Antidepressants Flashcards
What are the classes of antidepressants
Selective serotonin reuptake inhibitors (SSRIs)
Serotonin and Noradrenaline reuptake inhibitor (SNRI)
Tricyclic antidepressants (TCAs)
Noradrenergic and specific serotonin antidepressant (NaSSA)
Noradrenaline reuptake inhibitors (NARIs)
Monoamine Oxidase Inhibitors (MAOIs)
Reversible inhibitors of monoamine oxidase A (RIMAs)
Serotonin antagonist and reuptake inhibitor (SARI)
What is the MOA of SSRIs and give examples
Blocks the serotonin re-uptake → more serotonin in the synaptic cleft
Paroxetine, sertraline, citalopram, fluoxetine (preferred for CAMHS), escitalopram
How should SSRIs be taken
Requires 4-6 weeks to work
Continued for 6 months after remission (first episode) or 2 years (recurrence)
Then gradually stopped after 4 weeks
Should not be taken with Triptans, NSAIDs/aspirin
+ regular review
What are the side effects of SSRIs
Stomach/GI e.g. nausea, diarrhoea, constipation, GI bleeding
Sleep disturbance/insomnia with vivid dreams
Sexual dysfunction
Sodium - Hyponatraemia
Increased risk of suicide (In the first 1-2 weeks)
Serotonin syndrome
Others: Headache, dizziness, sweating, blurred vision, akathisia
Citalopram → QT prolongation
How should fluoxetine be swapped
Reduce dose over 2 weeks and wait 4-7 days after stopping before starting another
What is serotonin syndrome and what are the complications
Excessive serotonin in the synapses of the brain
From using antidepressants: side effect, in combination, overdose
Complications: DIC | rhabdomyolysis | renal failure/metabolic acidosis | seizures
What are the symptoms of serotonin syndrome
Altered mental state: agitation, confusion coma
Neuromuscular changes: myoclonus, hyperreflexia, hypertonia, tremor
Autonomic dysfunction: tachycardia, HTN, hyperthermia, diaphoresis, mydriasis (dilated pupil)
What is the management for serotonin syndrome
- Admit to hospital
- Stop offending medications
- Supportive measures (ABCDE) - airway management, renal care, IV fluids, temperature control
- Cyproheptadine (antihistamine + serotonin antagonist)
What is the MOA for SNRIs and give some examples
Blocks reuptake of serotonin > NA
(Will also block DA uptake at high doses)
Venlafaxine, duloxetine
Note: requires BP monitoring
What are the side effects of SNRIs
Headache
Stomach/GI e.g. nausea, diarrhoea, constipation, GI bleeding
Sleep disturbance/insomnia with vivid dreams
Sexual dysfunction
Sodium - Hyponatraemia
Increased risk of suicide (In the first 1-2 weeks)
Serotonin syndrome
Others: dizziness, sweating, blurred vision, akathisia
What is the MOA for TCAs and give some examples
Affects multiple transmitters (5-HT and NA re-uptake inhibition)
- High dose → all receptors
- Low dose → blocks H1 and 5-HT → good for sleep
Amitriptyline, nortiptryline, clomipramine, lofepramine
What are the side effects of tricyclic antidepressants
Anti-cholinergic/muscarinic effects (can’t see, can’t pee, can’t spit, can’t shit)
- Blurred vision
- Urinary retention
- Dry mouth
- Constipation
Cardiotoxic - QT prolongation, ST elevation, AV block
Anti-histaminergic: sedation, postural hypotension, weight gain
Thrombocytopenia
Cardiac (arrhythmia, MI, stroke, postural hypotension)
Lethal in overdose - do not give if risk of suicide
What is the MOA for NaSSAs and give some examples
Blocks presynaptic alpha-2-adrenergic receptors (Autoreceptor hence less feedback and more NA release)
Mirtazapine
What are the side effects of NaSSAs
Drowsiness (→ take in the evening)
Increased appetite
Weight gain
Give an example of Noradrenaline reuptake inhibitors (NARIs) and what are its side effects
Reboxetine
Dry mouth
Constipation
Excessive sweating
Urinary problems
Insomnia
Tachycardia
