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Antimicrobial Agents and Chemotherapy, February 1999, p. 322-328, Vol. 43, No. 2
Department of
Medicine1 and
Department of Pathology
and Laboratory Medicine,
Received 10 July 1998/Returned for modification 18 August
1998/Accepted 11 November 1998
A murine model of intratracheally induced histoplasmosis was used
to evaluate a new triazole antifungal agent, Schering (SCH) 56592, for
treatment of histoplasmosis. MICs were determined for SCH 56592, amphotericin B, and itraconazole by testing yeast-phase isolates from
20 patients by a macrobroth dilution method. The MICs at which 90% of
the isolates are inhibited were for 0.019 µg/ml for SCH 56592, 0.5 µg/ml for amphotericin B, and
0066-4804/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Comparison of a New Triazole Antifungal Agent, Schering
56592, with Itraconazole and Amphotericin B for Treatment of
Histoplasmosis in Immunocompetent Mice
0.019 µg/ml for itraconazole.
Survival studies were done on groups of 10 B6C3F1 mice with
a lethal inoculum of 105. All mice receiving 5, 1, or 0.25 mg of SCH 56592 per kg of body weight per day, 2.5 mg of amphotericin B
per kg every other day (qod), or 75 mg of itraconazole per kg per day
survived to day 29. Only 44% of mice receiving 5 mg of
itraconazole/kg/day survived to day 29. Fungal burden studies done in
similar groups of mice with a sublethal inoculum of 104
showed a reduction in CFUs and Histoplasma antigen levels
in lung and spleen tissue in animals treated with 2 mg of amphotericin B/kg qod, 1 mg of SCH 56592/kg/day, and 75 mg of itraconazole/kg/day, but not in those treated with lower doses of the study drugs (0.2 mg of
amphotericin B/kg qod, 0.1 mg of SCH 56592/kg/day, or 10 mg of
itraconazole/kg/day). Serum drug concentrations were measured 3 and
24 h after the last dose in mice (groups of five to seven mice),
each treated for 7 days with SCH 56592 (10 and 1 mg/kg/day) and
itraconazole (75 and 10 mg/kg/day). Mean levels measured by bioassay
were as follows: SCH 56592, 10 mg/kg/day (2.15 µg/ml at 3 h and
0.35 µg/ml at 24 h); SCH 56592, 1 mg/kg/day (0.54 µg/ml at
3 h and none detected at 24 h); itraconazole, 75 mg/kg/day (22.53 µg/ml at 3 h and none detected at 24 h);
itraconazole, 10 mg/kg/day (1.33 µg/ml at 3 h and none detected
at 24 h). Confirmatory results were obtained by high-pressure
liquid chromatography assay. These studies show SCH 56592 to be a
promising candidate for studies of treatment of histoplasmosis in humans.
*
Corresponding author. Mailing address: Histoplasmosis
Reference Laboratory, 1001 W. Tenth St., OPW 430, Indianapolis, IN
46202. Phone: (317) 630-6262. Fax: (317) 630-7522. E-mail:
lwheat{at}iupui.edu.
Antimicrobial Agents and Chemotherapy, February 1999, p. 322-328, Vol. 43, No. 2
0066-4804/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
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