Atomic force microscopy analysis and confocal Raman microimaging of coated pellets

Area of Science:

• Pharmaceutical Sciences
• Materials Science
• Analytical Chemistry

Background:

• Polymer-coated pellets are used for controlled drug release.
• Coating thickness significantly impacts drug release profiles.
• Understanding surface morphology is crucial for predicting release.

Purpose of the Study:

• To investigate the relationship between coating thickness, surface morphology, and drug release properties of polymer-coated pellets.
• To evaluate the utility of Atomic Force Microscopy (AFM) and confocal Raman microscopy in characterizing these systems.
• To elucidate the controlled release mechanism at the nanoscale.

Main Methods:

• Atomic Force Microscopy (AFM) was used to study surface morphology and behavior in aqueous media.
• Confocal Raman microscopy was employed to analyze the distribution of the active pharmaceutical ingredient (API).
• Results were correlated with prior Scanning Electron Microscopy (SEM) and drug release data.

Main Results:

• AFM revealed variations in surface crystalline material, with the thinnest coatings exhibiting the highest amounts.
• Confocal Raman microscopy confirmed API presence near the surface, correlating with coating thickness.
• In aqueous media, surface crystalline material rapidly dissolved, indicating a direct impact on release.

Conclusions:

• AFM is a powerful technique for analyzing dry pharmaceutical formulations and their release mechanisms.
• Combining AFM with Raman microscopy allows for detailed chemical and topographical analysis of coating surfaces.
• Coating thickness critically influences surface composition and the initial stages of drug dissolution and release.