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Antimicrobial effectiveness of liposomal polymyxin B against resistant Gram-negative bacterial strains

Misagh Alipour1, Majed Halwani, Abdelwahab Omri

  • 1Department of Chemistry and Biochemistry, Laurentian University, Sudbury, Ontario, Canada.

International Journal of Pharmaceutics
|January 1, 2008
PubMed

Insights

Liposome encapsulation enhances polymyxin B efficacy against Gram-negative bacteria, improving drug delivery and reducing toxicity. This study explores different liposome compositions for optimal antibiotic delivery and antimicrobial activity.

Area of Science:

  • Pharmacology and Pharmaceutics
  • Drug Delivery Systems
  • Antimicrobial Research

Background:

  • Polymyxin B is a critical antibiotic for Gram-negative infections but exhibits significant systemic toxicity.
  • Liposomal encapsulation is a strategy to improve antibiotic efficacy and reduce adverse effects.
  • The choice of liposome composition (e.g., DPPC/Chol vs. POPC/Chol) influences drug entrapment and release kinetics.

Purpose of the Study:

  • To investigate the incorporation of polymyxin B into liposomes composed of DPPC/Chol and POPC/Chol.
  • To evaluate the entrapment efficiency, release characteristics, and antimicrobial activity of liposomal polymyxin B formulations.
  • To assess the potential of liposomal polymyxin B for managing Gram-negative bacterial infections.

Main Methods:

  • Polymyxin B was encapsulated into DPPC/Chol and POPC/Chol liposomes using sonication and extrusion techniques.
  • Entrapment efficiency was quantified for both liposome types.
  • In vitro release studies in serum and saline were performed, followed by antimicrobial activity assessments (MICs) and penetration studies using Pseudomonas aeruginosa.

Main Results:

  • Sonicated DPPC/Chol liposomes showed significantly higher polymyxin B entrapment efficiency compared to POPC/Chol liposomes.
  • Extruded POPC/Chol liposomes exhibited better entrapment than DPPC/Chol liposomes, but DPPC/Chol liposomes showed faster release in serum and saline.
  • Liposomal polymyxin B formulations, particularly sonicated DPPC/Chol, demonstrated lower MICs and enhanced penetration into Pseudomonas aeruginosa compared to free drug.

Conclusions:

  • Liposomal formulation of polymyxin B can enhance its antimicrobial activity and improve penetration into resistant Gram-negative bacteria.
  • Liposome composition critically affects drug entrapment, release kinetics, and ultimately, therapeutic potential.
  • These findings suggest that liposomal polymyxin B holds promise for the effective management of Gram-negative infections.

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