Related Experiment Video
Updated: Aug 16, 2026

Transport Properties of Ibuprofen Encapsulated in Cyclodextrin Nanosponge Hydrogels: A Proton HR-MAS NMR Spectroscopy Study
Published on: August 15, 2016
Investigation of drug-cyclodextrin complexes by a phase-distribution method: some theoretical and practical
Már Másson1, Birna Vigdís Sigurdardóttir, Kristján Matthíasson
1Faculty of Pharmacy, University of Iceland, Hofsvallagata 53, IS-107 Reykjavik, Iceland. mmasson@hi.is
Abstract:
The purpose of the study was to evaluate an octanol-water phase distribution method for investigation of drug/cyclodextrin (D/CD) complexes and to compare stability constant values obtained by this method to values obtained by the phase solubility method. A general equation for determination of 1 : 1 D/CD complex stability constant (K1 : 1) from the slope of a phase-distribution diagram (a diagram of the reciprocal of the apparent partition coefficient vs. the total CD concentration) was derived. The equation accounted for the possible inclusion of the organic solvent in the CD cavity and the gradual saturation of the CD binding with increasing concentration of the guest compound. This method was used to determine K1 : 1 for 2-hydroxypropyl-beta-cyclodextrin (HPbetaCD) complexes of hydrocortisone, prednisolone, diazepam, beta-estradiol and diethylstilbestrol. These values were comparable to K1 : 1 values determined by the phase-solubility method. The phase-distribution method could also be applied to determine stability constants for the neutral and ionic forms of the weakly acidic drugs, naproxen and triclosan and the weakly basic drug lidocaine. The phase-distribution method is a very versatile and fast method and has the advantage, compared to the phase-solubility method, that it only requires very small drug samples. Thus, this method would be suitable for screening of new drug candidates.
Related Concept Videos
Analyte Adsorption and Distribution
In Vitro Drug Dissolution: Alternative Methods
In Vitro Drug Dissolution: Compendial Testing Models II
Extraction: Partition and Distribution Coefficients
For extracting a solute from an aqueous phase into an organic...
In Vitro Drug Dissolution: Compendial Testing Models I
Factors Influencing Drug Absorption: Drug Dissolution
