Antidepressants Flashcards
(55 cards)
What medications are associated with prolonged QTc?
TCAs Lithium SSRIs Venlafaxine (SNRI) Macrolides e.g. erythromycin and clarithromycin Sotalol Methadone
Name the different types of antidepressants
MAOIs TCAs SSRIs SNRIs NaSSA - NA and specific serotonergic antidepressant (Lithium)
Which patient groups should you be more cautious with prescribing antidepressants?
Renal or hepatic impairment - excretion and metabolism Cardiac problems - prolong QTc Epilepsy - increased risk of seizures Pregnant or breastfeeding Elderly or children
How should antidepressant switching occur?
Cross-tapering: reduction of old antidepressant whilst increasing the new antidepressant.
Aim is to minimise the fluctuation of serum antidepressant levels to reduce the risk of side effects and behavioural changes.
Name 2 MAOIs
Isocarboxazid
Phenelzine
Describe the mechanisms of action of MAOIs
Irreversible inhibition of MAO-A and MAO-B ➔ accumulation of monoamines (particularly dopamine and serotonin) in the synaptic cleft
Why has Phenelzine been discontinued?
‘Cheese reaction’
Hypertensive crisis due to accumulation of tyramine which is found in cheese, wine, and other foods.
Avoid indirect sympathomimetics.
Name 3 side effects of MAOIs
Risk of hypertensive crisis Postural hypotension and dizziness Euphoria Antimuscarinic effects Hepatotoxicity Insomnia Anxiety
List 2 cautions for MAOIs
Poorly controlled hypertension
Hyperthyroidism
List 2 contraindications for MAOIs
Pheochromocytoma
Stroke
What should be monitored if taking a MAOI?
Blood pressure - postural hypotension and HTN crisis
Name 2 TCAs
Amitriptyline - also used for neuropathic pain
Clomipramine - 2nd line OCD Tx
Imipramine
Trimipramine
Describe the mechanism of action of TCAs
Serotonin and NA reuptake inhibition
Name 3 side effects of TCAs
Sedation Impaired psychomotor function Antimuscarinic effects CVS: tachycardia, postural hypotension, prolonged QTc sudden cardiac death Lowers seizure threshold Weight gain
Why is TCA toxicity dangerous?
TCAs are cardiotoxic in overdose.
Most: Amitriptyline
Least: Lofepramine
What monitoring is advised when taking TCAs?
Cardiac and liver function
Longterm: U&Es, FBC, weight
Name 3 SSRIs
Sertraline
Fluoxetine
Paroxetine
Citalopram - prolongs QTc
Describe the mechanism of action of SSRIs
Inhibit the reuptake of serotonin ➔ accumulation in the synaptic cleft
Name 3 side effects of SSRIs
Nausea GI upset Agitation - early onset Sexual dysfunction Anorexia Vivid dreaming Prolonged QTc SIADH ➔ dilution hyponatraemia
Rare: Mania, increased suicidal ideation and self-harm (under 30s), EPSP
What are the extrapyramidal side effects?
Akathisia - restlessness
Tardive dyskinesia - involuntary twisting of facial muscles, late onset, can involve extremities (hands > feet)
Acute dyskinesias and dystonic reactions
Parkinsonism - rigidity, pill rolling tremor, bradykinesia
Akinesia
What is neuroleptic malignant syndrome?
Life-threatening reaction (10% mortality) in response to neuroleptic medication (within 1 month of starting).
Characterised by tetrad of: fever*, muscle rigidity, altered mental state, and autonomic dysfunction. Typically develops over a few days.
Tx: stop causative drug + ICU care
What is the consequence of SSRI toxicity
Serotonin syndrome:
Restlessness, XS sweating, tremor, shivering, myoclonus, confusion, convulsions, death
Which SSRI has the highest risk of Serotonin syndrome and why?
Paroxetine due to its short half life.
What should be monitored when taking SSRIs?
Risk of suicide, as SSRIs can increase the risk.
