15-09-23 - Antidepressants Flashcards
Learning outcomes
- understand what depression is
- recognise the typical symptoms of depression
- understand the possible theories of the causes of depression
- know the various categories of antidepressant drugs
- know the effects and the mechanisms of action of the various classes of anti-depressant drug
- understand the dangers and side effects of the various classes of drug
What is thought to be the cause of depression?
- Originally thought that low levels of serotonin was the cause
- Now not so clear but likely reduction in serotonin receptors in hippocampus
- Would help explain why SSRI takes so long to work
- Many studies show people with depression having what is assumed to be normal levels of serotonin
What is the role of Mono Amine Oxadase Inhibitors (MAOI)?
What is the role of MAO?
What does inhibiting them lead to?
What class of antidepressants are they?
What are 3 examples of MAOI antidepressants?
What are 6 side-effects of MAOI?
- Mono Amine Oxadase Inhibitors (MAOI) inhibit the activity of MAO enzymes
- MAO breaks down norepinephrine/serotonin and dopamine
- Inhibiting MAO increases level of all three transmitters
- They were the first class of antidepressants developed
- 3 examples of MAOI antidepressants:
1) Phenelzine
2) Selegiline – also used in Parkinsons
3) Tranylcypromine - 6 side-effects of MAOI:
1) Weakness
2) Headache
3) Weight gain
4) Dizziness
5) Fatigue
6) Impotence
What drugs should MAOI not be use in combination with?
Why is this?
What are 4 examples of foods that shouldn’t be mixed with MAOI?
Why is this?
What should be done after stopping MAOI before giving other antidepressants?
- MAOI should not be used in combination with:
1) SSRI/Tricyclic
2) Some analgesics such as morphine/Tramadol - This is because will increase serotonin to potentially dangerous levels causing confusion, hypertension, tremor, coma and possibly death.
- Foods high in tyramine may also cause a hypertensive crisis E.G:
1) Cheese
2) Certain meats such as venison
3) Alcohol
4) Some green vegetables i.e. broad beans - We should give 14 days washout after stopping MAOI before starting other antidepressants
What is an example of a reversible MAOI?
How does it work?
How does tyramine affect it?
How long is its action?
Why is this more advantageous than MAOI?
- Moclobemide is a reversible MAOI
- It works via reversible inhibition of MAO type A (Therefore called RIMA)
- Tyramine has less of an effect on reversible MAOI than MAOI
- Moclobemide is short acting, so medications can be changed with only one week washout period (unlike MAOI that needs 2 weeks)
What is the action of Tricyclic Antidepressants?
How does this affect neurotransmission?
- Tricyclic Antidepressants Act by inhibiting re-uptake of norepinephrine and serotonin by blocking the transporters responsible for re-uptake of these neurotransmitters.
- This leads to increasing concentration of neurotransmitters in the synapses and triggering further neurotransmission.
What are contraindications of Tricyclic Antidepressants?
Why is this?
What activity do tricyclics block?
What are 5 potential side-effects of Tricyclic Antidepressants?
- Tricyclics antidepressants should be used with caution in cardiovascular disease due to risk of arrythmias
- Tricyclics have antimuscarinic activity that blocks activity of the muscarinic acetylcholine receptor and so reduce intestinal mobility
- 5 potential side-effects of Tricyclic Antidepressants:
1) They can induce bradycardia followed by tachycardia
2) Reduce bronchial secretions
3) Urinary retention
* Don’t drain all of urine at once, as this can cause vasovagal collapse
4) Dry mouth
5) Confusion
What are 5 common tricyclic antidepressants?
- 5 common tricyclic antidepressants:
1) Amitriptyline
2) Clomipramine
3) Imipramine
4) Lofepramine
5) Nortriptyline
What are 8 uses of Tricyclic Antidepressants?
- 8 uses of Tricyclic Antidepressants:
1) Depression
2) Anxiety
3) Chronic pain (i.e. fibromyalgia, reflex sympathetic dystrophy syndrome)
4) IBS
5) Neuralgia
6) OCD
7) Nocturnal enuresis
8) PTSD
What is a drug related to tricyclics?
What effect does this drug have?
What is a concern about tricyclics?
- Trazodone is a drug related to tricyclics
- Trazodone is more sedating
- A concerns is that tricyclics are very dangerous in overdose so beware of how much you prescribe for a patient and use with caution in patients at high risk of suicide.
What is the action of Selective Serotonin Re-uptake Inhibitors (SSRI)?
How do SSRIs compare with tricyclic antidepressants?
What are serotonin receptors known as?
- Selective Serotonin Re-uptake Inhibitors SSRI work by increasing levels of neurotransmitter serotonin by limiting its reabsorption and pure SSRI have only a weak affinity for norepinephrine and dopamine transmitters
- SSRIs therefore, cleaner with generally fewer side effects and better tolerated by patients than tricyclic antidepressants
- Serotonin receptors are known as 5- hydroxytryptamine (5-HT)
How common are SSRIs? What are 6 uses of SSRIs?
- SSRIs are the most widely prescribed antidepressants
- 6 uses of SSRIs:
1) Depression
2) Anxiety
3) OCD
4) Panic disorder
5) PTSD
6) Eating disorders
Where are 5-HT serotonin receptors located?
What 5 neurotransmitters do 5-HT receptors modulate the release of?
What 6 factors do these neurotransmitters control?
- 5-HT receptors are found in the peripheral and central nervous systems mediating both excitatory and inhibitory neurotransmission
- 5 neurotransmitters do 5-HT receptors modulate the release of:
1) GABA
2) Dopamine
3) Epinephrine
4) Norepinephrine
5) Acetylcholine - 6 factors do these neurotransmitters control:
1) Aggression
2) Anxiety
3) Cognition
4) learning memory
5) Mood
6) Sleep
What are 7 different types of SSRI side-effects?
- 7 different types of SSRI side-effects:
1) Sexual
* dysfunction and reduced libido
2) Cardiac
* Some, especially citalopram, to be used with caution as can cause QT interval prolongation therefore dose dependant with citalopram
3) Bleeding
* Affects anticoagulants (i.e. warfarin and aspirin) and also increased risk of GI bleeds
4) Suicide/self-harm
* Possible increased risk of suicide especially in children and adolescents
* May only be prescribed in under-18s by a psychiatrist
5) Overdose
* Safer than other antidepressants
6) Worsening epilepsy
* Safer than other antidepressants
7) Other
* Nausea
* Rash
* Muscle aches
* Insomnia
* Sweating
Describe the 5 SSRIs from most toxic to least toxic (in picture)
Drugs that prolong the QT interval
