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| Author(s): |
Nilton Erbet Lincopan Huenuman
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ) |
| Defense date: | 2004-09-17 |
| Examining board members: |
Elsa Masae Mamizuka;
Elizabeth Pinheiro Gomes Areas;
Ana Maria Carmona Ribeiro;
Silvia Figueiredo Costa;
Marcia de Souza Carvalho Melhem
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| Advisor: | Elsa Masae Mamizuka |
| Abstract | |
Solubilization of amphotericin B (AMB) by dioctadecyldimethylammonium bromide (DODAB) bilayer fragments inspired this evaluation of its in vivo activity from survival and tissue burden experiments against systemic candidiasis in a mouse model. AMB (≤0.1 mg/mL) was simply added to a DODAB powder dispersion in water (10 mg/mL) previously prepared by sonication with tip; organic solvents completely absent. AMB aggregation state was evaluated from UV-visible light absorption and dynamic light scattering for aggegate sizing. AMB was stabilized by the DODAB bilayer fragments in its monomeric form, mixing of AMB and DODAB dispersion in pure water causing disappearance of large water insoluble drug aggregates. From survival experiments, both the bilayer, DOD/AMB, and the traditional deoxycholate/AMB formulation (DOC/AMB), had identical effect when given by the same route at the same dose of 0.4 mg/kg/day given i.p. for 10 days. From spleen and kidneys tissue burden experiments, similar efficacy of both preparations in reducing tissue CFU counting was obtained. The inexistence of information on DODAB toxicity led us to study the acute, subacute and chronic toxicity of the lipidic carrier as well as of the DOD/AMB formulation using previously described treatment. Cytotoxicity to renal epithelial cells as well as hepatic and renal function and histopathological and hematological alterations were evaluated in Swiss webster mice. In vitro, DOD/AMB presented the smaller cytotoxicity against the renal cell compared to the conventional DOC/AMB. In vivo, after treatment with DOD/AMB the only histological alteration observed in the kidney was the presence of an inflammatory infiltrate in the renal cortical region, while the use of DOC/AMB additionally generated a precocious tubular lesion which progressed to a degenerative glomerular damage. Independent of the incorporation of AMB, DODAB generated a generalised pro-inflammatory (immunostimulant) response with the formation of a granuloma in the site of innoculation, an increase of the splenic capsule and neutrophilia. In summary, DOD/AMB was as effective as DOC/AMB for treating systemic candidiasis in a mouse model and it is cheaper than other commercially available lipidic formulations. The monomeric solubilisation and stabilisation of AMB in the bilayer fragments, without solvents, presents a smaller nefrotoxicity in comparison to DOC/AMB, however, there is the need of modification in order to increase the incorporation of the drug, decreasing the concentration of the amphiphile, thus reducing the adverse effects observed in this study so that this formulation can compete with commercially available ones. (AU) | |