HOW DO PROZAC AND OTHER ANTIDEPRESSANTS WORK?
Prozac works by specifically inhibiting the uptake of serotonin at the nerve endings in the brain. This results in an increased concentration of serotonin at the synapse, which in turn increases the availability of serotonin at the critically important brain receptor sites, thought to result in normal nervous system transmission.
Prozac and the other SSRIs are highly specific in blocking the uptake only of serotonin, and not other neurotransmitters; that is why they are known as selective serotonin reuptake inhibitors (SSRIs). Because abnormalities in serotonin function have also been reported in obsessive-compulsive disorder, panic disorder, alcoholism, obesity, and other conditions, it is not surprising that some of these disorders have been successfully treated with Prozac and other SSRIs.
Tricyclic antidepressants, or TCAs, the most frequently used antidepressants over the past three or four decades prior to Prozac, were thought to alleviate depression by blocking norepinephrine and some serotonin uptake at the nerve terminals in the brain. This increased the levels of both neurotransmitters, permitting a return of normal nerve impulse flow, associated with the relief of depressive symptoms.
Other less commonly used older drugs, called MAOIs, or monoamine oxidase inhibitors, work in another way, by blocking the degradation of the enzyme monoamine oxidase at the nerve terminals. This leads to higher levels of norepinephrine and serotonin at the synapses and at critically important receptor sites. The final effects are similar to those achieved with the TCAs.
Prozac and other SSRIs including Zoloft, Paxil, Luvox, and Serzone, specifically block serotonin only.