Collect. Czech. Chem. Commun. 2002, 67, 245-256

Potentiometric Study of Carbisocaine Micellization and Inclusion Complexation with α-Cyclodextrin, β-Cyclodextrin, Methyl-β-cyclodextrin, and (Hydroxypropyl)-β-cyclodextrin

František Kopecký*, Mária Vojteková, Miloš Vrana and Katarína Čížová

Faculty of Pharmacy, Comenius University, 832 32 Bratislava, Slovak Republic


Micellization of the local anesthetic drug carbisocaine hydrochloride (BHCl) was studied by potentiometry with both cation- and anion-selective membrane electrodes in aqueous solution at 25 °C. The found critical micelle concentration 0.022 mol dm-3 and the concentration course of the free carbisocaine cation and chloride counterion in the micellar solution corresponded to the characteristic of cationic surfactants. In a more dilute aqueous solution, below critical micelle concentration, the complexation of carbisocaine cation BH+ with α-cyclodextrin (α-CD), β-cyclodextrin (β-CD) and its random substituted methyl (M-β-CD) and hydroxypropyl (HP-β-CD) derivatives was followed using the prepared cation-selective electrodes. The potentiometric data corroborated formation of the carbisocaine-cyclodextrin complexes (BH+)CD (1 : 1) with all the cyclodextrins and the respective complexation constants K11 were estimated using a modified Scatchard method. Slight deviations from 1 : 1 plots were marginally observed with α-CD and HP-β-CD. Bigger K11 value of the complexation with α-CD in comparison with β-CD indicated inclusion of the carbisocaine C7 alkyl chain into the cyclodextrin cavity and the role of the hydrophobic interaction in complexation with β-CDs was emphasized by the increasing magnitude of K11 in the order of HP-β-CD < β-CD < M-β-CD.

Keywords: Potentiometry; Ion-selective electrodes; Local anesthetics; Phenylcarbamate; Micelles; Cationic surfactants; Cyclodextrins; Inclusion complexes.

References: 25 live references.