CLINICAL PHARMACOKINETICS OF ONDANSETRON - A REVIEW

5-HT3 receptors are ubiquitous in the enteric, sympathetic, parasympat hetic and sensory nervous systems and in the central nervous system (C NS) (Kilpatrick et al 1990). In man 5-HT3 receptors are mainly situate d on enterochromaffin cells in the gastrointestinal mucosa, which are innervated by vagal afferents (Reynolds et al 1989), and the area post rema of the brain stem, which forms the chemoreceptor trigger zone. On dansetron is a selective antagonist at 5-HT3 receptors. It is 100 time s more potent than metoclopramide at this site (Tyers 1992). It shows limited binding to other receptors and has a wide therapeutic window. Ondansetron is a useful antiemetic which probably has both central and peripheral actions in patients undergoing radiotherapy, cytotoxic che motherapy or general anaesthesia (Naylor & Rudd 1992). This paper revi ews the pharmacokinetics of ondansetron in health and disease to provi de information for clinicians; it might alter prescribing and alert th em to possible drug interactions.