Antidepressants Flashcards
What is the cause of depression?
Originally it was thought to be low levels of serotonin but is more likely to be aa reduction in serotonin receptors in the hippocampus
Describe the mode of action of MonoAmine Oxadase Inhibitors
Inhibits MAO enzymes who’s function in to breakdown norepinephrine, serotonin and dopamine. Therefore inhibiting this enzyme increases levels of all three NTs
Name some MAOIs and the side effects
- Phenelzine,
- Selegiline (used in Parkinson’s),
- Tranylcypromine.
Side effects are weakness, headache, weight gain, dizziness, fatigue and impotence.
What are the interactions of MAOIs
They should not be used in combination with SSRI/Tricyclic, and analgesics such as morphine/tramadol. These will increase serotonin levels to potentially dangerous levels.
Foods high in tyramine such as cheese, alcohol, meats eg, venison and some green veg - causes hypertensive crisis.
Name a reversible MAOI (RIMA) and how it works
Moclobemide. It acts by reversibly inhibiting MAO type A enzymes.
How do tricyclic antidepressants work?
Inhibiting the re-uptake of norepinephrine and serotonin by blocking the transporters responsible for re-uptake
What are some of the uses of Tricyclic antidepressants?
Depression, Anxiety, Chronic pain, IBS, neuralgia, OCD, Nocturnal enuresis, PTSD
What are some of the side effects of tricyclic antidepressants?
- Increases risk of arrhythmias,
- Reduces intestinal mobility,
- Induce bradycardia followed by tachycardia,
- reduce bronchial secretions,
- urinary retention,
- Dry mouth and confusion
- Dangerous in overdose so be careful with suicide risk!
Name some common tricyclic antidepressants
- Amitriptyline,
- Clomipramine,
- Imipramine,
- Lofepramine,
- Nortriptyline.
What is Trazodone?
A drug related to the class of tricyclics which has a sedating effect.
How do selective serotonin re-uptake inhibitors work?
Increase the levels of serotonin by limiting re-absorption allowing for increased levels of the neurotransmitter. They have only a weak affinity for norepinephrine and dopamine so tend to have fewer side effects and are better tolerated.
What are the serotonin receptors?
5-hydroxytryptamine. (5-HT)
What are some of the uses of SSRIs?
- Depression
- Anxiety,
- OCD,
- Panic Disorder,
- PTSD,
- Eating Disorder
Name some examples of neurotransmitters that the 5-HT receptor modulates the release of and what impact this have.
GABA, Dopamine, Adrenaline, Noradrenaline and Acetylcholine. These NTs influence aggression, anxiety, cognition, learning memory, mood and sleep.
What are the side effects of SSRIs?
- Sexual dysfunction and reduced libido.
- Cardiac (citalopram can prolong the QT interval)
- Bleeding (increases risk of GI bleeding),
- Risk of suicide, especially in children and adolescents.
- Nausea,
- Rash,
- Sweating,
- Insomnia,
- Muscle aches,
- Epilepsy (may reduce seizure threshold)
What are the most toxic SSRIs?
Citalopram, Escitalopram, paroxetine, sertraline and then the least toxic is fluoxetine
Name two serotonin norepinephrine up-take inhibitor (SNRI)
Duloxetine and Venlafaxine
Name a presynmaptic alpha2-adrenoreceptor antagonist, its uses and side effectes
Mirtazapine. Used for depression, anxiety and PTSD but low dose can cause drowsiness and high dose can have stimulating effect
What are the uses and side effects of duloxetine
It is used for depression, neuropathic pain and stress urinary incontinence. Side effects include nausea, insomnia and dizziness
What are the uses and side effects of Venlafaxine
Used in major depressive disorder, anxiety, panic, social phobia, and often used in resistant depression
Name an antipsychotic which has anti-depressant properties?
Risperidone
What drug is used in bipolar?
Lithium. Can have adverse effects in kidney and thyroid
How are antidepressants used in pain management?
They have a direct effect on the mechanism of the pain. For example tricyclics work by blocking reuptake of noradrenaline and serotonin into nerve endings and increasing their levels in the pain control pathway
Prolongation of the QT interval can lead to?
Life threatening arrhythmia known as torsades de pointes.
Name some examples of drugs that can prolong the QT interval
Antimicrobials eg, eryhtromycin and clarithromycin.
Antiarrhythmias - Amiodarone.
Antipsychotics - Clozapine.
Antidepressants - Citalopram or amitriptyline,
Antiemetics - domperidone.
