Effect of polymer/basic drug interactions on the two-stage diffusion-controlled release from a poly(L-lactic acid)...

Area of Science:

• Materials Science
• Pharmaceutical Sciences
• Polymer Chemistry

Background:

• Poly(L-lactic acid) (P(L)LA) is a biodegradable polymer used in drug delivery systems.
• Understanding drug release mechanisms from polymer matrices is crucial for effective drug formulation.

Purpose of the Study:

• To investigate how drug physicochemical properties affect the release of basic drugs from P(L)LA matrices.
• To elucidate the role of polymer-drug interactions and P(L)LA matrix transformations in controlling drug release kinetics.

Main Methods:

• Fabrication of P(L)LA cylindrical matrices loaded with basic drugs.
• In vitro drug release studies in aqueous medium.
• Evaluation of polymer-drug interactions through drug partitioning.
• Analysis of P(L)LA matrix structural changes (amorphous to semicrystalline transformation).

Main Results:

• P(L)LA matrices exhibited a two-stage, diffusion-controlled drug release profile.
• Drug release was influenced by the transformation of P(L)LA from amorphous to semicrystalline states.
• Polymer-drug interactions and matrix porosity modulated drug diffusion rates.
• Increased drug content enhanced release rates at specific pH conditions due to altered partitioning.

Conclusions:

• Drug release from P(L)LA matrices is governed by a complex interplay of drug physicochemical properties, polymer-drug interactions, and matrix structural evolution.
• The findings provide insights into designing controlled-release drug delivery systems using P(L)LA.
• Further research can optimize P(L)LA-based formulations by tuning drug loading and considering pH-dependent interactions.