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Current Opinion in Microbiology Oct 2022Multidrug-resistant Plasmodium falciparum parasites are a major threat to public health in intertropical regions. Understanding the mechanistic basis, origins, and... (Review)
Review
Multidrug-resistant Plasmodium falciparum parasites are a major threat to public health in intertropical regions. Understanding the mechanistic basis, origins, and spread of resistance can inform strategies to mitigate its impact and reduce the global burden of malaria. The recent emergence in Africa of partial resistance to artemisinins, the core component of first-line combination therapies, is particularly concerning. Here, we review recent advances in elucidating the mechanistic basis of artemisinin resistance, driven primarily by point mutations in P. falciparum Kelch13, a key regulator of hemoglobin endocytosis and parasite response to artemisinin-induced stress. We also review resistance to partner drugs, including piperaquine and mefloquine, highlighting a key role for plasmepsins 2/3 and the drug and solute transporters P. falciparum chloroquine-resistance transporter and P. falciparum multidrug-resistance protein-1.
Topics: Antimalarials; Artemisinins; Drug Resistance; Humans; Malaria, Falciparum; Plasmodium falciparum; Protozoan Proteins
PubMed: 36007459
DOI: 10.1016/j.mib.2022.102193 -
Neurology India 2023Neuropsychiatric disorders, ranging from mild cognitive impairment to frank psychosis, have been associated with certain parasitic infections. The parasite may cause... (Review)
Review
Neuropsychiatric disorders, ranging from mild cognitive impairment to frank psychosis, have been associated with certain parasitic infections. The parasite may cause damage to the central nervous system in several ways: as a space-occupying lesion (neuro-cysticercosis), alteration of neurotransmitters (toxoplasmosis), generation of the inflammatory response (trypanosomiasis, schistosomiasis), hypovolemic neuronal injury (cerebral malaria), or a combination of these. Certain drugs like quinacrine (mepacrine), mefloquine, quinolone, and interferon alpha which are used to treat these parasitic infections can further cause neuropsychiatric adverse effects. This review summarizes the major parasitic infections that are associated with neuropsychiatric disorders and the pathogenesis involved in their processes. A high index of suspicion for parasitic diseases, especially in endemic areas, should be kept in patients presenting with neuropsychiatric symptoms. A multidimensional approach to identification of the offending parasite using serological, radiological, and molecular tests is required not only to ensure proper and prompt treatment of the primary parasitic infection but also to improve the prognosis of patients by complete resolution of neuropsychiatric symptoms.
Topics: Humans; Parasitic Diseases; Central Nervous System; Mental Disorders; Mefloquine; Cysticercosis
PubMed: 37148042
DOI: 10.4103/0028-3886.375424 -
International Journal For Parasitology.... Dec 2021According to WHO, 2019 witnessed 229 million cases of malaria globally, of which Africa accounted for 94% of cases. Early diagnosis and treatment are the basis of... (Review)
Review
According to WHO, 2019 witnessed 229 million cases of malaria globally, of which Africa accounted for 94% of cases. Early diagnosis and treatment are the basis of malaria management, and the need for good chemoprophylaxis especially for people travelling to endemic areas is vital. There are a number of drug options available for the prophylaxis of malaria, mefloquine being one of the drugs used. Mefloquine has been around from the 1970s, and was developed in the United States keeping in mind the soldiers that were being deployed to areas where chloroquine resistant strains of Plasmodium were discovered. Mefloquine was preferred for its once a week dosage. Within a decade of its introduction, reports of the side effects associated with its long-term use surfaced. Mefloquine is now reported to cause a myriad of neuropsychiatric side effects including anxiety, sleep disturbance, depression, dizziness and frank psychosis, especially in patients with pre-existing psychiatric disorders. Many countries like the United States and the United Kingdom have updated their drug boxes to include the warning of these potential neuropsychiatric effects. This paper reviews the side effects of mefloquine and why there is a need to revisit its use in Indian drug policy.
Topics: Antimalarials; Chloroquine; Humans; Malaria; Mefloquine; Military Personnel
PubMed: 34339933
DOI: 10.1016/j.ijpddr.2021.06.003 -
Molecules (Basel, Switzerland) Feb 2022Late-stage modification of drug molecules is a fast method to introduce diversity into the already biologically active scaffold. A notable number of analogs of... (Review)
Review
Late-stage modification of drug molecules is a fast method to introduce diversity into the already biologically active scaffold. A notable number of analogs of mefloquine, chloroquine, and hydroxychloroquine have been synthesized, starting from the readily available active pharmaceutical ingredient (API). In the current review, all the modifications sites and reactivity types are summarized and provide insight into the chemistry of these molecules. The approaches include the introduction of simple groups and functionalities. Coupling to other drugs, polymers, or carriers afforded hybrid compounds or conjugates with either easily hydrolyzable or more chemically inert bonds. The utility of some of the compounds was tested in antiprotozoal, antibacterial, and antiproliferative assays, as well as in enantiodifferentiation experiments.
Topics: Antimalarials; Chemistry Techniques, Synthetic; Humans; Hydroxychloroquine; Malaria; Mefloquine; Models, Molecular; Plasmodium; Quinolines
PubMed: 35164267
DOI: 10.3390/molecules27031003 -
Journal of Travel Medicine Jul 2020Pregnant travelers face numerous risks, notably increased susceptibility to or severity of multiple infections, including malaria. Because pregnant women residing in...
Pregnant travelers face numerous risks, notably increased susceptibility to or severity of multiple infections, including malaria. Because pregnant women residing in areas non-endemic for malaria are unlikely to have protective immunity, travel to endemic areas poses risk of severe illness and pregnancy complications, such as low birthweight and fetal loss. If travel to malaria-endemic areas cannot be avoided, preventive measures are critical. However, malaria chemoprophylaxis in pregnancy can be challenging, since commonly used regimens have varying levels of safety data and national guidelines differ. Furthermore, although chloroquine and mefloquine have wide acceptance for use in pregnancy, regional malaria resistance and non-pregnancy contraindications limit their use. Mosquito repellents, including N,N-diethyl-m-toluamide (DEET) and permethrin treatment of clothing, are considered safe in pregnancy and important to prevent malaria as well as other arthropod-borne infections such as Zika virus infection. Pregnant travelers at risk for malaria exposure should be advised to seek medical attention immediately if any symptoms of illness, particularly fever, develop.
Topics: Antimalarials; Chemoprevention; Chloroquine; Drug Resistance; Female; Humans; Malaria; Mefloquine; Pregnancy; Proguanil; Travel
PubMed: 32419013
DOI: 10.1093/jtm/taaa074 -
Briefings in Functional Genomics Sep 2019Plasmodium falciparum and Plasmodium vivax, the two protozoan parasite species that cause the majority of cases of human malaria, have developed resistance to nearly all... (Review)
Review
Plasmodium falciparum and Plasmodium vivax, the two protozoan parasite species that cause the majority of cases of human malaria, have developed resistance to nearly all known antimalarials. The ability of malaria parasites to develop resistance is primarily due to the high numbers of parasites in the infected person's bloodstream during the asexual blood stage of infection in conjunction with the mutability of their genomes. Identifying the genetic mutations that mediate antimalarial resistance has deepened our understanding of how the parasites evade our treatments and reveals molecular markers that can be used to track the emergence of resistance in clinical samples. In this review, we examine known genetic mutations that lead to resistance to the major classes of antimalarial medications: the 4-aminoquinolines (chloroquine, amodiaquine and piperaquine), antifolate drugs, aryl amino-alcohols (quinine, lumefantrine and mefloquine), artemisinin compounds, antibiotics (clindamycin and doxycycline) and a napthoquinone (atovaquone). We discuss how the evolution of antimalarial resistance informs strategies to design the next generation of antimalarial therapies.
Topics: Aminoquinolines; Anti-Bacterial Agents; Antimalarials; Artemisinins; Atovaquone; Drug Resistance; Drug Resistance, Multiple; Folic Acid Antagonists; Humans; Malaria; Plasmodium falciparum; Plasmodium vivax; Quinine
PubMed: 31119263
DOI: 10.1093/bfgp/elz008 -
Cells Apr 2020Many ligands directly target adenosine receptors (ARs). Here we review the effects of noncanonical AR drugs on adenosinergic signaling. Non-AR mechanisms include raising... (Review)
Review
Many ligands directly target adenosine receptors (ARs). Here we review the effects of noncanonical AR drugs on adenosinergic signaling. Non-AR mechanisms include raising adenosine levels by inhibiting adenosine transport (e.g., ticagrelor, ethanol, and cannabidiol), affecting intracellular metabolic pathways (e.g., methotrexate, nicotinamide riboside, salicylate, and 5-aminoimidazole-4-carboxamide riboside), or undetermined means (e.g., acupuncture). However, other compounds bind ARs in addition to their canonical 'on-target' activity (e.g., mefloquine). The strength of experimental support for an adenosine-related role in a drug's effects varies widely. AR knockout mice are the 'gold standard' method for investigating an AR role, but few drugs have been tested on these mice. Given the interest in AR modulation for treatment of cancer, CNS, immune, metabolic, cardiovascular, and musculoskeletal conditions, it is informative to consider AR and non-AR adenosinergic effects of approved drugs and conventional treatments.
Topics: Animals; Humans; Mice; Pharmaceutical Preparations; Receptors, Purinergic P1; Signal Transduction
PubMed: 32295065
DOI: 10.3390/cells9040956 -
Frontiers in Cell and Developmental... 2022An exaggerated inflammatory response is the hallmark of a plethora of disorders. ATP is a central signaling molecule that orchestrates the initiation and resolution of... (Review)
Review
An exaggerated inflammatory response is the hallmark of a plethora of disorders. ATP is a central signaling molecule that orchestrates the initiation and resolution of the inflammatory response by enhancing activation of the inflammasome, leukocyte recruitment and activation of T cells. ATP can be released from cells through pannexin (Panx) channels, a family of glycoproteins consisting of three members, Panx1, Panx2, and Panx3. Panx1 is ubiquitously expressed and forms heptameric channels in the plasma membrane mediating paracrine and autocrine signaling. Besides their involvement in the inflammatory response, Panx1 channels have been shown to contribute to different modes of cell death (i.e., pyroptosis, necrosis and apoptosis). Both genetic ablation and pharmacological inhibition of Panx1 channels decrease inflammation and contribute to a better outcome in several animal models of inflammatory disease involving various organs, including the brain, lung, kidney and heart. Up to date, several molecules have been identified to inhibit Panx1 channels, for instance probenecid (Pbn), mefloquine (Mfq), flufenamic acid (FFA), carbenoxolone (Cbx) or mimetic peptides like Panx1. Unfortunately, the vast majority of these compounds lack specificity and/or serum stability, which limits their application. The recent availability of detailed structural information on the Panx1 channel from cryo-electron microscopy studies may open up innovative approaches to acquire new classes of synthetic Panx1 channel blockers with high target specificity. Selective inhibition of Panx1 channels may not only limit acute inflammatory responses but may also prove useful in chronic inflammatory diseases, thereby improving human health. Here, we reviewed the current knowledge on the role of Panx1 in the initiation and resolution of the inflammatory response, we summarized the effects of Panx1 inhibition in inflammatory pathologies and recapitulate current Panx1 channel pharmacology with an outlook towards future approaches.
PubMed: 36438559
DOI: 10.3389/fcell.2022.1020826 -
The Journal of Antimicrobial... Feb 2023In early 2016, in Preah Vihear, Northern Cambodia, artesunate/mefloquine was used to cope with dihydroartemisinin/piperaquine-resistant Plasmodium falciparum parasites....
BACKGROUND
In early 2016, in Preah Vihear, Northern Cambodia, artesunate/mefloquine was used to cope with dihydroartemisinin/piperaquine-resistant Plasmodium falciparum parasites. Following this policy, P. falciparum strains harbouring molecular markers associated with artemisinin, piperaquine and mefloquine resistance have emerged. However, the lack of a viable alternative led Cambodia to adopt artesunate/mefloquine countrywide, raising concerns about a surge of triple-resistant P. falciparum strains.
OBJECTIVES
To assess the prevalence of triple-resistant parasites after artesunate/mefloquine implementation countrywide in Cambodia and to characterize their phenotype.
METHODS
For this multicentric study, 846 samples were collected from 2016 to 2019. Genotyping of molecular markers associated with artemisinin, piperaquine and mefloquine resistance was coupled with phenotypic analyses.
RESULTS
Only four triple-resistant P. falciparum isolates (0.47%) were identified during the study period. These parasites combined the pfk13 polymorphism with pfmdr1 amplification, pfpm2 amplification and/or pfcrt mutations. They showed significantly higher tolerance to artemisinin, piperaquine and mefloquine and also to the mefloquine and piperaquine combination.
CONCLUSIONS
The use of artesunate/mefloquine countrywide in Cambodia has not led to a massive increase of triple-resistant P. falciparum parasites. However, these parasites circulate in the population, and exhibit clear resistance to piperaquine, mefloquine and their combination in vitro. This study demonstrates that P. falciparum can adapt to more complex drug associations, which should be considered in future therapeutic designs.
Topics: Humans; Mefloquine; Plasmodium falciparum; Antimalarials; Artesunate; Cambodia; Prevalence; Artemisinins; Quinolines; Malaria, Falciparum; Drug Resistance
PubMed: 36508338
DOI: 10.1093/jac/dkac403