Dissolution Kinetics of a BCS Class II Active Pharmaceutical Ingredient: Diffusion-Based Model Validation and Prediction

Abstract

In this work, a diffusion-theory-based model has been devised to simulate dissolution kinetics of a poorly water-soluble drug, ibuprofen. The model was developed from the Noyes–Whitney equation in which the dissolution rate term is a function of the remaining particulate surface area and the concentration gradient across the boundary layer. Other dissolution parameters include initial particle size, diffusion coefficient, material density, and diffusion boundary layer thickness. It is useful for predicting nonsink circumstances under which pure API polydisperse powders are suspended in a well-mixing tank. The model was used to compare the accuracy of simulations using spherical (single dimensional characteristic length) and cylindrical particle (multidimensional characteristic lengths) geometries, with and without size-dependent diffusion layer thickness. Experimental data was fitted to the model to obtain the diffusion layer thickness as well as used for model validation and prediction. The CSDs of postdissolution were also predicted with this model, demonstrating good agreement between theory and experiment.

Evaluation of in vitro Dissolution Profile and Physicochemical Characterization of Polymer Based Formulations of Sparingly Soluble Rosuvastatin

“…2,3 The Noyes-Whiteny equation describes that dissolution rate of a API is directly proportionate to its solubility properties. 4 Among the other factors to improve drug release, solubility is the most important factor to be concerned of. [5][6][7] Several attempts have been made to upsurge the solubility of poorly soluble APIs from BCS class II group such as-salt formation, nanotechnology, co-crystallization, co-solvency, chemical modification, pH adjustment, hydrotropic, solubilizing agents, particle size reduction, physical modification, nanosuspension micronization, alteration of the crystal habit, self-microemulsifying drug delivery system, usage of complexing agents, by different surfactants, microemulsions, dispersion in carriers e.g.…”

Nanoscale Carbonate Ion-Selective Amperometric/Voltammetric Probes Based on Ion–Ionophore Recognition at the Organic/Water Interface: Hidden Pieces of the Puzzle in the Nanoscale Phase

“…In fact, dissolution is not an instantaneous process. Under the diffusion-limiting process, the dissolution rate of a solid solute is dependent on its surface area and the diffusion coefficient as well as the concentration gradient between the solid surface (or saturated) and bulk solution as described by the Noyes–Whitney equation normald C normald t = D · s d ( C s − C b ) where d C /d t is the dissolution rate, t is the time, D is the diffusion coefficient of the solute in the solution, s is the surface area of the dissolving solute exposed in the solvent, d is the thickness of the diffusion layer, i.e., the thickness of the boundary layer of the solvent between the surface of the dissolving substance and the bulk, C s is the concentration of the solute at the solid surface (or saturated), and C b is the concentration of the solute in the bulk solution. Especially for a bulky solute like CO 3 2– ionophore VII dissolved in fairly viscous DCE solution, a small magnitude of D is anticipated by the Stokes–Einstein equation below D = k T 6 π η r where k is the Boltzmann constant, T is the absolute temperature, η is the viscosity of solution, and r is the radius of the solute molecule.…”

“…In fact, dissolution is not an instantaneous process. Under the diffusion-limiting process, the dissolution rate of a solid solute is dependent on its surface area and the diffusion coefficient as well as the concentration gradient between the solid surface (or saturated) and bulk solution as described by the Noyes−Whitney equation 46 C t…”

On the diffusion of ketoprofen and ibuprofen in water: An experimental and theoretical approach

“…On the other hand, Gao et al [17] have developed a diffusion-theorybased model from Noyes-Whitney equation to simulate the dissolution kinetics of ibuprofen in water. Since the application of such a model implies knowing mutual diffusion coefficient of ibuprofen in water, it was obtained recurring to six estimation methods.…”