Atypical Anti-depressants

Brajesh LahriFinal Professional MBBS Student

All India Institute of Medical Sciences (AIIMS), Bhopal

By the end of discussion you should be able to…• Classify anti-depressants

• Enlist atypical anti-depressants

• Know about the mechanism of action of atypical anti-depressants

• Know about the indications of atypical anti-depressants

• Know about the side effects of atypical anti-depressants

Introduction• Major Depression and Mania are two extremes of affective disorders,

referring to pathological change in mood state.• Depression is characterized by symptoms like sad mood, loss of

interest and pleasure in activities, low energy, feeling of guilt, agitation, change in appetite, sleep disturbances, suicidal thoughts etc.• Anti-Depressants are drugs which help to elevate mood in depressive

illness.

Pathophysiology of depression• Many theories are given, most accepted is Monoamine Hypothesis.

• It states that deficiencies in various monoamine neurotransmitters are responsible for corresponding symptoms of depression.

• According to the monoamine hypothesis, Serotonin, norepinephrine, and dopamine are the neuro-transmitters associated in pathophysiology of depression.

**(Serotonin, Nor-epinephrine and Dopamine levels are decreased in depression)

Classification of Anti-Depressants

Anti-

Depr

essa

nts Reversible Inhibitors of

MAO-A (RIMAs)Examples: Moclobemide,

Clorgyline

Tri-Cyclic Anti-depressants (TCAs)

Examples: Imipramine, Amitriptyline, Clomipramine

Selective Serotonin Reuptake Inhibitors (SSRIs)

Examples: Fluoxetine, Paroxetine, Sertaline,

Citalopram, Dapoxetine

Serotonin and Nor-adrenaline Reuptake

Inhibitors (SNRIs)

Examples: Venlafaxine, Duloxetine

Atypical Anti-depressantsExamples: Trazodone,

Mirtazapine, Bupropion, Tianeptine

Atypical Anti-depressants

•Mirtazapine

• Trazodone

• Bupropion

• Tianeptine

• Agomelatine

Mirtazapine• Mechanism of Action Blocks α-1 receptors (present on NA neurons) and Hetero receptors (5HT-2) (present on 5-HT neurons), enhancing both NA and 5HT release.** Also, Mirtazapine is said to have some affinity for α-2 receptors, which is claimed to be related to their therapeutic efficacy, but this point is questionable.**(It is also a H1 blocker and quite sedative)• Adverse Effects- Increased appetite- Weight gain- Agranulocytosis (Rare)

Indications : Depression, OCD, Panic disorder, PTSD, SAD

Trazodone• Mechanism of Action Prominent α-1 adrenergic and weak 5-HT2A antagonistic action. Also acts by blocking uptake of 5HT.• Adverse Effects- Excessive Sedation-Inappropriate, prolonged and painful penile erection (Priapism)- Postural Hypotension (Due to α1 adrenergic blockade)

Indications : Generalized anxiety disorders (GAD), Panic Disorder, Eating Disorders

Bupropion• Mechanism of Action Inhibits re-uptake of Dopamine and Nor-Adrenaline. In addition may also increase the release of NA and DA.**(It has excitant rather than sedative activity)

• Adverse Effects -Insomnia and agitation- Decreases Seizure threshold

Indications : Depression, Eating Disorder, Cannabis dependence, Cocaine dependence, Nicotine dependence

Agomelatine• Mechanism of action: It acts as melatonin receptor agonist at MT1 and MT2 receptors. It also acts as a weak antagonist at 5-HT2c receptors • Adverse Effects : - Nausea and Dizziness - Increase in liver enzyme levels Indications : Depression,

resynchronization of disturbed circadian rhythm

Tianeptine• Mechanism of Action : It increases serotonin/5-HT uptake in the brain (in contrast with most antidepressant agents) and reduces stress-induced atrophy of neuronal dendrites.

• Adverse Effects: - Nausea, Constipation, Abdominal Pain- Dizziness, Headache- Hepatoxicity (Rare)

Indications : Useful in anxio-depressive states ,as well as in endogenous depression

Serotonin and Nor-Adrenaline reuptake inhibitors (SNRIs)• Venlafaxine• DuloxetineMechanism of Action : Inhibit uptake of both Nor-adrenaline and Serotonin, but do not interact with cholinergic, adrenergic or histaminergic receptors.Adverse Effects :- Dizziness ,Insomnia- Rise in BP (More common with Venlafaxine )- Associated with increased risk of Cardiac arrhythmias(Clinical significance is still unclear)

Indications: -Depression (Both) -Neuropathic pain (Duloxetine)

Reversible Inhibitors of MAO-A (RIMAs)• Moclobemide• ClorgylineMechanism of Action:Inhibit MAO-A enzyme which deaminates 5-HT and NA.Adverse Effects : -Nausea - Dizziness, Insomnia - Liver damage (Rare)

Indications: Depression and Social Phobia

References• Clinical Pharmacology-11th Edition - Bennett, Brown and Sharma• Goodman-Gilman’s -The Pharmacologic basis of Therapeutics- 12th

Edition – Brunton, Chabner, Knollmann• Essential Medical Pharmacology-7th Edition - K.D. Tripathi• Essential Evidence based Psychopharmacology- 2nd Edition- Stein ,

Lerer and Stahl

Thank You