Paroxetine HCL is a selective serotonin reuptake inhibitor (SSRI) predominantly prescribed for depression, anxiety disorders, obsessive-compulsive disorder, post-traumatic stress disorder, and related psychiatric conditions. Its primary mechanism involves blocking the serotonin transporter (SERT), which leads to increased levels of serotonin in the synaptic cleft and subsequently enhances serotonergic neurotransmission. While paroxetine is highly specific to serotonin reuptake inhibition, at higher doses it may also weakly inhibit norepinephrine reuptake, adding to its therapeutic profile in certain mood and anxiety disorders. The drug is lipophilic with high protein binding, is extensively metabolized in the liver primarily by the CYP2D6 pathway, and has a long elimination half-life, making it suitable for once-daily dosing in most patients.