Introduction

Malaria treatment may fail according to drug resistance of the infecting parasites or to bad absorption of the drug.
Epidemiological surveillance of drug susceptibility of malaria parasites is a major component of disease control. Measurement of in vitro response of the malaria parasites to drugs needs robust and precise methods.
The useful parameter for the monitoring of in vitro resistance is the concentration that inhibits 50% of the parasite’s activity (IC50). ICEstimator estimate IC50 concentration with the associated 95% confidence interval (95%CI).
A precise determination of IC50 is needed for comparison of data among populations of malaria parasites. Confidence Interval may help to discard estimates with insufficient precision.
The concentrations that inhibit 90% and 99% of the parasite’s activity (IC90 and IC99) can also be needed for comparison of data and are displayed in the 1.2 version.
This free website allows a simple management of data measuring effect of clones, strains or isolates of malaria parasites resulting from uptake of labelled nutrient (isotopic test), production of proteins (ELISA tests) or growth (schizont maturation). It implements the estimation of IC50 using the nls function of the R software (www.carn.r-project.org).
This website 1.2 version uses the same methodology as the 1.1 version with additional features (new features are available here).

If you use this software please quote the following publications :

Le Nagard H, Vincent C, Mentré F, Le Bras J. Online analysis of in vitro resistance to antimalarial drugs through nonlinear regression. Comput Methods Programs Biomed, Epub 2010.

Kaddouri H, Nakache S, Houzé S, Mentré F, Le Bras J. Drug Susceptibility of Plasmodium falciparum Clinical Isolates from Africa using Plasmodium Lactate Dehydrogenase Immunodetection Assay and inhibitory Emax model for precise IC50 measurement. Antimicrobial Agents and Chemotherapy, 2006, 50: 3343-3349.

The R source code of the program can be asked by email to herve.lenagard@inserm.fr. This program is a free source code distributed under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

A copy of the GNU General Public License can be found at: www.gnu.org/copyleft/gpl.html.

Without any tools we find a blurred value of IC50. Moreover we do not have confident intervals for this value. The method used in the ICEstimator function is the application of a nonlinear regression on the points. ICEstimator gives an estimated value of IC50 and its confident interval.