Protolytic Equilibria of Cetirizine in the Presence of Micelle-Forming Surfactants
The acid–base equilibria of cetirizine were investigated with and without the presence of differently charged micelle-forming surfactants (anionic, cationic, nonionic). The p<i>K</i><sub>a</sub> values were potentiometrically determined at 25 °C and at a constant ionic streng...
Saved in:
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-01-01
|
| Series: | Organics |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2673-401X/6/1/2 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | The acid–base equilibria of cetirizine were investigated with and without the presence of differently charged micelle-forming surfactants (anionic, cationic, nonionic). The p<i>K</i><sub>a</sub> values were potentiometrically determined at 25 °C and at a constant ionic strength (0.1 M NaCl). Experimental data were analyzed by applying the computer program Hyperquad 5.2.15. Based on a shift in the ionization constants (∆p<i>K</i><sub>a</sub>) in micellar solutions against the p<i>K</i><sub>a</sub> values determined in “pure” water under the same conditions, the effects of micelles on the protolytic equilibria of cetirizine were estimated. Applied micelles caused a shift in the protolytic equilibria of all cetirizine ionizable centers, with the piperazine function connected to aliphatic side moiety (∆p<i>K</i><sub>a1</sub> from −0.47 to +1.42), carboxyl group (∆p<i>K</i><sub>a2</sub> from −0.92 to +2.02), and piperazine nitrogen connected to phenyl rings (∆p<i>K</i><sub>a3</sub> from −2.01 to +2.19). Anionic SDS and nonionic Brij 35 micelles caused an increase in the p<i>K</i><sub>a</sub> values of the ionizable centers of cetirizine, while a decrease in the p<i>K</i><sub>a</sub> values was detected under the influence of cationic CTAB and nonionic TX-100 micelles. The change in the ionization pattern by micelles at pH values with biopharmaceutical significance provides indications of possible interactions of cetirizine with biomolecules of different charge and polarity under physiological conditions. |
|---|---|
| ISSN: | 2673-401X |