fluoxetine
n. an antidepressant that is the prototype of the SSRIs (selective serotonin reuptake inhibitors). It acts by inhibiting the serotonin transporter, preventing reuptake of serotonin into the terminal button (see axon) of the presynaptic neuron. This presumably results in higher levels of available neurotransmitter to interact with postsynaptic receptors. Fluoxetine differs from other SSRIs in that it and its biologically active metabolic product, norfluoxetine, have a prolonged half-life of 5 to 7 days after a single dose; thus, it takes 20 to 35 days for the drug to reach steady-state concentrations. Like other SSRIs, it should not be used with monoamine oxidase inhibitors. U.S. trade names: Prozac; Sarafem.