An introduction to the different types of anti depressants and their mechanism of actions.

1. Introduction and mechanism
of action
By : Ola S. Eldardiry

2. Anti depressants
Psychiatric medications given to patients with depressive disorders to
alleviate symptoms.
Types:
1. Monoamine oxidase inhibitors (MAOIs)
2. Noradrenaline and specific serotoninergic
antidepressants (NASSAs)
3. Serotonin and noradrenaline reuptake
inhibitors (SNRIs)
4. Selective serotonin reuptake inhibitors (SSRIs)
5. Tricyclics (TCAs)
Onset: delayed up to few weeks.
Duration of treatment: few months or several years
Serious problem = lack of compliance

3. Uses
• Agitation
• Obsessive compulsive disorders (OCD)
• Childhood enuresis (bedwetting)
• Depression
• Generalized anxiety disorder
• Major depressive disorder
• Manic-depressive disorders
• Posttraumatic stress disorder (PTSD)
• Social anxiety disorder
Primary (approved)

4. • Binge eating disorder
• Bulimia nervosa
• Chronic urticaria (hives)
• Fibromyalgia
• Osteoarthritis pain
• Hot flashes
• Diabetic peripheral neuropathic
pain
• Neuropathic pain
• Hyperhidrosis (drug-induced)
• Premenstrual symptoms
• Tourette syndrome
• Ruritus (itching)
• Migraines
• Snoring
“Off-label” – unapproved indication

5. Mechanism of action
Monoamine Oxidase Inhibitors (MAOIs)

7. Tricyclic Antidepressants (TCAs)

8. Selective Serotonin Reuptake Inhibitors (SSRIs)

9. Serotonin/ Norepinephrine/ Dopamine Reuptake Inhibition (SNRI) (Venlafaxine)

10. On comparison with SSRI:
• 5-HT2 receptors are blocked
• Don’t cause some side effects such as:
• Short-term increase in anxiety or insomnia
• Akathisia
• Sexual dysfunction
Serotonin-2 Receptor Antagonism with Serotonin
Reuptake Blockade (Nefazodone, Trazodone)

11. Norepinephrine and Dopamine Reuptake Inhibition (Bupropion)

12. α-2 Antagonism plus Serotonin-2 and Serotonin-3 Antagonism (Mirtazapine)

13. Noradrenalin Specific Reuptake Inhibitor (NRI) (Reboxetine)

14. Serotonin Reuptake Enhancer (Tianeptine)
• Tricyclic compound of
diabenzothiazepine type
• Increases presynaptic uptake of
serotonin after single + repeated
administration
• Not linked to any effects on 5-HT
post-synaptic systems
• No affinity for:
o α1 adrenergic
o H1 antihistaminic
o Muscarinic receptors
• Similar to TCAs but with faster onset
• Not stimulating nor sedative
• No anticholinergic effect
• No cardiovascular effect