Week 10 - Antidepressant Drugs Flashcards
What are the Monoamines?
Noradrenaline
Serotonin
Dopamine
How is Depression linked to Monoamines?
Depression = associated w deficiency of monoamines
What are Tricyclic Anti-depressants (TCAs)? what do they do? eg?
Blocks the reuptake of NA and Serotonin 5-HT
Stops neuron from taking neurotransmitters back up
Also antagonise Muscarinic, alpha-1 and H1 receptors
eg Desipramine
What are side effects of TCAs?
Cardiac toxicity -> arrhythmias, ventricular fibrillation
What are Selective Serotonin Reuptake Inhibitors (SSRIs)? what do they do? eg?
-> Selectively block the reuptake of 5-HT
- preferred to TCAs bc much better tolerated safety profile
eg Fluoxetine
What are side effects of SSRIs?
- disturbed sleep
- lower sex drive
- nausea and diarrhoea
- can cause initial increase in anxiety
What are acute increases in anxiety attributed to?
enhanced 5-HT stimulation of 5HT2A receptors before they undergo downregulation
What are Serotonin and Noradrenaline Reuptake Inhibitors (SNRIs)? what do they do? eg?
- similar MOA to TCAs
- block reuptake of both NA and 5-HT
eg Venlafaxine
What are Noradrenaline Reuptake Inhibitors (NRIs)? what do they do? eg?
- Block reuptake of NA
eg Reboxetine
What are Monoamine Oxidase (MAO) isoforms?
-> enzymes that metabolise intracellular NA, 5-HT and Dopamine (DA)
Inhibitors can be reversible and irreversible
What do MAOa and MAOb metabolise?
What are Irreversible Monoamine Oxidase (MAO) Inhibitors? What do they do? eg?
= Irreversible and non-selective MAOa/b inhibitor
- will cause an increase in NA, 5-HT, and DA
eg Tranylcypromine
What are some precautions to take with Irreversible MAO inhibitors?
Avoid foods rich in tyramine bc tyramine can cause hypertensive problems
What are Reversible Monoamine Oxidase (MAO) Inhibitors? What do they do? eg?
= Reversible and selective to MAOa
eg Moclobemide
What are Serotonin Antagonist and Reuptake Inhibitors (SARIs) ? What do they do? eg?
- Block 5-HT reuptake and antagonise 5-HT2A receptors simultaneously
- less incidence of acute anxiety compared to SSRIs // less potent than TCAs and SSRIs
eg Trazodone
What are Alpha2 Receptor Antagonists? What do they do? eg?
- Antogonise pre-synaptic a2 adrenoreceptors
- result in enhanced release of both NA and 5-HT
eg Mianserin
Unipolar vs Bipolar
Unipolar = one direction -> continuously depressed
Bipolar = fluctuation of mood
What are signs and symptoms of Bipolar Disorders?
How does Lithium help with Bipolar disorders? MoA?
- can be used for prophylaxis of manic and depressive episodes and for acute mania
- lacks effectiveness where mood is rapidly recycling
MoA:
- unclear
- lodges in voltage-dependent Na+ channels and not pumped out
- accumulates in excitable tissue -> and maybe inhibits dopamine release, increase serotonin release & disrupts cell signalling
Side effects of Lithium treatment?
- nephrotoxic
- can induce diabetes insipidus
- can be associated w hypothyroidism development
