Anti-depressants Flashcards
which drugs would you use to treat moderate-severe depression 1st, 2nd and 3rd line? explain why
1st line: SSRI - better tolerated and safer in OD
2nd line: alternative SSRI
3rd line: consider SNRI, tetracyclic antidepressant or tricyclic antidepressant
what is the MOA of SSRIs? name examples
Inhibit serotonin reuptake in pre-synaptic neurone, increasing amount available in synaptic cleft to generate AP in post-synaptic neurone.
- citalopram (preferred)
- fluoxetine (preferred)
- sertraline
- escitalopram
- paroxetine
which SSRI would you prescribe in someone with unstable angina or recent MI?
SERTRALINE - shown to be safe
name characteristic ADRs of SSRIs
- GI disturbance
- increased risk GI bleeding
- hypontraemia (due to inappropriate ADH secretion?)
- mania precipitation, possible increased suicidal ideation
- serotonin syndrome
name an ADR specific to citalopram
QT interval prolongation
what is serotonin syndrome?
- Relatively rare ADR caused by excessive central and peripheral serotonergic activity.
- Can occur following initiation, dose escalation, OD or addition of new serotonergic drug (esp. MAOI).
- Features:
- neuromuscular hyperactivity (tremor, hyperreflexia, clonus, myoclonus)
- autonomic dysfunction (tachycardia, BP changes, hyperthermia, diaphoresis, shivering, diarrhoea)
- altered mental state (agitation, confusion, mania)
suggest possible drug interactions with SSRIs
- NSAIDs or aspirin: if given, co-prescribe a PPI
- warfarin/heparin: avoid SSRIs and consider mirtazapine
- triptans
- St John’s wort
what advice would you give a pt starting an SSRI?
- delay in onset of effect (2-4 wks) and possible worsening of symptoms for 1st 2 wks
- pt should be reviewed 2 wks after initiation (1 wk for pts <30 yrs or at increased risk of suicide)
- if pt makes good response, therapy should be continued for at least 6 mths after remission - reduces risk of relapse
- when stopping SSRIs, dose should be gradually reduced over a 4 wk period
describe the MOA of SNRIs. name examples.
Decrease serotonin and noradrenaline re-uptake… increased serotonergic and noradrenergic neurotransmission.
- VENLAFAXINE
- DULOXETINE
suggest possible ADRs of SNRIs
As with SSRIs:
- GI disturbance
- increased risk GI bleeding
- hypontraemia (due to inappropriate ADH secretion?)
- mania precipitation, possible increased suicidal ideation
- serotonin syndrome
Plus:
- sleep disturbance
- increased BP
- dry mouth
describe the MOA of tetracyclic antidepressants. Name an example.
Pre-synaptic alpha2 R antagonists… increased central noradrenergic and serotonergic neurotransmission.
- MIRTAZAPINE
in which pts is mirtazapine particularly indicated?
In pts with insomnia and reduced appetite as side-effects include:
- sedation
- increased appetite and weight gain
In elderly pts as fewer side effects and interactions than many other antidepressants.
describe the MOA of tricyclic antidepressants. name some examples.
- Inhibit pre-synaptic re-uptake of serotonin and NA… increased serotonergic and noradrenergic neurotransmission.
- a1 adrenoR antagonist… decreased noradrenergic neurotransmission.
- mAChR antagonist… decreased cholinergic neurotransmission.
AMITRIPTYLINE, CLOMIPRAMINE, LOFEPRAMINE
in which pts are TCAs more likely to be used?
Less commonly used in depression due to ADRs and high risk in OD. But can be used in pts who also have neuropathic pain.
suggets ADRs of TCAs
- Anti-cholinergic effects:
- dry mouth
- constipation
- blurred vision
- urinary retention
- cognitive/memory impairment - Cardiotoxicity:
- increased HR
- impaired myocardial contraction
- arrythmias, inc. prolonged QT, VT and VF
- postural hypotension - Neurotoxicity:
- sedation
- impaired psychomotor performance
- lowered seizure threshold
- hallucinations and delirium
