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Updated: Dec 20, 2025

A Package of Established Analytical Tools to Investigate the Solid-State Alteration of Lipid-Based Excipients
Published on: August 9, 2022
Model for the Analysis of Membrane-Type Dissolution Tests for Inhaled Drugs
Göran Frenning1, Irès van der Zwaan1, Frans Franek2
1Department of Pharmacy and the Swedish Drug Delivery Center (SweDeliver), Uppsala University, P.O. Box 580, 751 23 Uppsala, Sweden.
Abstract:
Impactor-type dose deposition is a common prerequisite for dissolution testing of inhaled medicines, and drug release typically takes place through a membrane. The purpose of this work is to develop a mechanistic model for such combined dissolution and release processes, focusing on a drug that initially is present in solid form. Our starting points are the Noyes-Whitney (or Nernst-Brunner) equation and Fick's law. A detailed mechanistic analysis of the drug release process is provided, and approximate closed-form expressions for the amount of the drug that remains in solid form and the amount of the drug that has been released are derived. Comparisons with numerical data demonstrated the accuracy of the approximate expressions. Comparisons with experimental release data from literature demonstrated that the model can be used to establish rate-controlling release mechanisms. In conclusion, the model constitutes a valuable tool for the analysis of in vitro dissolution data for inhaled drugs.
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