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Antimicrobial Agents and Chemotherapy, January 2000, p. 150-155, Vol. 44, No. 1
Laboratorio de Doença de
Chagas1 and Laboratorio de Parasitologia
Celular e Molecular,3 Centro de Pesquisas Rene
Rachou, Fundaçao Oswaldo Cruz, Belo Horizonte, Minas Gerais,
Brazil; Departmento de Parasitología, Instituto de
Zoología Tropical, Universidad Central de Venezuela, Caracas
1041,2 and Laboratorio de
Química Biológica, Centro de Biofísica y
Bioquímica, Instituto Venezolano de Investigaciones
Científicas, Caracas 1020A,5 Venezuela;
and Schering Plough Research Institute, Kenilworth, New
Jersey 07033-05394
Received 29 April 1999/Returned for modification 24 September
1999/Accepted 25 October 1999
We have studied the in vivo activity of the new experimental
triazole derivative SCH 56592 (posaconazole) against a variety of
strains of the protozoan parasite Trypanosoma
(Schizotrypanum) cruzi, the causative
agent of Chagas' disease, in both immunocompetent and
immunosuppressed murine hosts. The T. cruzi strains used in the study were previously characterized as susceptible (CL), partially resistant (Y), or highly resistant (Colombiana, SC-28, and
VL-10) to the drugs currently in clinical use, nifurtimox and
benznidazole. Furthermore, all strains are completely resistant
to conventional antifungal azoles, such as ketoconazole. In the first
study, acute infections with the CL, Y, and Colombiana strains in
both normal and cyclophosphamide-immunosuppressed mice were treated
orally, starting 4 days postinfection (p.i.), for 20 consecutive daily doses. The results indicated that in immunocompetent animals SCH 56592 at 20 mg/kg of body weight/day provided protection (80 to 90%)
against death caused by all strains, a level comparable or superior to
that provided by the optimal dose of benznidazole (100 mg/kg/day).
Evaluation of parasitological cure revealed that SCH 56592 was able to
cure 90 to 100% of the surviving animals infected with the CL and Y
strains and 50% of those which received the benznidazole- and
nifurtimox-resistant Colombiana strain. Immunosuppression markedly
reduced the mean survival time of untreated mice infected with any of
the strains, but this was not observed for the groups which received
SCH 56592 at 20 mg/kg/day or benznidazole at 100 mg/kg/day. However,
the overall cure rates were higher for animals treated with SCH 56592 than among those treated with benznidazole. The results were confirmed
in a second study, using the same model but a longer (43-dose)
treatment period. Finally, a model for the chronic disease in which
oral treatment was started 120 days p.i. and consisted of 20 daily
consecutive doses was investigated. The results showed that SCH 56592 at 20 mg/kg/day was able to induce a statistically significant increase
in survival of animals infected with all strains, while benznidazole at
100 mg/kg/day was able to increase survival only in animals infected with the Colombiana strain. Moreover, the triazole was able to induce
parasitological cures in 50 to 60% of surviving animals, irrespective
of the infecting strain, while no cures were obtained with
benznidazole. Taken together, the results demonstrate that SCH 56592 has in vivo trypanocidal activity, even against T. cruzi strains naturally resistant to nitrofurans, nitroimidazoles, and conventional antifungal azoles, and that this activity is retained to a
large extent in immunosuppressed hosts.
0066-4804/0/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Activities of the Triazole Derivative SCH 56592 (Posaconazole)
against Drug-Resistant Strains of the Protozoan Parasite
Trypanosoma (Schizotrypanum) cruzi in
Immunocompetent and Immunosuppressed Murine Hosts
*
Corresponding author. Mailing address: Laboratorio de
Química Biológica, Centro de Biofísica y
Bioquímica, Instituto Venezolano de Investigaciones
Científicas, Apartado 21827, Caracas 1020A, Venezuela. Phone:
58-2-5041479. Fax: 58-2-5041093. E-mail:
jaurbina{at}cbb.ivic.ve.
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