Antidepressant Drugs

Introduction to Anti-Depressant Drugs

  • Speaker: Dr. Aliena Edun, BPharm, M.D

Types of Depression

  • Reactive or Secondary Depression:

    • Most common type, affecting 60% of patients.

    • Triggered by real stimuli (e.g., grief, illness).

  • Major Depression:

    • Affects 25% of patients, linked to genetic factors.

    • Typically treated with antidepressants or electroconvulsive therapy.

  • Bipolar Disorder:

    • Affects 10-15% of patients.

    • Managed with lithium bicarbonate and antidepressants.

Etiology of Depression

  • Caused by deficiency of monoamines (noradrenaline, serotonin, dopamine) at key brain sites.

  • Mania results from overproduction of these neurotransmitters, leading to extreme behaviors.

Symptoms of Depression

  • Persistent sadness, hopelessness, tearfulness.

  • Fatigue, self-criticism, irritability.

  • Decreased interest in daily life, changes in appetite, insomnia, chronic pain.

Treatment Strategies

  • Effective treatments include psychotherapy, behavioral therapies, and psychoactive drugs.

  • Antidepressants enhance NA, dopamine, serotonin action in the brain, supported by the biogenic amine theory.

Classification of Antidepressant Drugs

  1. Tricyclic Antidepressants (TCA’s):

    • Examples: Imipramine, Desipramine, Amitryptiline.

  2. Second Generation Antidepressants:

    • Examples: Amoxapine, Maprotiline.

  3. Atypical Antidepressants:

    • Examples: Nefazodone, Mirtazapine, Bupropion.

  4. Selective Serotonin Reuptake Inhibitors (SSRIs):

    • Examples: Fluoxetine, Sertraline, Citalopram.

  5. Serotonin/Norepinephrine Reuptake Inhibitors (SNRIs):

    • Examples: Venlafaxine, Duloxetine.

  6. Monoamine Oxidase Inhibitors (MAOIs):

    • Irreversible and reversible types (e.g., Isocarboxazid, Moclobemide).

Tricyclic Antidepressants (TCA’s)

  • Mechanism of Action: Prevent reuptake of serotonin and norepinephrine, increasing monoamine levels.

  • Uses: Major depressive disorder, panic disorder, OCD, and bed-wetting treatment.

  • Side Effects: Anticholinergic effects, cardiovascular issues, endocrine effects, sedation, convulsions.

Second Generation Antidepressants

  • Amoxapine and Maprotiline.

  • Fewer sedative and antimuscarinic actions than TCAs.

  • Side effects include parkinsonism, dry mouth, weight gain.

Atypical Antidepressants

  • Act on dopamine and norepinephrine receptors.

  • Bupropion: Reduces cravings in tobacco users, short half-life.

  • Mirtazapine: Sedative properties, less sexual side effects.

  • Trazodone: Sedative with priapism risk.

SSRIs (Selective Serotonin Reuptake Inhibitors)

  • Mechanism of Action: Inhibit serotonin reuptake, increase levels in synaptic cleft.

  • Side Effects: Loss of libido, insomnia, headache, discontinuation syndrome risk.

  • Uses: OCD, bulimia nervosa, panic disorder.

SNRIs (Serotonin/Norepinephrine Reuptake Inhibitors)

  • Mechanism of Action: Inhibit reuptake of serotonin and norepinephrine.

  • Effective for chronic pain and depression.

  • Venlafaxine: High doses may increase blood pressure.

  • Duloxetine: Should not be given to those with hepatic insufficiency.

MAOIs (Monoamine Oxidase Inhibitors)

  • Mechanism of Action: Prevent inactivation of monoamines, increasing availability.

  • Side Effects: Dry mouth, blurred vision, weight gain, hypotension.

  • Drug Interactions: Avoid tyramine-rich foods to prevent hypertensive reactions.