Antidepressants Flashcards
What was depression originally thought to be caused by?
- Low levels of serotonin
- Now not as clear but likely a reduction in serotonin receptors in hippocampus
WHat were the first class of antidepressants developed?
Mono Amine Oxidase Inhibitors (MAOI)
What does Mono Amine Oxidase break down?
- Norepinephrine
- Serotonin
- Dopamine
MAOIs therefore increase the levels of these 3 transmitters
What are some common MAOIs?
- Phenelzine
- Selegiline - also used in parkinsons
- Tranylcypromine
What are the side effects of Mono Amine Oxidase inhibitors MAOIs?
- Weakness
- Headache
- Weight gain
- Dizziness
- Fatigue
- Impotence
What should MAOIs not be used in combination with?
- SSRI/Tricyclic
- Analgesics such as morphine/tramadol as they will increase serotonin to potentially dangerous levels
How many days should be given after stopping MAOI before starting other antidepressants?
14
What foods should you avoid whilst taking MAOIs?
Foods high in tyramine may also cause a hypertensive crisis
- Cheese
- Certain meats such as venison
- Alcohol
- Some green vegetables i.e broad beans
How do Reversible MAOIs differ to MAOIs?
- Reversible inhibition of MAO type A ]
- Tyramine has less of an effect
- Only 1 week washout period
How do tricyclic antidepressants work?
- Inhibit re-uptake of norepinephrin and serotonin by blocking the transporters responsible for their re-uptake
- Increase concentration of neurotransmitters in the synapses and triggering further neurotransmission
What are tricyclic antidepressants used for?
- Depression
- Anxiety
- Chronic pain (i.e fibromyalgia, reflex sympathetic dystrophy syndrome)
- IBS
- Neuralgia
- OCD
- Nocturnal enuresis
- PTSD
What are the side-effects of tricyclic antidepressants?
- Arrythmias
- Antimuscarinic activity that blocks activity of the muscarinic Ach receptor and so reduce intestinal mobility
- Bradycardia followed by tachycardia, reduced bronchial secretions, urinary retention, dry mouth and confusion (not used in elderly)
- Use with caution in patients with high risk of suicide (very dangerous in overdose)
What are the common tricyclic antidepressants?
- Amitriptyline
- Clomipramine
- Imipramine
- Lofepramine
- Nortriptyline
What is a drug relating to tricyclics?
- Trazodone - more sedating
How are SSRIs believed to work?
- Limit re-absorption of serotonin thus increasing its leves
- Have only a weak affinity for norepinephrine and dopamine
- Most prescribed, Cleaner, less side-effects, better tolerated
What are serotonin receptors known as?
5-hydroxytryptamine (5-HT)
What are the uses of SSRIs?
- Depression (first line)
- Anxiety
- OCD
- Panic disorder
- PTSD
- Eating disorder
Where are 5-HT receptors found?
Peripheral and central nervous systems mediating both excitatory and inhibitory neurotransmission
What neurotransmitters do SSRIs modulate the release of?
- GABA
- Dopamine
- Epinephrine
- Norepinephrine
- Ach
What do 5-HT receptors have an influence on?
- Aggression
- Anxiety
- Cognition
- Learning memory
- Mood
- Sleep
What are the side-effects of SSRIs?
- Sexual: dysfunction, reduced libido
- Cardiac: QT interval prolongation therfore dose dependant with citalopram
- Bleeding: affects antocoagulants (i.e. warfarin and aspirin) and also increased risk of GI bleeds
- Suicide
- Overdose (safer than most)
- Epilepsy
- Nausea, rash, muscle aches, insomnia, sweating
Who is able to prescribe SSRIs to under 18s?
Only psychiatrists due to increased risk of suicide in adolescents and children
Name a serotonin norepinephrine up-take inhibitor)
Duloxetine
What are the uses of duloxetine (SNRI)?
- Depression
- Neuropathic pain (diabetes, fibromyalgia)
- Stress urinary incontinance
What are the side-effects of duloxetine (SNRI)?
- Nausea
- Insomnia
- Dizziness
WHat is mirtazapine?
A presynaptic alpha2-adrenoreceptor antagonist. Also a noradrenergic and specific serotonergic antidepressant NaSSA
What are the uses of Mirtazapine?
- Depression
- Anxiety
- PTSD
What are the side-effects of Mirtazapine?
- Low dose drowsiness so best taken at night
- Higher dose more stimulant effect
What is Venlafaxine?
Serotonin-norepinephrine re-uptake inhibitor (SNRI)
What are the uses of Venlafaxine (SNRI)?
- Major Depressive disorder
- Anxiety
- Panic
- Social phobia
- Metabolised in the body into desvenlafaxine (by cytochrome P206 isoenzyme in the liver)
- Often used in treatment of resistant depression
Name an antipsychotic which can be used for depression?
Risperidone
What antidepressant can be used in bipolar disorder?
Lithium
What are some possible adverse effects of lithium?
Adverse effects on thyroid and kidney function
How can antidepressants treat pain?
- Tricyclics by blocking re-uptake of NA and serotonin (5-HT) into the nerve endings and increasing their levels in the pain control pathways
- Can benefit fighting pain through direct effect and also though beneficial effects on sleep
What antidepressants can be used in fighting pain?
- Amnitriptyline, nortriptyline, duloxetine
- Duloxetine also liscensed for diabetic neuropathy
What is the life-threatening arrhythmia associated with QT-prolongation?
Torsades de pointes
What drug has a highlighted risk of QT-prolongation?
Citalopram
What groups of people have a greater risk of QT-prolongation?
- Major psychiatric disorders
- CV disease
- Elderly
- Women
How can anti-depressants increase the chances of suicide?
- Side-effect of increased stimulation
- Gives individual ‘drive’ to do something to oneself
Are SSRIs prolonged release drugs?
No - have a long half-life as is
What are some examples of SSRIs from most toxic to least toxic?
- Citalopram (QT interval)
- Escitalopram
- Paroxetine
- Sertraline
- Fluoxetine
