An Overview of Antidepressant Medications

Summary:

Selective Serotonin Reuptake Inhibitors (SSRIs):

• Mainly used for treating depression, replacing older drugs like TCAs and MAOIs.
• Examples: fluoxetine, citalopram, escitalopram, fluvoxamine, paroxetine, sertraline.
• Absorbed well orally; peak levels in 2-8 hours.
• Block reuptake of serotonin, increasing serotonin concentration in the synaptic cleft.
• Used to treat depression, OCD, panic disorder, generalized anxiety disorder, PTSD, social anxiety disorder, premenstrual dysphoric disorder, and alcohol dependence.
• Side effects: nausea, insomnia, headache, anxiety, sexual dysfunction, and risk of Serotonin Syndrome with MAOIs.

Serotonin Norepinephrine Reuptake Inhibitors (SNRIs):

• Drugs: venlafaxine, desvenlafaxine, duloxetine.
• Inhibit re-uptake of serotonin and norepinephrine.
• Useful for treating depression, especially with associated chronic pain symptoms.
• Side effects: nausea, dizziness, anxiety, insomnia, headache, and sexual dysfunction.

Serotonin Receptor Antagonists:

• Drugs: trazodone and nefazodone.
• Primarily block the 5-HT2A receptor.
• Adverse effects: sedation, gastrointestinal disturbances, and rare priapism (trazodone).
• Trazodone is often used for insomnia.

Tricyclic Antidepressants (TCAs):

• Previously dominant antidepressant class.
• Examples: imipramine, amitriptyline, and clomipramine.
• Block reuptake of monoamines.
• Used for major depression, bipolar disorder, panic disorder, OCD, and chronic pain.
• Side effects: blurred vision, dry mouth, dizziness, sedation, sexual dysfunction, and risk of arrhythmias.

Monoamine Oxidase Inhibitors (MAOIs):

• Inactivate monoamine oxidase enzyme leading to increased neurotransmitter levels.
• Drugs: phenelzine, tranylcypromine, isocarboxazid, selegiline.
• Used for certain unresponsive depression types.
• Side effects: hypotension, insomnia, weight gain, and the dangerous “cheese reaction” from dietary tyramine leading to hypertension and possible stroke.

Atypical Antidepressant:

• Varied mechanisms, including inhibition of neurotransmitter reuptake and receptor blockade.
• Examples: bupropion (affects NE and dopamine), trazodone and nefazodone (blocks certain 5-HT receptors), and mirtazapine (enhances noradrenaline and 5-HT release).

Excerpt:

An Overview of Antidepressant Medications

SELECTIVE SEROTONIN REUPTAKE INHIBITORS (SSRIs)

SSRIs have largely replaced TCAs and monoamine oxidase inhibitors (MAOIs) as the drugs of choice in treating depression. The SSRIs include fluoxetine  (the prototypic drug), citalopram, escitalopram, fluvoxamine, paroxetine, and sertraline.

Pharmacokinetics:

All of the SSRIs are well absorbed after oral administration. Peak levels are seen in approximately 2 to 8 hours on average. Food has little effect on absorption (except with sertraline, for which food increases its absorption).