Antidepressants Flashcards
What is the likely cause of depression
Reduction of serotonin receptors in the hippocampus
What are the different types of antidepressants?
- Mono Amine Oxidase Inhibitors
- Reversible Mono Amine Oxidase Inhibitors
- Tricyclic antidepressants
- Selective serotonin reuptake inhibitors
- Serotonin norepinephrine up take inhibitors
What is the mechanism of Mono Amine Oxidase Inhibitors?
- Inhibit MAO enzymes that break down norepinephrine/ serotonin and dopamine
- Inhibiting increases the levels of all of these neurotransmitters
Name examples of mono amine oxidase inhibitors
- Phenelzine
- Selegiline
- Tranycypromine
What are the side effects of mono amine oxidase inhibitors?
- Weakness
- Headache
- Weight gain
- Dizziness
- Fatigue
- Impotence
What are the interactions of mono amine oxidase inhibitors?
- Can cause dangerous levels of serotonin causing hypertension, confusion, tremor, coma and potentially death if used with SSRI tricyclic or some analgesics e.g. morphine or tramadol
- Need a 14 day washout period to avoid interactions
- Foods high in tyramine may cause hypertensive crisis e.g. cheese, certain meats, alcohol, some green vegetables
Example of reversible mono amine oxidase inhibitor
Moclobeminde
What are the interactions of reversible mono amine oxidase inhibitors?
- Tyramine has less of an effect
* Because it is a shorter acting medication can be changed with only a one week washout period
What is the mechasnim of tricyclic antidepressants?
- Inhibit the reuptake of norepinephrine and serotonin by blocking transporters responsible for re-uptake
- Increases the concentration of neurotransmitters in the synapse, triggering further neurotransmission
Name examples of tricyclic antidepressants
- Amitriptyline
- Clomipramine
- Imipramine
- Lofepramine
- Nortriptyline
What are the interactions of tricyclics?
- May cause arrhythmia in cardiovascular disease
* Very dangerous if overdosed (caution in suicidal patient)
What are the side effects of tricyclics?
- Reduced intestinal mobility
- Can induce bradycardia followed by tachycardia
- Reduce bronchial secretion
- Urinary retention
- Dry mouth
- Confusion
Why should tricyclics be avoided in the elderly?
Because of the side effects causing urinary retention, dry mouth and confusion
Trazodone
Related to tricyclics but more sedating
What is the mechanism of selective serotonin re-uptake inhibitors?
- Limits the reuptake of serotonin, acting on the 5-hydroxytryptamine (5HT) receptor
- Only have a weak affinity for norepinephrine and dopamine transmitters so are generally better tolerated with fewer side effects
Name examples of Selective Serotonin Re-uptake inhibitors
- Citalopram (most toxic)
- Escitalopram
- Paroextine
- Sertaline
- Fluoxetine (least toxic)
What are the side effects of selective serotonin re-uptake inhibitors?
- Sexual dysfunction and reduced libido
- Cardiac: some (esp. citalopram) can cause QT interval prolongation
- Bleeding: affects anticoagulants (i.e. warfarin), increasing risk of GI bleeds
- Possible increased risk of suicide
- Nausea
- Rash
- Sweating
- Headaches
- Insomnia
- Muscle aches
What are the interactions of selective serotonin reuptake inhibitors?
- Anticoagulants
* May reduced fit threshold in epilepsy
What is the mechanism of Duloxetine?
• Serotonin norepinephrine re-uptake inhibitor
What are the side effects of duloxetine?
- Nausea
- Insomnia
- Dizziness
Mechanism of Mirtazapine?
• Presynaptic alpha-2 adrenoreceptor antagonist and specific serotonergic antidepressant
What are the side effects of Mirtazapine?
- Low doses cause drowsiness so best taken at night
* High doses give a more stimulant effect so better taken in the morning
Mechanism of Venlafaxine
Serotonin norepinephrine reuptake inhibitor
What are the uses of venlafaxine?
- Major depressive disorder
- Anxiety
- Panic
- Social phobia
- Resistant depression
Name antipsychotics
- Risperidone
* Lithium
When is lithium used?
- Bipolar/mania mood stabilisation
- Possible adverse effects on the kidney and thyroid function
- Regular blood tests every 3-4 months
Which groups of people are more at risk of QTc prolongation?
- Major psychiatric disorder
- Cardiovascular disease
- Women
- The elderly
