Characterization of drug-loaded poly(d,l-lactide) microspheres

Area of Science:

• Biomaterials Science
• Drug Delivery Systems
• Polymer Chemistry

Background:

• Biodegradable polymers are crucial for controlled drug release.
• Microsphere technology offers potential for targeted delivery of therapeutics like lomustine and progesterone.
• Optimizing drug loading and particle morphology is key for effective microsphere-based drug delivery.

Purpose of the Study:

• To investigate the incorporation of lomustine and progesterone into biodegradable poly(d,l-lactide) microspheres.
• To characterize the effect of drug loading and process parameters on microsphere properties.
• To assess the stability of incorporated drugs within the microsphere matrix.

Main Methods:

• Utilized dichloromethane evaporation from dichloromethane-in-water emulsions to fabricate microspheres.
• Varied drug payloads (lomustine, progesterone) and process parameters (agitation, emulsifier concentration).
• Analyzed microsphere size, shape, drug incorporation efficiency, and drug stability.

Main Results:

• Achieved spherical microspheres with payloads up to 23% for lomustine and 68% for progesterone.
• Higher lomustine payloads resulted in irregular particles; high progesterone payloads led to surface drug crystals.
• Increased agitation decreased microsphere size; drug addition increased particle size.
• Drug incorporation efficiency was not significantly improved by higher emulsifier concentrations.
• Incorporation into microspheres reduced the shelf-life stability of both lomustine and progesterone.

Conclusions:

• Poly(d,l-lactide) microspheres can encapsulate lomustine and progesterone, but drug loading limits exist for optimal morphology.
• Process parameters critically influence microsphere characteristics and drug crystallization.
• The molecular dispersion of drugs within the polymer matrix negatively impacts their stability.