Audiometric changes associated with the treatment of uncomplicated falciparum malaria with co-artemether

Usher syndrome IIIA: a review of the disorder and preclinical research advances in therapeutic approaches

Usher syndrome (USH) is an autosomal recessive disorder characterized by sensorineural hearing loss, progressive pigmentary retinopathy, and vestibular dysfunction. The degree and onset of hearing loss vary among subtypes I, II, and III, while blindness often occurs in the second to fourth decades of life. Usher type III (USH3), characterized by postlingual progressive sensorineural hearing loss, varying levels of vestibular dysfunction, and varying degrees of visual impairment, typically manifests in the first to second decades of life. While USH3 is rare, it is highly prevalent in certain populations. RP61, USH3, and USH3A symbolize the same disorder, with the latter symbol used more frequently in recent literature. This review focuses on the clinical features, epidemiology, molecular genetics, treatment, and research advances for sensory deficits in USH3A.

The Ototoxicity of Antimalarial Drugs-A State of the Art Review

This review summarizes current knowledge about the occurrence of hearing and balance disorders after antimalarial drugs treatment. It also examines the clinical applications of antimalarials, their mechanisms behind this ototoxicity and how it can be monitored. It includes studies with larger numbers of patients and those in which auditory function was assessed using audiological tests. Some antimalarials have been repurposed for other conditions like autoimmune disorders, rheumatic diseases, some viral diseases and cancers. While old antimalarial drugs, such as quinoline derivatives, are known to demonstrate ototoxicity, a number of new synthetic antimalarial agents particularly artemisinin derivatives, demonstrate unknown ototoxicity. Adverse audiovestibular effects vary depending on the medication itself, its dose and route of administration, as well as the drug combination, treated disease and individual predispositions of the patient. Dizziness was commonly reported, while vestibular symptoms, hearing loss and tinnitus were observed much less frequently, and most of these symptoms were reversible. As early identification of ototoxic hearing loss is critical to introducing possible alternative treatments with less ototoxic medications, therefore monitoring systems of those drugs ototoxic side effects are much needed.

9,10-Anhydrodehydroartemisinin Attenuates Experimental Autoimmune Encephalomyelitis by Inhibiting Th1 and Th17 Cell Differentiation

Human inflammatory disease, multiple sclerosis (MS), is a demyelinating disease of central nervous system (CNS). The experimental autoimmune encephalomyelitis (EAE) is the most commonly used as experimental model because of its key pathological features' approximation of MS. The interaction between complex elements in immune system and in the CNS determines the MS pathogenesis. However, there is no cure for MS and the treatment for MS still encounters great challenges. Thus, finding a more effective disease-modifying treatment is imminent. In the present study, we investigated whether 9,10-Anhydrodehydroartemisin (ADART), a compound derived from artemisinin, could decrease demyelination in EAE and the underlying mechanisms. In established EAE mice, 100 mg/kg 9,10-Anhydrodehydroartemisinin (ADART) effectively reduced CNS and peripheral immune system infiltration inflammatory cells including CD4⁺ IFN-γ⁺ Th1 cells and CD4⁺ IL-17A⁺ Th17 cells. Correspondingly, the serum level of IFN-γ and IL-17A was also reduced. In vitro, ADART almost completely inhibited Th17 differentiation, and partially inhibited Th1 differentiation in 10 μM. This research revealed that ADART could be a great promising avenue among current therapies for MS.

Piperaquine Exposure Is Altered by Pregnancy, HIV, and Nutritional Status in Ugandan Women

Dihydroartemisinin-piperaquine (DHA-PQ) provides highly effective therapy and chemoprevention for malaria in pregnant African women. PQ concentrations of >10.3 ng/ml have been associated with reduced maternal parasitemia, placental malaria, and improved birth outcomes. We characterized the population pharmacokinetics (PK) of PQ in a post hoc analysis of human immunodeficiency virus (HIV)-infected and -uninfected pregnant women receiving DHA-PQ as chemoprevention every 4 or 8 weeks. The effects of covariates such as pregnancy, nutritional status (body mass index [BMI]), and efavirenz (EFV)-based antiretroviral therapy were investigated. PQ concentrations from two chemoprevention trials were pooled to create a population PK database from 274 women and 2,218 PK observations. A three-compartment model with an absorption lag best fit the data. Consistent with our prior intensive PK evaluation, pregnancy and EFV use resulted in a 72% and 61% increased PQ clearance, compared to postpartum and HIV-uninfected pregnant women, respectively. Low BMI at 28 weeks of gestation was associated with increased clearance (2% increase per unit decrease in BMI). Low-BMI women given DHA-PQ every 8 weeks had a higher prevalence of parasitemia, malaria infection, and placental malaria compared to women with higher BMIs. The reduced piperaquine exposure in women with low BMI as well as during EFV coadministration, compared to pregnant women with higher BMIs and not taking EFV, suggests that these populations could benefit from weekly instead of monthly dosing for prevention of malaria parasitemia. Simulations indicated that because of the BMI-clearance relationship, weight-based regimens would not improve protection compared to a 2,880 mg fixed-dose regimen when provided monthly. (The clinical trials described in this paper have been registered at ClinicalTrials.gov under identifiers NCT02163447 and NCT02282293.).

Optimal 10-Aminoartemisinins With Potent Transmission-Blocking Capabilities for New Artemisinin Combination Therapies-Activities Against Blood Stage P. falciparum Including PfKI3 C580Y Mutants and Liver Stage P. berghei Parasites

We have demonstrated previously that amino-artemisinins including artemiside and artemisone in which an amino group replaces the oxygen-bearing substituents attached to C-10 of the current clinical artemisinin derivatives dihydroartemisinin (DHA), artemether and artesunate, display potent activities in vitro against the asexual blood stages of Plasmodium falciparum (Pf). In particular, the compounds are active against late blood stage Pf gametocytes, and are strongly synergistic in combination with the redox active drug methylene blue. In order to fortify the eventual selection of optimum amino-artemisinins for development into new triple combination therapies also active against artemisinin-resistant Pf mutants, we have prepared new amino-artemisinins based on the easily accessible and inexpensive DHA-piperazine. The latter was converted into alkyl- and aryl sulfonamides, ureas and amides. These derivatives were screened together with the comparator drugs DHA and the hitherto most active amino-artemisinins artemiside and artemisone against asexual and sexual blood stages of Pf and liver stage P. berghei (Pb) sporozoites. Several of the new amino-artemisinins bearing aryl-urea and -amide groups are potently active against both asexual, and late blood stage gametocytes (IC₅₀ 0.4-1.0 nM). Although the activities are superior to those of artemiside (IC₅₀ 1.5 nM) and artemisone (IC₅₀ 42.4 nM), the latter are more active against the liver stage Pb sporozoites (IC₅₀ artemisone 28 nM). In addition, early results indicate these compounds tend not to display reduced susceptibility against parasites bearing the Pf Kelch 13 propeller domain C580Y mutation characteristic of artemisinin-resistant Pf. Thus, the advent of the amino-artemisinins including artemiside and artemisone will enable the development of new combination therapies that by virtue of the amino-artemisinin component itself will possess intrinsic transmission-blocking capabilities and may be effective against artemisinin resistant falciparum malaria.

Hearing of neonates without risk indicators for hearing loss and use of antimalarial drugs during pregnancy: a historical cohort study in the Northern Region of Brazil

INTRODUCTION

Studies have demonstrated the ototoxic effects of antimalarial drugs in individuals who receive these drugs, but little is known regarding the toxicity of these drugs in the newborn auditory system when administered to the mother receive the drug during pregnancy.

OBJECTIVE

To verify the incidence of hearing loss in neonates who have no other associated risk indicators, born to mothers treated for malaria during pregnancy.

METHODS

A retrospective, quantitative cohort study was developed at Hospital de Base Dr. Ary Pinheiro and Clínica Limiar, both located in the municipality of Porto Velho (Rondônia). The sample consisted of 527 newborns divided into two groups: exposed to antimalarials drugs during pregnancy group (n = 32) and non-exposed group (n = 495). Data collection took place from September 2014 to December 2015, through an interview with the mothers and/or guardians of the newborn, through the newborns' and the mothers' records, and the neonatal hearing screening database of the above-mentioned institutions.

RESULTS

All the neonates in the exposed group, assessed through the recording of transient otoacoustic emissions associated with the automated brainstem auditory evoked potential test, underwent neonatal hearing screening in the first examination. Among the newborns in the non-exposed group, 30 showed failure and were retested. Of these, one continued to fail and was referred for diagnosis, in whom the results showed to be within the normal range. Among the neonates of the exposed group, infection with Plasmodium vivax was the most frequent, and was similarly distributed among the gestational trimesters, and chloroquine was the most commonly used antimalarial drug treatment more often given during the third trimester; these findings did not show any influence on the audiological findings of the studied neonates.

CONCLUSION

The present study did not identify any cases of hearing loss in neonates born to mothers who used antimalarial drugs during gestation.

Antimalarial drugs and the prevalence of mental and neurological manifestations: A systematic review and meta-analysis

Background: Antimalarial drugs affect the central nervous system, but it is difficult to differentiate the effect of these drugs from that of the malaria illness. We conducted a systematic review to determine the association between anti-malarial drugs and mental and neurological impairment in humans.  Methods: We systematically searched online databases, including Medline/PubMed, PsychoInfo, and Embase, for articles published up to 14th July 2016. Pooled prevalence, heterogeneity and factors associated with prevalence of mental and neurological manifestations were determined using meta-analytic techniques.  Results: Of the 2,349 records identified in the initial search, 51 human studies met the eligibility criteria. The median pooled prevalence range of mental and neurological manifestations associated with antimalarial drugs ranged from 0.7% (dapsone) to 48.3% (minocycline) across all studies, while it ranged from 0.6% (pyrimethamine) to 42.7% (amodiaquine) during treatment of acute malaria, and 0.7% (primaquine/dapsone) to 55.0% (sulfadoxine) during prophylaxis. Pooled prevalence of mental and neurological manifestations across all studies was associated with an increased number of antimalarial drugs (prevalence ratio= 5.51 (95%CI, 1.05-29.04); P=0.045) in a meta-regression analysis. Headaches (15%) and dizziness (14%) were the most common mental and neurological manifestations across all studies. Of individual antimalarial drugs still on the market, mental and neurological manifestations were most common with the use of sulphadoxine (55%) for prophylaxis studies and amodiaquine (42.7%) for acute malaria studies. Mefloquine affected more domains of mental and neurological manifestations than any other antimalarial drug.  Conclusions: Antimalarial drugs, particularly those used for prophylaxis, may be associated with mental and neurological manifestations, and the number of antimalarial drugs taken determines the association. Mental and neurological manifestations should be assessed following the use of antimalarial drugs.

Antimalarial drugs and the prevalence of mental and neurological manifestations: A systematic review and meta-analysis

Background: Antimalarial drugs affect the central nervous system, but it is difficult to differentiate the effect of these drugs from that of the malaria illness. We conducted a systematic review to determine the association between anti-malarial drugs and mental and neurological impairment in humans.  Methods: We systematically searched online databases, including Medline/PubMed, PsychoInfo, and Embase, for articles published up to 14th July 2016. Pooled prevalence, heterogeneity and factors associated with prevalence of mental and neurological manifestations were determined using meta-analytic techniques.  Results: Of the 2,349 records identified in the initial search, 51 human studies met the eligibility criteria. The median pooled prevalence range of mental and neurological manifestations associated with antimalarial drugs ranged from 0.7% (dapsone) to 48.3% (minocycline) across all studies, while it ranged from 0.6% (pyrimethamine) to 42.7% (amodiaquine) during treatment of acute malaria, and 0.7% (primaquine/dapsone) to 55.0% (sulfadoxine) during prophylaxis. Pooled prevalence of mental and neurological manifestations across all studies was associated with an increased number of antimalarial drugs (prevalence ratio= 5.51 (95%CI, 1.05-29.04); P=0.045) in a meta-regression analysis. Headaches (15%) and dizziness (14%) were the most common mental and neurological manifestations across all studies. Of individual antimalarial drugs still on the market, mental and neurological manifestations were most common with the use of sulphadoxine (55%) for prophylaxis studies and amodiaquine (42.7%) for acute malaria studies. Mefloquine affected more domains of mental and neurological manifestations than any other antimalarial drug.  Conclusions: Antimalarial drugs, particularly those used for prophylaxis, may be associated with mental and neurological manifestations, and the number of antimalarial drugs taken determines the association. Mental and neurological manifestations should be assessed following the use of antimalarial drugs.

Adverse neuropsychiatric effects of antimalarial drugs

INTRODUCTION

Antimalarial drugs are the primary weapon to treat parasite infection, save lives, and curtail further transmission. Accumulating data have indicated that at least some antimalarial drugs may contribute to severe neurological and/or psychiatric side effects which further complicates their use and limits the pool of available medications.

AREAS COVERED

In this review article, we summarize published scientific studies in search of evidence of the neuropsychiatric effects that may be attributed to the commonly used antimalarial drugs administered alone or in combination. Each individual drug was used as a search term in addition to keywords such as neuropsychiatric, adverse events, and neurotoxicity.

EXPERT OPINION

Accumulating data based on published reports over several decades have suggested that among the major commonly used antimalarial drugs, only mefloquine exhibited clear indications of serious neurological and/or psychiatric side effects. A more systematic approach to assess the neuropsychiatric adverse effects of new or repurposed antimalarial drugs on their safety, tolerability and efficacy phases of clinical studies and in post-marketing surveillance, is needed to ensure that these life-saving tools remain available and can be prescribed with appropriate caution and medical judgment.

Investigation of ototoxicity of artesunate as add-on therapy in patients with metastatic or locally advanced breast cancer: new audiological results from a prospective, open, uncontrolled, monocentric phase I study

PURPOSE

Artesunate (ART) has been used for a long time in the treatment of Plasmodium falciparum malaria and has been considered safe. The present phase I study aimed to determine the daily dose of ART that is well tolerated as add-on therapy in patients with breast cancer for 4 weeks of therapy. Ototoxicity could be a potential safety concern in settings different from malaria. Therefore, comprehensive audiological assessment was essential.

METHODS

The ARTIC M33/2 study was a prospective, open, uncontrolled, monocentric phase I dose-escalation study to evaluate the safety and tolerability of ART in patients with advanced breast cancer. Patients received either 100, 150 or 200 mg oral ART daily for a test phase of 4 weeks as add-on therapy to their ongoing oncological treatment. For the investigation of the safety of ART for hearing, an audiological assessment was performed with each patient before the intake of ART and after 4 weeks of therapy.

RESULTS

Twenty-three female patients were included in the study. During the test phase, four patients had adverse events (AEs) of the auditory system possibly related to the intake of ART. However, none of these AEs was classified as severe AE (SAE) and did not require treatment interruption. Four patients had AEs concerning the vestibular system (vertigo) during the test phase, one of which was classified as SAE. However, the SAE was fully reversible after discontinuation of ART.

CONCLUSION

None of the audiological results after 4 weeks of therapy with ART showed any dose-limiting auditory toxicity. However, audiological monitoring in further clinical studies with prolonged use of oral ART in doses up to 200 mg daily is warranted. The ARTIC M33/2 study is registered at eudract.ema.europa.eu with the Number 2007-004432-23 and at clinicaltrials.gov with the Number NCT00764036.

Severe malaria in children leads to a significant impairment of transitory otoacoustic emissions--a prospective multicenter cohort study

BACKGROUND

Severe malaria may influence inner ear function, although this possibility has not been examined prospectively. In a retrospective analysis, hearing impairment was found in 9 of 23 patients with cerebral malaria. An objective method to quickly evaluate the function of the inner ear are the otoacoustic emissions. Negative transient otoacoustic emissions are associated with a threshold shift of 20 dB and above.

METHODS

This prospective multicenter study analyses otoacoustic emissions in patients with severe malaria up to the age of 10 years. In three study sites (Ghana, Gabon, Kenya) 144 patients with severe malaria and 108 control children were included. All malaria patients were treated with parental artesunate.

RESULTS

In the control group, 92.6 % (n = 108, 95 % confidence interval 86.19-6.2 %) passed otoacoustic emission screening. In malaria patients, 58.5 % (n = 94, malaria vs controls p < 0.001, 95 % confidence interval 48.4-67.9 %) passed otoacoustic emission screening at the baseline measurement. The value increased to 65.2 % (n = 66, p < 0.001, 95 % confidence interval 53.1-75.5 %) at follow up 14-28 days after diagnosis of malaria. The study population was divided into severe non-cerebral malaria and severe malaria with neurological symptoms (cerebral malaria). Whereas otoacoustic emissions in severe malaria improved to a passing percentage of 72.9 % (n = 48, 95 % confidence interval 59-83.4 %) at follow-up, the patients with cerebral malaria showed a drop in the passing percentage to 33 % (n = 18) 3-7 days after diagnosis. This shows a significant impairment in the cerebral malaria group (p = 0.012 at days 3-7, 95 % confidence interval 16.3-56.3 %; p = 0.031 at day 14-28, 95 % confidence interval 24.5-66.3 %).

CONCLUSION

The presented data show that 40 % of children have involvement of the inner ear early in severe malaria. In children, audiological screening after severe malaria infection is not currently recommended, but is worth investigating in larger studies.

Adherence to Artemisinin-Based Combination Therapy for the Treatment of Uncomplicated Malaria: A Systematic Review and Meta-Analysis

Adherence to artemisinin-based combination therapy (ACT) is not clearly defined. This meta-analysis determines the prevalence and predictors of adherence to ACT. Twenty-five studies and six substudies met the inclusion criteria. The prevalence of ACT adherence in the public sector was significantly higher compared to retail sector (76% and 45%, resp., P < 0.0001). However, ACT adherence was similar across different ACT dosing regimens and formulations. In metaregression analysis prevalence estimates of adherence significantly decrease with increasing year of study publication (P = 0.046). Factors found to be significant predictors of ACT adherence were years of education ≥ 7 {odds ratio (OR) (95% CI) = 1.63 (1.05–2.53)}, higher income {2.0 (1.35–2.98)}, fatty food {4.6 (2.49–8.50)}, exact number of pills dispensed {4.09 (1.60–10.7)}, and belief in traditional medication for malaria {0.09 (0.01–0.78)}. The accuracy of pooled estimates could be limited by publication bias, and differing methods and thresholds of assessing adherence. To improve ACT adherence, educational programs to increase awareness and understanding of ACT dosing regimen are interventions urgently needed. Patients and caregivers should be provided with an adequate explanation at the time of prescribing and/or dispensing ACT.

Neuroauditory toxicity of artemisinin combination therapies-have safety concerns been addressed?

Although artemisinin-based combination therapies (ACTs) are widely viewed as safe drugs with a wide therapeutic dose range, concerns about neuroauditory safety of artemisinins arose during their development. A decade ago, reviews of human data suggested a potential neuro-ototoxic effect, but the validity of these findings was questioned. With 5–10 years of programmatic use, emerging artemisinin-tolerant falciparum malaria in southeast Asia, and the first calls to consider an increased dose of artemisinins, we review neuroauditory safety data on ACTs to treat uncomplicated falciparum malaria. Fifteen studies reported a neurological or auditory assessment. The large heterogeneity of neuro-ototoxic end points and assessment methodologies and the descriptive nature of assessments hampered a formal meta-analysis and definitive conclusions, but they highlight the persistent lack of data from young children. This subgroup is potentially most vulnerable to any neuroauditory toxicity because of their development stage, increased malaria susceptibility, and repeated ACT exposure in settings lacking robust safety monitoring.

Sesquiterpene lactones: adverse health effects and toxicity mechanisms

Sesquiterpene lactones (STLs) present a wide range of biological activities, mostly based on their alkylating capabilities, which underlie their therapeutic potential. These compounds are the active constituents of a variety of plants, frequently used as herbal remedies. STLs such as artemisinin and its derivatives are in use as first-line antimalarials while others, such as parthenolide, have recently reached cancer clinical trials. However, the toxicological profile of these compounds must be thoroughly characterized, since the same properties that make STL useful medicines can also cause severe toxicity. STL-containing plants have long been known to induce a contact dermatitis in exposed farm workers, and also to cause several toxic syndromes in farm animals. More recently, concerns are been raised regarding the genotoxic potential of these compounds and the embryotoxicity of artemisinins. A growing number of STLs are being reported to be mutagenic in different in vitro and in vivo assays. As yet no systematic studies have been published, but the genotoxicity of STLs seems to depend not so much on direct DNA alkylation as on oxidative DNA damage and other partially elucidated mechanisms. As the medicinal use of these compounds increases, further studies of their toxic potential are needed, especially those focusing on the structural determinants of genotoxicity and embryotoxicity.

First-in-man safety and pharmacokinetics of synthetic ozonide OZ439 demonstrates an improved exposure profile relative to other peroxide antimalarials

Aims

To assess the safety and pharmacokinetics of a new synthetic ozonide antimalarial, OZ439, in a first-in-man, double-blind study in healthy volunteers.

Methods

OZ439 was administered as single oral daily doses of a capsule formulation (50–1200 mg) or an oral dispersion (400–1600 mg, fed and fasted states) and for up to 3 days as an oral dispersion (200–800 mg day⁻¹). Plasma concentrations of OZ439 and its metabolites were measured by LC-MS.

Results

The pharmacokinetic (PK) profile of OZ439 was characterized by a t_max of around 3 h, followed by a multiphasic profile with a terminal half-life of 25–30 h. The PK parameters were approximately dose proportional for each group and profiles of the metabolites followed a similar pattern to that of the parent compound. Following dosing for 3 days, accumulation was less than two-fold but steady-state was not achieved. In the presence of food, no effect was observed on the t_1/2 of OZ439 while the exposure was increased by 3 to 4.5-fold. Exposure was higher and inter-subject variability was reduced when OZ439 was administered as an oral dispersion compared with a capsule. The urinary clearance of OZ439 and its metabolites was found to be negligible and OZ439 did not induce CYP3A4. The antimalarial activity profiles of a subset of serum samples suggested that the major antimalarial activity originated from OZ439 rather than from any of the metabolites.

Conclusion

The safety and pharmacokinetic profile of OZ439 merits progression to phase 2a proof of concept studies in the target population of acute uncomplicated malaria.

Reversible audiometric threshold changes in children with uncomplicated malaria

Background. Plasmodium falciparum malaria, as well as certain antimalarial drugs, is associated with hearing impairment in adults. There is little information, however, on the extent, if any, of this effect in children, and the evidence linking artemisinin combination therapies (ACTs) with hearing is inconclusive. Methods. Audiometry was conducted in children with uncomplicated malaria treated with artesunate-amodiaquine (n = 37), artemether-lumefantrine (n = 35), or amodiaquine (n = 8) in Accra, Ghana. Audiometry was repeated 3, 7, and 28 days later and after 9 months. Audiometric thresholds were compared with those of a control group of children (n = 57) from the same area. Findings. During the acute stage, hearing threshold levels of treated children were significantly elevated compared with controls (P < 0.001). The threshold elevations persisted up to 28 days, but no differences in hearing thresholds were evident between treated children and controls after 9 months. The hearing thresholds of children treated with the two ACT regimens were comparable but lower than those of amodiaquine-treated children during acute illness. Interpretation. Malaria is the likely cause of the elevated hearing threshold levels during the acute illness, a finding that has implications for learning and development in areas of intense transmission, as well as for evaluating potential ototoxicity of new antimalarial drugs.

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.

Randomized, prospective, three-arm study to confirm the auditory safety and efficacy of artemether-lumefantrine in Colombian patients with uncomplicated Plasmodium falciparum malaria

The safety of artemether-lumefantrine in patients with acute, uncomplicated Plasmodium falciparum malaria was investigated prospectively using the auditory brainstem response (ABR) and pure-tone thresholds. Secondary outcomes included polymerase chain reaction-corrected cure rates. Patients were randomly assigned in a 3:1:1 ratio to either artemether-lumefantrine (N = 159), atovaquone-proguanil (N = 53), or artesunate-mefloquine (N = 53). The null hypothesis (primary outcome), claiming that the percentage of patients with a baseline to Day-7 ABR Wave III latency increase of > 0.30 msec is ≥ 15% after administration of artemether-lumefantrine, was rejected; 2.6% of patients (95% confidence interval: 0.7-6.6) exceeded 0.30 msec, i.e., significantly below 15% (P < 0.0001). A model-based analysis found no apparent relationship between drug exposure and ABR change. In all three groups, average improvements (2-4 dB) in pure-tone thresholds were observed, and polymerase chain reaction-corrected cure rates were > 95% to Day 42. The results support the continued safe and efficacious use of artemether-lumefantrine in uncomplicated falciparum malaria.

Meningeal inflammation increases artemether concentrations in cerebrospinal fluid in Papua New Guinean children treated with intramuscular artemether

Although the artemisinin-associated neurotoxicity identified in vitro and in animal studies has not been confirmed clinically, only one adult study has measured cerebrospinal fluid (CSF) concentrations after administration of conventional doses. Potential artemisinin neurotoxicity could be serious in children, especially those with meningitis and, consequently, a compromised blood-brain barrier. We measured CSF/plasma artemether and dihydroartemisinin (DHA) concentrations in 32 Papua New Guinean children with a mean age of 39 months with suspected or proven severe falciparum malaria who underwent a single lumbar puncture after intramuscular artemether administration. CSF artemether concentrations were 0 to 43.5 μg/liter and CSF concentration/plasma concentration ratios were 0 to 38.1%. DHA was measurable in CSF in only two children. The seven children with meningeal inflammation (CSF white cell count > 20/mm(3)) had higher CSF artemether concentration/plasma artemether concentration ratios than those without (median, 6.7% [interquartile ratio, 2.5 to 27.8%]% versus 0.0% [interquartile ratio, 0.0 to 2.5%]; P = 0.002). Meningeal inflammation was associated with a 4.6-fold increase in the CSF artemether concentration/plasma artemether concentration ratio in a population pharmacokinetic model. These data suggest that pharmacovigilance should be heightened when intramuscular artemether is given to severely ill children with evidence of meningeal inflammation.

Murine cerebral malaria: histopathology and ICAM 1 immunohistochemistry of the inner ear

OBJECTIVE

To evaluate the pathophysiologic changes in the inner ear during the course of severe cerebral malaria in an established animal model, C57 BL/6J mice.

METHODS

This study aims to examine the hearing threshold, the histological changes and ICAM-1 expression in the murine cochlea.

RESULTS

Four of seven mice showed an expected hearing loss of 20 dB or more. The light microscopy of the inner ear did not show any morphologic alterations. The immunohistochemical analysis for ICAM-1 showed intensive staining in the stria vascularis of sick animals and hardly any reaction in healthy controls.

CONCLUSION

The up-regulation of ICAM-1 in the stria vascularis - generating the endocochlear potential - suggests its involvement in plasmodial infection.

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.

Artemether-lumefantrine in the treatment of uncomplicated Plasmodium falciparum malaria

The World Health Organization strongly recommends artemisinin-based combination therapy (ACT) regimens for the treatment of uncomplicated Plasmodium falciparum malaria cases in endemic areas. Among the combinations of compounds that are available at present, excellent results have been obtained for the artemisinin derivative artemether, in a combination galenic preparation with lumefantrine (artemether-lumefantrine, AL). Here, the pharmacological properties and the therapeutic options of both substances are briefly reviewed and a cursory overview is given on recent trials that have compared the therapeutic effects of AL in the standard 6-dose regimen with other antimalarials and combinations. In order to ensure the most achievable and reliable adherence and compliance of children in the treatment of malaria, a dispersible formulation of AL is now attainable. Recent reports on the emergence of resistance to ACT regimens in Asia, however, are alarming.

Discovery, mechanisms of action and combination therapy of artemisinin

Despite great international efforts, malaria still inflicts an enormous toll on human lives, especially in Africa. Throughout history, antimalarial medicines have been one of the most powerful tools in malaria control. However, the acquisition and spread of parasite strains that are resistant to multiple antimalarial drugs have become one of the greatest challenges to malaria treatment, and are associated with the increase in morbidity and mortality in many malaria-endemic countries. To deal with this grave situation, artemisinin-based combinatory therapies (ACTs) have been introduced and widely deployed in malarious regions. Artemisinin is a new class of antimalarial compounds discovered by Chinese scientists from the sweet wormwood Artemisia annua. The potential development of resistance to artemisinins by Plasmodium falciparum threatens the usable lifespan of ACTs, and therefore is a subject of close surveillance and extensive research. Studies at the Thai-Cambodian border, a historical epicenter of multidrug resistance, have detected reduced susceptibility to artemisinins as manifested by prolonged parasite-clearance times, raising considerable concerns on resistance development. Despite this significance, there is still controversy on the mode of action of artemisinins. Although a number of potential cellular targets of artemisinins have been proposed, they remain to be verified experimentally. Here, we review the history of artemisinin discovery, discuss the mode of action and potential drug targets, and present strategies to elucidate resistance mechanisms.

alpha/beta-Arteether-induced mania in a predisposed adolescent

Artemisinin, by the name of Qinghaosu, has been used in China for the treatment of fever over the years. Recently, a number of artemisinin derivatives such as artesunate, artemether, dihydroartemisinin, and arteether have been developed and have found widespread clinical use because of their efficacy against resistant forms of all plasmodial species and a favorable side-effect profile. However, concerns have been expressed about the neurotoxic effects of artemisinin derivatives based on some animal and human studies. We present a case of alpha/beta-arteether-induced mania in an adolescent having a family history of chloroquine-induced psychosis to discuss the hereditary predispositions, possible mechanisms, management, and clinical implications of this rare adverse event.

Mosquito-borne diseases

Despite centuries of control efforts, mosquito-borne diseases are flourishing worldwide. With a disproportionate effect on children and adolescents, these conditions are responsible for substantial global morbidity and mortality. Malaria kills more than 1 million children annually, chiefly in sub-Saharan Africa. Dengue virus has expanded its range over the past several decades, following its principal vector, Aedes aegypti, back into regions from which it was eliminated in the mid-20th century and causing widespread epidemics of hemorrhagic fever. West Nile virus has become endemic throughout the Americas in the past 10 years, while chikungunya virus has emerged in the Indian Ocean basin and mainland Asia to affect millions. Japanese encephalitis virus, too, has expanded its range in the Indian subcontinent and Australasia, mainly affecting young children. Filariasis, on the other hand, is on the retreat, the subject of a global eradication campaign. Efforts to limit the effect of mosquito-borne diseases in endemic areas face the twin challenges of controlling mosquito populations and delivering effective public health interventions. Travelers to areas endemic for mosquito-borne diseases require special advice on mosquito avoidance, immunizations, and malaria prophylaxis.

Mefloquine neurotoxicity: a literature review

A literature review revealed that mefloquine neurotoxicity has been demonstrated at both the preclinical and clinical levels, with nausea, dizziness, sleep disturbances, anxiety and psychosis, amongst other adverse neuropsychiatric events, reported in users. Females and individuals of low body mass index (BMI) are at apparent greater risk. Mechanisms of possible neurotoxicity may include binding to neuroreceptors and cholinesterases, inhibition of sarcoendoplasmic reticulum ATPase (SERCA) and interference with cellular Ca(2+) homeostasis, accumulation in the CNS, and reductions in CNS efflux in individuals possessing certain MDR1 polymorphisms. It may be prudent to avoid mefloquine in females and low BMI individuals, and in combination with other potentially neurotoxic agents such as the artemisinin antimalarials.

Efficacy and safety of artemether-lumefantrine dispersible tablets compared with crushed commercial tablets in African infants and children with uncomplicated malaria: a randomised, single-blind, multicentre trial

BACKGROUND

Combination treatments, preferably containing an artemisinin derivative, are recommended to improve efficacy and prevent Plasmodium falciparum drug resistance. Our aim was to show non-inferiority of a new dispersible formulation of artemether-lumefantrine to the conventional crushed tablet in the treatment of young children with uncomplicated malaria.

METHODS

We did a randomised non-inferiority study on children weighing 5-35 kg with uncomplicated P falciparum malaria in Benin, Kenya, Mali, Mozambique, and Tanzania. The primary outcome measure was PCR-corrected 28-day parasitological cure rate. We aimed to show non-inferiority (with a margin of -5%) of dispersible versus crushed tablet. We constructed an asymptotic one-sided 97.5% CI on the difference in cure rates. A computer-generated randomisation list was kept centrally and investigators were unaware of the study medication administered. We used a modified intention-to-treat analysis. This trial is registered with ClinicalTrials.gov, number NCT00386763.

FINDINGS

899 children aged 12 years or younger were randomly assigned to either dispersible (n=447) or crushed tablets (n=452). More than 85% of patients in each treatment group completed the study. 812 children qualified for the modified intention-to-treat analysis (n=403 vs n=409). The PCR-corrected day-28 cure rate was 97.8% (95% CI 96.3-99.2) in the group on dispersible formulation and 98.5% (97.4-99.7) in the group on crushed formulation. The lower bound of the one-sided 97.5% CI was -2.7%. The most common drug-related adverse event was vomiting (n=33 [7%] and n=42 [9%], respectively). No signs of ototoxicity or relevant cardiotoxicity were seen.

INTERPRETATION

A six-dose regimen of artemether-lumefantrine with the new dispersible formulation is as efficacious as the currently used crushed tablet in infants and children, and has a similar safety profile.

Complications of traditional Chinese/herbal medicines (TCM)--a guide for perplexed oncologists and other cancer caregivers

INTRODUCTION

Cancer patients often seek complementary or alternative medicines to supplement or replace treatments prescribed by licensed medical practitioners. Traditional Chinese/herbal medicine (TCM) is a popular complementary intervention among cancer patients of Asian ethnicity, many of whom take it during their conventional treatment. Few of these patients inform their doctors, however, creating a risk of unexpected sequelae arising from either pharmacologic toxicity, unsuitable dosing, interactions with anti-cancer drugs or other medications, adulteration, or idiosyncratic reactions. If unrecognized, these problems may be misattributed to conventional treatment toxicity or disease progression, and remedial action may be inappropriate or delayed.

GOALS OF WORK

The purpose of this review is to help oncologists recognize the common presentations of TCM-related problems in cancer patients-such as abnormal liver function tests, unexpectedly severe myelosuppression, hemostatic defects, renal functional impairment, or suspected drug interactions-and to teach strategies by which these problems can be anticipated, prevented, or managed.

CONCLUSION

Through sensitive understanding of the reasons favoring TCM usage, oncologists can gain the trust and respect of their TCM-using patients while ensuring the safety and efficacy of conventional anticancer treatments.

Auditory assessment of patients with acute uncomplicated Plasmodium falciparum malaria treated with three-day mefloquine-artesunate on the north-western border of Thailand

Background

The use of artemisinin derivatives has increased exponentially with the deployment of artemisinin combination therapy (ACT) in all malarious areas. They are highly effective and are considered safe, but in animal studies artemisinin derivatives produce neurotoxicity targeting mainly the auditory and vestibular pathways. The debate remains as to whether artemisinin derivatives induce similar toxicity in humans.

Methods

This prospective study assessed the effects on auditory function of a standard 3-day oral dose of artesunate (4 mg/kg/day) combined with mefloquine (25 mg/kg) in patients with acute uncomplicated falciparum malaria treated at the Shoklo Malaria Research Unit, on the Thai-Burmese border. A complete auditory evaluation with tympanometry, audiometry and auditory brainstem responses (ABR) was performed before the first dose and seven days after initiation of the antimalarial treatment.

Results

Complete auditory tests at day 0 (D0) and day 7 (D7) were obtained for 93 patients. Hearing loss (threshold > 25 dB) on admission was common (57%) and associated with age only. No patient had a threshold change exceeding 10 dB between D0 and D7 at any tested frequency. No patient showed a shift in Wave III peak latency of more than 0.30 msec between baseline and D7.

Conclusion

Neither audiometric or the ABR tests showed clinical evidence of auditory toxicity seven days after receiving oral artesunate and mefloquine.

Ototoxicity of artemether/lumefantrine in the treatment of falciparum malaria: a randomized trial

Background

Due to increasing drug resistance, artemisinin-based combination chemotherapy (ACT) has become the first-line treatment of falciparum malaria in many endemic countries. However, irreversible ototoxicity associated with artemether/lumefantrine (AL) has been reported recently and suggested to be a serious limitation in the use of ACT. The aim of the study was to compare ototoxicity, tolerability, and efficacy of ACT with that of quinine and atovaquone/proguanil in the treatment of uncomplicated falciparum malaria.

Methods

Ninety-seven patients in south-west Ethiopia with slide-confirmed malaria were randomly assigned to receive either artemether/lumefantrine or quinine or atovaquone/proguanil and followed-up for 90 days. Comprehensive audiovestibular testing by pure tone audiometry (PTA), transitory evoked (TE) and distortion product (DP) otoacoustic emissions (OAE) and brain stem evoked response audiometry (BERA) was done before enrolment and after seven, 28 and 90 days.

Results

PTA and DP-OAE levels revealed transient significant cochlear hearing loss in patients treated with quinine but not in those treated with artemether/lumefantrine or atovaquone/proguanil. TE-OAE could be elicited in all examinations, except for three patients in the Q group on day 7, who suffered a transient hearing loss greater than 30 dB. There was no evidence of drug-induced brain stem lesions by BERA measurements.

Conclusion

There was no detrimental effect of a standard oral regimen of artemether/lumefantrine on peripheral hearing or brainstem auditory pathways in patients with uncomplicated falciparum malaria. In contrast, transient hearing loss is common after quinine therapy and due to temporary outer hair cell dysfunction.

Safety and tolerability of combination antimalarial therapies for uncomplicated falciparum malaria in Ugandan children

Background

Combination antimalarial therapy is recommended for the treatment of uncomplicated falciparum malaria in Africa; however, some concerns about the safety and tolerability of new regimens remain. This study compared the safety and tolerability of three combination antimalarial regimens in a cohort of Ugandan children.

Methods

A longitudinal, single-blind, randomized clinical trial of children was conducted between November 2004 and May 2007 in Kampala, Uganda. Upon diagnosis of the first episode of uncomplicated malaria, participants were randomized to treatment with amodiaquine + sulphadoxine-pyrimethamine (AQ+SP), artesunate + amodiaquine (AS+AQ), or artemether-lumefantrine (AL). Once randomized, participants received the same regimen for all subsequent episodes of uncomplicated malaria. Participants were actively monitored for adverse events for the first 14 days after each treatment, and then passively followed until their next study medication treatment, or withdrawal from study. Outcome measures included the risk of adverse events at 14 and 42 days after treatment.

Results

Of 601 enrolled children, 382 were diagnosed with at least one episode of uncomplicated malaria and were treated with study medications. The median age at treatment was 6.3 years (range 1.1 – 12.3 years). At 14 days of follow-up, AQ+SP treatment was associated with a higher risk of anorexia, weakness, and subjective fever than treatment with AL, and a higher risk of weakness, and subjective fever than treatment with AS+AQ. Treatment with AL was associated with a higher risk of elevated temperature. Repeated episodes of neutropaenia associated with AS+AQ were detected in one participant. Considering only children less than five years, those who received AQ+SP were at higher risk of developing moderate or severe anorexia and weakness than those treated with AL (anorexia: RR 3.82, 95% CI 1.59 – 9.17; weakness: RR 5.40, 95% CI 1.86 – 15.7), or AS+AQ (anorexia: RR 2.10, 95% CI 1.04 – 4.23; weakness: RR 2.26, 95% CI 1.01 – 5.05). Extending the analysis to 42 days of follow-up had little impact on the findings.

Conclusion

This study confirms the safety and tolerability of AS+AQ and AL in Ugandan children, and suggests that AQ+SP is safe, but less well-tolerated, particularly in younger children. As newer antimalarial regimens are deployed, collecting data on their safety and tolerability will be essential.

Trial registration

Current Controlled Trials Identifier ISRCTN37517549

Polymorphism of antimalaria drug metabolizing, nuclear receptor, and drug transport genes among malaria patients in Zanzibar, East Africa

Artemisinin-based combination therapy is a main strategy for malaria control in Africa. Zanzibar introduced this new treatment policy in 2003. The authors have studied the prevalence of a number of functional single nucleotide polymorphisms (SNPs) in genes associated with the elimination of the artemisinin-based combination therapy compounds in use in Zanzibar to investigate the frequencies of subgroups potentially at higher drug exposure and therefore possible higher risk of toxicity. One hundred three unrelated children with uncomplicated malaria from the Unguja and Pemba islands of Zanzibar were enrolled. With use of polymerase chain reaction (PCR)-restriction fragment length polymorphism and real-time PCR-based allele discrimination methods, the CYP2B6 (G15631T), CYP3A4 (A-392G), CYP3A5 (A6986G, G14690A, 27131-132 insT, C3699T) SNPs and MDR1 SNPs C3435T, G2677T/A, and T-129C were analyzed. PCR product sequencing was applied to regulatory regions of MDR1, the CYP3A4 proximal promoter, and to exons 2 and 5 of PXR, a gene coding for a nuclear factor activated by artemisinin antimalarials and associated with the transcription induction of most of the studied genes. Homozygous subjects for alleles coding for low activity proteins were found at the following frequencies: 1) MDR1: 2.9%; 2) CYP2B6: 9.7%; 3) CYP3A5: 14.1%; and 4) CYP3A4: 49.5%. No functionally relevant allele was found in the analyzed regions of PXR. A new MDR1 SNP was found (T-158C), located in a putative antigen recognition element. Ten (10.1%) subjects were predicted to be low metabolizers simultaneously for CYP3A4 and CYP3A5. This fraction of the population is suggested to be under higher exposure to certain antimalarials, including lumefantrine and quinine.

Assessment of safety of the major antimalarial drugs

Antimalarial drugs remain the major intervention tool for the global malaria control efforts that save millions of lives. Nonetheless, emergence and spread of Plasmodium parasites resistant against chloroquine and other major antimalarial drugs has brought the urgency to develop a new generation of safe and effective drugs against malaria. In this article, the safety data for major antimalarial drugs is reviewed. Although an ample amount of clinical data regarding the safety and tolerability of several of these drugs in older children and adults is available, more critical safety and tolerability studies in pregnant women and young children is desirable. To offset the partial loss in efficacy due to drug resistance in malaria parasites acquired against specific drugs, treatment regimens often rely upon the combination of two or more drugs. However, combination therapy requires additional safety, toxicity and tolerability studies in all population groups where these drugs are administered. A uniform standard in assessing the safety and tolerability of antimalarial drugs will be useful in the formulation and implementation of malaria treatment policies that are based on the drug effectiveness, safety and tolerability.

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.

Evaluation of the safety and relative bioavailability of a new dihydroartemisinin tablet formulation in healthy Thai volunteers

A new dihydroartemisinin (DHA) tablet formulation has been developed by the Thai Government Pharmaceutical Organization (GPO). In this report, its in vitro dissolution and in vivo pharmacokinetics as well as its safety in healthy volunteers were evaluated, using the DHA tablet made by Dafra Pharma NV as a reference. A two-period crossover clinical study design was utilised. Twenty-four volunteers were randomly allocated to two sequences (12 volunteers in each) to receive a 200mg single oral dose of either the GPO or Dafra formulation with a wash-out period of 5-7 days. In vitro, the GPO formulation dissolved more readily. In vivo, the GPO formulation had a higher maximum plasma concentration and approximately 149% (90% CI 125-179%) greater bioavailability. Both formulations were well tolerated. Interestingly, significant decreases in haemoglobin and haematocrit values (P<0.001) were noted following administration of one dose of DHA (decrease of 0.73 g/dl haemoglobin and 2.0% haematocrit compared with baseline) or two doses of DHA (decrease of 0.95 g/dl haemoglobin and 3.3% haematocrit compared with baseline). The second dose was associated with additional toxicity compared with one dose with regard to haematocrit (P<0.001) but not haemoglobin. This finding warrants further investigation, since the drug will be used for the treatment of malaria in which anaemia is a consequence.