INFOBOX Telemetric capsules represent a minimally invasive and relatively simple way to study the physiological conditions in the human GI tract. Different systems—such as the Heidelberg pH capsule or SmartPill™—which sometimes differ considerably in their functionalities, are commercially available. In most cases, the data from these systems are used to describe the magnitude and variability of certain physiological factors (e.g., pH, temperature, pressure), and to explain certain drug product performance phenomena.