Effect of polymer source variation on the properties and performance of risperidone microspheres

Area of Science:

• Polymer Chemistry
• Materials Science
• Pharmaceutical Sciences

Background:

• Poly (lactic-co-glycolic acid) (PLGA) polymers exhibit inherent heterogeneity, posing challenges for consistent characterization.
• This variability in PLGA properties impedes the development of reliable long-acting drug delivery systems, such as microspheres.

Purpose of the Study:

• To identify subtle physicochemical differences and degradation profiles among PLGA polymers from various suppliers.
• To evaluate the influence of these different PLGA sources on the characteristics and in vitro performance of risperidone-loaded microspheres.

Main Methods:

• Four PLGA polymers with similar specifications were sourced and characterized for physicochemical properties (viscosity, molecular weight, monomer ratio, Tg, blockiness).
• Risperidone microspheres were prepared using a consistent solvent extraction/evaporation method with each PLGA type.
• Microsphere attributes (particle size, porosity) and in vitro drug release (burst effect, release rate) were analyzed.

Main Results:

• Despite similar manufacturer data, PLGA polymers displayed variations in inherent viscosity, molecular weight, blockiness, and residue.
• Microspheres formulated with different PLGAs exhibited distinct critical quality attributes and in vitro release profiles.
• A significant linear correlation was identified between risperidone release rate and the PLGA blockiness parameter.

Conclusions:

• PLGA polymer heterogeneity, particularly blockiness, significantly affects the performance of PLGA-based microspheres.
• The established correlation between PLGA blockiness and drug release offers a new parameter for optimizing controlled drug delivery systems.
• Further investigation into PLGA blockiness is warranted for advancing PLGA-based controlled release technologies.