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Clinical Microbiology Reviews, 10 1996, 512-531, Vol 9, No. 4
J Brajtburg and J Bolard
Amphotericin B (AmB), the drug of choice for the treatment of most systemic
fungal infections, is marketed under the trademark Fungizone, as an
AmB-deoxycholate complex suitable for intravenous administration. The
association between AmB and deoxycholate is relatively weak; therefore,
dissociation occurs in the blood. The drug itself interacts with both
mammalian and fungal cell membranes to damage cells, but the greater
susceptibility of fungal cells to its effects forms the basis for its
clinical usefulness. The ability of the drug to form stable complexes with
lipids has allowed the development of new formulations of AmB based on this
property. Several lipid-based formulations of the drug which are more
selective in damaging fungal or parasitic cells than mammalian cells and
some of which also have a better therapeutic index than Fungizone have been
developed. In vitro investigations have led to the conclusion that the
increase in selectivity observed is due to the selective transfer of AmB
from lipid complexes to fungal cells or to the higher thermodynamic
stability of lipid formulations. Association with lipids modulates AmB
binding to lipoproteins in vivo, thus influencing tissue distribution and
toxicity. For example, lipid complexes of AmB can be internalized by
macrophages, and the macrophages then serve as a reservoir for the drug.
Furthermore, stable AmB-lipid complexes are much less toxic to the host
than Fungizone and can therefore be administered in higher doses.
Experimentally, the efficacy of AmB-lipid formulations compared with
Fungizone depends on the animal model used. Improved therapeutic indices
for AmB-lipid formations have been demonstrated in clinical trials, but the
definitive trials leading to the selection of an optimal formulation and
therapeutic regimen have not been done.
Copyright © 1996 by the American Society for Microbiology. All rights reserved.
Carrier effects on biological activity of amphotericin B
Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
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