Biodistribution of amphotericin B when delivered through cholesterol hemisuccinate vesicles in normal and A. fumigatus infected mice

New delivery systems for amphotericin B applied to the improvement of leishmaniasis treatment

Leishmaniasis is one of the six major tropical diseases targeted by the World Health Organization. It is a life-threatening disease of medical, social and economic importance in endemic areas. No vaccine is yet available for human use, and chemotherapy presents several problems. Pentavalent antimonials have been the drugs of choice to treat the disease for more than six decades; however, they exhibit high toxicity and are not indicated for children, for pregnant or breastfeeding women or for chronically ill patients. Amphotericin B (AmpB) is a second-line drug, and although it has been increasingly used to treat visceral leishmaniasis (VL), its clinical use has been hampered due to its high toxicity. This review focuses on the development and in vivo usage of new delivery systems for AmpB that aim to decrease its toxicity without altering its therapeutic efficacy. These new formulations, when adjusted with regard to their production costs, may be considered new drug delivery systems that promise to improve the treatment of leishmaniasis, by reducing the side effects and the number of doses while permitting a satisfactory cost-benefit ratio.

An optimized nanoparticle delivery system based on chitosan and chondroitin sulfate molecules reduces the toxicity of amphotericin B and is effective in treating tegumentary leishmaniasis

Amphotericin B (AmpB) is active against leishmaniasis, but its use is hampered due to its high toxicity observed in patients. In this study, a nanoparticles-delivery system for AmpB (NQC-AmpB), containing chitosan and chondroitin sulfate molecules, was evaluated in BALB/c mice against Leishmania amazonensis. An in vivo biodistribution study, including biochemical and toxicological evaluations, was performed to evaluate the toxicity of AmpB. Nanoparticles were radiolabeled with technetium-99m and injected in mice. The products presented a similar biodistribution in the liver, spleen, and kidneys of the animals. Free AmpB induced alterations in the body weight of the mice, which, in the biochemical analysis, indicated hepatic and renal injury, as well as morphological damage to the kidneys of the animals. In general, no significant organic alteration was observed in the animals treated with NQC-AmpB. Mice were infected with L. amazonensis and treated with the nanoparticles or free AmpB; then, parasitological and immunological analyses were performed. The NQC-AmpB group, as compared to the control groups, presented significant reductions in the lesion size and in the parasite burden in all evaluated organs. These animals presented significantly higher levels of IFN-γ and IL-12, and low levels of IL-4 and IL-10, when compared to the control groups. The NQC-AmpB system was effective in reducing the infection in the animals, and proved to be effective in diminishing the toxicity evoked by AmpB, which was observed when it was administered alone. In conclusion, NQC-AmpB could be considered a viable possibility for future studies in the treatment of leishmaniasis.

Drug delivery strategies for therapy of visceral leishmaniasis

IMPORTANCE OF THE FIELD

Visceral leishmaniasis (VL) is the most overwhelming type of leishmaniasis associated with the poverty of developing countries and usually mortal if untreated. Most of the conventionally used dosage forms offer us the shortcomings of toxic side effects and emergence of drug resistance. Several efforts have been made to overcome the barriers involved in the treatment of VL. Colloidal carriers extensively represent the drug delivery systems (DDSs) for intracellular localization of antileishmanial compounds in macrophage-rich organs such as liver, spleen and bone marrow. These DDSs offer superior therapeutic efficacy over the conventional treatment in terms of site-specific drug delivery with reduced side effects. However, after 35 years of research in the field, AmBisome (Amphotericin B liposome for injection, Astellas Pharma US, Inc.) is the only DDS used against the VL.

AREAS COVERED IN THIS REVIEW

A literature search was performed (for drugs and DDSs against VL) on PubMed and through Google.

WHAT THE READER WILL GAIN

This review aims to describe the pathophysiology of VL and its current conventional treatment with special reference to DDSs designed against VL.

TAKE HOME MESSAGE

On reviewing the conventional drugs and DDSs developed against VL, it is concluded that advances in the field of targeted drug delivery can result in more efficient strategies for the therapy of VL.

Mixed micellar nanoparticle of amphotericin B and poly styrene-block-poly ethylene oxide reduces nephrotoxicity but retains antifungal activity

Mixed micellar nanoparticle consisting of amphotericin B (AmB) and poly styrene-block-poly ethylene oxide (PS-block-PEO) was prepared by high pressure homogenizer. Nephrotoxicity of the nanoparticle was investigated along with antifungal activity and self-aggregation status of the drug in the nanoparticle. Nephrotoxicity was markedly reduced when AmB was intravenously administered to rats as mixed micellar nanoparticle with PS-block-PEO in terms of transmission electron microscopy of tubular cells and creatinine clearance. Antifungal activity of AmB was not altered when the drug was in the form of mixed micellar nanoparticle compared to both conventional formulation and AmB micelle treated by same procedure without PS-block-PEO. Self-aggregation status of AmB molecules revealed monomeric in the mixed micellar nanoparticle with PS-block-PEO up to the therapeutic level of the drug (1-3 mM). The reduced nephrotoxicity of AmB in mixed micellar nanoparticle may be associated with the existence of the drug as monomeric form in the nanoparticle. Based on our result, formulation of AmB as mixed micellar nanoparticle with PS-block-PEO may be a promising alternative for the treatment of fungal diseases in patients who are at risk of renal dysfunction.

Antileishmanial efficacy of amphotericin B bearing emulsomes against experimental visceral leishmaniasis

Amphotericin B (AmB) was formulated in trilaurin-based emulsomes (nanosize lipid particles) stabilized by soya phosphatidylcholine (PC), as a new delivery system for macrophage targeting for the treatment of visceral leishmaniasis (VL). Emulsomes were modified by coating them with macrophage-specific ligand (O-palmitoyl mannan, OPM). The antileishmanial activity of AmB-deoxycholate (AmB-Doc) and emulsome entrapped AmB was tested in vitro in Leishmania donovani infected macrophage-amastigote system (J774A.1 cells), which showed higher efficacy of OPM grafted AmB emulsomes (TLEs-OPM) over plain AmB emulsomes (TLEs) and AmB-Doc. The in vivo antileishmanial activity of the AmB (0.5 mg/kg) was tested in AmB-Doc, TLEs and TLEs-OPM forms against VL in L. donovani infected hamsters. Formulation TLEs-OPM eliminated intracellular amastigotes of L. donovani within splenic macrophages more efficiently (73.7 +/- 6.7% parasite inhibition) than the formulation TLEs (51.7 +/- 5.4% parasite inhibition) (P < 0.01) or AmB-Doc (30.4 +/- 4.8% parasite inhibition) (P < 0.001). Our results suggest that these newer formulations (plain and ligand appended emulsomes) are a promising alternative to the conventional AmB-Doc formulation for the treatment of VL.

Reduced renal toxicity of nanoparticular amphotericin B micelles prepared with partially benzylated poly-L-aspartic acid

A partially benzylated poly-L-aspartic acid (PBPA) was synthesized and investigated as a potential renal protective agent for the toxicity of amphotericin B (AmB) when the drug was administered as nanoparticular micelle. Nanoparticular AmB micelles were prepared by slow dialysis of the drug against distilled water at the elevated pH of 11.5 and subsequent sonication with the polymer solution. The resulting nanoparticular AmB micelles with PBPA showed an average diameter of about 20 nm and demonstrated significantly less damage to the tubular cells of the rat's kidney in terms of transmission electron microscopic study. There was little or no damage on the brush border of tubular cells 7 d after single intravenous dose of AmB 5 mg/kg in the rats when the drug was administered as nanoparticuar micelles with PBPA. The reduced renal toxicity appears to be due to the alteration of self-aggregation status of AmB. Molar absorptivity of AmB at 412 nm (a marker for the prevalence of non-aggregated AmB) was significantly higher in the nanoparticular AmB micelles with PBPA than those in AmB micelles without PBPA as well as in Fungizone. This result indicates an association of the reduced nephrotoxicity and the prevalence of non-aggregated AmB. Mechanisms for the reduced renal toxicity may also include the formation of electrostatic complex between anionic groups of PBPA and hydroxyl groups of AmB.

Synthesis of decapeptide ofl-aspartic acid and benzyl-l-aspartic acid by solid phase peptide synthesis

Polyene macrolide amphotericin B (AmB) is the drug of choice for the treatment of disseminated fungal infections. However, because of its pronounced side effects, the drug has limited applicability. There are few interesting reports, which state that co-administration of the drug with homo-peptide of polyaspartic acid reduces the side effects of the drug. In our present study, an approach has been made to systematically synthesize low molecular weight heteropeptides consisting of L-aspartic acid and its derivative. It was hypothesized that such heteropeptides will reduce the toxic side effects of the drug by facile hydrophobic binding between the polymer and the drug. We have employed the strategy of solid phase peptide synthesis (SPPS) to synthesize low molecular weight hetero-peptides by using L-aspartic acid and benzyl-L-aspartic acid to induce the hydrophobic binding between the peptide and the drug. In future, the proposed methodology can be employed to tailor other polypeptides substituted with benzyl groups to reduce the nephrotoxicity of AmB.

Evaluation of the relationship of the molecular aggregation state of amphotericin B in medium to its genotoxic potential

This work analyzes the genotoxicity potential, in the G2 phase of the cellular cycle, of an amphotericin B (AmB) commercially available form (Fungizone), and correlates it with the physicochemical properties of this product in aqueous media. The genotoxic studies were performed using peripheral blood lymphocytes from human donors. The chromosome aberrations and mitotic index were determined. Absorption spectra of Fungizone were obtained by dispersion of the stock solution in water for injection at various AmB concentrations, and using different cuvette path lengths for spectrophotometric determination. The absorption spectra of Fungizone in water are concentration dependent. High concentrations of Fungizone present a spectrum with an intense band at 340 nm, characteristic of AmB self-association. Conversely, at low concentrations, the spectra are similar to those obtained with AmB in methanol, with a positive band at 409 nm, assigned to AmB monomeric form. Similarly, the cytogenetic analysis shows an important decrease on the mitotic index, which is also concentration dependent when compared with control. Furthermore, the chromosome aberrations present a small, not statistically significant, increase only at the highest concentration. The results suggest that the Fungizone presents a cytotoxicity similar to membrane pore formation in mammalian cells that depends on the existence of self-associated AmB. In the presence of only monomeric forms, this phenomenon disappears. However, no genotoxicity was observed in this study.

Treatment of experimental visceral leishmaniasis with amphotericin B in stable albumin microspheres

Hydrophilic albumin microspheres are proposed as a new delivery system for amphotericin B (AMB; AMB microspheres). The acute toxicity of AMB microspheres was lower than that of the AMB-deoxycholate (AMB-Doc) reference formulation in hamsters. Lethal doses in healthy and infected animals were improved at least eight times. Intravenous bolus administration of doses of AMB microspheres up to 40 mg/kg of body weight did not produce acute symptoms of toxicity. The efficacy of this new formulation was tested against Leishmania infantum-infected hamsters at doses of 2, 10, 20, and 40 mg/kg. With the 2-mg/kg dose, the activity of AMB, as assessed through the parasite load reductions in the liver and spleen and the evolution of antibody levels, was also improved (P < 0.05) by use of the AMB microsphere system. At the higher doses of 10, 20, and 40 mg/kg, reductions in parasite levels of more than 99% were achieved in the liver and spleen after the administration of AMB microspheres. A pharmacokinetic study was performed to study the serum, liver, and spleen AMB concentrations after administration of AMB microspheres and the reference formulation. Interestingly, a significant accumulation of AMB in the spleen and liver was observed after AMB microsphere administration. Our results suggest that this new formulation is a promising alternative to the conventional AMB-Doc formulation for the treatment of visceral leishmaniasis.