Antidepressants Flashcards
Mechanism of SSRI
1. 5HT1A centrally • Relief of depression • Anxiolytic effect 2. 5HT2A in spinal cord • Sexual dysfunction: delayed ejaculation, anorgasmia, decreased interest/libido 3. 5HT2C/5HT2A in brain • Activation: anxiety, insomnia • Worst with fluoxetine, paroxetine • Warn patients anxiety may worsen in first 1-2 wk of treatment 4. 5HT3A in gut • GI upset: nausea, vomiting, bloating • Take with food
Treatment strategies for refractory depression
- Start with SSRI/SNRI/Mirtazepine
- Reassess every 1-2 weeks for 3-4 weeks
a. Full response->continue
b. No or partial->optimise, reassess every 4-8 weeks - If partial response->combine, augment
- If no response->switch
Pharmacological approach, changing drugs
- Optimisation of dose
- Augmentation->with drug not an antidepressant (thyroid, lithium, atypical)
- Combination
- Substitute
First line and second line
- SSRI/SNRI/Mirtazepine
2. TCA, mianserin, MAOI
Side effects
- Agitation
- GIT: nausea, anorexia, diarrhea, discomfort
- Insomnia
- Hypertension
- Orthostatic hypotension
- Sedation
- Sexual dysfunction->decreased libido, anorgasmia, ejaculatory disturbance
- Weight gain
- Bleeding
- Hyponatremia
- Serotonin toxicity
Most sedating->option if insomnia
Mirtazepine, take at night
Also fewer sexual dysfunction
Avoid in liver impairment
Duloxetine
Avoid in evening because of insomnia
Fluoxetine
Moclobemide
Initial weight loss
Fluoxetine
Fluvoxamine
Paroxetine
Sertraline
++Orthostatic hypotension
Fluoxetine Paroxetine Sertraline SNRIs Moclobemide
Risks of hyponatremia
Risk factors for hyponatraemia include:
older age
female gender
low body weight
concurrent drugs (eg diuretics, NSAIDs, carbamazepine, chemotherapy)
impaired renal function
comorbidity (eg hypothyroidism, diabetes, chronic obstructive pulmonary disease, hypertension, stroke, head injury)
hot weather.
First line treatment option for depression with psychosis
- ECT
Counselling a patient on antidepressants
- SSRIs are used to treat depression, to restore the balance of neurotransmitters affected in depression
- They can take 2-4 weeks to build up effect, best to wait 3-4 weeks before deciding it doesn’t work. Can increase dose over 2-4 weeks as tolerated.
- May experience some initial anxiety in the first 1-2 weeks, this is normal. Neurovegetative states improve first, then cognition. If you have any +agitation, restless, anxiety, see your doctor. May +suicidality in children/young people
- Usual course is for 6 months, tablet taken every day and then tapered slowly. May be for longer.
- 5-7 in 10 people will have good response in first few weeks. Twice as likely to improve, but not in everybody.
- Do not stop taking the medication suddenly, do not take any more than prescribed.
- SSRIs have similar efficacy.
- Most common side effects include: diarrhea, nausea, vomiting and headaches.
- Other possible are: sedation, sexual dysfunction, bleeding, change in sodium, insomnia and weight gain.
- Not addictive but can have withdrawal symptoms if stopped abruptly: dizzy, anxiety, sleep, flu like, diarrhea, abdominal pain, parasthesia, mood swings, low mood.
- Precautions: do not take with medicines to treat migraine, St Johns wart, alcohol
- If you miss a dose, do not double the dose
