ABSTRACT
Most drugs are administered orally, and the gastrointestinal tract is frequently exposed to high concentrations of substances given with the aim of acting at low concentrations elsewhere in the body. It is known that a number of drugs influence physiological and morphological patterns, and may lead to clinically important problems. Drugs alter gastrointestinal motility and secretion, and cause mucosal lesions throughout the alimentary tract. Absorption of drugs is a complex process influenced by the type of formulation, by the origin and surface of gastrointestinal mucosal membranes and by physicochemical properties of the luminal contents. Highly sensitive and well-standardised techniques are available for the recording and quantification of motility and for the measurement of passage of liquid and solid substances through the gastrointestinal tract.
