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Development of enteric-coated timed-release matrix tablets for colon targeting
J Alvarez-Fuentes1, M Fernández-Arévalo, M L González-Rodríguez
1Departamento de Farmacia y Tecnología Farmacéutica, Universidad de Sevilla, C/Prof. García González, s/n, 41012 Sevilla, Spain.
Journal of Drug Targeting
|December 29, 2004
Summary
A novel enteric-coated matrix tablet system effectively targets the colon using pH-sensitive and time-dependent release. This drug delivery system ensures gastric resistance and controlled drug release for improved colon targeting.
Area of Science:
- Pharmaceutical Technology
- Drug Delivery Systems
- Polymer Science
Background:
- Colon drug delivery remains challenging due to the gastrointestinal tract's complex environment.
- Developing systems for targeted colon drug delivery is crucial for treating local diseases and improving systemic bioavailability.
- Existing systems often face limitations in achieving precise and reliable colon targeting.
Purpose of the Study:
- To develop and evaluate a novel oral drug delivery system for colon targeting.
- To design enteric-coated matrix tablets that utilize both pH-sensitive and time-dependent release mechanisms.
- To investigate the influence of formulation variables on drug release and lag time for effective colonic delivery.
Main Methods:
- Matrix tablets were prepared by direct compression using hydroxyethylcellulose (HEC) with ethylcellulose (EC) or microcrystalline cellulose (MCC) and theophylline as a model drug.
- Tablets were coated with Eudragit S100, a pH-sensitive polymer, to achieve gastric resistance.
- Drug release studies were conducted using the USP basket method in sequential dissolution media simulating gastrointestinal pH variations.
Main Results:
- The enteric-coated matrix tablets demonstrated successful gastric resistance and a significant lag time before drug release, indicating effective colonic targeting.
- The level of enteric coating was identified as the critical factor for lag-phase duration, while matrix composition governed the drug release rate.
- Formulations with higher hydroxyethylcellulose (HEC) content exhibited faster drug release; microcrystalline cellulose (MCC)-HEC combinations were superior to ethylcellulose (EC)-HEC.
- Optimal results were achieved with 27% coated drug/MCC/HEC tablets (1:0.3:0.7 w/w), showing a 260-minute lag time and approximately 90% drug release within 10 hours.
Conclusions:
- The developed enteric-coated matrix tablet system is a promising approach for colon-specific drug delivery.
- The combination of pH-sensitive coating and swellable/erodible matrix provides a reliable mechanism for achieving a desired lag time and controlled drug release.
- This system offers potential for improved therapeutic efficacy in treating colonic diseases through targeted drug delivery.