[Antidepressant and antimanic drugs--pharmacological mechanisms and pharmacokinetics]

In Japan, fifteen drugs, including tricyclic and non-tricyclic antidepressants or an MAO inhibitor, are clinically available for treatment of depression. However, the pharmacological mechanism(s) of their antidepressive effect remain uncertain. "Receptor hypothesis" that functional changes of monoamine receptors after chronic treatment, such as down-regulation of beta-adrenoceptor or 5-HT2 receptor, bring about a therapeutic effect, seems to be unsatisfactory. Recent studies focus on interaction between antidepressants and intracellular signal transduction pathways. For effective and safe uses of antidepressants, especially in aged patients or those with hepatic and renal diseases, pharmacokinetics such as distribution, protein binding and metabolism must be well understood. In this paper, pharmacokinetic characteristics of antidepressants are also reviewed.