Artemisinin-based Combination Therapy Research Articles

Structure-Based Optimization of Protease-Inhibitor Interactions to Enhance Specificity of Human Stefin-A against Falcipain-2 from the Plasmodium falciparum 3D7 Strain.

The emergence of resistance in Plasmodium falciparum to frontline artemisinin-based combination therapies has raised global concerns and emphasized the identification of new drug targets for malaria. Cysteine protease falcipain-2 (FP2), involved in host hemoglobin degradation and instrumental in parasite survival, has long been proposed as a promising malarial drug target. However, designing active-site-targeted small-molecule inhibitors of FP2 becomes challenging due to their off-target specificity toward highly homologous human cysteine cathepsins. The use of proteinaceous inhibitors, which have nonconserved exosite interactions and larger interface area, can effectively circumvent this problem. In this study, we report for the first time that human stefin-A (STFA) efficiently inhibits FP2 with Ki values in the nanomolar range. The FP2-STFA complex crystal structure, determined in this study, and sequence analyses identify a unique nonconserved exosite interaction, compared to human cathepsins. Designing a mutation Lys68 > Arg in STFA amplifies its selectivity garnering a 3.3-fold lower Ki value against FP2, and the crystal structure of the FP2-STFAK68R complex shows stronger electrostatic interaction between side-chains of Arg68 (STFAK68R) and Asp109 (FP2). Comparative structural analyses and molecular dynamics (MD) simulation studies of the complexes further confirm higher buried surface areas, better interaction energies for FP2-STFAK68R, and consistency of the newly developed electrostatic interaction (STFA-R68-FP2-D109) in the MD trajectory. The STFA-K68R mutant also shows higher Ki values against human cathepsin-L and stefin, a step toward eliminating off-target specificity. Hence, this work underlines the design of host-based proteinaceous inhibitors against FP2, with further optimization to render them more potent and selective.

Malaria in Children: Updates on Management and Prevention.

Malaria in Children: Updates on Management and Prevention.

Neurobehavioral and biochemical responses to artemisinin-based drug and aflatoxin B1 co-exposure in rats.

Populations in malaria endemic areas are frequently exposed to mycotoxin-contaminated diets. The possible toxicological outcome of co-exposure to dietary aflatoxin B1 (AFB1) and artemisinin-based combination therapy warrants investigation to ascertain amplification or attenuation of cellular injury. Here, we investigated the neurobehavioral and biochemical responses associated with co-exposure to anti-malarial drug coartem, an artemether-lumefantrine combination (5mg/kg body weight, twice a day and 3days per week) and AFB1 (35 and 70µg/kg body weight) in rats. Motor deficits, locomotor incompetence, and anxiogenic-like behavior induced by low AFB1 dose were significantly (p < 0.05) assuaged by coartem but failed to rescue these behavioral abnormalities in high AFB1-dosed group. Coartem administration did not alter exploratory deficits typified by reduced track plot densities and greater heat map intensity in high AFB1-dosed animals. Furthermore, the reduction in cerebral and cerebellar acetylcholinesterase activity, anti-oxidant enzyme activities, and glutathione and thiol levels were markedly assuaged by coartem administration in low AFB1 group but not in high AFB1-dosed animals. The significant attenuation of cerebral and cerebellar oxidative stress indices namely reactive oxygen and nitrogen species, xanthine oxidase activity, and lipid peroxidation by coartem administration was evident in low AFB1 group but not high AFB1 dose. Although coartem administration abated nitric oxide level, activities of myeloperoxidase, caspase-9, and caspase-3 in animals exposed to both doses of AFB1, these indices were significantly higher than the control. Coartem administration ameliorated histopathological and mophometrical changes due to low AFB1 exposure but not in high AFB1 exposure. In conclusion, contrary to AFB1 alone, behavioral and biochemical responses were not altered in animals singly exposed to coartem. Co-exposure to coartem and AFB1 elicited no additional risk but partially lessened neurotoxicity associated with AFB1 exposure.

Short tandem repeat polymorphism in the promoter region of cyclophilin 19B drives its transcriptional upregulation and contributes to drug resistance in the malaria parasite Plasmodium falciparum.

Resistance of the human malaria parasites, Plasmodium falciparum, to artemisinins is now fully established in Southeast Asia and is gradually emerging in Sub-Saharan Africa. Although nonsynonymous SNPs in the pfk13 Kelch-repeat propeller (KREP) domain are clearly associated with artemisinin resistance, their functional relevance requires cooperation with other genetic factors/alterations of the P. falciparum genome, collectively referred to as genetic background. Here we provide experimental evidence that P. falciparum cyclophilin 19B (PfCYP19B) may represent one putative factor in this genetic background, contributing to artemisinin resistance via its increased expression. We show that overexpression of PfCYP19B in vitro drives limited but significant resistance to not only artemisinin but also piperaquine, an important partner drug in artemisinin-based combination therapies. We showed that PfCYP19B acts as a negative regulator of the integrated stress response (ISR) pathway by modulating levels of phosphorylated eIF2α (eIF2α-P). Curiously, artemisinin and piperaquine affect eIF2α-P in an inverse direction that in both cases can be modulated by PfCYP19B towards resistance. Here we also provide evidence that the upregulation of PfCYP19B in the drug-resistant parasites appears to be maintained by a short tandem repeat (SRT) sequence polymorphism in the gene's promoter region. These results support a model that artemisinin (and other drugs) resistance mechanisms are complex genetic traits being contributed to by altered expression of multiple genes driven by genetic polymorphism at their promoter regions.

Synergistic antimalarial treatment of Plasmodium berghei infection in mice with dihydroartemisinin and Gymnema inodorum leaf extract

BackgroundChemotherapy is crucial in the fight against malaria. The rise of resistance to most antimalarial medicines has been a serious hurdle to effective treatment. Artemisinin-based combination therapies (ACTs) are currently the most effective antimalarial medication. Malaria parasites are growing more resistant to ACTs, particularly in Southeast Asia. As a result, effective alternative antimalarials are in high demand. The leaf extract of Gymnema inodorum (GIE) has previously shown promise as an effective antimalarial. Therefore, this study evaluated the antimalarial potential of combination dihydroartemisinin (DHA) and GIE therapy against Plasmodium berghei in a mouse model.MethodsThe medications were evaluated using the standard 4-day test for determining the 50% effective dosage (ED50) of DHA and GIE on P. berghei ANKA (PbANKA). DHA and GIE were combined using a fixed-ratio approach, with DHA/GIE ED50s of 100/0, 80/20, 60/40, 40/60, 20/80, and 0/100, respectively.ResultsThe ED50 against PbANKA was determined to be 2 mg/kg of DHA and 100 mg/kg of GIE. The 60/40 (DHA/GIE) ratio demonstrated significantly higher antimalarial activity than the other ratios (p < 0.001) against PbANKA, with 88.95% inhibition, suggesting synergistic efficacy (combination index (CI) = 0.68695). Furthermore, this ratio protected PbANKA-infected mice against loss of body weight and packed cell volume decline, leading to a longer survival time over 30 days.ConclusionOur results suggest that GIE could be an effective adjuvant to DHA that can enhance the antimalarial effects in the treatment of PbANKA-infected mice.

Revealing the artemisinin and piperaquine treatment failure: a systematic review

Background: Artemisinin-based combination therapy (ACT) consists of a potent artemisinin component. Since the dihydroartemisinin performance effectiveness depends on piperaquine interaction still challenging, further research needs to establish the current status of artemisinin resistance relative to its geography and recognize any drug resistance interaction between dihydroartemisinin and piperaquine. Aim: This systematic review was aimed to find out the effect of dihydroartemisinin and piperaquine interaction concerning resistance, recurrence, parasitological failure, clinical failure, parasite clearance time, parasite reduction ratio, cure rate, which may affect treatment failure of patients with uncomplicated P. falciparum. Method: The article was not limited to year and country. This study analyzed any effect of interaction. Pubmed and Scopus were used as electronic databases, and MeSH terms and keywords were used to find specific studies. A total of 2131 studies were initially identified; however, 20 were eligible for qualitative synthesis. Result: The dihydroartemisinin piperaquine cure rate reported in Asia and Africa was above 98%. Eight RCTs, eleven prospective cohort studies, and one retrospective and prospective cohort study were included in this review. Design studies did not compare the same anti-malarial drug pattern, so it was difficult to do a pooled analysis. Even though this drug combination did not show a clear description of piperaquine resistance can affect artemisinin resistance, the adequate clinical and parasitological failure (ACPR) from this research reached above 93%, and for early treatment failure (ETF), late clinical failure (LCF), and late parasitological failure (LPF), were almost 0 %. Conclusion: The dihydroartemisinin-piperaquine combination still has highly efficacious therapy to fight malaria in some areas based on these multiple factors and reviews.

-Pharmacokinetics of antimalarial drugs used to treat uncomplicated malaria in breastfeeding mother-infant pairs: An observational pharmacokinetic study.

Background: Data surrounding the exposure of the breastfed infant to drugs and any associated risks are sparse. Drugs usually are transferred to milk in small quantities, and many have been used without obviously noticeable infant toxicity for many years - this lack of a 'safety signal' has further reduced the interest in studying mother-to-infant transfer of the drugs. In sub-Saharan Africa, pregnant women are at risk of Plasmodium falciparuminfection, and one in four women have evidence of placental infection at the time of delivery. Artemisinin-based combination therapies (ACTs), primarily artemether-lumefantrine (AL), are the current first-line treatment for uncomplicated Plasmodium falciparum malaria, with the same dosing recommendations in breastfeeding women as those in the adult population. Dihydroartemisinin-piperaquine (DP) is routinely used as an alternative to AL in Uganda. However, lactation pharmacokinetics (PK) of ACTs are unknown. Pharmacokinetic characterization of anti-malarial transfer to breast milk and breastfed infants is crucial in understanding the potential consequences to the infant, in terms of therapeutic- and prophylactic effects as well as potential toxicity. Methods: This observational study will enroll 30 mother-infant pairs, and aims to characterize the breastmilk transfer of antimalarial medications (AL and DP) to infants when these ACTs are administered to mothers as part of treatment for uncomplicated malaria. In addition, we will assess the mental health of the breastfeeding mothers enrolled as well as the well-being of their children. PK samples of maternal blood, breastmilk and breastfeeding infant's blood will be obtained at specific times points. Pharmacokinetic data will be analyzed using a population pharmacokinetic approach. Conclusions: We anticipate that findings from this research will guide to develop a PK model describing lumefantrine and piperaquine disposition and will provide a framework to foster other lactation pharmacokinetic studies in different disease areas.

Parasitology and Covid-19: epidemiological, immunological, pathological, and therapeutic aspects

&lt;abstract&gt; &lt;p&gt;Studies suggest that there is a complex interaction between parasitic infections, human microbiota, and host immunity. Reports have shown that there is the prevalence of viral diseases have inverse correlations with their severities (as is the case for Covid-19), their resulting mortalities, and helminth infections in endemic areas. This review study was conducted to discover the possible association between parasitic infections and Covid-19 epidemics from immunological, pathological, and therapeutic aspects. Our studies were conducted by reviewing texts, reports, and articles on reputable websites such as PubMed, Science Direct, medRxvi, Google Scholar, and bioRxiv published by 2022 07 April for keywords such as a parasite, helminth, radioactive, COVID-19 or SARS-CoV-2. In particular, reports of co-infection with helminths with complications and severity of Covid-19 in endemic areas were considered. The findings indicate that parasitic helminths can regulate host immune responses associated with a viral infection. For example, intestinal parasitic infections may be effective in reducing the symptoms of SARS-CoV-2 and the complications of Covid-19. Infected hosts can induce an innate and Th2-compatible immune response to CD4&lt;sup&gt;+&lt;/sup&gt; T cells, eosinophils, and interleukins (IL-4, IL-5, and IL-10). Chronic helminth infections prevent strong immune responses by altering the host response to T helper 2 (Th2). Interestingly, some antimalarial drugs, such as Artemisinin-based combination therapies (ACTs), may inhibit SARS-CoV-2-induced severe acute respiratory syndrome (SARS). Parasitic infections may alter the host's immune response to SARS-CoV-2 with potentially beneficial or detrimental effects. However, more large-scale epidemiological studies are needed to uncover the links between parasitic infections and COVID-19 and to clarify existing ambiguities.&lt;/p&gt; &lt;/abstract&gt;

Development, Optimization, and Validation of a Novel HPLC Method for Simultaneous Quantification of Artesunate and Amodiaquine in Tablet Formulations

Artemisinin-based combination therapy (ACTs) has become the primary first-line treatment for mild falciparum malaria in the majority of African countries. A fixed-dose combination of amodiaquine and artesunate is commonly employed to enhance treatment compliance and achieve successful malaria outcomes. In this study, a specific, accurate, linear, precise, and repeatable method was optimized, verified, and applied for the simultaneous estimation of artesunate and amodiaquine HCl in a commercially available artesunate-amodiaquine tablet with a dosage of 100 mg/270 mg. The optimization process involved two steps. Firstly, the top three were carefully selected out of seven characteristics influencing the separation. These key elements required fine-tuning, namely the column type, ion pair, and the residual amount of acetonitrile (ACN) remaining after elution. In the second step, a Box-Behnken experimental design, coupled with Derrenguer's desirability approach, was utilized to identify the ideal target conditions. The optimized method demonstrated excellent specificity, accuracy, linearity, precision, and repeatability, allowing for the reliable simultaneous estimation of artesunate and amodiaquine HCl in the artesunate-amodiaquine tablet. This method offers a valuable tool for quality control and dosage determination in the pharmaceutical industry. By employing advanced experimental techniques and focusing on critical parameters, the study contributes to analytical methodologies in malaria treatment.

Investigation of new ferrocenyl-artesunate derivatives as antiparasitics.

Artesunate (Ars) is a semisynthetic antimalarial drug and is a part of the artemisinin-based combination therapy arsenal employed for malaria treatment. The drug functions mainly by activation of its endoperoxide bridge leading to increased oxidative stress in malaria parasites. The purpose of this study was to ascertain the antiparasitic effects of combining ferrocene and Arsvia short or long chain ester or amide linkages (C1-C4). The compounds were evaluated for growth inhibition activity on the apicomplexan parasites, Plasmodium falciparum (P. falciparum) and Toxoplasma gondii (T. gondii). All the complexes demonstrated good activity against T. gondii with IC50 values in the low micromolar range (0.28-1.2 μM) and good to excellent antimalarial activity against a chloroquine sensitive strain of P. falciparum (NF54). Further investigations on T. gondii revealed that the likely mode of action (MoA) is through the generation of reactive oxygen species. Additionally, immunofluorescence microscopy suggested a novel change in the morphology of the parasite by complex C3, an artesunate-ferrocenyl ethyl amide complex. The complexes were not cytotoxic or showed low cytotoxicity to two normal cell lines tested.

Sequential analysis of erythrocyte aggregation in P. falciparum malaria with and without ASAQ therapy by optical signal and image analysis

The aggregation of erythrocytes is an important mechanism for blood flow through the cardiovascular system. In malaria, this is complicated by infection caused by P. falciparum and is further complicated by the severity of parasitemia. Hence analysis of this micro-mechanism is essential to know the changes in blood not only in diseased conditions but also after artemisinin combination therapy (ASAQ) to alleviate suffering. For analysis purposes, aggregation of erythrocytes was determined by LED laser aggregometer, represented in terms of various parameters related to the changes in laser transmitted intensity. Formed aggregates are further analyzed by imaging and image-processing methods. For this study blood samples from young adults (18 – 40 years old) infected with P. falciparum (n= 80), without any other serious illness, were performed. These samples were selected based on the severity of parasitemia, and were divided into low (LP), medium1 (MP1), medium 2 (MP2), and high (HP) parasitemia. For three days, the selected individuals were treated with artemisinin-based combination therapy ASAQ (Artesunate 4 mg/kg and amodiaquine 10 mg base/ kg once a day). Healthy subjects (n=20) without any history of the disease were selected as a control group. The results, as obtained by various parameters, show a significant elevation of aggregation of erythrocytes (P< 0.05) in P. falciparum malaria with the increase of parasitemia level. There was a decrease in the aggregation after treatment on day four tending towards normal. Thus the current study shows the potential beneficial role of ASAQ on erythrocytes aggregation, which may contribute to reducing the harmful effects on various organs in P. falciparum-infected blood.

Approaches to imported malaria prevention, management, and elimination in Jazan, Kingdom of Saudi Arabia

Malaria is a problem to public health particularly in endemic areas, being a major cause of illness and death. Thus, this study aimed to summarize updated information regarding approaches to imported malaria prevention, management, and elimination in Jazan in the Kingdom of Saudi Arabia (SA). This review was performed through an electronic literature search for relevant studies identified using keywords on the MEDLINE database, including malaria infection, prevalence, diagnosis, and management. Similar keywords were used to search and identify relevant articles on Google Scholar. Anti-malarial medications could be used to manage positive malaria diagnosis including Artemisinin-based combination therapies, Chloroquine with proguanil, and atovaquone with proguanil to cure the disease. Vector control plays a great role in controlling and eliminating malaria, and the two core widely applicable control measures are long-lasting insecticide-treated nets and indoor residual spraying. In addition, surveillance is a great strategy for preventing infection. There is a surveillance system for malaria in SA, and it is mandatory for primary health centers and hospitals to report 24 hours of all cases of malaria to the elimination program unit. Moreover, vaccination is a core public health intervention for infection prevention and control. However, there is no licensed vaccine for the prevention of malaria.

The current use of the artemisinin-based Combination Therapies in adult patients at a Tertiary Hospital, South-South Nigeria

Objective: The antimalarial preferences, tolerability, and cost of the Artemisinin-based combination therapies (ACTs) among adult patients and caregivers are largely understudied despite being the recommended treatment for Plasmodium falciparum. We, therefore, evaluated antimalarial preferences, tolerability, and cost of the ACTs among adult patients attending the University of Benin Teaching Hospital, Nigeria. Methods: This was a cross-sectional study conducted among adult patients and their caregivers at the University of Benin Teaching Hospital, Nigeria, using a semi-structured questionnaire. Their preferred antimalarial medication, previous use of antimalarial monotherapies, current ACT use; cost considerations, and adverse effects profile were sought. Result: Six hundred respondents were recruited with a mean age of 41.4±16.3years and M/F ratio of 1.4. The majority (88.0 %), reported that they had between 1-5 episodes of malaria fever in a year. Only 28.2% received doctors’ prescriptions while 85.8% purchased their antimalarial medications from a pharmacy. Sixty percent of the respondents used at least one ACT; mainly Artemether-Lumefantrine (AL) 312 (52.0%). Only 9.3% reported previous adverse effects with the ACTs with 4.0% of respondents discontinuing their medications. The mean (SD) cost of purchasing ACTs was 1,516.47±760.3 (3.65 USD) Naira. Conclusion: This study showed adult patients’ preference for the ACTs, especially Artemether-Lumefantrine despite some inclination towards antimalarial monotherapies and parenteral route. There was also a high rate of use of malaria presumptive treatment, but only a few reported adverse effects. There is a need to make ACTs affordable because the cost is still presently high for most Nigerians.

Efficacy and safety of pyronaridine-artesunate (Pyramax®) for the treatment of uncomplicated Plasmodium vivax malaria in Northwest Ethiopia

BackgroundDeclining efficacy of chloroquine for the treatment Plasmodium vivax malaria has been reported in different endemic settings in Ethiopia. This highlights the need to assess alternative options for P. vivax treatment with artemisinin-based combination therapy, such as pyronaridine-artesunate. This treatment regimen has shown high efficacy for uncomplicated malaria in both Africa and Asia. However, limited data are available from Ethiopia. This study was conducted to assess the efficacy and safety of pyronaridine-artesunate for the treatment of uncomplicated P. vivax malaria in Northwest Ethiopia.MethodsA single arm prospective efficacy study was conducted in the Hamusite area, Northwest Ethiopia. Fifty-one febrile adult patients with uncomplicated P. vivax malaria were enrolled between March and July 2021. Patients were treated with pyronaridine-artesunate once daily for three days. Clinical and parasitological parameters were monitored over a 42-day follow-up period using the standard World Health Organization protocol for therapeutic efficacy studies.ResultsA total of 4372 febrile patients were screened with 51 patients enrolled and 49 completing the 42-day follow-up period. The PCR-uncorrected adequate clinical and parasitological response (ACPR) was 95.9% (47/49; 95% CI 84.9–99.0) on day 42. Two patients had recurrences [4.0% (2/49); 95% CI 0.7–12.1] on days 35 and 42. The parasite clearance rate was rapid with fast resolution of clinical symptoms; 100% of participants had cleared parasitaemia on day 1 and fever on day 2. All 16 (31.4%) patients with gametocyte carriage on day 0 had cleared by day 1. There were no serious adverse events.ConclusionIn this small study, pyronaridine-artesunate was efficacious and well-tolerated for the treatment of uncomplicated P. vivax malaria. In adults in the study setting, it would be a suitable alternative option for case management.

Discovery of potent Plasmodium falciparum protein kinase 6 (PfPK6) inhibitors with a type II inhibitor pharmacophore

Malaria is a devastating disease that causes significant global morbidity and mortality. The rise of drug resistance against artemisinin-based combination therapy demonstrates the necessity to develop alternative antimalarials with novel mechanisms of action. We report the discovery of Ki8751 as an inhibitor of essential kinase PfPK6. 79 derivatives were designed, synthesized and evaluated for PfPK6 inhibition and antiplasmodial activity. Using group efficiency analyses, we established the importance of key groups on the scaffold consistent with a type II inhibitor pharmacophore. We highlight modifications on the tail group that contribute to antiplasmodial activity, cumulating in the discovery of compound 67, a PfPK6 inhibitor (IC50 = 13 nM) active against the P. falciparum blood stage (EC50 = 160 nM), and compound 79, a PfPK6 inhibitor (IC50 < 5 nM) with dual-stage antiplasmodial activity against P. falciparum blood stage (EC50 = 39 nM) and against P. berghei liver stage (EC50 = 220 nM).

Anemia, Thrombocytopenia, and Changes in Biochemical Parameters Occurring in Patients with Uncomplicated Plasmodium falciparum Malaria: Data Analysis from Antimalarial Efficacy-Randomized Trials in Dakar and Kaolack Regions, Senegal.

Artemisinin-based Combination Therapies (ACTs) are widely used in the treatment of uncomplicated malaria. Plasmodium falciparum infection is often accompanied by disturbances of hematological and biochemical parameters. The objective of this study was to evaluate the changes in biochemical and hematological parameters during uncomplicated malaria in patients treated with ACTs. Data from patient with uncomplicated Plasmodium falciparum malaria were pooled from different open-randomized trial evaluating the efficacy of Artesunate-Mefloquine (ASMQ), Artesunate-Amodiaquine (ASAQ), Artemether-Lumefantrine (AL), and Dihydro-artemisinin-Piperaquine (DHAPQ) combinations. Biochemical (transaminases, creatinine, and bilirubin) and hematological (hemoglobin and platelet levels) parameters were performed at baseline (D0) and at day 7 after treatment (D7). Data were analyzed as both continuous and categorical variables with 95% confidence interval. Risks and trends were calculated using multivariate logistic random effect models. A total of 720 patients with completed biological data were included in the analysis (320 in the AL arm, 160 in the ASMQ arm, 120 in the DHAPQ arm, and 88 in the ASAQ arm). The mean age of the patients was 9.43 ± 9.1 years. Male subjects represented 58.47% (sex ratio was 1.4 for males). The mean hemoglobin level at inclusion (D0) was 9.79 g/dl and anemia (Hb < 11 g/dl) was 71.43% (aOR = 1.16 [0.68 - 1.98]p = 0.57). At D7, hemoglobin level was 9.63 g/dl and anemia was significantly more frequent (78.29% [p = 0.002]). The mean platelet count at day 0 was 154075.5 platelets/mm3 of blood and 339328.7 platelets/mm3 at day 7. Thrombocytopenia was about 53.61% and was associated with malaria (aOR = 3.4 [2.18 - 5.3]p < 10-3). 19.58% of patients had abnormal ALT and 40.28% had abnormal AST at D0. 27.22% of patients had normal bilirubin at D0. Renal function was normal in all patients in the study. Normalization of transaminases was noted between D0 and D7. The percentage of subjects with normal bilirubin increased between D0 and D7. Renal function did not vary significantly between D0 and D7. Results from this analysis showed that subjects with high parasitaemia had a greater risk of anemia and thrombocytopenia. Artemisinin combinations were well-tolerated as no major biological disturbances were noted. The effects of ACTs on hematologic and biochemical parameters were not different.

Macro environment determinants affecting the availability of artemisinin-based combination therapies in Uganda

PurposeArtemisinin-based combination therapies (ACTs) have been developed to treat uncomplicated malaria. However, scanty studies exist to inform the role of macro factors in explaining the nonavailability of ACT in developing countries. Therefore, this paper aims to evaluate the different macro-environment factors affecting the availability of ACTs in the public hospital setting.Design/methodology/approachThis study applied a quantitative methodological approach and structural equation modeling (SEM) to test hypotheses statistically. SEM examines linear causal relationships among variables while accounting for measurement error. Confirmatory factor analysis (CFA) was used to assess model reliability. CFA and SEM were used to determine the shared variance-covariance of variables, define the latent construct and provide a more precise way to account for the error variances associated with the variables, which, if untested, could lead to biased parameter estimates. This was guided by the data collected from 40 general public hospitals with 283 respondents.FindingsThis study’s results support a model for promoting social-cultural, technological and legal factors. The availability of ACTs is significantly affected by legal factors. Improving legal aspects by a unit can enhance ACT availability by 0.59. Political factors scored the least, and they do not influence the availability of malaria drugs.Research limitations/implicationsThe design was quantitative and cross-sectional. Future research could be longitudinal with a mixed-method approach and consider other external stakeholders.Practical implicationsReducing the impact of the nonavailability of antimalarial drugs in general public hospitals requires a holistic concerted and coordinated supply chain approach that tackles the political, economic, social-cultural norms, technological and legal factors.Originality/valueThe authors develop and test a model using macro factors: political, economic, social, cultural, technological and legal factors. This model is relevant for many developing countries to supply chain coordination perpetually experiencing medicine shortages.

Engineering yeast for industrial-level production of the antimalarial drug artemisinin

Artemisinin-based combination therapies are the gold standard treatment for uncomplicated malaria. A seminal study by Paddon et al. detailed an efficient approach for producing artemisinic acid from engineered yeast and its conversion to artemisinin, and demonstrated how to use metabolic engineering and synthetic biology for the production of bioactive compounds.

Breaking the cycle of malaria treatment failure.

Treatment of symptomatic malaria became a routine component of the clinical and public health response to malaria after the second world war. However, all antimalarial drugs deployed against malaria eventually generated enough drug resistance that they had to be removed from use. Chloroquine, sulfadoxine-pyrimethamine, and mefloquine are well known examples of antimalarial drugs to which resistance did and still does ready evolve. Artemisinin-based combination therapies (ACTs) are currently facing the same challenge as artemisinin resistance is widespread in Southeast Asia and emerging in Africa. Here, I review some aspects of drug-resistance management in malaria that influence the strength of selective pressure on drug-resistant malaria parasites, as well as an approach we can take in the future to avoid repeating the common mistake of deploying a new drug and waiting for drug resistance and treatment failure to arrive. A desirable goal of drug-resistance management is to reduce selection pressure without reducing the overall percentage of patients that are treated. This can be achieved by distributing multiple first-line therapies (MFT) simultaneously in the population for the treatment of uncomplicated falciparum malaria, thereby keeping treatment levels high but the overall selection pressure exerted by each individual therapy low. I review the primary reasons that make MFT a preferred resistance management option in many malaria-endemic settings, and I describe two exceptions where caution and additional analyses may be warranted before deploying MFT. MFT has shown to be feasible in practice in many endemic settings. The continual improvement and increased coverage of genomic surveillance in malaria may allow countries to implement custom MFT strategies based on their current drug-resistance profiles.

Genomic characterization of Plasmodium falciparum genes associated with anti-folate drug resistance and treatment outcomes in eastern India: A molecular surveillance study from 2008 to 2017.

After being used vigorously for the previous two decades to treat P. falciparum, chloroquine and sulfadoxine-pyrimethamine were replaced in 2009 with an artemisinin-based combination therapy (artesunate-sulfadoxine-pyrimethamine) in an effort to combat multidrug-resistant parasites. We set out to assess the genetic variants of sulfadoxine-pyrimethamine resistance and the effectiveness of its treatment in eastern India prior to, during, and 6 to 8 years following the introduction of the new pharmacological regime. In 2008-2009, 318 P. falciparum-positive patients got the recommended doses of sulfadoxine-pyrimethamine. We used 379 additional isolates from 2015 to 2017 in addition to the 106 isolates from 2010. All 803 isolates from two study sites underwent in vitro sulfadoxine-pyrimethamine sensitivity testing and genomic characterisation of sulfadoxine-pyrimethamine resistance (pfdhfr and pfdhps). In Kolkata and Purulia, we observed early treatment failure in 30.7 and 14.4% of patients, respectively, whereas recrudescence was found in 8.1 and 13.4% of patients, respectively, in 2008-2009. In 2017, the proportion of in vitro pyrimethamine and sulfadoxine resistance steadily grew in Kolkata and Purulia despite a single use of sulfadoxine-pyrimethamine. Treatment failures with sulfadoxine-pyrimethamine were linked to quintuple or quadruple pfdhfr- pfdhps mutations (AICII-AGKAT, AICII-AGKAA, AICII-SGKGT, AICII-AGKAA, AICNI-AGKAA) in 2008-2009 (p < 0.001). The subsequent spread of mutant-haplotypes with higher in vitro sulfadoxine-pyrimethamine resistance (p < 0.001), such as the sextuple (dhfr-AIRNI+dhps-AGEAA, dhfr-ANRNL+dhps-AGEAA) and septuple (dhfr-AIRNI+dhps-AGEAT), mutations were observed in 2015-2017. This successive spread of mutations with high in vitro sulfadoxine-pyrimethamine resistance confirmed the progressive increase in antifolate resistance even after an 8-year withdrawal of sulfadoxine-pyrimethamine.