive treatment for malaria

Pharmacokinetics and efficacy of piperaquine and chloroquine in Melanesian children with uncomplicated malaria

The disposition of chloroquine (CQ) and the related 4-aminoquinoline, piperaquine (PQ), were compared in Papua New Guinean children with uncomplicated malaria. Twenty-two children were randomized to 3 days of PQ phosphate at 20 mg/kg/day (12 mg of PQ base/kg/day) coformulated with dihydroartemisinin (DHA-PQ), and twenty children were randomized to 3 days of CQ at 10 mg base/kg/day with a single dose of sulfadoxine-pyrimethamine (CQ-SP). After a 42-day intensive sampling protocol, PQ, CQ, and its active metabolite monodesethyl-chloroquine (DECQ) were assayed in plasma by using high-performance liquid chromatography. A two-compartment model with first-order absorption was fitted to the PQ and CQ data. There were no significant differences in age, gender, body weight, or admission parasitemia between the two groups. The PCR-corrected 42-day adequate clinical and parasitological responses were 100% for DHA-PQ and 94% for CQ-SP, but P. falciparum reinfections during follow-up were common (33 and 18%, respectively). For PQ, the median volume of distribution at steady state, allowing for bioavailability (Vss/F), was 431 liters/kg (interquartile range [IQR], 283 to 588 liters/kg), the median clearance (CL/F) was 0.85 liters/h/kg (IQR, 0.67 to 1.06 liters/h/kg), the median distribution half-life (t 1/2 alpha) was 0.12 h (IQR, 0.05 to 0.66 h), and the median elimination half-life (t 1/2 beta) was 413 h (IQR, 318 to 516 h). For CQ, the median Vss/F was 154 liters/kg (IQR, 101 to 210 liters/kg), the median CL/F was 0.80 liters/h/kg (IQR, 0.52 to 0.96 liters/h/kg), the median t 1/2 alpha was 0.43 h (IQR, 0.05 to 1.82 h), and the median t 1/2 beta was 233 h (IQR, 206 to 298 h). The noncompartmentally derived median DECQ t 1/2 beta was 290 h (IQR, 236 to 368 h). Combined molar concentrations of DECQ and CQ were higher than those of PQ during the elimination phase. Although PQ has a longer t 1/2 beta than CQ, its prompt distribution and lack of active metabolite may limit its posttreatment malaria-suppressive properties.

Safety and toxicity of sulfadoxine/pyrimethamine: implications for malaria prevention in pregnancy using intermittent preventive treatment

Plasmodium falciparum infection during pregnancy is strongly associated with maternal anaemia and low birth weight, contributing to substantial morbidity and mortality in sub-Saharan Africa. Intermittent preventive treatment in pregnancy with sulfadoxine/pyrimethamine (IPTp-SP) has been one of the most effective approaches to reduce the burden of malaria during pregnancy in Africa. IPTp-SP is based on administering >or=2 treatment doses of sulfadoxine/pyrimethamine to pregnant women at predefined intervals after quickening (around 18-20 weeks). Randomised, controlled trials have demonstrated decreased rates of maternal anaemia and low birth weight with this approach. The WHO currently recommends IPTp-SP in malaria-endemic areas of sub-Saharan Africa. However, implementation has been suboptimal in part because of concerns of potential drug toxicities. This review evaluates the toxicity data of sulfadoxine/pyrimethamine, including severe cutaneous adverse reactions, teratogenicity and alterations in bilirubin metabolism. Weekly sulfadoxine/pyrimethamine prophylaxis is associated with rare but potentially fatal cutaneous reactions. Fortunately, sulfadoxine/pyrimethamine use in IPTp programmes in Africa, with 2-4 treatment doses over 6 months, has been well tolerated in multiple IPTp trials. However, sulfadoxine/pyrimethamine should not be administered concurrently with cotrimoxazole given their redundant mechanisms of action and synergistic worsening of adverse drug reactions. Therefore, HIV-infected pregnant women in malaria endemic areas who are already receiving cotrimoxazole prophylaxis should not also receive IPTp-SP. Although folate antagonist use in the first trimester is associated with neural tube defects, large case-control studies have demonstrated that sulfadoxine/pyrimethamine administered as IPTp (exclusively in the second and third trimesters and after organogenesis) does not result in an increased risk of teratogenesis. Folic acid supplementation is recommended for all pregnant women to reduce the rate of congenital anomalies but high doses of folic acid (5 mg/day) may interfere with the antimalarial efficacy of sulfadoxine/pyrimethamine. However, the recommended standard dose of folic acid supplementation (0.4 mg/day) does not affect antimalarial efficacy and may provide the optimal balance to prevent neural tube defects and maintain the effectiveness of IPTp-SP. No clinical association between sulfadoxine/pyrimethamine use and kernicterus has been reported despite the extensive use of sulfadoxine/pyrimethamine and related compounds to treat maternal malaria and congenital toxoplasmosis in near-term pregnant women and newborns. Although few drugs in pregnancy can be considered completely safe, sulfadoxine/pyrimethamine - when delivered as IPTp - has a favourable safety profile. Improved pharmacovigilance programmes throughout Africa are now needed to confirm its safety as access to IPTp-SP increases. Given the documented benefits of IPTp-SP in malaria endemic areas of Africa, access to this treatment for pregnant women should continue to expand.

A Randomized Controlled Trial of Extended Intermittent Preventive Antimalarial Treatment in Infants

BACKGROUND

Intermittent preventive antimalarial treatment in infants (IPTi) with sulfadoxine-pyrimethamine reduces falciparum malaria and anemia but has not been evaluated in areas with intense perennial malaria transmission. It is unknown whether an additional treatment in the second year of life prolongs protection.

METHODS

A randomized, double-blinded, placebo-controlled trial with administration of sulfadoxine-pyrimethamine therapy at 3, 9, and 15 months of age was conducted with 1070 children in an area in Ghana where malaria is holoendemic. Participants were monitored for 21 months after recruitment through active follow-up visits and passive case detection. The primary end point was malaria incidence, and additional outcome measures were anemia, outpatient visits, hospital admissions, and mortality. Stratified analyses for 6-month periods after each treatment were performed.

RESULTS

Protective efficacy against malaria episodes was 20% (95% confidence interval [CI], 11%-29%). The frequency of malaria episodes was reduced after the first 2 sulfadoxine-pyrimethamine applications (protective efficacy, 23% [95% CI, 6%-36%] after the first dose and 17% [95% CI, 1%-30%] after the second dose). After the third treatment at month 15, however, no protection was achieved. Protection against the first or single anemia episode was only significant after the first IPTi dose (protective efficacy, 30%; 95% CI, 5%-49%). The number of anemia episodes increased after the last IPTi dose (protective efficacy, -24%; 95% CI, -50% to -2%).

CONCLUSION

In an area of intense perennial malaria transmission, sulfadoxine-pyrimethamine-based IPTi conferred considerably lower protection than reported in areas where the disease is moderately or seasonally endemic. Protective efficacy is age-dependent, and extension of IPTi into the second year of life does not provide any benefit.

Review of intermittent preventive treatment for malaria in infants and children

Malaria is one of the greatest killers of children in the world. Treatment is available, but there are problems with affordability, availability, accessibility and increasing drug resistance. A new regime, intermittent preventive treatment in infants (IPTi) shows promise. It involves giving a treatment course of antimalarial drugs, regardless of parasitaemia, at intervals over the first year of life. The aim is to decrease the frequency of malarial illness while allowing the development of natural immunity. Its strength is that it can be linked with the childhood immunisation schedule. Early studies are encouraging, but much remains to be learned before its potential place in the prevention of malaria in children can be determined and it can safely be introduced as public policy. A review of the literature was performed in July 2006 for references relating to IPTi and other forms of personal prevention of malaria in infants and children.

Intermittent preventive treatment for malaria in pregnancy in Africa: what's new, what's needed?

Falciparum malaria is an important cause of maternal, perinatal and neonatal morbidity in high transmission settings in Sub-Saharan Africa. Intermittent preventive treatment with sulphadoxine-pyrimethamine (SP-IPT) has proven efficacious in reducing the burden of pregnancy-associated malaria but increasing levels of parasite resistance mean that the benefits of national SP-IPT programmes may soon be seriously undermined in much of the region. Hence, there is an urgent need to develop alternative drug regimens for IPT in pregnancy. This paper reviews published safety and efficacy data on various antimalarials and proposes several candidate combination regimens for assessment in phase II/III clinical trials.

Reducing the burden of malaria in pregnancy by preventive strategies

Malaria is one of the most common and preventable causes of adverse birth outcomes. In Africa, important progress has been made in the past decade with the introduction of a preventive strategy for malaria in pregnancy consisting of intermittent preventive treatment in pregnancy (IPTp) and insecticide-treated nets, yet their coverage is still unacceptably low and malaria continues to demand a huge toll on pregnant women and their newborn babies. Increasing the frequency of dosing of IPTp with sulfadoxine-pyrimethamine might provide temporary respite, but increasing resistance to sulfadoxine-pyrimethamine makes research into safe, efficacious, and affordable alternatives for IPTp one of the highest priorities for the control of malaria in pregnancy. A number of promising alternatives are, or will soon be, available that need to be evaluated as IPTp after their safety and pharmacokinetics in pregnancy have first been assessed in parasitaemic women. Little is known about appropriate control strategies in Asia and Latin America for Plasmodium falciparum and Plasmodium vivax malaria in pregnancy, which in most countries rely on responsive case management approaches. The role of case management based on proactive screening for malaria infection of women attending antenatal care or preventive approaches with insecticide-treated nets or IPTp are urgently needed. To achieve these objectives, multicentre and multidisciplinary approaches are required across the range of malaria transmission settings that include assessment of immunological effect of successful preventions, the perceptions and acceptability of different preventive approaches, and their cost-effectiveness.

Modelling the impact of intermittent preventive treatment for malaria on selection pressure for drug resistance

Background

Intermittent preventive treatment (IPT) is a promising intervention for malaria control, although there are concerns about its impact on drug resistance.

Methods

The key model inputs are age-specific values for a) baseline anti-malarial dosing rate, b) parasite prevalence, and c) proportion of those treated with anti-malarials (outside IPT) who are infected. These are used to estimate the immediate effect of IPT on the genetic coefficient of selection (s). The scenarios modelled were year round IPT to infants in rural southern Tanzania, and three doses at monthly intervals of seasonal IPT in Senegal.

Results

In the simulated Tanzanian setting, the model suggests a high selection pressure for drug resistance, but that IPTi would only increase this by a small amount (4.4%). The percent change in s is larger if parasites are more concentrated in infants, or if baseline drug dosing is less common or less specific. If children aged up to five years are included in the Tanzanian scenario then the predicted increase in s rises to 31%. The Senegalese seasonal IPT scenario, in children up to five years, results in a predicted increase in s of 16%.

Conclusion

There is a risk that the useful life of drugs will be shortened if IPT is implemented over a wide childhood age range. On the other hand, IPT delivered only to infants is unlikely to appreciably shorten the useful life of the drug used.

Drugs for preventing malaria in pregnant women

BACKGROUND

Malaria contributes to maternal illness and anaemia in pregnancy, especially in first-time mothers, and can harm the mother and the baby. Drugs given routinely to prevent or mitigate the effects of malaria during pregnancy are often recommended.

OBJECTIVES

To assess drugs given to prevent malaria infection and its consequences in pregnant women living in malarial areas. This includes prophylaxis and intermittent preventive treatment (IPT).

SEARCH STRATEGY

We searched the Cochrane Infectious Diseases Group Specialized Register (March 2006), CENTRAL (The Cochrane Library 2006, Issue 1), MEDLINE (1966 to March 2006), EMBASE (1974 to March 2006), LILACS (1982 to March 2006), and reference lists. We also contacted researchers working in the field.

SELECTION CRITERIA

Randomized and quasi-randomized controlled trials comparing antimalarial drugs given regularly with no antimalarial drugs for preventing malaria in pregnant women living in malaria-endemic areas.

DATA COLLECTION AND ANALYSIS

Both authors extracted data and assessed methodological quality. Dichotomous variables were combined using relative risks (RR) and weighted mean differences (WMD) for mean values, both with 95% confidence intervals (CI).

MAIN RESULTS

Sixteen trials (12,638 participants) met the inclusion criteria; two used adequate methods to conceal allocation. Antimalarials reduced antenatal parasitaemia when given to all pregnant women (RR 0.53, 95% CI 0.33 to 0.86; 328 participants, 2 trials), placental malaria (RR 0.34, 95% CI 0.26 to 0.45; 1236 participants, 3 trials), but no effect was detected with perinatal deaths (2890 participants, 4 trials). In women in their first or second pregnancy, antimalarial drugs reduced severe antenatal anaemia (RR 0.62, 95% CI 0.50 to 0.78; 2809 participants, 1 prophylaxis and 2 IPT trials), antenatal parasitaemia (RR 0.27, 95% CI 0.17 to 0.44, random-effects model; 2906 participants, 6 trials), and perinatal deaths (RR 0.73, 95% CI 0.53 to 0.99; 1986 participants, 2 prophylaxis and 1 IPT trial; mean birthweight was higher (WMD 126.70 g, 95% CI 88.64 to 164.75 g; 2648 participants, 8 trials), and low birthweight less frequent (RR 0.57, 95% CI 0.46 to 0.72; 2350 participants, 6 trials). Proguanil performed better than chloroquine in one trial of women of all parities in relation to maternal fever episodes. Sulfadoxine-pyrimethamine performed better than chloroquine in two trials of low-parity women.

AUTHORS' CONCLUSIONS

Chemoprophylaxis or IPT reduces antenatal parasite prevalence and placental malaria when given to women in all parity groups. They also have positive effects on birthweight and possibly on perinatal death in low-parity women.

Review: Intermittent preventive treatment--a new approach to the prevention of malaria in children in areas with seasonal malaria transmission

Intermittent preventive treatment, the administration of a full course of an anti-malarial treatment to a population at risk at specified time points regardless of whether or not they are known to be infected, is now a recommended approach to the prevention of malaria in pregnancy and is being explored as a potential way of preventing malaria in infants. However, in many malaria endemic areas, the main burden of malaria is in older children and increasing use of insecticide treated bednets is likely to increase further the proportion of episodes of malaria that occur in older children. Recently, it has been shown in Senegal and in Mali that intermittent preventive treatment given to older children during the malaria transmission season can be remarkably effective in preventing malaria. This approach to malaria control is likely to be most effective in areas with a high level of malaria transmission concentrated in a short period of the year. However, several issues need to be addressed before intermittent preventive treatment in children can be advocated for use in malaria control programmes. These include: (1) determination of whether intermittent preventive treatment adds to the protection afforded by other control measures such as insecticide-treated bednets; (2) whether an effective and sustainable delivery system can be found; (3) choice of drug to be used; (4) optimum timing of drug administration; (5) the requisite interval between treatments. The potential benefits of intermittent preventive treatment in children are substantial; more research is needed to determine if this is a practical approach to malaria control.

Modelling malaria control

White discusses a new study that models the impact of deploying intermittent presumptive treatment of malaria upon the spread of drug resistance.

Artemisinin combination therapies for treatment of uncomplicated malaria in Uganda

OBJECTIVES

To compare the efficacy and safety of artemisinin combination therapies for the treatment of uncomplicated falciparum malaria in Uganda.

DESIGN

Randomized single-blind controlled trial.

SETTING

Tororo, Uganda, an area of high-level malaria transmission.

PARTICIPANTS

Children aged one to ten years with confirmed uncomplicated P. falciparum malaria.

INTERVENTIONS

Amodiaquine + artesunate or artemether-lumefantrine.

OUTCOME MEASURES

Risks of recurrent symptomatic malaria and recurrent parasitemia at 28 days, unadjusted and adjusted by genotyping to distinguish recrudescences and new infections.

RESULTS

Of 408 participants enrolled, 403 with unadjusted efficacy outcomes were included in the per-protocol analysis. Both treatment regimens were highly efficacious; no recrudescences occurred in patients treated with amodiaquine + artesunate, and only two occurred in those treated with artemether-lumefantrine. However, recurrent malaria due to new infections was common. The unadjusted risk of recurrent symptomatic malaria was significantly lower for participants treated with artemether-lumefantrine than for those treated with amodiaquine + artesunate (27% versus 42%, risk difference 15%, 95% CI 5.9%-24.2%). Similar results were seen for the risk of recurrent parasitemia (51% artemether-lumefantrine versus 66% amodiaquine + artesunate, risk difference 16%, 95% CI 6.2%-25.2%). Amodiaquine + artesunate and artemether-lumefantrine were both well-tolerated. Serious adverse events were uncommon with both regimens.

CONCLUSIONS

Amodiaquine + artesunate and artemether-lumefantrine were both highly efficacious for treatment of uncomplicated malaria. However, in this holoendemic area, despite the excellent performance of both regimens in terms of efficacy, many patients experienced recurrent parasitemia due to new infections. Artemether-lumefantrine was superior to amodiaquine + artesunate for prevention of new infections. To maximize the benefit of artemisinin combination therapy in Africa, treatment should be integrated with strategies to prevent malaria transmission. The impact of frequent repeated therapy on the efficacy, safety, and cost-effectiveness of new artemisinin regimens should be further investigated.

Seasonal intermittent preventive treatment with artesunate and sulfadoxine-pyrimethamine for prevention of malaria in Senegalese children: a randomised, placebo-controlled, double-blind trial

BACKGROUND

In the Sahel and sub-Sahelian regions of Africa, malaria transmission is highly seasonal. During a short period of high malaria transmission, mortality and morbidity are high in children under age 5 years. We assessed the efficacy of seasonal intermittent preventive treatment-a full dose of antimalarial treatment given at defined times without previous testing for malaria infection.

METHODS

We did a randomised, placebo-controlled, double-blind trial of the effect of intermittent preventive treatment on morbidity from malaria in three health-care centres in Niakhar, a rural area of Senegal. 1136 children aged 2-59 months received either one dose of artesunate plus one dose of sulfadoxine-pyrimethamine or two placebos on three occasions during the malaria transmission season. The primary outcome was a first or single episode of clinical malaria detected through active or passive case detection. Primary analysis was by intention-to-treat. This study is registered with , number NCT00132561.

FINDINGS

During 13 weeks of follow-up, the intervention led to an 86% (95% CI 80-90) reduction in the occurrence of clinical episodes of malaria. With passive case detection, protective efficacy against malaria was 86% (77-92), and when detected actively was 86% (78-91). The incidence of malaria in children on active drugs was 308 episodes per 1000 person-years at risk, whereas in those on placebo it was 2250 episodes per 1000 person-years at risk. 13 children were not included in the intention-to-treat analysis, which was restricted to children who received a first dose of antimalarial or placebo. There was an increase in vomiting in children who received the active drugs, but generally the intervention was well tolerated.

INTERPRETATION

Intermittent preventive treatment could be highly effective for prevention of malaria in children under 5 years of age living in areas of seasonal malaria infection.

Chemoprophylaxis and intermittent treatment for preventing malaria in children

BACKGROUND

Malaria causes repeated illness in children living in endemic areas. Policies of giving antimalarial drugs at regular intervals (prophylaxis or intermittent treatment) are being considered for preschool children.

OBJECTIVES

To evaluate chemoprophylaxis and intermittent treatment with antimalarial drugs to prevent malaria in young children living in malaria endemic areas.

SEARCH STRATEGY

We searched the Cochrane Infectious Diseases Group Specialized Register (April 2005), CENTRAL (The Cochrane Library Issue 1, 2005), MEDLINE (1966 to April 2005), EMBASE (1974 to April 2005), LILACS (1982 to April 2005), and reference lists of identified trials. We also contacted researchers.

SELECTION CRITERIA

Randomized and quasi-randomized controlled trials comparing antimalarial drugs given at regular intervals (prophylaxis or intermittent treatment) with placebo or no drug in children aged one month to six years or less living in an area where malaria is endemic.

DATA COLLECTION AND ANALYSIS

We independently extracted data and assessed methodological quality. We used relative risk (RR) or weighted mean difference with 95% confidence intervals (CI) for meta-analyses. Where we detected heterogeneity and considered it appropriate to combine the trials, we used the random-effects model (REM).

MAIN RESULTS

Nineteen trials (14,393 participants) met the inclusion criteria. Children receiving antimalarial drugs as prophylaxis or intermittent treatment had fewer clinical malaria episodes (RR 0.52, 95% CI 0.35 to 0.77, REM; 4051 participants, 8 trials), and severe anaemia was less common (RR 0.54, 95% CI 0.42 to 0.68; 2727 participants, 8 trials). We did not detect a difference in the number of deaths from any cause (RR 0.82, 95% CI 0.65 to 1.04; 7929 participants, 9 trials), but the confidence intervals do not exclude a potentially important difference. None of the trials reported serious adverse events. Three trials measured morbidity and mortality six months to two years after stopping regular antimalarial drugs; overall, there was no statistically significant difference, but participant numbers were small.

AUTHORS' CONCLUSIONS

Prophylaxis and intermittent treatment with antimalarial drugs reduce clinical malaria and severe anaemia in preschool children. There is insufficient evidence to detect an effect on mortality.

The promise and potential challenges of intermittent preventive treatment for malaria in infants (IPTi)

Intermittent preventive treatment (IPT) administers a full therapeutic course of an anti-malarial drug at predetermined intervals, regardless of infection or disease status. It is recommended by the World Health Organization (WHO) for protecting pregnant women from the adverse effects of malaria (IPTp) and shows great potential as a strategy for reducing illness from malaria during infancy (IPTi). Administered concurrently with standard immunizations, IPTi is expected to reduce the frequency of clinical disease, but to allow blood-stage infections to occur between treatments, thus allowing parasite-specific immunity to develop. While wide deployment of IPTi is being considered, it is important to assess other potential effects. Transmission conditions, drug choice and administration schedule will likely affect the possibility of post-treatment rebound in child morbidity and mortality and the increased spread of parasite drug resistance and should be considered when implementing IPTi.