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A Refined Thin-Film Model for Drug Dissolution Considering Radial Diffusion - Simulating Powder Dissolution.
Karthik Salish1, Chi So1, Seong Hoon Jeong2
1Synthetic Molecule Pharmaceutical Sciences, Genentech, Inc., 1 DNA Way, South San Francisco, CA, 94080, USA.
Pharmaceutical Research
|April 8, 2024
Summary
A refined thin-film model accurately describes drug powder dissolution, outperforming traditional models. The study highlights that not all particle surfaces contribute to dissolution, cautioning against using specific surface area for predictions.
Area of Science:
- Pharmaceutical Sciences
- Physical Chemistry
- Materials Science
Background:
- Accurate modeling of drug particle dissolution is crucial for formulation development.
- Existing models often simplify diffusion processes and particle behavior.
- Understanding dissolution kinetics informs drug delivery and bioavailability.
Purpose of the Study:
- To refine a thin-film model for drug particle dissolution, incorporating radial diffusion in a spherical boundary layer.
- To demonstrate the model's capability in describing the dissolution behavior of bulk drug powders.
- To compare the refined model's performance against classic dissolution formalisms.
Main Methods:
- Refinement of a previously established radial diffusion-based model.
- Simulation of bulk powder dissolution, accounting for evolving particle size and diffusion layer thickness.
- In vitro dissolution testing of fractionated hydrochlorothiazide powders to validate the model.
Main Results:
- The refined model showed good agreement with experimental dissolution data for various hydrochlorothiazide particle sizes.
- The model tended to over-predict dissolution rates for smaller particles.
- The classic Nernst-Brunner model under-estimated dissolution rates, while specific surface area calculations over-predicted them.
Conclusions:
- The radial diffusion-based thin-film model effectively describes drug powder dissolution.
- The Nernst-Brunner equation may under-estimate dissolution due to its translational diffusion assumption.
- Specific surface area alone is not a reliable predictor of drug dissolution due to non-contributing surfaces.
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