O G Ademowo1, C M Nneji, A D A Adedapo. 1. Postgraduate Institute for Medical Research & Training , College of Medicine, University of Ibadan, Ibadan, Nigeria. ademowo_g@yahoo.com
Abstract
BACKGROUND & OBJECTIVES: Methylene blue (MB), a thiazine dye is used in the treatment of various methemoglobinaemias. However, sporadic reports have shown some antimalarial therapeutic effect when administered to patients with clinical manifestations of malaria. The inhibitory concentration of schizont maturation and antimalarial activity of MB have not been fully elucidated. The present study therefore aimed at determining the antimalarial activity of MB in Plasmodium falciparum isolates obtained from children with malaria using standard in vitro drug susceptibility test. METHODS: Twenty children (8 boys and 12 girls) within the age range 4.5-11.5 yr were enrolled into the study and 2 ml of blood withdrawn aseptically. The standard microtest technique of schizont inhibition assay was used to culture fresh isolates obtained from P. falciparum infected patients. Chloroquine (CQ) and quinine (QN) were used as reference standards for in vitro drug susceptibility tests. RESULTS: The mean 50 per cent inhibitory concentration (IC(50)) values were 9.59 +/- 3.25nM, 196 +/-21.11nM and 607 +/- 27.41nM for MB, CQ and QN respectively. Ten of the 14 isolates were sensitiveto MB, 11 were sensitive to CQ while nine were sensitive to QN. Three isolates were resistant to CQ,and of these, two were sensitive to MB and one was sensitive to QN. INTERPRETATION & CONCLUSION: This preliminary study showed that MB has high antimalarial activity comparable with CQ and QN and may be used as a potent schizonticidal drug against CQ-resistant isolates.
BACKGROUND & OBJECTIVES:Methylene blue (MB), a thiazine dye is used in the treatment of various methemoglobinaemias. However, sporadic reports have shown some antimalarial therapeutic effect when administered to patients with clinical manifestations of malaria. The inhibitory concentration of schizont maturation and antimalarial activity of MB have not been fully elucidated. The present study therefore aimed at determining the antimalarial activity of MB in Plasmodium falciparum isolates obtained from children with malaria using standard in vitro drug susceptibility test. METHODS: Twenty children (8 boys and 12 girls) within the age range 4.5-11.5 yr were enrolled into the study and 2 ml of blood withdrawn aseptically. The standard microtest technique of schizont inhibition assay was used to culture fresh isolates obtained from P. falciparum infectedpatients. Chloroquine (CQ) and quinine (QN) were used as reference standards for in vitro drug susceptibility tests. RESULTS: The mean 50 per cent inhibitory concentration (IC(50)) values were 9.59 +/- 3.25nM, 196 +/-21.11nM and 607 +/- 27.41nM for MB, CQ and QN respectively. Ten of the 14 isolates were sensitiveto MB, 11 were sensitive to CQ while nine were sensitive to QN. Three isolates were resistant to CQ,and of these, two were sensitive to MB and one was sensitive to QN. INTERPRETATION & CONCLUSION: This preliminary study showed that MB has high antimalarial activity comparable with CQ and QN and may be used as a potent schizonticidal drug against CQ-resistant isolates.
Authors: Mathieu Gendrot; Océane Delandre; Marie Gladys Robert; Francis Tsombeng Foguim; Nicolas Benoit; Rémy Amalvict; Isabelle Fonta; Joel Mosnier; Marylin Madamet; Bruno Pradines; On Behalf Of The French National Reference Centre For Imported Malaria Study Group Journal: Pharmaceuticals (Basel) Date: 2021-04-09