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Effect of comonomer ratio on hydrocortisone diffusion from sustained-release composite capsules
Journal of Biomedical Materials Research
|May 1, 1978
Summary
This study shows that increasing vinyl acetate in ethylene-vinyl acetate copolymer capsules enhances hydrocortisone diffusion. Copolymer ratio significantly impacts drug release more than initial drug content.
Area of Science:
- Materials Science
- Polymer Chemistry
- Pharmaceutical Sciences
Background:
- Drug delivery systems require controlled release mechanisms.
- Hydrocortisone is a widely used anti-inflammatory drug.
- Ethylene-vinyl acetate copolymers offer tunable properties for drug encapsulation.
Purpose of the Study:
- To investigate the in vitro release kinetics of hydrocortisone from composite polymer capsules.
- To determine the effect of vinyl acetate comonomer content on drug diffusion rates.
- To explore the relationship between copolymer composition, crystallinity, and drug release.
Main Methods:
- Fabrication of composite polymer capsules with varying ethylene-vinyl acetate copolymer compositions.
- In vitro drug release studies of hydrocortisone over 120 days.
- Calculation of diffusion constants based on release data.
Main Results:
- Higher vinyl acetate content in the copolymer matrix increased hydrocortisone diffusion rate.
- Initial drug load (20 mg vs. 40 mg) had a less significant effect on daily release compared to copolymer ratio.
- Diffusion constants varied with vinyl acetate content and initial drug concentration.
Conclusions:
- Vinyl acetate comonomer content is a key factor controlling hydrocortisone diffusion from ethylene-vinyl acetate copolymer systems.
- Copolymer crystallinity is suggested as a major factor influencing the diffusion rate.
- The study provides insights into designing controlled-release hydrocortisone formulations.