Clinical pharmacokinetics of ondansetron. A review

Abstract

5-HT3 receptors are ubiquitous in the enteric, sympathetic, parasympathetic and sensory nervous systems and in the central nervous system (CNS). In man 5-HT3 receptors are mainly situated on enterochromaffin cells in the gastrointestinal mucosa, which are innervated by vagal afferents, and the area postrema of the brain stem, which forms the chemoreceptor trigger zone. Ondansetron is a selective antagonist at 5-HT3 receptors. It is 100 times 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 chemotherapy or general anaesthesia. This paper reviews the pharmacokinetics of ondansetron in health and disease to provide information for clinicians; it might alter prescribing and alert them to possible drug interactions.