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PLG microparticles stabilised using enteric coating polymers as oral vaccine delivery systems
A Delgado1, E C Lavelle, M Hartshorne
1Department of Pharmaceutical Sciences, University of Nottingham, University Park, UK.
Vaccine
|August 7, 1999
Summary
Novel microparticles using enteric polymers Eudragit and carboxymethylethylcellulose (CMEC) enhanced oral vaccine delivery. CMEC-stabilized microparticles showed superior antigen protection and induced higher salivary IgA antibody levels in mice.
Area of Science:
- Biomaterials Science
- Vaccine Delivery Systems
- Polymer Chemistry
Background:
- Oral vaccine delivery faces challenges with antigen degradation in the gastrointestinal tract.
- Poly(dl-lactide-co-glycolide) (PLG) microparticles are a promising platform for oral vaccines.
- Developing effective stabilizers for PLG microparticles is crucial for enhancing antigen protection and immunogenicity.
Purpose of the Study:
- To formulate and evaluate novel poly(dl-lactide-co-glycolide) microparticles for oral vaccine delivery using enteric polymers Eudragit L100-55 and carboxymethylethylcellulose (CMEC) as stabilizers.
- To compare the antigen-protective capacity and immunogenicity of microparticles stabilized by CMEC and Eudragit against those stabilized by polyvinyl alcohol (PVA).
Main Methods:
- Formulation of ovalbumin (OVA)-loaded PLG microparticles using Eudragit L100-55, CMEC, or PVA as stabilizers.
- Characterization of microparticle size, morphology, and surface composition using techniques like XPS and SSIMS.
- In vitro assessment of antigen (OVA) protection against enzymatic degradation by pepsin and trypsin.
- Evaluation of microparticle stability in simulated gastric fluid.
- In vivo oral immunisation of mice to assess humoral immune responses (serum IgG and salivary IgA).
Main Results:
- All formulated microparticles were spherical, <5 microm in diameter.
- CMEC- and Eudragit-stabilized microparticles demonstrated significantly higher protection of encapsulated OVA against pepsin at pH 1.2 and trypsin at pH 7.4 compared to PVA.
- Microparticles stabilized with CMEC showed a higher percentage of intact OVA after incubation in simulated gastric fluid.
- Oral immunisation with all microparticle formulations induced specific serum IgG and salivary IgA antibodies.
- CMEC-stabilized microparticles elicited significantly higher levels of specific salivary IgA antibodies to OVA compared to Eudragit- and PVA-stabilized formulations.
Conclusions:
- Enteric polymers Eudragit and CMEC are effective stabilizers for PLG microparticles intended for oral vaccine delivery.
- CMEC-stabilized microparticles offer superior antigen protection in the gastrointestinal environment.
- This formulation strategy holds potential for improving the efficacy of oral vaccine delivery systems.