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Challenges in classifying recurrent Plasmodium vivax infections constrain surveillance of antimalarial efficacy and transmission. Recurrent infections may arise from activation of dormant liver stages (relapse), blood-stage treatment failure (recrudescence) or reinfection. Molecular inference of familial relatedness (identity-by-descent or IBD) can help resolve the probable origin of recurrences. As whole genome sequencing of P. vivax remains challenging, targeted genotyping methods are needed for scalability. We describe a P. vivax marker discovery framework to identify and select panels of microhaplotypes (multi-allelic markers within small, amplifiable segments of the genome) that can accurately capture IBD. We evaluate panels of 50-250 microhaplotypes discovered in a global set of 615 P. vivax genomes. A candidate global 100-microhaplotype panel exhibits high marker diversity in the Asia-Pacific, Latin America and horn of Africa (median HE = 0.70-0.81) and identifies 89% of the polyclonal infections detected with genome-wide datasets. Data simulations reveal lower error in estimating pairwise IBD using microhaplotypes relative to traditional biallelic SNP barcodes. The candidate global panel also exhibits high accuracy in predicting geographic origin and captures local infection outbreak and bottlenecking events. Our framework is open-source enabling customised microhaplotype discovery and selection, with potential for porting to other species or data resources.
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Malaria Vivax , Plasmodium vivax , Recurrencia , Plasmodium vivax/genética , Malaria Vivax/parasitología , Malaria Vivax/epidemiología , Humanos , Haplotipos/genética , Polimorfismo de Nucleótido Simple , Genoma de Protozoos/genética , GenotipoRESUMEN
AIMS: This study describes the pharmacokinetic (PK)/target engagement (TE) relationship of tozorakimab, an anti-interleukin (IL)-33 antibody, by building a mechanistic population PK/TE model using phase 1 biomarker data. METHODS: The analysis included tozorakimab PK and TE in serum assessed in 60 tozorakimab-treated participants, including healthy adults and patients with mild chronic obstructive pulmonary disease. Scenarios evaluated three dose frequencies (once every 2, 4 or 6 weeks) administered subcutaneously at seven doses of tozorakimab (30, 60, 90, 120, 150, 300 or 600 mg). For each dose, simulations were performed with 5000 virtual individuals to predict systemic TE. Inhibition of IL-33/soluble ST2 (sST2) complex levels at trough PK at steady state was assessed in each dosing scenario. The PK/TE modelling analyses were performed using a nonlinear mixed-effect modelling approach. RESULTS: The final two-compartment PK model with tozorakimab binding IL-33 in the central compartment adequately described the systemic PK and TE of tozorakimab at population and individual levels. The mean PK parameter estimates of absorption rate, central volume of distribution and clearance were 0.48 (90% confidence interval [CI]: 0.40-0.59, 1/day), 12.64 (90% CI: 8.60-18.62, L) and 0.87 (90% CI: 0.65-1.16, L/day), respectively. Consistent with the observed value, tozorakimab bioavailability was 45%. For all three dose frequencies, predicted inhibition of systemic IL-33/sST2 levels was more than 95% at doses greater than 90 mg. CONCLUSIONS: The PK/TE model reliably quantified the relationship between PK and systemic TE of tozorakimab, with potential utility for predicting clinical dose-response relationships and supporting clinical dose selection.
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Plasmodium vivax is now the main cause of malaria outside Africa. The gametocytocidal effects of antimalarial drugs are important to reduce malaria transmissibility, particularly in low-transmission settings, but they are not well characterized for P. vivax. The transmission-blocking effects of chloroquine, artesunate, and methylene blue on P. vivax gametocytes were assessed. Blood specimens were collected from patients presenting with vivax malaria, incubated with or without the tested drugs, and then fed to mosquitos from a laboratory-adapted colony of Anopheles dirus (a major malaria vector in Southeast Asia). The effects on oocyst and sporozoite development were analyzed under a multi-level Bayesian model accounting for assay variability and the heterogeneity of mosquito Plasmodium infection. Artesunate and methylene blue, but not chloroquine, exhibited potent transmission-blocking effects. Gametocyte exposures to artesunate and methylene blue reduced the mean oocyst count 469-fold (95% CI: 345 to 650) and 1,438-fold (95% CI: 970 to 2,064), respectively. The corresponding estimates for the sporozoite stage were a 148-fold reduction (95% CI: 61 to 470) and a 536-fold reduction (95% CI: 246 to 1,311) in the mean counts, respectively. In contrast, high chloroquine exposures reduced the mean oocyst count only 1.40-fold (95% CI: 1.20 to 1.64) and the mean sporozoite count 1.34-fold (95% CI: 1.12 to 1.66). This suggests that patients with vivax malaria often remain infectious to anopheline mosquitos after treatment with chloroquine. Use of artemisinin combination therapies or immediate initiation of primaquine radical cure should reduce the transmissibility of P. vivax infections.
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A porous three-component hydrogen bonded framework, 1â biphenâ TP, was prepared from a tetra-amidinium component (14+) and two different dianions, benzene-1,4-dicarboxylate (terephthalate, TP2-) and biphenyl-4,4'-dicarboxylate (biphen2-). Interestingly, when the framework was prepared in ethanol/water, 1â biphenâ TP forms even when an excess of either dicarboxylate is present. However, when only water is used as solvent, only two-component frameworks are formed.
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In preparation for mass vaccinations with R21/Matrix-M™ combined with mass administrations of dihydroartemisinin, piperaquine, and a single low dose primaquine we assessed the tolerability, safety, and potential interactions of this combination affecting immunogenicity or pharmacokinetics. 120 healthy Thai volunteers were randomised to receive either antimalarials combined with vaccinations (n = 50), vaccinations alone (n = 50), or antimalarials only (n = 20). Three rounds of vaccines and antimalarials were administered one month apart. The vaccine was well tolerated alone and in combination with the antimalarials. None of the participants failed completion of the 3-dose vaccine course. There was no significant difference in the vaccine immunogenicity or in the pharmacokinetics of piperaquine given individually or in combination. This study supports proceeding to a large trial of mass vaccinations with R21/Matrix-M™ combined with mass antimalarial administration in Bangladesh.
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Investment in community health workers is essential.
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Antimaláricos , Artemisininas , Agentes Comunitarios de Salud , Resistencia a Medicamentos , Malaria Falciparum , Plasmodium falciparum , Humanos , África/epidemiología , Antimaláricos/uso terapéutico , Artemisininas/uso terapéutico , Artemisininas/farmacología , Agentes Comunitarios de Salud/economía , Resistencia a Medicamentos/genética , Malaria Falciparum/tratamiento farmacológico , Malaria Falciparum/epidemiología , Plasmodium falciparum/efectos de los fármacos , Plasmodium falciparum/genéticaRESUMEN
Disturbed flow is one of the pathological initiators of endothelial dysfunction in intimal hyperplasia (IH) which is commonly seen in vascular bypass grafts, and arteriovenous fistulas. Various in vitro disease models have been designed to simulate the hemodynamic conditions found in the vasculature. Nonetheless, prior investigations have encountered challenges in establishing a robust disturbed flow model, primarily attributed to the complex bifurcated geometries and distinctive flow dynamics. In the present study, we aim to address this gap by introducing an in vitro bypass flow model capable of inducing disturbed flow and other hemodynamics patterns through a pulsatile flow in the same model. To assess the model's validity, we employed computational fluid dynamics (CFD) to simulate hemodynamics and compared the morphology and functions of human umbilical venous endothelial cells (HUVECs) under disturbed flow conditions to those in physiological flow or stagnant conditions. CFD analysis revealed the generation of disturbed flow within the model, pinpointing the specific location in the channel where the effects of disturbed flow were observed. High-content screening, a single-cell morphological profile assessment, demonstrated that HUVECs in the disturbed flow area exhibited random orientation, and morphological features were significantly distinct compared to cells in the physiological flow or stagnant condition after a two days of flow exposure. Furthermore, HUVECs exposed to disturbed flow underwent extensive remodeling of the adherens junctions and expressed higher levels of endothelial cell activation markers compared to other hemodynamic conditions. In conclusion, our in vitro bypass flow model provides a robust platform for investigating the associations between disturbed flow pattern and vascular diseases.
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BACKGROUND: Artemisinin resistance in Plasmodium falciparum threatens global malaria elimination efforts. To contain and then eliminate artemisinin resistance in Eastern Myanmar a network of community-based malaria posts was instituted and targeted mass drug administration (MDA) with dihydroartemisinin-piperaquine (three rounds at monthly intervals) was conducted. The prevalence of artemisinin resistance during the elimination campaign (2013-2019) was characterized. METHODS: Throughout the six-year campaign Plasmodium falciparum positive blood samples from symptomatic patients and from cross-sectional surveys were genotyped for mutations in kelch-13-a molecular marker of artemisinin resistance. RESULT: The program resulted in near elimination of falciparum malaria. Of 5162 P. falciparum positive blood samples genotyped, 3281 (63.6%) had K13 mutations. The prevalence of K13 mutations was 73.9% in 2013 and 64.4% in 2019. Overall, there was a small but significant decline in the proportion of K13 mutants (p < 0.001). In the MDA villages there was no significant change in the K13 proportions before and after MDA. The distribution of different K13 mutations changed substantially; F446I and P441L mutations increased in both MDA and non-MDA villages, while most other K13 mutations decreased. The proportion of C580Y mutations fell from 9.2% (43/467) before MDA to 2.3% (19/813) after MDA (p < 0.001). Similar changes occurred in the 487 villages where MDA was not conducted. CONCLUSION: The malaria elimination program in Kayin state, eastern Myanmar, led to a substantial reduction in falciparum malaria. Despite the intense use of artemisinin-based combination therapies, both in treatment and MDA, this did not select for artemisinin resistance.
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Antimaláricos , Artemisininas , Resistencia a Medicamentos , Malaria Falciparum , Plasmodium falciparum , Artemisininas/farmacología , Artemisininas/uso terapéutico , Mianmar , Malaria Falciparum/parasitología , Malaria Falciparum/epidemiología , Antimaláricos/farmacología , Antimaláricos/uso terapéutico , Resistencia a Medicamentos/genética , Plasmodium falciparum/efectos de los fármacos , Plasmodium falciparum/genética , Humanos , Estudios Transversales , Femenino , Masculino , Adolescente , Adulto , Administración Masiva de Medicamentos , Adulto Joven , Mutación , Niño , Preescolar , Persona de Mediana Edad , Quinolinas/farmacología , Quinolinas/uso terapéutico , Erradicación de la Enfermedad/estadística & datos numéricos , PiperazinasRESUMEN
Current guidelines advise against primaquine treatment for breastfeeding mothers to avoid the potential for haemolysis in infants with G6PD deficiency. To predict the haemolytic risk, the amount of drug received from the breast milk and the resulting infant drug exposure need to be characterised. Here, we develop a pharmacokinetic model to describe the drug concentrations in breastfeeding women using venous, capillary, and breast milk data. A mother-to-infant model is developed to mimic the infant feeding pattern and used to predict their drug exposures. Primaquine and carboxyprimaquine exposures in infants are <1% of the exposure in mothers. Therefore, even in infants with the most severe G6PD deficiency variants, it is highly unlikely that standard doses of primaquine (0.25-1 mg base/kg once daily given to the mother for 1-14 days) would cause significant haemolysis. After the neonatal period, primaquine should not be restricted for breastfeeding women (Clinical Trials Registration: NCT01780753).
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Antimaláricos , Lactancia Materna , Lactancia , Leche Humana , Primaquina , Humanos , Femenino , Primaquina/farmacocinética , Primaquina/administración & dosificación , Antimaláricos/farmacocinética , Antimaláricos/administración & dosificación , Lactante , Leche Humana/química , Leche Humana/metabolismo , Adulto , Recién Nacido , Hemólisis/efectos de los fármacos , Modelos BiológicosRESUMEN
BACKGROUND: The COVID-19 pandemic affected all WHO member states. We compared and contrasted the COVID-19 treatment guidelines of each member state with the WHO COVID-19 therapeutic guidelines. METHODS: Ministries of Health or accessed National Infectious Disease websites and other relevant bodies and experts were contacted to obtain national guidelines (NGs) for COVID-19 treatment. NGs were included only if they delineated specific pharmacological treatments for COVID-19, which were stratified by disease severity. We conducted a retrospective review using the adapted Reporting Checklist for Public Versions of Guidelines (RIGHT-PVG) survey checklist and a derived comparative metric based on the WHO guidelines was performed. RESULTS: COVID-19 therapeutics NGs could be obtained from 109 of the 194 WHO member states. There was considerable variation in guidelines and in disease severity stratifications. Therapeutic recommendations in many NGs differed substantially from the WHO guidelines. Overall in late 2022, 93% of NGs were recommending at least one treatment which had proved to be ineffective in large randomised trials, and was not recommended by WHO. Corticosteroids were not recommended in severe disease in nearly 10% of NGs despite overwhelming evidence of their benefit. NGs from countries with low-resource settings showed the greatest divergence when stratified by gross domestic product per year, Human Development Index and the Global Health Security Index. DISCUSSION: Our study is limited to NGs that were readily accessible, and it does not reflect the availability of recommended medicines in the field. Three years after the start of the SARS-CoV-2 pandemic, available COVID-19 NGs vary substantially in their therapeutic recommendations, often differ from the WHO guidelines, and commonly recommend ineffective, unaffordable or unavailable medicines.
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Tratamiento Farmacológico de COVID-19 , COVID-19 , Guías de Práctica Clínica como Asunto , SARS-CoV-2 , Organización Mundial de la Salud , Humanos , Estudios Retrospectivos , Antivirales/uso terapéutico , Pandemias , Salud GlobalRESUMEN
Capillary samples offer practical benefits compared with venous samples for the measurement of drug concentrations, but the relationship between the two measures varies between different drugs. We measured the concentrations of lumefantrine, mefloquine, piperaquine in 270 pairs of venous plasma and concurrent capillary plasma samples collected from 270 pregnant women with uncomplicated falciparum or vivax malaria. The median and range of venous plasma concentrations included in this study were 447.5 ng/mL (8.81-3,370) for lumefantrine (day 7, n = 76, median total dose received 96.0 mg/kg), 17.9 ng/mL (1.72-181) for desbutyl-lumefantrine, 1,885 ng/mL (762-4,830) for mefloquine (days 3-21, n = 90, median total dose 24.9 mg/kg), 641 ng/mL (79.9-1,950) for carboxy-mefloquine, and 51.8 ng/mL (3.57-851) for piperaquine (days 3-21, n = 89, median total dose 52.2 mg/kg). Although venous and capillary plasma concentrations showed a high correlation (Pearson's correlation coefficient: 0.90-0.99) for all antimalarials and their primary metabolites, they were not directly interchangeable. Using the concurrent capillary plasma concentrations and other variables, the proportions of venous plasma samples predicted within a ±10% precision range was 34% (26/76) for lumefantrine, 36% (32/89) for desbutyl-lumefantrine, 74% (67/90) for mefloquine, 82% (74/90) for carboxy-mefloquine, and 24% (21/89) for piperaquine. Venous plasma concentrations of mefloquine, but not lumefantrine and piperaquine, could be predicted by capillary plasma samples with an acceptable level of agreement. Capillary plasma samples can be utilized for pharmacokinetic and clinical studies, but caution surrounding cut-off values is required at the individual level.CLINICAL TRIALSThis study is registered with ClinicalTrials.gov as NCT01054248.
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Antimaláricos , Lumefantrina , Malaria Falciparum , Malaria Vivax , Mefloquina , Piperazinas , Quinolinas , Humanos , Femenino , Mefloquina/sangre , Mefloquina/uso terapéutico , Mefloquina/farmacocinética , Antimaláricos/sangre , Antimaláricos/uso terapéutico , Antimaláricos/farmacocinética , Embarazo , Quinolinas/sangre , Quinolinas/farmacocinética , Quinolinas/uso terapéutico , Lumefantrina/uso terapéutico , Lumefantrina/sangre , Malaria Falciparum/tratamiento farmacológico , Malaria Falciparum/sangre , Adulto , Malaria Vivax/tratamiento farmacológico , Malaria Vivax/sangre , Adulto Joven , Etanolaminas/sangre , Etanolaminas/farmacocinética , Etanolaminas/uso terapéutico , Fluorenos/sangre , Fluorenos/uso terapéutico , Fluorenos/farmacocinética , AdolescenteRESUMEN
BACKGROUND: Effective antiviral drugs prevent hospitalisation and death from COVID-19. Antiviral efficacy can be efficiently assessed in vivo by measuring rates of SARS-CoV-2 clearance estimated from serial viral genome densities quantitated in nasopharyngeal or oropharyngeal swab eluates. We conducted an individual patient data meta-analysis of unblinded arms in the PLATCOV platform trial to characterise changes in viral clearance kinetics and infer optimal design and interpretation of antiviral pharmacometric evaluations. METHODS: Serial viral density data were analysed from symptomatic, previously healthy, adult patients (within 4 days of symptom onset) enrolled in a large multicentre, randomised, adaptive, pharmacodynamic, platform trial (PLATCOV) comparing antiviral interventions for SARS-CoV-2. Viral clearance rates over 1 week were estimated under a hierarchical Bayesian linear model with B-splines used to characterise temporal changes in enrolment viral densities and clearance rates. Bootstrap re-sampling was used to assess the optimal duration of follow-up for pharmacometric assessment, where optimal was defined as maximising the expected Z score when comparing effective antivirals with no treatment. PLATCOV is registered at ClinicalTrials.gov, NCT05041907. FINDINGS: Between Sept 29, 2021, and Oct 20, 2023, 1262 patients were randomly assigned in the PLATCOV trial. Unblinded data were available from 800 patients (who provided 16â818 oropharyngeal viral quantitative PCR [qPCR] measurements), of whom 504 (63%) were female. 783 (98%) patients had received at least one vaccine dose and 703 (88%) were fully vaccinated. SARS-CoV-2 viral clearance was biphasic (bi-exponential). The first phase (α) was accelerated by effective interventions. For all the effective interventions studied, maximum discriminative power (maximum expected Z score) was obtained when evaluating serial data from the first 5 days after enrolment. Over the 2-year period studied, median viral clearance half-lives estimated over 7 days shortened from 16·6 h (IQR 15·3 to 18·2) in September, 2021, to 9·2 h (8·0 to 10·6) in October, 2023, in patients receiving no antiviral drugs, equivalent to a relative reduction of 44% (95% credible interval [CrI] 19 to 64). A parallel reduction in viral clearance half-lives over time was observed in patients receiving antiviral drugs. For example, in the 158 patients assigned to ritonavir-boosted nirmatrelvir (3380 qPCR measurements), the median viral clearance half-life reduced from 6·4 h (IQR 5·7 to 7·3) in June, 2022, to 4·8 h (4·2 to 5·5) in October, 2023, a relative reduction of 26% (95% CrI -4 to 42). INTERPRETATION: SARS-CoV-2 viral clearance kinetics in symptomatic, vaccinated individuals accelerated substantially over 2 years of the pandemic, necessitating a change to how new SARS-CoV-2 antivirals are compared (ie, shortening the period of pharmacodynamic assessment). As of writing (October, 2023), antiviral efficacy in COVID-19 can be efficiently assessed in vivo using serial qPCRs from duplicate oropharyngeal swab eluates taken daily for 5 days after drug administration. FUNDING: Wellcome Trust.
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Antivirales , COVID-19 , SARS-CoV-2 , Humanos , SARS-CoV-2/efectos de los fármacos , COVID-19/virología , Antivirales/uso terapéutico , Antivirales/farmacocinética , Antivirales/farmacología , Femenino , Adulto , Masculino , Persona de Mediana Edad , Tratamiento Farmacológico de COVID-19 , Betacoronavirus/efectos de los fármacos , Carga Viral/efectos de los fármacos , Teorema de Bayes , Pandemias , Infecciones por Coronavirus/tratamiento farmacológico , Infecciones por Coronavirus/virología , Neumonía Viral/tratamiento farmacológico , Neumonía Viral/virología , AncianoRESUMEN
BACKGROUND: Effective antiviral drugs accelerate viral clearance in acute COVID-19 infections; the relationship between accelerating viral clearance and reducing severe clinical outcomes is unclear. METHODS: A systematic review was conducted of randomized controlled trials (RCTs) of antiviral therapies in early symptomatic COVID-19, where viral clearance data were available. Treatment benefit was defined clinically as the relative risk of hospitalization/death during follow-up (≥14â days), and virologically as the SARS-CoV-2 viral clearance rate ratio (VCRR). The VCRR is the ratio of viral clearance rates between the intervention and control arms. The relationship between the clinical and virological treatment effects was assessed by mixed-effects meta-regression. RESULTS: From 57 potentially eligible RCTs, VCRRs were derived for 44 (52â384 participants); 32 had ≥1 clinical endpoint in each arm. Overall, 9.7% (R2) of the variation in clinical benefit was explained by variation in VCRRs with an estimated linear coefficient of -0.92 (95% CI: -1.99 to 0.13; Pâ=â0.08). However, this estimate was highly sensitive to the inclusion of the recent very large PANORAMIC trial. Omitting this outlier, half the variation in clinical benefit (R2â=â50.4%) was explained by variation in VCRRs [slope -1.47 (95% CI -2.43 to -0.51); Pâ=â0.003], i.e. higher VCRRs were associated with an increased clinical benefit. CONCLUSION: Methods of determining viral clearance in COVID-19 studies and the relationship to clinical outcomes vary greatly. As prohibitively large sample sizes are now required to show clinical treatment benefit in antiviral therapeutic assessments, viral clearance is a reasonable surrogate endpoint.
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Antivirales , Tratamiento Farmacológico de COVID-19 , COVID-19 , Progresión de la Enfermedad , SARS-CoV-2 , Humanos , COVID-19/virología , Antivirales/uso terapéutico , SARS-CoV-2/efectos de los fármacos , Ensayos Clínicos Controlados Aleatorios como Asunto , Carga Viral/efectos de los fármacos , Resultado del Tratamiento , HospitalizaciónRESUMEN
OBJECTIVE: Hemodialysis patients usually receive an arteriovenous fistula (AVF) in the arm as vascular access conduit to allow dialysis 2-3 times a week. This AVF introduces the high flow necessary for dialysis, but over time the ever-present supraphysiological flow is the leading cause of complications. This study aims to develop an implantable device able to non-invasively remove the high flow outside dialysis sessions. METHODS: The developed prototype features a magnetic ring allowing external coupling and torque transmission to non-invasively control an AVF valve. Mock-up devices were implanted into arm and sheep cadavers to test sizes and locations. The transmission torque, output force, and valve closure are measured for different representative skin thicknesses. RESULTS: The prototype was placed successfully into arm and sheep cadavers. In the prototype, a maximum output force of 78.9 ± 4.2 N, 46.7 ± 1.9 N, 25.6 ± 0.7 N, 13.5 ± 0.6 N and 6.3 ± 0.4 N could be achieved non-invasively through skin thicknesses of 1-5 mm respectively. The fistula was fully collapsible in every measurement through skin thickness up to the required 4 mm. CONCLUSION: The prototype satisfies the design requirements. It is fully implantable and allows closure and control of an AVF through non-invasive torque transmission. In vivo studies are pivotal in assessing functionality and understanding systemic effects. SIGNIFICANCE: A method is introduced to transfer large amounts of energy to a medical implant for actuation of a mechanical valve trough a closed surface. This system allows non-invasive control of an AVF to reduce complications related to the permanent high flow in conventional AVFs.
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Derivación Arteriovenosa Quirúrgica , Animales , Ovinos , Derivación Arteriovenosa Quirúrgica/instrumentación , Diseño de Equipo , Torque , Diálisis Renal/instrumentación , Diálisis Renal/métodosRESUMEN
In our recent paper on the clinical pharmacology of tafenoquine (Watson et al., 2022), we used all available individual patient pharmacometric data from the tafenoquine pre-registration clinical efficacy trials to characterise the determinants of anti-relapse efficacy in tropical vivax malaria. We concluded that the currently recommended dose of tafenoquine (300 mg in adults, average dose of 5 mg/kg) is insufficient for cure in all adults, and a 50% increase to 450 mg (7.5 mg/kg) would halve the risk of vivax recurrence by four months. We recommended that clinical trials of higher doses should be carried out to assess their safety and tolerability. Sharma and colleagues at the pharmaceutical company GSK defend the currently recommended adult dose of 300 mg as the optimum balance between radical curative efficacy and haemolytic toxicity (Sharma et al., 2024). We contend that the relative haemolytic risks of the 300 mg and 450 mg doses have not been sufficiently well characterised to justify this opinion. In contrast, we provided evidence that the currently recommended 300 mg dose results in sub-maximal efficacy, and that prospective clinical trials of higher doses are warranted to assess their risks and benefits.
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Aminoquinolinas , Antimaláricos , Malaria Vivax , Adulto , Humanos , Antimaláricos/uso terapéutico , Hemólisis , Malaria Vivax/tratamiento farmacológico , Primaquina/uso terapéutico , Estudios Prospectivos , Metaanálisis como AsuntoRESUMEN
Background: Primaquine is an 8-aminoquinoline antimalarial. It is the only widely available treatment to prevent relapses of Plasmodium vivax malaria. The 8-aminoquinolines cause dose-dependent haemolysis in glucose-6-phosphate dehydrogenase deficiency (G6PDd). G6PDd is common in malaria endemic areas but testing is often not available. As a consequence primaquine is underused. Methods: We conducted an adaptive pharmacometric study to characterise the relationship between primaquine dose and haemolysis in G6PDd. The aim was to explore shorter and safer primaquine radical cure regimens compared to the currently recommended 8-weekly regimen (0.75 mg/kg once weekly), potentially obviating the need for G6PD testing. Hemizygous G6PDd healthy adult Thai and Burmese male volunteers were admitted to the Hospital for Tropical Diseases in Bangkok. In Part 1, volunteers were given ascending dose primaquine regimens whereby daily doses were increased from 7.5 mg up to 45 mg over 15-20 days. In Part 2 conducted at least 6 months later, a single primaquine 45 mg dose was given. Results: 24 volunteers were enrolled in Part 1, and 16 in Part 2 (13 participated in both studies). In three volunteers, the ascending dose regimen was stopped because of haemolysis (n=1) and asymptomatic increases in transaminases (n=2; one was hepatitis E positive). Otherwise the ascending regimens were well tolerated with no drug-related serious adverse events. In Part 1, the median haemoglobin concentration decline was 3.7 g/dL (range: 2.1-5.9; relative decline of 26% [range: 15-40%]). Primaquine doses up to 0.87 mg/kg/day were tolerated subsequently without clinically significant further falls in haemoglobin. In Part 2, the median haemoglobin concentration decline was 1.7 g/dL (range 0.9-4.1; relative fall of 12% [range: 7-30% decrease]). The ascending dose primaquine regimens gave seven times more drug but resulted in only double the haemoglobin decline. Conclusions: In patients with Southeast Asian G6PDd variants, full radical cure treatment can be given in under 3 weeks compared with the current 8-week regimen. Funding: Medical Research Council of the United Kingdom (MR/R015252/1) and Wellcome (093956/Z/10/C, 223253/Z/21/Z). Clinical trial number: Thai Clinical Trial Registry: TCTR20170830002 and TCTR20220317004.