Drug diffusion front movement is important in drug release control from swellable matrix tablets

Area of Science:

• Pharmaceutical Sciences
• Materials Science

Background:

• Controlled drug delivery systems aim to optimize therapeutic efficacy and patient compliance.
• Hydroxypropyl methylcellulose (HPMC) is a widely used polymer for developing swellable matrices for oral drug delivery.

Purpose of the Study:

• To investigate the swelling and drug release behavior of buflomedil pyridoxalphosphate from HPMC-based controlled release devices.
• To elucidate the mechanisms governing drug release by analyzing the interplay of swelling, diffusion, and erosion fronts.

Main Methods:

• Preparation of swellable controlled release devices incorporating buflomedil pyridoxalphosphate within an HPMC matrix.
• In vitro investigation of device swelling and drug release kinetics under varying system parameters.
• Analysis of distinct fronts (swelling, drug diffusion, erosion) and their influence on release profiles.

Main Results:

• Three distinct fronts—swelling, drug diffusion (visualized by drug color), and erosion—were identified during the release process.
• Drug release rate was significantly influenced by initial porosity and polymer molecular weight.
• The drug diffusion front's position was identified as the primary determinant of overall system release behavior.
• Dissolved drug gel layer thickness, separating diffusion and erosion fronts, strongly correlated with fractional drug release.
• Increased drug solubility (by altering pH/ionic strength) reduced gel layer thickness, reinforcing the diffusion front's control.

Conclusions:

• The drug diffusion front movement is the critical factor controlling buflomedil pyridoxalphosphate release from HPMC matrices.
• Understanding and controlling the gel layer dynamics are essential for designing effective swellable controlled release systems.