Drug Therapies - Anti-depressants Flashcards
What conditions are Anti-depressants prescribed for?
Depression (incl BPD)
Organic mood disorders
Schizoaffective disorder
Anxiety disorders e.g. OCD, panic & social phobia
How long do anti-depressants take to work?
2-4wks.
The guidelines state a therapeutic trial should last atleast 2 months before you change drug
How long after a depressive episode should someone be on prophylactic anti-depressants?
Depends on how many episdoes they’ve had?
1st = 6 months/1 yr
2nd = 2yrs
3rd = ~lifelong
What are the categories of anti-depressants?
SSRIs - Selective Seratonin reuptake inhibitors
SNRIs - Serotonin & Noradrenaline reuptake inhibitors
TCAs - Tricyclic
MAOIs - Monoamine Oxidase inhibitors
Novel e,g, Mirtazepine & Buproprion
In what order would we generally use anti-depressants?
1) SSRI
2) 2nd SSRI or augment with a novel agent
3) SNRIs
4) TCAs or MAOIs
TCAs are very effective, why aren’t they more commonly used?
1st - Easy to OD
2nd - Heavy side effects:
- Antihistaminic e.g. sedation & weight gain
- Anticholinergic e.g. Dry mouth & constipation
- Antiadrenergic e.g. Orthostatic hypotension & sexual dysfunction
What are the types of TCAs?
Tertiary - Worse side effects e.g. Amitryptiline
Secondary - active metabolites of tertiary
How do MAOIs work?
Bind irreversible to Monoamine oxidase preventing deactivation of dopamine & serotonin
Why don’t we use MAOIs much?
Side effects:
- Orthostatic HTN
- Weight gain
- Dry mouth
- Sedation
- Sleep disturbance
- HTN crisis (cheese reaction, due to tyramine)
- Serotonin syndrome => Hyperpyrexia, CV shock & death
What are the major side effects of SSRIs?
GI
Sexual dysfunction (main reason patients drop out)
Acitivation syndrome
Discontinuation syndrome
What’s Acitivation syndrome?
Increased serotonin from SSRIs –>:
Nausea, anxiety, panic & agitation
It only lasts 2-10 days so warn and reassure your patients
What is discontinuation syndrome?
Agitation, nausea, disquilibriujm & dysphoria when stopping an SSRI
Fluoxetine has a long half life so can be used to wean off SSRIs
What are the major SSRIs?
Paroxetine Sertraline! Fluoxetine! Citalopram! Escitalopram` Fluvoxamine
pros & cons of paroxetine?
Good for anxiety as it has quite a lot of sedation
+/- for Sertraline?
Has relatively few side effects
Pros of Prozac (Fluloxetine)>
Has a long half life so it’s good for compliance issues and preventing discontinuation syndrome
What’s the big risk from from citalopram
Dose dependant QT prolongation
How do SNRI’s work?
Affect both serotonin and noradrenaline reuptake, hence they work like TCAs without the big bad side effects
List some SNRIs?
Venlafaxine
Duloxetine
Pros & Cons of venlafaxine?
an SNRI:
Pros = g#ood renal clearance & short half life –> little toxic buildup
Cons = Dose dependant diastolic bp increase
QT prolongation
Sexual dysfunction
Bad discontinuation syndrome (due to short half life)
Why use duloxetine over venlafaxing?
Less BP effect so useful in that context
List the major 2 novel antidepressants?
Mirtazepine
Buproprion
What are the risks with mirtazapine?
Increases serum cholesterol & Triglycerides
Weight gain & appetite increase
Sedating at low doses
Pros and cons of Buproprion?
A good augmenter with few side effects. No weight gain, sexual dysfunction, sedation or cardiac problems
But increases seizure risk
What drugs can we use to treat Resistant Depression?
1) Combination antidepressants e.g. SSRI/SNRI with mirtazapine
2) Adjunctive lithium
3) Adjunctive Anti-psychotic
4) ECT
What else are SNRI’s helpful with?
Neuropathic pain
