Spray dried polymyxin B liposome for inhalation against gram-negative bacteria

Area of Science:

• Pharmaceutical Sciences
• Drug Delivery Systems
• Antimicrobial Research

Background:

• Polymyxin B (PMB) exhibits significant toxicity and bacterial resistance, limiting its clinical application.
• Inhalation therapy offers a promising route for localized drug delivery to the lungs, potentially mitigating systemic toxicity.

Purpose of the Study:

• To develop and characterize liposomal dry powder formulations of polymyxin B (PMB) for inhalation.
• To evaluate the safety and efficacy of inhaled liposomal PMB against bacterial infections in the lungs.

Main Methods:

• Liposomal dry powder formulation of PMB using thin-film hydration and spray-drying.
• Characterization of physical properties, aerodynamic performance (NGI), and in vitro drug release.
• Assessment of cytotoxicity (MTT assay) and antimicrobial activity (bioassay, flow cytometry).

Main Results:

• Spray-dried liposomes exhibited particle sizes between 259.83–518.73 nm and positive zeta potentials.
• No chemical interactions were observed between PMB and excipients (FTIR); powders were amorphous (DSC) and spherical (SEM).
• Aerodynamic diameter was 1.72–2.75 nm with 25–26% fine particle fraction (FPF); 90.3% PMB release within 2 hours; effective killing of *Pseudomonas aeruginosa* and *Escherichia coli*.

Conclusions:

• Liposomal dry powder inhalation is an effective delivery system for PMB.
• The formulation demonstrated reduced toxicity and potent antimicrobial activity against key lung pathogens.
• This approach offers a promising strategy to overcome PMB toxicity and bacterial resistance in respiratory infections.