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Parameters influencing the antigen release from spray-dried poly(DL-lactide) microparticles
B Baras1, M A Benoit, J Gillard
1Laboratoire de Pharmacie Galénique, Industrielle et Officinale, Ecole de Pharmacie, Université Catholique de Louvain, Brussels, Belgium. benoit.baras@pasteur-lille.fr
International Journal of Pharmaceutics
|June 14, 2000
Summary
Spray-dried polylactide (PLA) microparticles offer a promising vaccine delivery system for sustained antigen release, potentially eliminating the need for booster shots. This study optimized parameters for controlled antigen loading and release kinetics.
Area of Science:
- Biomaterials Science
- Pharmaceutical Technology
- Vaccine Delivery Systems
Background:
- Developing long-lasting vaccine delivery systems is crucial for improving global immunization coverage and reducing the need for frequent booster doses.
- Microparticle-based drug delivery systems, particularly those utilizing biodegradable polymers like polylactide (PLA), offer potential for controlled and sustained release of therapeutic agents, including antigens.
Purpose of the Study:
- To investigate the impact of spray-drying parameters and polymer solution characteristics on the properties of polylactide (PLA) microparticles for vaccine delivery.
- To evaluate the loading efficiency and release kinetics of a model antigen (bovine serum albumin, BSA) from PLA microparticles.
- To confirm the stability and integrity of the encapsulated antigen after processing and release.
Main Methods:
- Production of microparticles via spray-drying using high molecular weight polylactide (PLA R207).
- Systematic variation of technological parameters (inlet air temperature, feed spray rate) and polymeric solution properties (polymer concentration, solvent composition - dichloromethane/chloroform mixture).
- Characterization of microparticles for morphology, size, and bovine serum albumin (BSA) loading. Analysis of BSA release profiles over 24 hours using SDS-PAGE electrophoresis and isoelectric focusing.
Main Results:
- Microparticle size ranged from 3.08 to 9.43 microm, with BSA loading varying from 2.45% to 18.20% (w/w).
- BSA release rates varied significantly (11.17% to 92.60% in 24 h), influenced by inlet temperature, spray rate, and solvent composition (DCM/CFM mixture reduced burst release).
- Increased PLA concentration decreased BSA release rate, while antigen physicochemical characteristics were preserved post-release.
Conclusions:
- Spray-dried PLA microparticles are a viable system for encapsulating hydrophilic antigens, demonstrating potential for long-lasting, controlled vaccine delivery.
- Optimization of spray-drying and formulation parameters allows for tunable antigen loading and release profiles, paving the way for single-dose vaccines.
- The study confirms the stability of the model antigen within the microparticles, supporting their application in vaccine formulations requiring sustained immune response.