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Hemolytic and antifungal activity of liposome-entrapped amphotericin B prepared by the precipitation method
1Department of Chemical Engineering, Korea Advanced Institute of Science and Technology, Yusong-Gu, Taejon, Korea.
Abstract:
A new method of preparing liposomes containing amphotericin B (AmB) was developed with the purpose of reducing the toxicity of AmB without causing a loss in its antifungal activity. The procedure involved the precipitation of AmB and egg phosphatidylcholine (PC) in phosphate buffered saline (PBS, pH 7.4) or tris buffered saline (TBS, pH 7.4) by evaporating methanol and chloroform, which had been previously mixed in the buffer solution, at 4 degrees C and 600 mm Hg. The in vitro toxicity of the precipitated liposomes containing 3, 6, 9, 12, and 15 wt% AmB was compared with that of the film-swollen liposomes containing the equivalent contents of the drug. The hemolytic ability of the precipitated liposomes at 37 degrees C was 50.3% at maximum of the film-swollen liposomes at a dose of 30 micrograms AmB/ml, as measured after 17-hr incubation. The significant reduction in the hemolysis effect may in fact be attributed to the reduced rate of drug release from the precipitated liposomes. The precipitated liposomes were multilayered and aggregates of AmB were embedded in the bilayers. These aggregates of AmB would be responsible for an intensive positive peak around 330 nm and reduced toxicity. Despite the decrease in toxicity, the activity of the precipitated liposomes against Candida albicans remained almost equipotent to that of the film-swollen liposomes. Therefore, liposomes prepared by the precipitation method are less toxic but equally as active.
Insights
A novel precipitation method creates less toxic liposomal amphotericin B (AmB) without compromising antifungal efficacy. This liposomal AmB preparation offers a safer alternative for treating fungal infections.
Area of Science:
- Pharmaceutical Sciences
- Drug Delivery Systems
- Mycology
Background:
- Amphotericin B (AmB) is a potent antifungal agent but exhibits significant toxicity.
- Liposomal formulations aim to reduce AmB toxicity while preserving antifungal activity.
- Conventional liposome preparation methods may not fully mitigate AmB-associated adverse effects.
Purpose of the Study:
- To develop a new method for preparing liposomes containing amphotericin B (AmB).
- To reduce the toxicity of AmB without compromising its antifungal activity.
- To characterize the physicochemical properties and in vitro performance of the novel liposomal formulation.
Main Methods:
- Liposomes were prepared by precipitating AmB and egg phosphatidylcholine (PC) in buffered saline.
- Methanol and chloroform solvents were evaporated under controlled conditions (4°C, 600 mm Hg).
- In vitro toxicity (hemolysis) and antifungal activity against Candida albicans were compared with film-swollen liposomes.
Main Results:
- Precipitated liposomes exhibited significantly reduced hemolytic activity compared to film-swollen liposomes.
- Reduced AmB release rate from precipitated liposomes correlated with decreased toxicity.
- Precipitated liposomes showed AmB aggregates embedded in bilayers, indicated by a peak at 330 nm.
- Antifungal activity against Candida albicans remained comparable between precipitated and film-swollen liposomes.
Conclusions:
- The precipitation method yields less toxic liposomal amphotericin B.
- This novel formulation maintains potent antifungal activity.
- Liposomes prepared by precipitation represent a promising strategy for safer AmB delivery.