Pharmacology of Antidepressants Flashcards
What is the monoamine hypothesis?
States that depression results from functional deficit of monoamine transmitters un particular serotonin (5-HT) and noradrenaline
What was monoamine hypothesis based off?
- Off evidence that drugs that deplete stores of monoamines can induce low mood
- Also CSF from depressed patients have reduced levels of monoamines or metabolites
-However not that simple: these are just parts of a complex pathway that are modifiable
Most drugs that treat depression act to increase monoaminergic transmission
Examples of SSRIs?
Fluoxetine
Citalopram
Sertraline
Paroxetine
MOA of SSRIs?
Selectively inhibit reuptake of serotonin (5-HT) from synaptic cleft
Common side effects of SSRIs?
- Nausea
- Headache
- Worsened anxiety
- Transient increase in self harm in adolescents/young people
- Sweating
- Sexual dysfunction
- Hyponatraemia
- Discontinuation effects
What side effect of SSRIs is especially important in elderly people?
Hyponatraemia
Examples of tricyclic antidepressants?
Imipramine
Dosulepin
Amitriptyline
Lofepramine
MOA of Tricyclic antidepressants?
Block the uptake of monoamines, serotonin and noradrenaline into presynaptic terminals equally
-This causes increased concentration of these neurotransmitters in synaptic cleft
Common side effects of tricyclic antidepressants?
Think of anticholinergic effect (as they also block muscarinic receptors)
Blurred vision Dry mouth Constipation Urinary retention Sedation Weight gain Postural hypotension Tachycardia Arrhythmias Cardiotoxicity in overdose
What is the root cause of side effects from tricylic antidepressants?
Anticholinergic effect
Which drug group is more safe: SSRIs or tricyclic antidepressants?
SSRIs
TADs are relatively dangerous compared to SSRIs
Examples of monoamine oxidase inhibitors?
Phenelzine (irreversible)
Moclobemide (reversible)
MOA of monoamine oxidase inhibitors?
Monoamine oxidase usually breaks down monoamines such as serotonin and NA so inhibition of these enzyme increases levels of these transmitters
Common side effects with the irreversible monoamine oxidase inhibitor?
Irreversible inhibitors cause deadly reaction with cheese
Phenelzine
Side effects of monoamine oxidase inhibitors?
Potentiate (increase) actions of some other drugs (barbituates) by decreasing their metabolism
Insomnia
Postural hypotension
Peripheral oedema
