amphotericin-b and dimethyldioctadecylammonium

Amphotericin B (AmB) is widely used in the treatment of systemic fungal infections, despite its toxic effects. Nephrotoxicity, ascribed as the most serious toxic effect, has been related to the state of aggregation of the antibiotic. In search of the increase in AmB antifungal activity associated with low toxicity, several AmB-amphiphile formulations have been proposed. This work focuses on the structural characterization of a specific AmB formulation: AmB associated with sonicated dioctadecyl dimethylammonium bromide (DODAB) aggregates. Here, it was confirmed that sonicated DODAB dispersion is constituted by DODAB bicelles, and that monomeric AmB is much more soluble in bicelles than in DODAB vesicles. A new optical parameter is proposed for the estimation of the relative amount of amphiphile-bound monomeric AmB. With theoretical simulations of the spectra of spin labels incorporated in DODAB bicelles it was possible to prove that monomeric AmB binds preferentially to lipids located at the edges of DODAB bicelles, rigidifying them, and decreasing the polarity of the region. That special binding of monomeric AmB along the borders of bicelles, where the lipids are highly disorganized, could be used in the formulation of other carriers for the antibiotic, including mixtures of natural lipids which are known to form bicelles.

Topics: Amphotericin B; Antifungal Agents; Calorimetry, Differential Scanning; Chemistry, Pharmaceutical; Electron Spin Resonance Spectroscopy; Lipid Bilayers; Molecular Structure; Polyenes; Quaternary Ammonium Compounds; Sonication

Coverage of antifungal drug particles (miconazole and amphotericin B) with cationic lipid and evaluation of a synergistic action between lipid and drug.. Miconazole and amphotericin B were mixed with cationic bilayer fragments (BF) of dioctadecyldimethylammonium bromide (DODAB) at extreme drug to lipid molar proportions (P). Light scattering for particle sizing and zeta-potential analysis evaluated effects of cationic lipid on drug particle size and charge. Colony counts evaluated viability of Candida spp. and Cryptococcus neoformans over a range of P.. BF loading capacity for monomeric amphotericin B is 0.1 mM amphotericin B at 2 mM DODAB (P = 1:20). Above this low P, amphotericin B aggregates in the dispersion. At high P, addition of chaotropic K2HPO4 (0.2-2 mM) converts miconazole or amphotericin B aggregates into negatively charged particles with affinity for cationic lipid, which then surrounds each drug particle with a cationic layer. The combined in vitro action of lipid-covered drug particles against Candida and C. neoformans depends on P and interaction time. DODAB by itself kills C. neoformans and Candida at 2 and 2 to > 250 mg/L minimal fungicidal concentration (MFC). In combination, over the first hour, fungicidal activity is due to DODAB with lipid capsules retarding drug action. At 48 h interaction time and 10(4) cfu/mL, MFC (mg/L) against Candida albicans is reduced from 4 to 1 amphotericin B (at 2 DODAB), and from 8 to 1 miconazole (at 1 DODAB).. DODAB may be a suitable candidate for use in combination with miconazole for antifungal therapy.

Topics: Amphotericin B; Antifungal Agents; Candida; Chemistry, Pharmaceutical; Drug Combinations; Lipids; Miconazole; Molecular Structure; Particle Size; Quaternary Ammonium Compounds; Surface-Active Agents

Therapeutic activity of an effective and less nephrotoxic amphotericin B (AMB) formulation with dioctadecyldimethylammonium bromide (DODAB) bilayer fragments (named DODAB/AMB) inspired this toxicity survey in mice. At low drug to lipid molar ratios, hepatotoxicity, spleen damage and blood changes in comparison to DOC/AMB (sodium desoxycholate/amphotericin B, Fungizone) are evaluated ultimately showing toxic effects associated to DODAB only. Swiss Webster female mice were given DODAB, DODAB/AMB or DOC/AMB intraperitonially (ip) for 10 consecutive days (0.4 mg/kg/day AMB; 80 mg/kg/day DODAB) and repeated dose-toxicity was evaluated at the end of the treatment period (on day 11) and after a recovery period of 6 months from biochemical and hematological parameters plus histopathological examination of spleen and liver. Both at day 11 and 180, DODAB in the formulation administered ip causes irreversible changes in spleen such as fibrosis and leukocytes infiltration as a consequence of the administration route. Whereas focal necrosis is induced by DODAB in liver at day 180, DOC/AMB causes more severe multifocal necrosis both at day 11 and day 180. In the kidneys, the novel formulation preserves integrity of tubules and glomeruli in contrast to the serious damage caused by DOC/AMB as shown previously. The majority of the toxic effects observed for the novel formulation were due to the DODAB carrier used at 10mg/mL, i.e., at a rather high concentration and further studies should minimize DODAB dose.

Topics: Amphotericin B; Animals; Chemistry, Pharmaceutical; Female; Kidney; Liver; Mice; Quaternary Ammonium Compounds; Spleen

Evaluation of nephrotoxicity of a novel amphotericin B (AMB) formulation with dioctadecyldimethylammonium bromide (DODAB) bilayer fragments (DOD/AMB).. Dose-dependent cytotoxicity of DOD/AMB was evaluated in vitro against cultured kidney epithelial cells in culture. For in vivo experiments, Swiss Webster female mice were injected intraperitoneally for 10 consecutive days with 0.4 mg/kg/day AMB in the form of traditional bile salt desoxycholate (DOC)/AMB or DOD/AMB. Body and spleen weight, and biochemical and histopathological data were obtained at days 11 and 180 after injection.. Nephrotoxicity of the novel formulation was lower than that of Fungizone (DOC/AMB), which is the traditional AMB formulation using DOC. Dose-dependent cytotoxicity of DOD/AMB was lower than that exhibited by DOC/AMB. At day 11, DODAB and DOD/AMB caused loss of body weight and increase in spleen weight, which were not observed for DOC/AMB, although the changes were reversible and weights returned to control values at day 180. Ten days after injection, biochemical parameters for hepatic and renal function remained unaltered. At day 180, renal cortex histopathology revealed leucocytic infiltration and moderate hydropic degeneration of the renal tubules in the DODAB and DOD/AMB groups, in contrast to more severe lesions observed for the DOC/AMB group such as tubular cystic degeneration and glomerular injury, which were absent for the former groups.. The DOD/AMB formulation exhibited differential cytotoxicity and low nephrotoxicity, but there were also important aspects of general toxicity that will require evaluation with full-scale toxicity protocols.

Topics: 3T3 Cells; Amphotericin B; Animals; Antifungal Agents; Candida albicans; Chlorocebus aethiops; Dose-Response Relationship, Drug; Drug Combinations; Female; Humans; Kidney; Lipid Bilayers; Liver; Mice; Mice, Inbred BALB C; Quaternary Ammonium Compounds; Toxicity Tests; Vero Cells

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 (< or =0.1 g/L) was simply added to a DODAB powder dispersion in water (10 g/L) previously prepared by sonication in the absence of organic solvents. The AMB aggregation state was evaluated from UV-visible light absorption and dynamic light scattering for aggregate 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, DODAB/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 intraperitoneally for 10 days. From spleen and kidneys tissue burden experiments, similar efficacy of both preparations in reducing tissue cfu counts was obtained. In summary, DODAB/AMB was as effective as DOC/AMB for treating systemic candidiasis in a mouse model.

Topics: Amphotericin B; Animals; Antifungal Agents; Candida albicans; Candidiasis; Chemical Phenomena; Chemistry, Pharmaceutical; Chemistry, Physical; Colloids; Colony Count, Microbial; Dose-Response Relationship, Drug; Drug Stability; Lipid Bilayers; Mice; Microbial Sensitivity Tests; Particle Size; Quaternary Ammonium Compounds; Scattering, Radiation; Spectrophotometry, Ultraviolet; Survival Analysis