Related Experiment Video
Updated: Aug 10, 2026

Transport Properties of Ibuprofen Encapsulated in Cyclodextrin Nanosponge Hydrogels: A Proton HR-MAS NMR Spectroscopy Study
Published on: August 15, 2016
Influence of aqueous diffusion layer on passive drug diffusion from aqueous cyclodextrin solutions through biological
T Loftsson1, F Konrádsdóttir, M Másson
1Faculty of Pharmacy, University of Iceland, Reykjavik, Iceland. thorstlo@hi.is
Abstract:
Most drugs permeate biological membranes via passive diffusion and it is generally assumed that the main barrier is the lipophilic structure of the membrane. However, we have observed that the unstirred water layer adjacent to the membrane surface can in some cases be a barrier just as effective as the lipophilic membrane itself. Hydrophilic cyclodextrins can enhance drug delivery through biological membranes by increasing the availability of dissolved drug molecules immediate to the membrane surface, i.e. by increasing drug delivery through the unstirred water layer. Cyclodextrins and drug/ cyclodextrin complexes are, in most cases, unable to permeate lipophilic membranes. Thus, excess cyclodextrin, more than is needed to solubilize the drug in the aqueous exterior, will hamper drug delivery through biological membranes.
Related Concept Videos
Passive Diffusion: Overview and Kinetics
When administered orally, drugs establish a substantial concentration gradient between the gastrointestinal (GI) lumen and the bloodstream, expediting their diffusion into...
Drug Absorption Mechanism: Passive Membrane Transport
Theories of Dissolution: Diffusion Layer Model
This process starts with a thin layer, saturated with the drug, forming at the interface between the solid and liquid. The solute then diffuses from this layer into the main solution. The Noyes-Whitney equation suggests that the rate of dissolution relies on the diffusion...
Cellular Membranes and Drug Transport
Phospholipids arrange themselves into a bilayer, with hydrophilic heads oriented outward and hydrophobic tails facing inward.
Facilitated Diffusion
In this process, substrates such as organic compounds and ions interact with a transporter on one side, triggering conformational changes in proteins that enable...
Diffusion

