Selective Serotonin Reuptake Inhibitors  
 The selective serotonin reuptake inhibitors (SSRIs) are a group of  
antidepressant drugs that specifically inhibit serotonin reuptake, having 300-  
to 3000-fold greater selectivity for the serotonin transporter, as compared  
to the norepinephrine transporter.Moreover, the SSRIs have little blocking activity at muscarinic, ?-adrenergic,  
and histaminic H1 receptors.