Matrices containing NaCMC and HPMC 2. Swelling and release mechanism study

Area of Science:

• Pharmaceutical Sciences
• Materials Science

Background:

• Controlled drug release systems utilize polymer matrices to modulate drug delivery.
• Hydroxypropylmethylcellulose (HPMC) and sodium carboxymethylcellulose (NaCMC) are widely used hydrophilic polymers in oral dosage forms.

Purpose of the Study:

• To investigate the swelling behavior of combined HPMC and NaCMC matrix systems (MB) with a model drug.
• To correlate the morphological changes during swelling with the drug release performance across different pH environments.
• To understand the gel layer characteristics and their impact on drug release kinetics.

Main Methods:

• Tablets containing a drug-polymer mixture (MB) and reference tablets with individual polymers were prepared.
• Swelling studies were conducted at three different pH values (acidic and neutral).
• Morphological analysis of the gel layer and drug release profiles were evaluated.

Main Results:

• MB matrices exhibited similar swelling at pH 4.5 and 6.8 but different behavior in acidic conditions.
• At pH 1, NaCMC formed a rigid, partially crosslinked gel, while HPMC and MB formed physical, non-crosslinked gels.
• At pH 4.5 and 6.8, all systems showed physical gel formation, with MB matrices achieving constant drug release via diffusion and erosion.

Conclusions:

• The pH-dependent swelling behavior of HPMC/NaCMC matrices significantly influences drug release mechanisms.
• MB matrices demonstrate potential for zero-order drug release at neutral pH due to stable gel layer formation and combined diffusion-erosion mechanisms.
• Understanding polymer-drug interactions and matrix morphology is crucial for designing effective controlled-release formulations.