Choosing an antidepressant

What is available and how does it work ? more than 30 agents for unipolar depression

Most antidepressants work by enhancing the activity of monoamine neurotransmitters : serotonin , noradrenaline /norepinephrine or dopamine this is based on theories that implicate a deficiency of monoamines in the biology of depression popularly called the " Amine hypothesis " it is either reuptake inhibition , enzyme inhibition or activity at pre- postsynaptic receptors

SSRIs -Selectively block the reuptake of 5-HT autoreceptors leading to ↑ed serotonin in the neuronal synaptic clefts- leading to down regulation of the receptors Examples - citalopram /escitalopram ,fluoxetine , paroxetine, sertraline , fluvoxamine Relatively safe in OD

Tricyclic antidepressants -TCAs block the reuptake of both norepinephrine ( NE ) and serotonin ( 5HT ) In addition TCAs also antagonize postsynaptic alpha 1 adrenoceptors , histamine ( H1 ) receptors , muscarinic cholinergic receptors and serotonin 5HT 2 receptors - reason for the excess SEs and toxicity Examples- Amitriptyline , nortriptyline , imipramine , clomipramine , dothiepin , doxepin , lofepramine Similar in structure to antipsychotics such as chlorpromazine and share the wide range of pharmacological action Greatest risk with OD ( except for lofepramine )

Monoamine-oxidase inhibitors Block the...