Antidepressant Medication Flashcards
In depression, what is there increased function of?
somatodendritic 5-HT1A receptor
In depression, what is there a decrease of?
postsynaptic 5-HT1A receptor number and function
What is the function of SSRIs?
inhibit 5-HT/serotonin uptake
down-regulate 5-HT autoreceptors
What do SSRIs increase the stimulation of?
postsynaptic 5-HT1A receptors
What does NRI stand for?
Norepinephrine reuptake inhibitor
What is the function of NRIs?
Down regulates a2 receptors
decreases inhibition of 5-HT release
increased postsynaptic 5-HT1A receptor stimulation
What does NaSSA stand for?
Noradrenergic and specific serotonergic antidepressants
What is the function of NaSSAs?
Antagonize the a2-adrenergic receptor
increases 5-HT and noradrenaline concentrations
Major classes of antidepressant drugs
Selective serotonin re-uptake inhibitors & serotonin-norepinephrine re-uptake inhibitors
Tricyclic
Monoamine Oxidase Inhibitors
Tricyclic drug examples
imipramine
amitriptyline
clomipraline
Function of tricyclic antidepressants
block uptake of amines by nerve terminals
compete for binding site of amine transporter
most inhibit noradrenaline and 5-HT uptake
Mono-amine oxidase inhibitor examples
phenelzine
tranylcypromine
isocarboxazid
moclobemide
What is the importance of mono-amine oxidase inhibitors?
MAO-A enzyme has substrate preference for 5-HT
Which mono-amine oxidase inhibitor may be used for major depression and social phobia?
Moclobemide
Why do tricyclic drugs have low rates of elimination?
plasma protein binding
tissue binding
Main adverse effects of tricyclic antidepressants
sedation (H1 block) postural hypotension (a-adrenoceptor block) dry mouth blurred vision constipation (muscarinic block)
Less common adverse effects of tricyclic antidepressants
occasional mania and convulsions
risk of ventricular dysrhythmias
Tricyclic antidepressant drug interactions
alcohol
anaesthetics
hypotensive drugs
NSAIDs
What drug should not be given with tricyclics?
Monoamine oxidase inhibitors
Why is postural hypotension a common side effect of monoamine oxidase inhibitors?
amines accumulate within peripheral sympathetic nerve terminals
displaces Noradrenaline from storage vesicles
reduces vasoconstriction
Adverse effects of Monoamine-oxidase inhibitors
excessive central stimulation
increased appetite, weight gain
anticholinergic effects (dry mouth, blurred vision)
How does MAO inhibition cause the ‘cheese reaction’?
allows tyramine to be absorbed
What are the effects of tyramine absorption?
enhances the sympathomimetic effect
severe acute hypertension
severe throbbing headache
intracranial haemorrhage
What do Paroxetine and Fluoxetine inhibit, and what should they not be used in combination with?
hepatic metabolism by CYP2D6
should not be used in combination with TCAs
