• Using your textbooks, draw up a classification of the drugs that are used as antidepressants.

TCA’S	MAOI’S	SSRI’S	SNRI’S	NARI’S	Tetracyclic and Unicyclic	5-HT antagonist
Tertiary amine: Impramine Amitriptyline Trimipramine Chlorimipramine Secondary amine Nortriptyline Desimipramine	Phenelzine Isocarboxazid Tranylcypromine Selegiline Moclobemide	Fluoxetine Sertraline Citalopram Paroxetine Escitalopram	Venlafaxine Duloxetine Desvenlafaxine	Reboxetine	Bupropion Mirtazapine Amoxapine Maprotiline	Trazodone Nefazodone Vortioxetine

• What do the existing drugs all have in common regarding their mechanisms of action?

They al promote monoamine activity by increasing NA and 5-HT levels at the central synapse( re-uptake inhibition, degradation inhibition or the blockage of the presynaptic α2 receptor)

• How long does it take for the antidepressive effects of these drugs to appear? What is the reason for this?

The onset of the drug is very slow and can take up to 6-8 weeks for effects to be seen even thou the increase in monoamine concentrations can bw seen within hours after administration due to the action that of the anti-depressants that still needs to be altered in the brain.

• How do the TADs and the selective serotonin reuptake inhibitors (SSRI’s) differ in respect of:
  • Efficacy

TAD’s: needs to be titrated to the minimum effective dose

SSRI’s: can be started on the full dose

• side effects

TAD’s: sedation, tremors, insomnia, disturbed vision, dry mouth, urinary retention, confusion, orthostatic hypotension, dysrhythmias convulsions, weight gain and sexual dysfunction. 

SSRI’s: Insomnia, tremors, GIT disturbances, headache, ↓ libido, sexual dysfunction, anxiety (acute), EPS, withdrawal syndrome. ↓ appetite, non-sedating,  acute increase in 5-HT synaptic activity initially causes acute anxiety, later 5-HT decreases again.

• safety?

TAD’s: Not safe in overdose but it is commonly the drug used for suicide.

SSRI’s: safer with regards to overdose.

• What is the action of mirtazapine?

Blockade of α2, 5-HT2A, 5-HT2c and 5-HT3 receptors. It also blocks H1 and α1 and causes the indirect stimulation of 5-HT1A

• What is the action of venlafaxine?

Blockade of 5-HTand NA re-uptake(more potent for 5- HT than for NA).

Moderately selective blockade of SERT and NET

• What is the action of agomelatine?

Antagonist: 5-HT2C

Agonist: Melatonergic R’s – MT1 & MT2 &NA release.