Computed Tomography Imaging and Characteristics of In Situ Forming Implants with Different PLGA Endcaps

Area of Science:

• Biomaterials Science
• Drug Delivery Systems
• Polymer Chemistry

Background:

• In situ-forming implants (ISFIs) are long-acting injectables.
• Poly-(lactic-co-glycolic acid) (PLGA) is a key biodegradable polymer in ISFIs.
• PLGA end-cap chemistry critically affects ISFI performance and drug release.

Purpose of the Study:

• To investigate the impact of PLGA end-caps on ISFI formation and drug release.
• To characterize ISFI morphology and internal structure using computed tomography (CT) imaging.
• To establish a scientific basis for optimizing ISFI formulations.

Main Methods:

• Utilized leuprolide acetate as a model drug for ISFI formulation.
• Employed computed tomography (CT) imaging for detailed in vitro and in vivo characterization.
• Analyzed implant morphology, phase inversion, and drug release profiles.

Main Results:

• Acid-ended PLGA ISFIs exhibited a higher initial burst release and faster drug elution.
• Ester-ended PLGA ISFIs demonstrated a more sustained drug release profile, reaching plateau around day 50.
• CT imaging revealed distinct morphological differences: spherical implants for acid-ended PLGA and irregular shapes for ester-ended PLGA.

Conclusions:

• PLGA end-cap chemistry is a critical determinant of ISFI drug delivery performance.
• CT imaging provides valuable insights into ISFI formation and drug release mechanisms.
• This study offers a foundation for rational design and optimization of PLGA-based ISFIs.