The method of action of prozac

Prozac is a member of the selective serotonin reuptake inhibitors (SSRI) family. It has been successful as a treatment for depression, obsessive compulsive disorder and bulimia. Its actions have been linked to its inhibition of CNS neuronal uptake of serotonin. The exact mechanism of action of fluoxetine is still not completely understood. Fluoxetine inhibits specifically the serotonin reuptake pump which functions to inactivate serotonin after its release from serotonergic nerve terminal. This causes an increased concentration of serotonin in the synaptic cleft. The enhanced serotonergic input to other neuronal systems in brain is believed to cause primary and secondary (adaptive) changes in neurotransmission and results in remission of depressive symptoms.

normal	depressed	Prozac

How does it differ from other antidepressants?

The older tricylic antidepressants (TCAs) such as imipramine are equally as effective in relieving depression as prozac. Prozac causes fewer adverse heart related events (such as a drop in blood pressure or unusual rhythm) and fewer anticholinergic effects (dry mouth, constipation,blurred vision, urinary retention ) than TCAs. It is also less likely to cause drowsiness or weight changes associated with the older TCA's.

Prozac as a painkiller?

Fluoxetine is also known to have an antinociceptive effect although the pain alleviating mechanism is yet to be determined. Serotoninergic deficiency is known to be a significant factor in psychological depression as well as chronic pain. It is not clear whether the use of fluoxetine as a painkiller on acute treatment is separate from its action as an antidepressant. The antidepressant action however, is only observed after a number of weeks. A significant observation is that fluoxetine retains its antidepressant actions whereas tolerance develops to the pain-killing effect.

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