Partition coefficients in vitro: artificial membranes as a standardized distribution model
Document Type
Article
Publication Title
European Journal of Pharmaceutical Sciences
Abstract
The lipophilicity of β-adrenoceptor antagonists (RS)-propranolol and (S)-dihydroalprenolol is characterized in a standardized liposomal partition system at 37°C. Apparent partition coefficients in the range of pH 2 to pH 12 were determined by a two-chamber equilibrium dialysis between small unilamellar phosphatidylcholine liposomes (lipophilic phase) and universal buffer solutions adjusted in ionic strength and osmolality (hydrophilic phase). Above pH 4.5, the partition behavior of both compounds ideally follows the pH-dependent degree of dissociation of the drug. Data analysis as performed by a nonlinear curve fitting procedure revealed a perfect correspondence between the fitted pKa values and the respective thermodynamic dissociation constants at 37°C. The fitted true partition coefficient was 1892.8±58.1 for (RS)-propranolol and 1105.9±31.6 for (S)-dihydroalprenolol. Below pH 4.5, drug partitioning was influenced by an acid-induced change in the lipophilic phase. © 1994.
First Page
273
Last Page
282
DOI
10.1016/0928-0987(94)90022-1
Publication Date
1-1-1994
Recommended Citation
Pauletti, Giovanni M. and Wunderli-Allenspach, Heidi, "Partition coefficients in vitro: artificial membranes as a standardized distribution model" (1994). Pharmaceutical and Administrative Sciences Faculty Publications. 209.
https://doi.org/10.1016/0928-0987(94)90022-1
https://collections.uhsp.edu/pharm-admin-sciences_pubs/209