Week 1- pharmacology of mood stabilisers Flashcards
When are anti-depressants used clinically?
In moderate-severe depression Anxiety disorders Panic disorders, OCD, PTSD, Bulimia nervosa Neuropathic pain Dysthymia (persistent depressive disorder)
Describe the three classes of anti-depressants
Mono-amine reuptake inhibitors (made up of tricyclics, selective serotonin reuptake inhibitors, non selective uptake inhibitors, noradrenaline reuptake inhibitors)
Monoamine oxidase inhibitors
Atypical drugs
What are monoamines?
Refer to particular neurotransmitters- noradrenaline, dopamine and serotonin(5-HT).
What do monoamine reuptake inhibitors do?
Stop the reuptake of the monoamines (noradrenaline, serotonin and dopamine) resulting in an increase in concentrations of the neurotransmitters in the synapse.
What is the monoamine hypothesis?
Depression leads to a reduction in monoamine transmitters in particular serotonin (5-HT) and noradrenaline.
Drugs that deplete stores of monamines also cause low mood.
Drugs that treat depression increase concentrations of monoamines.
How do monoamine oxidase inhibitors work?
They can either be irreversible (phenelzine) or reversible (mocloclobemide) inhibitors of monoamine oxidase A and B.
Name some side effects of monoamine oxidase inhibitors
Potentiates effects of other drugs by decreasing their metabolism
Insomnia
Postural hypotension
Peripheral oedema
Cheese/hypersensitive crisis. Cheese contains tyramine which cannot be broken down in the gut due to the monoamine oxidase inhibitors.
How do tricyclic antidepressants work?
Block the reuptake of monoamines into presynaptic terminals.
Mainly noradrenaline and 5-HT.
Common side effects of tricyclic antidepressants?
Anticholinergic- Dry mout, blurred vision, constipation, urinary retention
Sedation
Weight gain
Cardiovascular- postural hypotension, tachycardia, arrhythmias
How do selective serotonin reuptake inhibitors (SSRIs) work?
Selectively inhibit the reuptake of serotonin from the synaptic cleft.
Name some examples of SSRI’s?
Citalopram
Fluoxetine
Sertraline
Paraoxetine
Common side effects of SSRIs?
Nausea Headache Sweating/vivid dreams Worsened anxiety Sexual dysfunction Hyponatraemia (in the elderly) Transient increase in self harm. Discontinuation effects
What does SNRI stand for?
Serotonin and noradrenaline reuptake inhibitors.
Name some examples of SNRI’s
Venlafaxine
Duloxetine
How do SNRI’s work?
Block the reuptake of monoamines in the presynaptic terminal
Side effects of SNRI’s
Similar to SSRI’s however have fewer side effects to tricyclic antidepressants
Name some atypical antidepressant drugs
Mitrazapine (blocks alpha 2, 5-HT2 and 5HT3)
However can block serotonergic side effects if given with SSRI’s
Dopamine uptake inhibitors- bupropion
NOTE ABOUT ANTIDEPRESSANTS
They all have delayed onset of several weeks.
Side effects will differ with dose.
Describe the principles of treating bipolar disorder
Acute treatment is too raise the mood in depressive bouts and to decrease mood in manic bouts.
However long term treatment is too stabilise the mood.
Which drug is used in bipolar disorder?
Lithium. Usually given as lithium carbonate.
How does lithium work?
May block phosphatidylinositol pathway or inhibit glycogen synthase kinase 3B.
Side effects of lithium
Dry mouth/strange taste Polyuria/polydipsia Tremor Hypothyroidism Long term reduced renal function Nephrogenic diabetes insipidus Weight gain
Name some toxic effects of lithium
Vomiting Diarrhoea Ataxia Coarse tremor Drowsiness Convulsions Coma
What other drugs can be used in the long term treatment of bipolar disorder?
Anticonvulsants can be used e.g. carbamazepine and valproic acid.
Antipyschotics
Name some side effects of using anticonvulsants in the treatment of bipolar?
Carbamazepine- drowsiness, ataxia, cardiovascular effects, induces liver enzymes
Valproic acid- Teratogenicity
How do antipyschotics work in bipolar disorder?
Dopamine antagonism plus 5 HT antagonism
Side effects of anti-psychotics as mood stabilisers
Sedation
Weight gain
Metabolic syndrome
Extra-pyramidal side effects
Name some anti-psychotics
Quetiapine, Arpiprazole, Olanzapine, Lurasidone
