11.05.2 Drugs that Modify the Actions of 5-HT
Selective serotonin re-uptake inhibitors (SSRI) are an important class of anti-depressants with additional anxiolytic properties. They prevent reuptake of 5-HT into the nerve terminal, thereby prolonging 5-HT effects (e.g. fluoxetine).
5-HT2 receptor antagonism is associated with some anti-psychotic effects (e.g. atypical anti-psychotics such as clozapine and some older generation typical anti-psychotics e.g. chlorpromazine). However, blockade of 5-HT receptors alone does not give an anti-psychotic effect.
5-HT3 receptor antagonists are excellent anti-emetic agents, blocking the receptors in the gastrointestinal tract as well as at the chemoreceptor trigger zone. They are particularly useful in treating nausea and vomiting associated with cancer chemotherapy and radiotherapy. (eg Setrons: ondansetron)
In migraine, 3 classes of drugs used to treat migraine all act on serotonergic transmission. The ergot alkaloids (ergotamine) and Triptans (e.g. sumatriptan) act via 5-HT1B/1D receptors to elicit cerebral vasoconstriction as do 5-HT2 receptor antagonists (e.g. pizotifen).