| Popis: |
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. For the measurement of drug effects on the gastrointestinal tract, a wide variety of methods is used which originate from different specialities, such as anatomy, physiology, chemistry, biochemistry, clinical medicine and radiology. These methods are summarised in this chapter with regard to the measurement of motility, secretion, drug absorption, drug safety and assessment of drug efficacy in diseases. In pharmacological studies in humans, consideration should first be given to the magnitude of the expected effect. On this basis a rational choice of methods can be made. However, it should be recognised that often the most sensitive and accurate measurements are also difficult to perform. |
