Antidepressants Flashcards
(24 cards)
What is the first line class of drug treatment for adults with unipolar depression, anxiety or OCD?
SSRIs - selective serotonin reuptake inhibitor
Fluoxetine + citalopram (most commonly preferred), sertraline, escitalopram, paroxetine, fluvoxamine, dapoxetine
How do SSRIs work?
Block pre-synaptic serotonin receptors - inhibiting the uptake of serotonin and increasing the amount of serotonin in the synapse
Also downregulate the number of 5-HT receptors
Predominantly acts in the prefrontal cortex
Patients report low feelings are less pronounced, they do not increase ‘happiness’
(though we dont really know and this means literally nothing)
What side effects are common?
GI most common:
N+V, abdo pain, silent reflux, GI bleed
Can give omeprazole (also if taking NSAID)
Feelings of agitation, tremor, anxiety, dizziness, blurred vision
Sexual dysfunction - low libido, erectile dysfunction, delayed ejaculation
Emotional numbness
What is serotonin syndrome?
Typically resulting from the use of 2+ serotonergic drugs - including SSRIs and other AntiD’s; street drugs - MDMA/amphetamines/cocaine/hallucinogens; St John’s Wort
Uncommon, short lived condition that can be fatal
Symptoms - triad: (SAC)
Cognitive = headache, agitation, hypomania, confusion, hallucination, coma
Autonomic =
tachycardia, sweating, shivering, dilated pupils, HTN, hyperthermia, N+V
Somatic = myoclonus, hyperreflexia, tremor
Management:
Stop drug
IV fluids +/- benzodiazepines if necessary
5-HT2A antagonists such as cyproheptadine in severe
What interactions are common?
Almost endless list
Some significant common ones are: aspirin/NSAIDs - GI bleeding risk - must co-prescribe with PPI
Warfarin/heparin - antiplatelet effect - try Mirtazepine
Triptans - just avoid SSRI
MAOIs - risk of serotonin syndrome
Fluoxetine + paroxetine are most commonly associated with interactions
How does the treatment plan work?
Started on lowest possible dose thought to improve symptoms
Taken daily for 2-4wks before benefit is felt - 2wk review with doctor is typical; if increased suicide risk - r/v in 1wk
Mild side effects may be present early but will usually settle
If taken for 4-6 weeks with no improvement return to doctor for titration upwards or review/switch if proving ineffective at higher doses
Should remain on for 6m after remission to reduce risk of relapse
Reduce over 4wks to minimise discontinuation symptoms
What happens if one SSRI unsuccessful?
Ensure trialled at maximum dose
Try another in the same class before changing type of antidepressant
Switch to mirtazapine, lofepramine, reboxetine etc
Antidepressant effects greatest when medications (in the same class) are mixed, though not in nice guidelines and should never mix with MAOIs as can cause serotonin syndrome
What is the relationship between hyponatraemia and antidepressants?
Possible side effect - usually in the elderly
Most commonly associated with SSRIs
Should be considered in all patients who develop drowsiness, confusion or convulsions
What are some cautions/contraindications for SSRI prescription?
Bipolar disorder - can precipitate mania
Bleeding disorders - can exacerbate
Epilepsy - only taken if well controlled
Diabetes
Serious kidney, liver or heart problems
Narrow angle glaucoma
Pregnancy:
First trimester - congential heart defects
Third trimester - persistent pulmonary HTN
Weigh up risks/benefits
Breastfeeding:
Paroxetine or sertraline are usually recommended and are considered safe to use
Children + adolescents: higher self harm and suicidal ideation; Fluoxetine is the drug of choice if depressed
Which antidepressants should be considered for more severe forms of depression?
Tricyclics
Venlafaxine
How do tricyclics work?
Block the reuptake of serotonin and noradrenaline
Various members in the class have different selectivities for each receptor type
They are also classed into more sedating and less sedating
What are some sedating tricyclics?
Used for anxious/agitated patients
Amitryptaline, clomipramine, dosulepin, doxepin, trazadone, trimaprimine
What are some less sedating tricyclics?
Used for patients who are withdrawn or apathetic
Imapramine, nortripyline, lofepramine
What are some side effects of tricyclics?
Antimuscarinic - dry mouth, pupil dilation and photosensitivity, no sweating, constipation, urinary retention, brady/tachy/arrhythmias
Weight gain/loss, postural hypotension, rash, sedation
How do you prescribe amitryptaline?
Migraine + chronic tension headache prophylaxis, neuropathic pain including phantom limb pain, abdominal pain in those unresponsive to other drugs
It is not however recommended in major depressive disorder due to an increased risk of fatality in overdose
What are SNRIs?
Block the reuptake of serotonin and noradrenaline
Examples are duloxetine, venlafaxine
What is Mirtazepine?
Could be a tetracyclic or a noradrenaline and specific serotonergic antidepressants (NASSA) - we dont really know..
Blocks - alpha-2 adrenergic receptors, histamine and serotonin (though doesnt inhibit reuptake)
Similar side effect profile to SSRI but fewer sexual side effects and more sedating/hypnotic initially (so can give for those with insomniac symptoms, take in evening)
Also improves appetite - give if weight/appetite concerns
What are MAOIs?
Monoamine oxidase inhibitors
Inhibit breakdown of NAd, 5HT, DA by inhibiting MAO enzyme
Much less frequently used due to diet/drug interactions; specialist prescription only
Examples - tranylcypromine (SE: HTN crisis), isocarboxazid and phenelzine (SE: hepatotoxicity); moclobemide (2nd line)
Indicated in severe refractory depression; also particularly successful if atypical/hypochondriacal/hysterical features
Response after 3+wks, and an additional 1-2 to become maximal
What is a washout period?
Time between switching serotinergic antidepressants - detox almost
Cross fading dose titrations here are also possible ie introducing one whilst decreasing the dose of another
Longer washout periods (of abstinence) are needed when switching to or from irreversible MAOIs as serotonin syndrome is more common here (see guidance)
What augmenting agents can be used along side antidepressants?
Lithium, quetiapine;
also aripiprazole, olanzapone, rispridone (unlicensed)
Specialist prescription only
What SSRI is best used after MI?
Sertraline and citalopram are the safest according to current evidence
What effect does citalopram (+escitalopram) have on QT interval?
Associated with dose-dependent QT interval prolongation and should not be used in those with: congenital long QT syndrome; known pre-existing QT interval prolongation; or in combination with other medicines that prolong the QT interval (lots of antipsychotics)
Maximum daily dose is now 40 mg for adults; 20 mg for patients older than 65 years; and 20 mg for those with hepatic impairment
What are some discontinuation symptoms of SSRIs?
Gastrointestinal symptoms: pain, cramping, diarrhoea, vomiting Increased mood change Restlessness Difficulty sleeping Unsteadiness Sweating Paraesthesia
Should reduce SSRI over 4wks to minimise risk (unnecessary with fluoxetine due to longer half life; more common in paroxetine)
What is a classic side effect of MAOIs?
Tyramine reaction:
Foods high in Tyramine e.g. cheese - may bring on a hypertensive crisis
