Rate-modulating PHBHV/PCL microparticles containing weak acid model drugs.

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Drug Delivery Systems

Background:

• Poly(hydroxybutyrate-co-hydroxyvalerate) (PHBHV) is a biodegradable polymer with potential in drug delivery.
• Poly(epsilon-caprolactone) (PCL) is another biocompatible polymer often blended to modify material properties.

Purpose of the Study:

• To investigate how varying PCL content in PHBHV/PCL blended microparticles affects drug release profiles.
• To determine the primary drug release mechanism from these blended microparticles.

Main Methods:

• Microparticles were prepared with different ratios of PHBHV and PCL.
• Encapsulation efficiencies of diclofenac and indomethacin were determined.
• Drug release kinetics were analyzed using biexponential and Baker-Lonsdale equations.
• Differential scanning calorimetry (DSC) was used to assess thermal properties.

Main Results:

• Encapsulation efficiencies for both drugs were approximately 85%.
• Microparticle size and surface area varied with PCL concentration.
• Drug release half-lives significantly increased with decreasing PCL concentration, indicating sustained release.
• Drug diffusion and solubility product (DC(s,m)) correlated with PCL concentration.

Conclusions:

• The PCL concentration in PHBHV/PCL blends is a key factor in controlling drug release kinetics.
• Drug release is primarily governed by diffusion through the polymer matrix.
• Systematic variation of PCL content allows for tailored drug release profiles.