Frequency of glucose-6-phosphate dehydrogenase deficiency in malaria patients from six African countries enrolled in two randomized anti-malarial clinical trials

<p>Abstract</p> <p>Background</p> <p>Glucose-6-phosphate dehydrogenase (G6PD) deficiency is common in populations living in malaria endemic areas. G6PD genotype and phenotype were determined for malaria patients enrolled in the chlorproguanil-dapsone-artesunate (CDA) phase III clinical trial programme.</p> <p>Methods</p> <p>Study participants, aged > 1 year, with microscopically confirmed uncomplicated <it>Plasmodium falciparum </it>malaria, and haemoglobin ≥ 70 g/L or haematocrit ≥ 25%, were recruited into two clinical trials conducted in six African countries (Burkina Faso, Ghana, Kenya, Nigeria, Tanzania, Mali). G6PD genotype of the three most common African forms, G6PD*B, G6PD*A (A376G), and G6PD*A- (G202A, A542T, G680T and T968C), were determined and used for frequency estimation. G6PD phenotype was assessed qualitatively using the NADPH fluorescence test. Exploratory analyses investigated the effect of G6PD status on baseline haemoglobin concentration, temperature, asexual parasitaemia and anti-malarial efficacy after treatment with CDA 2/2.5/4 mg/kg or chlorproguanil-dapsone 2/2.5 mg/kg (both given once daily for three days) or six-dose artemether-lumefantrine.</p> <p>Results</p> <p>Of 2264 malaria patients enrolled, 2045 had G6PD genotype available and comprised the primary analysis population (1018 males, 1027 females). G6PD deficiency prevalence was 9.0% (184/2045; 7.2% [N = 147] male hemizygous plus 1.8% [N = 37] female homozygous), 13.3% (273/2045) of patients were heterozygous females, 77.7% (1588/2045) were G6PD normal. All deficient G6PD*A- genotypes were A376G/G202A. G6PD phenotype was available for 64.5% (1319/2045) of patients: 10.2% (134/1319) were G6PD deficient, 9.6% (127/1319) intermediate, and 80.2% (1058/1319) normal. Phenotype test specificity in detecting hemizygous males was 70.7% (70/99) and 48.0% (12/25) for homozygous females. Logistic regression found no significant effect of G6PD genotype on adjusted mean baseline haemoglobin (p = 0.154), adjusted mean baseline temperature (p = 0.9617), or adjusted log mean baseline parasitaemia (p = 0.365). There was no effect of G6PD genotype (p = 0.490) or phenotype (p = 0.391) on the rate of malaria recrudescence, or reinfection (p = 0.134 and p = 0.354, respectively).</p> <p>Conclusions</p> <p>G6PD deficiency is common in African patients with malaria and until a reliable and simple G6PD test is available, the use of 8-aminoquinolines will remain problematic. G6PD status did not impact baseline haemoglobin, parasitaemia or temperature or the outcomes of anti-malarial therapy.</p> <p>Trial registration</p> <p>Clinicaltrials.gov: <a href="http://www.clinicaltrials.gov/ct2/show/NCT00344006">NCT00344006</a> and <a href="http://www.clinicaltrials.gov/ct2/show/NCT00371735">NCT00371735</a>.</p

Review of pyronaridine anti-malarial properties and product characteristics.

Pyronaridine was synthesized in 1970 at the Institute of Chinese Parasitic Disease and has been used in China for over 30 years for the treatment of malaria. Pyronaridine has high potency against Plasmodium falciparum, including chloroquine-resistant strains. Studies in various animal models have shown pyronaridine to be effective against strains resistant to other anti-malarials, including chloroquine. Resistance to pyronaridine appears to emerge slowly and is further retarded when pyronaridine is used in combination with other anti-malarials, in particular, artesunate. Pyronaridine toxicity is generally less than that of chloroquine, though evidence of embryotoxicity in rodents suggests use with caution in pregnancy. Clinical pharmacokinetic data for pyronaridine indicates an elimination T1/2 of 13.2 and 9.6 days, respectively, in adults and children with acute uncomplicated falciparum and vivax malaria in artemisinin-combination therapy. Clinical data for mono or combined pyronaridine therapy show excellent anti-malarial effects against P. falciparum and studies of combination therapy also show promise against Plasmodium vivax. Pyronaridine has been developed as a fixed dose combination therapy, in a 3:1 ratio, with artesunate for the treatment of acute uncomplicated P. falciparum malaria and blood stage P. vivax malaria with the name of Pyramax® and has received Positive Opinion by European Medicines Agency under the Article 58 procedure

Clinical spectrum and severity of hemolytic anemia in glucose 6-phosphate dehydrogenase-deficient children receiving dapsone

Drug-induced acute hemolytic anemia led to the discovery of G6PD deficiency. However, most clinical data are from isolated case reports. In 2 clinical trials of antimalarial preparations containing dapsone (4,4′-diaminodiphenylsulfone; 2.5 mg/kg once daily for 3 days), 95 G6PD-deficient hemizygous boys, 24 G6PD-deficient homozygous girls, and 200 girls heterozygous for G6PD deficiency received this agent. In the first 2 groups, there was a maximum decrease in hemoglobin averaging -2.64 g/dL (range -6.70 to +0.30 g/dL), which was significantly greater than for the comparator group receiving artemether-lumefantrine (adjusted difference -1.46 g/dL; 95% confidence interval -1.76, -1.15). Hemoglobin concentrations were decreased by ≥ 40% versus pretreatment in 24/119 (20.2%) of the G6PD-deficient children; 13/119 (10.9%) required blood transfusion. In the heterozygous girls, the mean maximum decrease in hemoglobin was -1.83 g/dL (range +0.90 to -5.20 g/dL); 1 in 200 (0.5%) required blood transfusion. All children eventually recovered. All the G6PD-deficient children had the G6PD A- variant, ie, mutations V68MandN126D. Drug-induced acutehemolytic anemia in G6PD A- subjects can be life-threatening, depending on the nature and dosage of the drug trigger. Therefore, contrary to current perception, in clinical terms the A- type of G6PD deficiency cannot be regarded as mild. This study is registered at http://www.clinicaltrials.gov as NCT00344006 and NCT00371735. © 2012 by The American Society of Hematology

Review of the clinical pharmacokinetics of artesunate and its active metabolite dihydroartemisinin following intravenous, intramuscular, oral or rectal administration

Artesunate (AS) is a clinically versatile artemisinin derivative utilized for the treatment of mild to severe malaria infection. Given the therapeutic significance of AS and the necessity of appropriate AS dosing, substantial research has been performed investigating the pharmacokinetics of AS and its active metabolite dihydroartemisinin (DHA). In this article, a comprehensive review is presented of AS clinical pharmacokinetics following administration of AS by the intravenous (IV), intramuscular (IM), oral or rectal routes. Intravenous AS is associated with high initial AS concentrations which subsequently decline rapidly, with typical AS half-life estimates of less than 15 minutes. AS clearance and volume estimates average 2 - 3 L/kg/hr and 0.1 - 0.3 L/kg, respectively. DHA concentrations peak within 25 minutes post-dose, and DHA is eliminated with a half-life of 30 - 60 minutes. DHA clearance and volume average between 0.5 - 1.5 L/kg/hr and 0.5 - 1.0 L/kg, respectively. Compared to IV administration, IM administration produces lower peaks, longer half-life values, and higher volumes of distribution for AS, as well as delayed peaks for DHA; other parameters are generally similar due to the high bioavailability, assessed by exposure to DHA, associated with IM AS administration (> 86%). Similarly high bioavailability of DHA (> 80%) is associated with oral administration. Following oral AS, peak AS concentrations (Cmax) are achieved within one hour, and AS is eliminated with a half-life of 20 - 45 minutes. DHA Cmax values are observed within two hours post-dose; DHA half-life values average 0.5 - 1.5 hours. AUC values reported for AS are often substantially lower than those reported for DHA following oral AS administration. Rectal AS administration yields pharmacokinetic results similar to those obtained from oral administration, with the exceptions of delayed AS Cmax and longer AS half-life. Drug interaction studies conducted with oral AS suggest that AS does not appreciably alter the pharmacokinetics of atovaquone/proguanil, chlorproguanil/dapsone, or sulphadoxine/pyrimethamine, and mefloquine and pyronaridine do not alter the pharmacokinetics of DHA. Finally, there is evidence suggesting that the pharmacokinetics of AS and/or DHA following AS administration may be altered by pregnancy and by acute malaria infection, but further investigation would be required to define those alterations precisely

Clinical spectrum and severity of hemolytic anemia in glucose 6-phosphate dehydrogenase-deficient children receiving dapsone

Drug-induced acute hemolytic anemia led to the discovery of G6PD deficiency. However, most clinical data are from isolated case reports. In 2 clinical trials of antimalarial preparations containing dapsone (4,4′-diaminodiphenylsulfone; 2.5 mg/kg once daily for 3 days), 95 G6PD-deficient hemizygous boys, 24 G6PD-deficient homozygous girls, and 200 girls heterozygous for G6PD deficiency received this agent. In the first 2 groups, there was a maximum decrease in hemoglobin averaging -2.64 g/dL (range -6.70 to +0.30 g/dL), which was significantly greater than for the comparator group receiving artemether-lumefantrine (adjusted difference -1.46 g/dL; 95% confidence interval -1.76, -1.15). Hemoglobin concentrations were decreased by ≥ 40% versus pretreatment in 24/119 (20.2%) of the G6PD-deficient children; 13/119 (10.9%) required blood transfusion. In the heterozygous girls, the mean maximum decrease in hemoglobin was -1.83 g/dL (range +0.90 to -5.20 g/dL); 1 in 200 (0.5%) required blood transfusion. All children eventually recovered. All the G6PD-deficient children had the G6PD A- variant, ie, mutations V68MandN126D. Drug-induced acutehemolytic anemia in G6PD A- subjects can be life-threatening, depending on the nature and dosage of the drug trigger. Therefore, contrary to current perception, in clinical terms the A- type of G6PD deficiency cannot be regarded as mild. This study is registered at http://www.clinicaltrials.gov as NCT00344006 and NCT00371735. © 2012 by The American Society of Hematology

Safety, Tolerability, Pharmacokinetics, and Antimalarial Activity of the Novel Plasmodium Phosphatidylinositol 4-Kinase Inhibitor MMV390048 in Healthy Volunteers.

MMV390048 is a novel antimalarial compound that inhibits Plasmodium phosphatidylinositol-4-kinase. The safety, tolerability, pharmacokinetic profile, and antimalarial activity of MMV390048 were determined in healthy volunteers in three separate studies. A first-in-human, double-blind, randomized, placebo-controlled, single-ascending-dose study was performed. Additionally, a volunteer infection study investigated the antimalarial activity of MMV390048 using the Plasmodium falciparum induced blood-stage malaria (IBSM) model. Due to the high pharmacokinetic variability with the powder-in-bottle formulation used in both of these studies, a third study was undertaken to select a tablet formulation of MMV390048 to take forward into future studies. MMV390048 was generally well tolerated when administered as a single oral dose up to 120 mg, with rapid absorption and a long elimination half-life. Twelve adverse events were considered to be potentially related to MMV390048 in the first-in-human study but with no obvious correlation between these and MMV390048 dose or exposure. Although antimalarial activity was evident in the IBSM study, rapid recrudescence occurred in most subjects after treatment with 20 mg MMV390048, a dose expected to be subtherapeutic. Reformulation of MMV390048 into two tablet formulations (tartaric acid and Syloid) resulted in significantly reduced intersubject pharmacokinetic variability. Overall, the results of this study suggest that MMV390048 is well tolerated in humans, and the pharmacokinetic properties of the compound indicate that it has the potential to be used for antimalarial prophylaxis or inclusion in a single-dose cure. MMV390048 is currently being tested in a phase 2a study in Ethiopian adults with acute, uncomplicated falciparum or vivax malaria monoinfection. (The three clinical trials described here were each registered with ClinicalTrials.gov as follows: first-in-human study, registration no. NCT02230579; IBSM study, registration no. NCT02281344; and formulation optimization study, registration no. NCT02554799.)

Randomised controlled trial of two sequential artemisinin-based combination therapy regimens to treat uncomplicated falciparum malaria in African children: a protocol to investigate safety, efficacy and adherence.

BACKGROUND: Management of uncomplicated Plasmodium falciparum malaria relies on artemisinin-based combination therapies (ACTs). These highly effective regimens have contributed to reductions in malaria morbidity and mortality. However, artemisinin resistance in Asia and changing parasite susceptibility to ACT in Africa have now been well documented. Strategies that retain current ACT as efficacious treatments are urgently needed. METHODS: We present an open-label, randomised three-arm clinical trial protocol in three African settings representative of varying malaria epidemiology to investigate whether prolonged ACT-based regimens using currently available formulations can eliminate potentially resistant parasites. The protocol investigates whether a sequential course of two licensed ACT in 1080 children aged 6-120 months exhibits superior efficacy against acute P. falciparum malaria and non-inferior safety compared with standard single-course ACT given to 540 children. The primary endpoint is PCR-corrected clinical and parasitological response at day 42 or day 63 of follow-up. Persistence of PCR-detectable parasitaemia at day 3 is analysed as a key covariate. Secondary endpoints include gametocytaemia, occurrence of treatment-related adverse events in the double-ACT versus single-ACT arms, carriage of molecular markers of drug resistance, drug kinetics and patient adherence to treatment. DISCUSSION: This protocol addresses efficacy and safety of sequential ACT regimens in P. falciparum malaria in Africa. The approach is designed to extend the useful life of this class of antimalarials with maximal impact and minimal delay, by deploying licensed medicines that could be swiftly implemented as sequential double ACT by National Malaria Control Programmes, before emerging drug resistance in Africa becomes a major threat to public health

Safety of a fixed-dose combination of artesunate and amodiaquine for the treatment of uncomplicated Plasmodium falciparum malaria in real-life conditions of use in Côte d’Ivoire

Additional file 2. Adverse-event reporting as a function of the interval between treatment initiation and the home visit

Open-label comparative clinical study of chlorproguanil-dapsone fixed dose combination (Lapdap) alone or with three different doses of artesunate for uncomplicated Plasmodium falciparum malaria.

UNLABELLED: The objective of this study was to determine the appropriate dose of artesunate for use in a fixed dose combination therapy with chlorproguanil-dapsone (CPG-DDS) for the treatment of uncomplicated falciparum malaria. METHODS: Open-label clinical trial comparing CPG-DDS alone or with artesunate 4, 2, or 1 mg/kg at medical centers in Blantyre, Malawi and Farafenni, The Gambia. The trial was conducted between June 2002 and February 2005, including 116 adults (median age 27 years) and 107 children (median age 38 months) with acute uncomplicated Plasmodium falciparum malaria. Subjects were randomized into 4 groups to receive CPG-DDS alone or plus 4, 2 or 1 mg/kg of artesunate once daily for 3 days. Assessments took place on Days 0-3 in hospital and follow-up on Days 7 and 14 as out-patients. Efficacy was evaluated in the Day 3 per-protocol (PP) population using mean time to reduce baseline parasitemia by 90% (PC90). A number of secondary outcomes were also included. Appropriate artesunate dose was determined using a pre-defined decision matrix based on primary and secondary outcomes. Treatment emergent adverse events were recorded from clinical assessments and blood parameters. Safety was evaluated in the intent to treat (ITT) population. RESULTS: In the Day 3 PP population for the adult group (N = 85), mean time to PC90 was 19.1 h in the CPG-DDS group, significantly longer than for the +artesunate 1 mg/kg (12.5 h; treatment difference -6.6 h [95%CI -11.8, -1.5]), 2 mg/kg (10.7 h; -8.4 h [95%CI -13.6, -3.2]) and 4 mg/kg (10.3 h; -8.7 h [95%CI -14.1, -3.2]) groups. For children in the Day 3 PP population (N = 92), mean time to PC90 was 21.1 h in the CPG-DDS group, similar to the +artesunate 1 mg/kg group (17.7 h; -3.3 h [95%CI -8.6, 2.0]), though the +artesunate 2 mg/kg and 4 mg/kg groups had significantly shorter mean times to PC90 versus CPG-DDS; 14.4 h (treatment difference -6.4 h [95%CI -11.7, -1.0]) and 12.8 h (-7.4 h [95%CI -12.9, -1.8]), respectively. An analysis of mean time to PC90 for the Day 14 PP and ITT populations was consistent with the primary analysis. Treatment emergent, drug-related adverse events were experienced in 35.3% (41/116) of adults and 70.1% (75/107) of children; mostly hematological and gastroenterological. The nature and incidence of adverse events was similar between the groups. No dose-related changes in laboratory parameters were observed. Nine serious adverse events due to any cause occurred in five subjects including two cases of hemolysis believed to be associated with drug treatment (one adult, one child). One adult died of anaphylactic shock, not associated with investigational therapy. CONCLUSIONS: CPG-DDS plus artesunate demonstrated advantages over CPG-DDS alone for the primary efficacy endpoint (mean time to PC90) except in children for the 1 mg/kg artesunate dose. Based on a pre-defined decision matrix, the primary endpoint in the child group supported an artesunate dose of 4 mg/kg. Secondary endpoints also supported a 4 mg/kg artesunate dose to take forward into the remainder of the development program. TRIAL REGISTRATION: ClinicalTrials.gov NCT00519467

Drug-Drug Interaction Analysis of Pyronaridine/Artesunate and Ritonavir in Healthy Volunteers

A multiple dose, parallel group study was conducted to assess for a drug-drug interaction between the pyronaridine/artesunate (PA) combination antimalarial and ritonavir. Thirty-four healthy adults were randomized (1:1) to receive PA for 3 days or PA with ritonavir (100 mg twice daily for 17 days, PA administered on Days 8–10). Pharmacokinetic parameters for pyronaridine, artesunate, and its active metabolite dihydroartemisinin (DHA) were obtained after the last PA dose and for ritonavir on Days 1 and 10. Ritonavir coadministration did not markedly change pyronaridine pharmacokinetics but resulted in a 27% increase in artesunate area under the curve (AUC) and a 38% decrease in DHA AUC. Ritonavir exposure was increased 3.2-fold in the presence of PA. The only relevant safety observations were increases in liver enzymes, only reaching a clinically significant grade in the PA + ritonavir arm. It was concluded that coadministered ritonavir and PA interact to alter exposure to artesunate, DHA, and ritonavir itself