Deeper insight into the drug release mechanisms in Eudragit RL-based delivery systems

Area of Science:

• Polymer science
• Pharmaceutical technology
• Materials science

Background:

• Eudragit RL is a widely used polymer in drug delivery systems.
• Understanding the plasticization effects of active pharmaceutical ingredients (APIs) is crucial for controlling drug release.
• Tartaric acid, metoprolol free base, and metoprolol tartrate are potential plasticizers for Eudragit RL.

Purpose of the Study:

• To investigate the plasticizing effects of tartaric acid, metoprolol free base, and metoprolol tartrate on Eudragit RL films.
• To determine the diffusion coefficients of water and these compounds within the polymer matrix.
• To elucidate the drug release mechanisms from Eudragit RL systems.

Main Methods:

• Preparation of thin films of Eudragit RL incorporating varying concentrations of plasticizers.
• Exposure of films to HCl, phosphate buffer, and distilled water.
• Application of Fick's second law of diffusion to determine apparent diffusivities.
• Analysis of film swelling and shrinking behavior.

Main Results:

• Water penetration and drug release were predominantly diffusion-controlled, irrespective of the release medium.
• Metoprolol tartrate exhibited a more pronounced plasticizing effect than tartaric acid, increasing diffusion coefficients.
• Metoprolol free base showed limited plasticization in the wet state due to precipitation, complicating mass transport.
• Film shrinking was observed due to leaching of plasticizers, leading to reduced flexibility.

Conclusions:

• The plasticizing effect of metoprolol tartrate enhances drug diffusion in Eudragit RL systems.
• Metoprolol free base precipitation poses challenges for predictable drug release from Eudragit RL.
• Understanding these mechanisms aids in optimizing Eudragit RL-based dosage forms for controlled drug delivery.