Microencapsulation using poly(L-lactic acid) IV: Release properties of microcapsules containing phenobarbitone.

Area of Science:

• Polymer science
• Pharmaceutical technology
• Drug delivery systems

Background:

• Poly(L-lactic acid) microcapsules offer potential for controlled drug release.
• Phenobarbitone is an anticonvulsant medication requiring precise dosage forms.

Purpose of the Study:

• To investigate the preparation and characterization of phenobarbitone-loaded poly(L-lactic acid) microcapsules.
• To evaluate the effect of polymer molecular weight and drug loading on microcapsule properties and drug release kinetics.

Main Methods:

• Water/oil emulsification and evaporation technique for microencapsulation.
• Varying polymer molecular weights and core loadings.
• In vitro drug release studies at pH 2 and 9 at 37°C.

Main Results:

• Particle size increased with higher core loading and polymer molecular weight.
• Drug release followed a square root of time relationship, with ~90% released within 2 hours.
• Release rate was influenced by microcapsule size and surface area; normalized rates increased with phenobarbitone content.
• Rapid release observed at pH 9 and pH 2, particularly for high molecular weight polymers.

Conclusions:

• Poly(L-lactic acid) microcapsules provide rapid release of phenobarbitone, influenced by formulation parameters.
• The release mechanism is complex, affected by polymer properties and environmental pH.
• Microcapsule swelling and disintegration were observed, particularly for low molecular weight polymers.