Simultaneous Analysis of Dissolution and Permeation Profiles of Nanosized and Microsized Formulations of Indomethacin Using the In Vitro Dissolution Absorption System 2.

The in vitro dissolution absorption system 2 (IDAS2), a recent invention comprised a conventional dissolution vessel containing 2 permeation chambers with Caco-2 cell monolayers mounted with their apical side facing the dissolution media, permits simultaneous measurement of dissolution and permeation of drugs from intact clinical dosage forms. The objectives of this study were (1) to assess the utility of IDAS2 in the determination of the effect of particle size on in vitro performance of indomethacin and (2) to find out whether the behavior in IDAS2 of 2 indomethacin products differing in particle size is correlated with their in vivo behavior. Indomethacin dissolution and permeation across Caco-2 cell monolayers were simultaneously measured in IDAS2; the dissolution and permeation profiles were simultaneously modeled using a simple two-compartment model. Compared to microsized indomethacin, the nanosized formulation increased the dissolution rate constant by fivefold, whereas moderately increasing the permeation rate constant and the kinetic solubility. As a result, the drug amount permeated across the Caco-2 cell monolayers doubled in the nanosized versus microsized formulation. The in vitro results showed a good correlation with in vivo human oral pharmacokinetic parameters, thus emphasizing the physiological relevance of IDAS2 data in predicting in vivo absorption.