Successful Aspects of the Coadministration of Sterol 14α-Demethylase Inhibitor VFV and Benznidazole in Experimental Mouse Models of Chagas Disease Caused by the Drug-Resistant Strain of Trypanosoma cruzi

Abstract

Up to now, no vaccines are available for Chagas disease, and the current therapy is largely unsatisfactory. Novel imidazole-based scaffolds of protozoan sterol 14α-demethylase (CYP51) inhibitors have demonstrated potent antiparasitic activity with no acute toxicity. Presently our aim was to investigate the effectiveness of the experimental 14α-demethylase inhibitor VFV in the mouse models of Trypanosoma cruzi infection using a naturally drug-resistant Colombiana strain, under monotherapy and in association with the reference drug, benznidazole (Bz). The treatment with VFV resulted in complete parasitemia suppression and 100% animal survival when administered orally (given in 10% DMSO plus 5% Arabic gum) at 25 mg/kg (bid) for 60 days. However, as parasite relapse was found using VFV alone under this treatment scheme, the coadministration of VFV with Bz was assayed giving simultaneously (for 60 days, bid) by oral route, under two different drug vehicles (10% DMSO plus 5% Gum Arabic with or without 3% Tween 80). All tested mice groups resulted in >99.9% of parasitemia decrease and 100% animal survival. qPCR analysis performed on cyclophosphamide immunosuppressed mice revealed that, although presenting lack of cure, VFV given as monotherapy was 14-fold more active than Bz, and the coadministration of Bz plus VFV (given simultaneously, using 10% DMSO plus 5% Gum Arabic as vehicle) resulted in 106-fold lower blood parasitism as compared to the monotherapy of Bz. Another interesting finding was the parasitological cure in 70% of the animals treated with Bz and VFV when the coadministration was given using the VFV suspension in 10% DMSO + Arabic gum + Tween 80 (a formulation that we have found to provide a better pharmacokinetics), even after immunosuppression using cyclophosphamide cycles, supporting the promising aspect of the drug coadministration in improving the efficacy of therapeutic arsenal against T. cruzi.

Keywords: Chagas disease; Colombiana strain; Trypanosoma cruzi; VFV; VNI; benznidazole; coadministration.

Figure 1:

Effect of VFV (25 mg/kg/day, in 10 % dimethyl sulfoxide (DMSO) plus 5 % Gum Arabic administered simultaneously with Benznidazole (Bz) – 100 mg/kg/day) for 60 days in the experimental mouse model of Chagas disease caused by the Colombiana strain of Trypanosoma cruzi (n=5). (A) Parasitemia levels and (B) Percentage of cumulative mortality.

Figure 2:

Pharmacokinetics of VNI and VFV in mice after a single oral administration dose of 25 mg/kg depending on formulation: DGAT (3% Tween 80, 10% DMSO, 5% Arabic gum) or HPCD (20% hydroxypropyl-β-cyclodextrin). 16 mice were used for testing of each drug and two mice were used for each of the 8 independent experimental points. A. Plasma concentration profiles. B. Tissue distribution 4 hours after administration. Panel A, p< 0.001 between VNI/DGAT and VNI/HPCD; and p<0.0015 between VFV/DGAT and VFV/HPCD. Panel B, ★ p<0.015 ; ◆p< 0.02 (Two-Way-Anova).

Figure 3:

Effect of VFV (25 mg/kg/day) administered simultaneously with Benznidazole (Bz) - 100mg/kg/day) for 60 days in the experimental mouse model of Chagas disease caused by the Colombiana strain of Trypanosoma cruzi (n=10). (A) Parasitemia levels and (B) Percentage of cumulative mortality. VFV was diluted in 10 % DMSO + 5% Arabic gum + 3 % Tween 80 – DGAT.