A Monomer‐Micelle Model for the Formation of Simple Taurocholate Micelles

Abstract

A kinetic dialysis technique was used to validate a relationship between monomer taurocholate (TC) concentration and total TC concentration in TC solutions containing 0.15 M NaCl and 0.01 M buffer (pH = 7.4). Based on the experimental data and Mukerjee's equations, the number average degree and the weight average degree of TC aggregates were estimated to be nearly the same (~5), indicating that simple TC micelles were the only aggregates. Furthermore, the TC dimer concentration was quantified to be negligible. According to the validated relationship, aggregation number of 5 for simple TC micelles, and the definition of critical micelle concentration (CMC), a modified monomer-micelle model was used for describing simple TC micelle formation. Moreover, the CMC value was estimated to be~6.3 mM, which is consistent with the reported value of~6.0 mM.

Concomitant intake of alcohol may increase the absorption of poorly soluble drugs

“…The FaSSGF used to mimic human gastric fluid contains 80 lM taurocholate and 20 lM lecithin, derived from soybean oil. Lecithin has a critical micelle concentration (CMC) well below 1 nM (King and Marsh, 1987) whereas taurocholate has a reported CMC of 6.3 mM (Yang et al, 2010). The low concentration of taurocholate in FaSSGF in relation to its CMC implies that the bile salt may primarily have wetting effects during dissolution in the medium.…”

Determination of Binding Affinity for Chenodeoxycholate in Equilibrium with Sulfobutylether-β-Cyclodextrin

“…However, a leakage of SBE‐β‐cyclodextrin to the receiver side may occur because of degradation of the dialysis membrane within 2 days. To minimize the leakage, a kinetic dialysis technique was used because with this technique each sample took approximately 90 min only 18. In addition, the concentration of the unbound CDC was maintained to be lower than 1 mM based on the 1:1 inclusion binding.…”

“…A two‐chamber diffusion cell with each chamber having approximately 2.2 mL volume and approximately 0.785 cm 2 diffusion surface was used 18. Moreover, a 2–3 cm length of the dialysis membrane was soaked in distilled water for approximately 30 min prior to use.…”

“…After the diffusion rate of CDC in the solution containing SBE‐β‐cyclodextrin and CDC has been measured and the total concentration of CDC is already known, the total permeability coefficient ( P t ) in the solution can be estimated to be lower than P s . Therefore, the concentration of CDC monomers in the solution can be determined as a product of the total concentration of CDC and a ratio of P t / P s 18…”

“…A kinetic dialysis technique together with a marker of 14 C‐labeled CDC was used to determine the monomer concentration of CDC with respect to the total CDC and SBE‐β‐cyclodextrin concentrations 18. On the basis of the kinetic dialysis data and the two‐site binding model, the binding affinity was quantified at the best curve fitting using a least‐squares technique.…”