Antidepressants Flashcards
(46 cards)
What are the different types of antidepressants?
SSRIs SNRIs Mirtazapine (NaSSA) TCAs MAOIs
Which type of antidepressant is first-line for depression? Why?
SSRI
Similar efficacy to TCAs, but fewer adverse effects and safer in overdose
How do SSRIs work?
Reduces presynaptic reuptake of serotonin after release
Therefore, increases the concentration available for neurotransmission
Later on there is down-regulation of post-synaptic receptors (this is thought to be the long-term therapeutic effect and takes a couple of weeks)
What are the common side effects of SSRIs?
Restlessness/agitation on initiation (countered by BDZs) Nausea, GI disturbance Headache Weight changes (either direction) Sexual dysfunction (both men and women)
What are the less common side effects of SSRIs?
Bleeding
Suicidal ideation
Why do SSR|s cause bleeding?
Serotonin receptors found on platelets
Can cover with a PPI of at risk of peptic ulcers e.g. also taking NSAIDs/aspirin
Why can there be suicidal ideation in the first 2 weeks of taking SSRIs?
Due to the combination of increased motivation and lack of therapeutic effect as of yet
This is particularly relevant in the younger male population
Which are the 5 most common SSRIs? What are their doses (mgs)?
Sertraline (50-200) - therapeutic dose is 100, but start at 50 and increase Citalopram (20-40)/escitalopram (10-20) Fluoxetine (20-60) Paroxetine (20-60)
Which is usually the first-line SSRI? Why?
Sertraline
It is the safest in cardiac disease
Generally well-tolerated
Why is citalopram/escitalopram not used in older people?
QT prolongation
More of an issue if other drugs they are taking have the same effect
What do you have to be wary of when switching from fluoxetine and why?
Serotonin syndrome
This is due to its very long half life
The metabolites can stay in the system for days
What do you have to be wary of when stopping paroxetine and why?
Discontinuation syndrome
It has the shortest half life of all SSRIs
What are the monitoring requirements for SSRIs?
Within the first 2 weeks
Then every 2-4 weeks fir the first 3 months
Then at longer intervals e.g. 6 months
What are the interactions of SSRIs?
NSAIDs, Warfarin/heparin, Aspirin, Triptans, (drugs that increase risk of bleeding - need to co-prescribe gastroprotection), MAOIs
Atomoxetine (don’t give fluoxetine or paroxetine), antipsychotics (as they too prolong the QT interval)
What is discontinuation syndrome?
An unpleasant, but not life-threatening syndrome
Influenced by half-life (the shorter the half-life the bigger the problem)
What are the symptoms of discontinuation syndrome?
Sweating, shakes, agitation, insomnia, headaches, irritability, NV, paraesthesia, clonus
Which antidepressants are the most likely to trigger discontinuation syndrome?
Paroxetine
Venlafaxine
How can discontinuation syndrome be prevented?
Taper off by taking and not taking on alternate day/snapping tablets in half
Can also switch to fluoxetine and then reduce the fluoxetine
What is serotonin syndrome?
Due to excess serotonin in the system
Usually when SSRIs are combined with other antidepressants/tramadol
How does serotonin syndrome present?
Cognitive
- headaches, agitation, hypomania, confusion, coma
Autonomic
- shivering, sweating, hyperthermia, tachycardia, nausea, diarrhoea
Somatic
- myoclonus, hyper-reflexia, tremor
Triad of autonomic hyperactivity, altered mental state and neuromuscular excitation
What is the treatment for serotonin syndrome?
Supportive (fluids and monitoring)
What is the mechanism of action of SNRIs?
Acts in the same way as SSRIs, but also reduces noradrenaline reuptake
What can SNRIs also be used for apart from depression/anxiety?
Neuropathic pain
What are the side effects of SNRIs?
Same as SSRIs, but greater propensity for sedation, nausea and sexual dysfunction