FTIR microscopy and confocal Raman microscopy for studying lateral drug diffusion from a semisolid formulation

Area of Science:

• Materials Science
• Analytical Chemistry
• Biomedical Engineering

Background:

• Understanding drug diffusion in artificial membranes is crucial for developing effective drug delivery systems.
• Heterogeneous drug distribution can significantly impact therapeutic outcomes.
• Advanced microscopy techniques are needed to visualize and quantify drug penetration at microscale levels.

Purpose of the Study:

• To investigate the lateral (2D) drug diffusion of dithranol in artificial acceptor membranes.
• To analyze the depth profile (3D) of dithranol distribution within these membranes.
• To assess the capabilities of FTIR and confocal Raman microscopy for characterizing drug diffusion.

Main Methods:

• Fourier transform infrared (FTIR) microscopy was employed to map dithranol distribution (25microm x 25microm resolution) by integrating an IR band at 1430cm(-1).
• Transmission and reflection modes of FTIR microscopy were limited to membrane thicknesses below 15microm.
• Confocal Raman microscopy (CRM) was utilized to analyze the depth profile of dithranol distribution, from 1.5microm to 49microm.

Main Results:

• FTIR analysis revealed a heterogeneous distribution of dithranol particles within the artificial membrane.
• This non-uniform particle distribution resulted in non-uniform drug diffusion across the membrane surface.
• CRM successfully provided depth profiles, elucidating the three-dimensional distribution of dithranol.

Conclusions:

• FTIR and CRM are effective complementary techniques for characterizing drug diffusion and distribution in artificial membranes.
• The study highlights the complex, non-uniform nature of dithranol diffusion, impacting artificial membrane performance.
• These findings contribute to the development of more predictable and efficient drug delivery systems.