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
What is the MOA of monoamine oxidase inhibitors (MAOIs) and give examples
Increases the availability of 5-HT and NA in the synapses
Older = irreversible e.g. Phenelzine, tranylcypromine
Newer = reversible e.g. Moclobemide
What are the side effects of MAOIs
Tyramine interaction → hypertensive crisis
- Cheese, smoked meats, yoghurt, chocolate, coffee, tea
Postural hypotension, dizziness
Headache
Drowsiness, insomnia
Blurred vision
N&V
Constipation
What are the symptoms of stopping antidepressants suddenly
Discontinuation syndrome (FIRM STOP)
Flu-like symptoms
Insomnia, vivid dreams
Restlessness, irritability
Mood swings
Sweating
Tummy: pain, cramps, D&V
Off balance (ataxia), dizziness
Paraesthesia: Electric shock sensation, tingling
What is ECT
Inducing a generalised tonic-clonic seizure (under GA and muscle-relaxant) for about 30 secs
Given twice a week, usually 6-12 treatments
What are the indications for ECT
Severe/refractory depression: only in life-threatening situation e.g. poor oral intake, acutely suicidal, treatment resistant
Catatonia
Severe, uncontrolled mania
What are the contraindications to ECT
No absolute CIs
Caution with:
- Pregnancy
- Heart disease/stroke
- Poor anaesthetic risk
- Raised ICP
- Pacemaker
- Epilepsy
What are the side effects of ECT
Main risk is of the anaesthetic: MI, arrhythmia, aspiration, apnoea, malignant hyperthermia, pneumonia, death
Short-term:
- Headaches and nausea
- Muscle aches
- Confusion
- Cardiac arrhythmi
- Memory problem (retrograde > anterograde) - should recover by 6 months
Long-term: impaired memory, apathy, anhedonia
What is the difference between bilateral and unilateral ECT
Bilateral ECT- shorter duration, lower dose - USUALLY RECOMMENDED
- Effective at threshold, more efficacious, quicker
- More likely to get cognitive SE, language, or visuospatial problems
Unilateral ECT- non-dominant side
- Fewer cognitive SE
- Technically difficult, not as effective, slower action
