Treatment of murine candidiasis and cryptococcosis with amphotericin B incorporated into egg lecithin-bile salt mixed micelles

Abstract

Amphotericin B (AmB) with deoxycholate (Fungizone) and AmB incorporated into mixed micelles (AmB-mixMs) composed of egg lecithin with glycocholate, deoxycholate, or taurocholate were compared as treatments for murine infections. For mice infected with Candida albicans, treatment consisted of a single intravenous injection; for mice infected with Cryptococcus neoformans, treatment consisted of two intravenous injections. The maximal tolerated doses of AmB as Fungizone were 1.25 mg/kg of body weight in mice with candidiasis and 2.5 mg/kg of body weight in mice with cryptococcosis. The AmB-mixMs were nontoxic to mice at doses of 80 and 100 mg/kg of body weight and were therapeutically more active than the maximal tolerated dose of Fungizone in both models of infection. However, when Fungizone or AmB-mixMs were administered at equivalent doses ofAmB, AmB-mixMs were more active in treating murine candidiasis, whereas Fungizone was more active in treating murine cryptococcosis.Amphotericin B (AmB) formulated with deoxycholate and sodium phosphate is used clinically as Fungizone. It is highly effective in the treatment of systemic fungal infections, but its usefulness is limited by its toxicity to patients (10). The problem is further aggravated in immunocompromised patients, in whom opportunistic fungal infections caused by Cryptococcus neoformans and various species of Candida may be life-threatening (30).In experimental studies in animals, the therapeutic index of AmB has been improved by incorporating it into several types of lipid-based formulations such as multilamellar lipid vesicles composed of saturated phospholipids (22) or small unilamellar vesicles composed of egg lecithin and cholesterol (1,14) or by complexing AmB to open lipid structures composed of saturated phosphatidylcholine (9) or cholesteryl ester (18). The preparation and standardization of some of these formulations are associated with a range of technical and commercial problems (32) which may make long-term use difficult. While some of these formulations have undergone successful clinical trials in humans (2), treatment failures have been reported (24). Moreover, the safety of the long-term use of synthetic saturated phospholipids in the clinical setting has not been determined. While progress in the development of rational approaches to the development of delivery systems is impressive (19,21,22,28), these efforts have been hampered because of the deficiency in our understanding of the molecular basis of the biological activities of formulations containing AmB. Therefore, a vehicle which retains optimal therapeutic properties and that can be used safely is still being sought.In previous in vitro studies, we observed that mixed micelles prepared from unsaturated phosphatidylcholine (egg yolk lecithin) and bile salt (glycocholate) significantly decreased the toxicity of Fungizone for human erythrocytes and cultured L cell fibroblasts, while it retained potent activity against Candida albicans and C. neoformans (6)

Amphotericin B incorporated into egg lecithin-bile salt mixed micelles: molecular and cellular aspects relevant to therapeutic efficacy in experimental mycoses

“…The decreased toxicity to mice and the improved therapeutic indices of Egam and Edam compared with that of Fungizone described in the companion report (11) may in turn be associated with these in vitro findings.…”

“…Egam and Edam were prepared as described in the companion report (11). Briefly, 387 ,ul of chloroform containing 38.7 mg (0.05 mmol) of egg lecithin and then either glycocholate or deoxycholate were added to sterile scintillation vials.…”

“…Recently, the therapeutic efficacies of novel formulations of AmB complexed to either egg lecithin and glycocholate (Egam) or to egg lecithin and deoxycholate (Edam) were compared with that of AmB as Fungizone in murine models of candidiasis and cryptococcosis (11). These formulations were nontoxic at doses 80-fold higher than the maximal tolerated doses in mice infected with Candida albicans and 40-fold higher than the maximal tolerated doses in mice infected with Cryptococcus neoformans.…”

Preparation, characterization, and evaluation of amphotericin B-loaded MPEG-PCL-g-PEI micelles for local treatment of oral <em>Candida albicans</em>

“…Apart from that, there have been many reports that self-aggregated AmB is toxic to both mammalian and fungal cell membranes, while the monomeric form of the drug is toxic to fungal cell membrane only. 55,56 The favorable result with cell and tissue toxicity of AmB-incorporated micelles appears to be associated with the existence of the drug molecules in the monomeric form in the micelles, whereas …”

Development of Novel Lyophilized Mixed Micelle Amphotericin B Formulation for Treatment of Systemic Fungal Infection

“…In the previous studies simple micellar solubilization as well as MM solubilization have been researched [26,27]. Among MM, Amph B incorporated in egg lecithin-bile salt micelles have been studied for the treatment of murine candidiasis, cryptococcosis [28], experimental mycoses [29] and for systemic fungal infections [30]. Earlier studies also demonstrated that an MM formulation with bile salts reduces pain on I. V. infusion [31].…”