Collection of Czechoslovak Chemical Communications - digital archive 

Abstract

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.