Enantiospecific Antitrypanosomal in Vitro Activity of Eflornithine

The polyamine synthesis inhibitor eflornithine is a recommended treatment for the neglected tropical disease Gambian human African trypanosomiasis in late stage. This parasitic disease, transmitted by the tsetse fly, is lethal unless treated. Eflornithine is administered by repeated intravenous infusions as a racemic mixture of L-eflornithine and D-eflornithine. The study compared thein vitroantitrypanosomal activity of the two enantiomers with the racemic mixture against threeTrypanosoma brucei gambiensestrains. Antitrypanosomalin vitroactivity at varying drug concentrations was analysed by non-linear mixed effects modelling. For all three strains, L-eflornithine was more potent than D-eflornithine. Estimated 50% inhibitory concentrations of the three strains combined were 9.1 μM (95% confidence interval [8.1; 10]), 5.5 μM [4.5; 6.6], and 50 μM [42; 57] for racemic eflornithine, L-eflornithine and D-eflornithine, respectively. The higherin vitropotency of L-eflornithine warrants further studies to assess its potential for improving the treatment of late-stage Gambian human African trypanosomiasis.