Iram Shahzadi1, Imran Nazir2, Thi Nhu Quynh Phan3, Andreas Bernkop-Schnürch4. 1. Center for Chemistry and Biomedicine, Department of Pharmaceutical Technology, Institute of Pharmacy, University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria. 2. Center for Chemistry and Biomedicine, Department of Pharmaceutical Technology, Institute of Pharmacy, University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria; Department of Pharmacy, COMSATS University Islamabad, Abbottabad Campus, 22060 Abbottabad, Pakistan. 3. Center for Chemistry and Biomedicine, Department of Pharmaceutical Technology, Institute of Pharmacy, University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria; Faculty of Pharmacy, University of Medicine and Pharmacy, Hue University, Viet Nam. 4. Center for Chemistry and Biomedicine, Department of Pharmaceutical Technology, Institute of Pharmacy, University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria. Electronic address: andreas.bernkop@uibk.ac.at.
Abstract
AIM: The study was aimed to investigate the impact of superassociation of hydrophobic ion pairs (HIPs) on membrane permeability. METHODS: Toluidine blue O (TBO) as a cationic model compound was complexed with anionic counter ions having different physiochemical properties namely dodecanoate (DD), oleate (OL), deoxycholate (DC), docusate (DO) and dodecyl sulfate (DS). TBO HIPs were characterized regarding log P, zeta potential and stability over 8 h at pH 7.4. Association and dissociation constants (Ka and Kd) were calculated by applying quasi-equilibrium equation to the double reciprocal plots of log P versus counter ion concentrations. Permeation studies of free TBO, superassociated TBO HIPs and HIPs applied as entirely dissociated form were carried out across human colorectal adenocarcinoma-derived cell line (Caco-2) and freshly excised rat intestinal mucosa. RESULTS: TBO HIPs of increasing lipophilicity ranging from log P 0.59 to 2.35 were obtained as a result of ion pairing with anionic counter ions. Zeta potential of TBO shifted from positive to negative due to ion pairing. HIPs with DO and DS showed highest stability at pH 7.4. Association constant (Ka) values for TBO HIPs were found in the following rank order; DS > DO > OL > DC > DD. Due to superassociation of HIPs, permeation of TBO was efficiently improved up to 3.1-fold across Caco-2 cells and up to 2.5-fold across rat intestinal mucosa. CONCLUSION: Superassociated HIPs showed generally a significantly higher membrane permeability than free TBO and entirely dissociated HIPs.
AIM: The study was aimed to investigate the impact of superassociation of hydrophobic ion pairs (HIPs) on membrane permeability. METHODS:Toluidine blue O (TBO) as a cationic model compound was complexed with anionic counter ions having different physiochemical properties namely dodecanoate (DD), oleate (OL), deoxycholate (DC), docusate (DO) and dodecyl sulfate (DS). TBO HIPs were characterized regarding log P, zeta potential and stability over 8 h at pH 7.4. Association and dissociation constants (Ka and Kd) were calculated by applying quasi-equilibrium equation to the double reciprocal plots of log P versus counter ion concentrations. Permeation studies of free TBO, superassociated TBO HIPs and HIPs applied as entirely dissociated form were carried out across humancolorectal adenocarcinoma-derived cell line (Caco-2) and freshly excised rat intestinal mucosa. RESULTS:TBO HIPs of increasing lipophilicity ranging from log P 0.59 to 2.35 were obtained as a result of ion pairing with anionic counter ions. Zeta potential of TBO shifted from positive to negative due to ion pairing. HIPs with DO and DS showed highest stability at pH 7.4. Association constant (Ka) values for TBO HIPs were found in the following rank order; DS > DO > OL > DC > DD. Due to superassociation of HIPs, permeation of TBO was efficiently improved up to 3.1-fold across Caco-2 cells and up to 2.5-fold across rat intestinal mucosa. CONCLUSION: Superassociated HIPs showed generally a significantly higher membrane permeability than free TBO and entirely dissociated HIPs.
Authors: Yoon Tae Goo; Sangkil Lee; Ji Yeh Choi; Min Song Kim; Gi Hyeong Sin; Sun Ho Hong; Chang Hyun Kim; Seh Hyon Song; Young Wook Choi Journal: Drug Deliv Date: 2022-12 Impact factor: 6.819