Related Experiment Video
Updated: Jun 10, 2026

An Intestine/Liver Microphysiological System for Drug Pharmacokinetic and Toxicological Assessment
Published on: December 3, 2020
Computational oral absorption simulation of free base drugs
1Global Research & Development, Sandwich Laboratories, Research Formulation, Pfizer Inc., CT13 9NJ Sandwich, Kent, UK. Kiyohiko.Sugano@pfizer.com
Abstract:
The purpose of the present study was to investigate the oral absorption simulation of free base drugs. In the case of a low solubility free base drug, a portion of drug particles remains incompletely dissolved during the stomach transit and can reach the small intestine. As the pH is neutralized in the small intestine, the solubility of the drug decreases and the concentration gradient around the particles becomes a negative value. The drug particles would then grow because of this negative concentration gradient resulting in a reduction of the dissolved drug concentration. The modified Nernst Brunner equation was used to simulate both particle dissolution and growth (particle growth is the opposite phenomena of particle dissolution). Albendazole, aprepitant, dipyridamole, gefitinib and ketoconazole were used as model drugs (all free solid form (not salts)). The effect of stomach pH on oral absorption was appropriately simulated. Based on the simulation results, it was suggested that the dissolution patterns in the gastrointestinal tract were significantly different depending on the dose-solubility ratio in the stomach.
Related Concept Videos
Factors Influencing Drug Absorption: Drug Dissolution
Non-Oral Extravascular Drug Absorption Routes
Lipophilic drugs that are stable at salivary pH (6) and exhibit minimal binding to the oral mucosa are absorbed more effectively...
Factors Influencing Drug Absorption: Physicochemical Parameters
Enhanced drug absorption can be achieved by reducing particle sizes and increasing surface areas, thereby facilitating...
Methods for Studying Drug Absorption: In vitro
The diffusion cell method uses a two-compartment cell, including a donor compartment with the drug solution, which simulates the environment where the drug is applied, and a receptor compartment with a buffer solution, which simulates the environment...
Drug Absorption: Overview
When drugs are injected intravenously, they directly enter the systemic circulation. Alternatively, orally administered drugs navigate through the gastrointestinal (GI) tract.
Oral Drug Delivery Systems: Introduction
