psychiatric disorders
Medications for Treatment of Depression
Selective Serotonin Reuptake Inhibitors (SSRIs)
These medications prevent reuptake ofserotonin(5-hydroxytryptamine [5-HT]). SSRIs includecitalopram,escitalopram,fluoxetine,fluvoxamine,paroxetine,sertraline, andvilazodone. Although these medications have the same mechanism of action, differences in their clinical properties make selection important. Selective serotonin reuptake inhibitors (SSRIs) have a wide therapeutic margin; they are relatively easy to administer, with little need for dose adjustment (except forfluvoxamine). By preventing reuptake of 5-HT presynaptically, SSRIs result in more 5-HT to stimulate postsynaptic 5-HT receptors. SSRIs are selective to the 5-HT system but not specific for the different 5-HT receptors. They stimulate 5-HT1receptors, with antidepressant and anxiolytic effects, but they also stimulate 5-HT2receptors, commonly causing anxiety, insomnia, and sexual dysfunction, and 5-HT3receptors, commonly causing nausea and headache. Thus, SSRIs can paradoxically relieve and cause anxiety. A few patients may seem more agitated, depressed, and anxious within a week of starting SSRIs or increasing the dose, and there have been concerns about Antidepressants and Suicide Risk . Sexual dysfunction (especially difficulty achieving orgasm but also Libido and Drug interactions are relatively uncommon; however,fluoxetine,paroxetine, andfluvoxaminecan inhibit cytochrome P-450 (CYP450) isoenzymes, which can lead to serious drug interactions. For example, these medications can inhibit the metabolism of certain beta-blockers, includingpropranololandmetoprolol, potentially resulting in hypotension and bradycardia. Discontinuation symptoms (eg, irritability, anxiety, nausea) can occur if the medication is stopped abruptly; such effects are less likely withfluoxetine. 