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The antimalarial agent mefloquine inhibits ATP-sensitive K-channels.

ABSTRACT: The aim of this study was to determine whether antimalarial agents inhibit ATP-sensitive potassium (K(ATP)) channels and thereby contribute to the observed side-effects of these drugs. Mefloquine (10 - 100 microM), but not artenusate (100 microM), stimulated insulin release from pancreatic islets in vitro. Macroscopic K(ATP) currents were studied in inside-out patches excised from Xenopus oocytes expressing cloned K(ATP) channels. Mefloquine (IC(50) approximately 3 microM), quinine (IC(50) approximately 3 microM), and chloroquine inhibited the pancreatic beta-cell type of K(ATP) channel Kir6.2/SUR1. Artenusate (100 microM) was without effect. Mefloquine and quinine also blocked a truncated form of Kir6.2 (Kir6. 2DeltaC36) when expressed in the absence of SUR1. The extent of block was similar to that observed for Kir6.2/SUR1 currents. Our results suggest that inhibition of the beta-cell K(ATP) channel accounts for the ability of quinoline-based antimalarial drugs to stimulate insulin secretion, and thereby produce hypoglycaemia. The results also indicate that quinoline-based antimalarial agents inhibit K(ATP) channels by interaction with the Kir6.2 subunit. This subunit is common to beta-cell, neuronal, cardiac, skeletal muscle, and some smooth muscle K(ATP) channels suggesting that K(ATP) channel inhibition may contribute to the other side effects of these drugs, which include cardiac conduction abnormalities and neuropsychiatric disturbances.

SUBMITTER: Gribble FM

PROVIDER: S-EPMC1572394 | biostudies-literature | 2000 Oct

REPOSITORIES: biostudies-literature

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The antimalarial agent mefloquine inhibits ATP-sensitive K-channels.

Gribble F M FM Davis T M TM Higham C E CE Clark A A Ashcroft F M FM

British journal of pharmacology 20001001 4

The aim of this study was to determine whether antimalarial agents inhibit ATP-sensitive potassium (K(ATP)) channels and thereby contribute to the observed side-effects of these drugs. Mefloquine (10 - 100 microM), but not artenusate (100 microM), stimulated insulin release from pancreatic islets in vitro. Macroscopic K(ATP) currents were studied in inside-out patches excised from Xenopus oocytes expressing cloned K(ATP) channels. Mefloquine (IC(50) approximately 3 microM), quinine (IC(50) appro ...[more]

PMID: 11030725

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Project description:BackgroundDeclining in susceptibility of Plasmodium falciparum to mefloquine is reported in South-East Asia. A revisiting on mefloquine pharmacokinetics-pharmacodynamics (PK/PD) could assist in finding new appropriate dosage regimens in combination with artesunate as a three-day course treatment.ObjectiveThis study aimed to investigate promising alternative artesunate-mefloquine combination regimens that are effective for the treatment of patients with mefloquine-sensitive and resistant P. falciparum malaria.MethodsData collected during 2008-2009 from 124 patients with uncomplicated P. falciparum malaria were included in the analysis, 90 and 34 patients with sensitive and recrudescence response, respectively. All patients were treated with a three-day combination of artesunate-mefloquine. Population PK-PD models were developed. The developed models were validated with clinically observed data. Simulations of clinical efficacy of alternative mefloquine regimens were performed based on mefloquine sensitivity, patients' adherence and parasite biomass.ResultsThe developed PK/PD models well described with clinically observed data. For mefloquine-resistant P. falciparum, a three-day standard regimen of artesunate-mefloquine is suitable (>50% efficacy) only when the level of parasite sensitivity was < 1.5-fold of the cut-off level (IC50 < 36 nM). For mefloquine-sensitive parasite with IC50 < 23.19 nM (0.96-fold), all regimens provided satisfactory efficacy. In the isolates with IC50 of 24 nM, regimen-I is recommended. Curative treatment criteria for mefloquine and artesunate were C336h (>408 ng.mL-1) or Cmax/IC50 (>130.1 g.m/M), and Cmax/IC50 (>381.2 g.m/M), respectively.ConclusionsClinical use of a three-day standard artesunate-mefloquine is suitable only when the IC50 of P. falciparum isolates is lower than 36 nM. Otherwise, other ACT regimens should be replaced. For mefloquine-sensitive parasite, a dose reduction is recommended with the IC50 is lower than 23.19 nM.

Project description:ATP-sensitive potassium channels (KATP channels) are hetero-octameric nucleotide-gated ion channels that couple cellular metabolism to excitability in various tissues. In the heart, KATP channels are activated during ischaemia and potentially during adrenergic stimulation. In the vasculature, they are normally active at a low level, reducing vascular tone, but the ubiquitous nature of these channels leads to complex and poorly understood channelopathies as a result of gain- or loss-of-function mutations. Zebrafish (ZF) models of these channelopathies may provide insights to the link between molecular dysfunction and complex pathophysiology, but this requires understanding the tissue dependence of channel activity and subunit specificity. Thus far, direct analysis of ZF KATP expression and functional properties has only been performed in pancreatic β-cells. Using a comprehensive combination of genetically modified fish, electrophysiology and gene expression analysis, we demonstrate that ZF cardiac myocytes (CM) and vascular smooth muscle (VSM) express functional KATP channels of similar subunit composition, structure and metabolic sensitivity to their mammalian counterparts. However, in contrast to mammalian cardiovascular KATP channels, ZF channels are insensitive to potassium channel opener drugs (pinacidil, minoxidil) in both chambers of the heart and in VSM. The results provide a first characterization of the molecular properties of fish KATP channels and validate the use of such genetically modified fish as models of human Cantú syndrome and ABCC9-related Intellectual Disability and Myopathy syndrome. KEY POINTS: Zebrafish cardiac myocytes (CM) and vascular smooth muscle (VSM) express functional KATP channels of similar subunit composition, structure and metabolic sensitivity to their mammalian counterparts. In contrast to mammalian cardiovascular KATP channels, zebrafish channels are insensitive to potassium channel opener drugs (pinacidil, minoxidil) in both chambers of the heart and in VSM. We provide a first characterization of the molecular properties of fish KATP channels and validate the use of such genetically modified fish as models of human Cantú syndrome and ABCC9-related Intellectual Disability and Myopathy syndrome.

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The antimalarial agent mefloquine inhibits ATP-sensitive K-channels.

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The antimalarial agent mefloquine inhibits ATP-sensitive K-channels.

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