Antidepressants - venlafaxine and mirtazipine Flashcards
What are indications for venlafaxine and mirtazipine?
- Major depression where first line SSRIs are ineffective
- Generalised anxiety disorder
What is the mechanism of action of venlafaxine?
Serotonin and norad reuptake inhibitor interfering with uptake of these neurotransmitters from the synaptic cleft. Also increases monoamine availibility for neurotransmission, and antagonises muscarinic and histamine receptors
What is the mechanism of action of mirtazapine?
An antagonist of inhibitory pre-synaptic a2 adrenoreceptors. Also increases availibility of monoamines for neurotransmission and antagonises H1 receptors
What are common adverse side effects of both mirtazipine and venlafaxine?
- GI upset
- Headache
- Abnormal dreams
- Insomnia
- Confusion
- Convulsions
- Hyponatraemia
- Serotonin syndrome
- Suicidal thoughts/behaviour
What are adverse effects of venlafaxine which are not caused by mirtazipine?
- Prolonged QT
- Increase VT risk
What can occur with sudden drug withdrawal?
- GI upset
- Neurological upset
- Flu-like syndrome
- Sleep disturbance
What information should you give patients who you are starting on mirtazapine or venlafaxine?
Symptoms should improve over a few weeks
Don’t stop suddenly - reduce slowly
Mirrtazapine - if symptoms of infection seek advise
