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Antimicrobial Agents and Chemotherapy, June 2000, p. 1598-1603, Vol. 44, No. 6
Department of Medical Microbiology and
Infectious Diseases, Erasmus University of Rotterdam, 3000 DR
Rotterdam,1 and EM Unit, University of
Maastricht, 6200 MD Maastricht,2 The Netherlands
Received 23 December 1999/Returned for modification 14 February
2000/Accepted 21 March 2000
Heated (20 min at 70°C) amphotericin B-desoxycholate (hAMB-DOC)
was further characterized, as was another formulation obtained after
centrifugation (60 min, 3000 × g), hcAMB-DOC.
Conventional AMB-DOC consisted of individual micelles (approximately 4 nm in diameter) and threadlike aggregated micelles, as revealed by
cryo-transmission electron microscopy. For both hAMB-DOC and hcAMB-DOC,
pleiomorphic cobweb structures were observed with a mean particle size
of approximately 300 nm as determined by laser diffraction. The potent
antifungal activity of AMB-DOC against Candida albicans is
not reduced by heating. Effective killing of C. albicans
(>99.9% within 6 h) was obtained at 0.1 mg/liter with each of
the AMB formulations. For AMB-DOC, hAMB-DOC, and hcAMB-DOC, cation
release (86Rb+) from C. albicans of
0066-4804/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Mild Heating of Amphotericin B-Desoxycholate: Effects on
Ultrastructure, In Vitro Activity and Toxicity, and Therapeutic
Efficacy in Severe Candidiasis in Leukopenic Mice
50% was observed at 0.8, 0.4, and 0.4 mg/liter, respectively. After
heating of AMB-DOC, toxicity was reduced 16-fold as determined by red
blood cell (RBC) lysis. For AMB-DOC, hAMB-DOC, and hcAMB-DOC, hemolysis
of
50% was observed at 6.4, 102.4, and 102.4 mg/liter, respectively.
In contrast, AMB-DOC and its derivates showed similar toxicities in
terms of cation release from RBC. For AMB-DOC, hAMB-DOC, and hcAMB-DOC,
cation release (86Rb+) of
50% was observed
at 1.6, 0.8, and 0.8 mg/liter, respectively. In persistently leukopenic
mice with severe invasive candidiasis, higher dosages of both hAMB-DOC
and hcAMB-DOC were tolerated than those of conventional AMB-DOC (3 versus 0.8 mg/kg of body weight, respectively), resulting in
significantly improved therapeutic efficacy. In conclusion, this new
approach of heating AMB-DOC may be of great value for further
optimizing the treatment of severe fungal infections.
*
Corresponding author. Mailing address: Department of
Medical Microbiology and Infectious Diseases, Erasmus University of
Rotterdam, P.O. Box 1738, 3000 DR Rotterdam, The Netherlands. Phone:
31-10-4087664. Fax: 31-10-4089454. E-mail:
vanetten{at}kmic.fgg.eur.nl.
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