Psychiatric Management Flashcards
Common receptor effects of adrenergic
Sweating Tremor Headaches Nausea Dizziness
Common muscarinic (acetylcholine) receptor effects
Dry mouth, difficulty swallowing, thirst
Difficulty urinating, urinary retention
Hot flushed skin, dry skin
Common histamine receptor effects
Dry mouth
Drowsiness
Dizziness
N+V
Features of antidepressants
Work on serotonin activity - increase activity at post synaptic receptors Most of their effect in 2-3 weeks Most commonly used = SSRIs - SNRIs - Mirtazapine - Tricyclics - MAOIs
Method of action of SSRIs
Selective Serotonin Reuptake Inhibitors
- increase serotonin activity by reducing the presynaptic reuptake of serotonin after release
- more serotonin sits in nerve junction
- leads to down regulation of post-synaptic receptors
Side effects of SSRIs
Sense of restlessness and agitation on induction - countered by use of benzodiazepines
Nausea and GI disturbance
Headache
Weight change
Sexual dysfunction
Uncommon
- bleeding - due to serotonin receptors on GI tract and platelets
- suicidal ideation particularly teenagers and early 20s - due to increased motivation before increased optimism
Examples of SSRIs
Sertraline - safest in cardiac disease
Citalopram/Escitalopram - careful of QTc prolongation
Fluoxetine - watch out for serotonin syndrome when switching
Paroxetine - watch out for discontinuation syndrome
Method of action of SNRIs
Serotonin and Noradrenaline Reuptake Inhibitors
- bind to noradrenaline and serotonin reuptake inhibitors
- leads to down regulation of post-synaptic receptors
Evidence base for use in neuropathic pain also
Side effects for SNRIs
Sedation
Nausea
Sexual dysfunction
Types of SNRIs
Duloxetine - low dose range
Venlafaxine - more efficacious and can go to a higher dose
- caution with higher doses in heart disease
Method of action of Mirtazapine
Acts as 5HT-2 and 5HT-3 serotonin receptor antagonist Strong H1 (histamine) activity -> sedation
Side effects of mirtazapine
Sedation
Weight gain
Features of tricyclic antidepressants
Reasonably effective - useful for those who do not responds to SSRIs Newer tricyclics (lofepramine and nortriptyline) tolerated better than older tricyclics (amitriptyline) Used at low doses for neuropathic pain
Side effects of tricyclic antidepressants
Muscarinic and histamine effects
Can be fatal in overdose - QTc prolongation and arrhythmias
Features of MAOIs
Monoamine Oxidase Inhibitors
- MAOI-A - work more on serotonin
- MAOI-B - work more on dopamine
Possibly more effective for atypical depression
Types of MAOIs
Irreversible = more dangerous - phenelzine - isocarboxazid Reversible = less dangerous - moclobamide - tranylcypromine
Considerations of MAOIs
Significant and dangerous interaction with other drugs
Potential for tyramine reaction leading to hypertensive crisis - avoid chees, pickled meats, wine
If changing to another antidepressant needs a washout period - up to 6 weeks
Features of vortioxetine
Serotonergic activity
Effective
Well tolerated - common side effect is nausea but less severe
Evidence for improvement in difficult to treat cognitive symptoms
Considerations when choosing an antidepressant
What has been used before
Was it effective/tolerated
Are there particular symptoms or co-morbidities to address
- weight loss and insomnia = mirtazapine
- neuropathic pain = SSRIs
In new cases start with an SSRI unless major weight loss and insomnia - consider mirtazapine
Considerations for increasing/switching antidepressant
Don't need to wait 4 weeks to have idea about effectiveness For depression - if no benefit then switch - if partial effect then increase dose For anxiety - consider increasing dose If struggling with side effects - may get better in couple of weeks - switch is cannot stand
Define discontinuation syndrome
Group of symptoms occur when antidepressant stopped
- antidepressants not addictive
Influenced by half life - shorter half life = bigger problem
Features of discontinuation syndrome
Sweating Shakes Agitation Insomnia Headaches Irritability Nausea Vomiting Paraesthesia Clonus
How to prevent discontinuation syndrome
Go slow
- can alternate days of taking or snap tablets in half
Sometimes worth switching to Fluoxetine and reducing
Paroxetine and venlafaxine trickiest
Define serotonin syndrome
Symptoms caused by excess serotonin
- risk when starting another antidepressant after fluoxetine
Features of serotonin syndrome
Cognitive
- headaches, agitation, hypomania, confusions, coma
Autonomic
- shivering, sweating, hyperthermia, tachycardia, nausea and diarrhoea
Somatic
- myoclonus, hyper-reflexia and tremor
Treatment of serotonin syndrome
Supportive
- fluids
- monitoring
Method of action of antipsychotics
Reduce level of dopamine activity as D2 receptors antagonists
- target pathways = mesocortical and mesolimbic
- unwanted pathways = nigrostriatal (movement) and tuberoinfundibular (hypothalamic-pituitary-adrenal axis)
Classes of antipsychotics
Typical
- older
- more likely to cause extra-pyramidal side effects
- bind to more muscarinic and histaminic receptors
Atypical
- more serotonergic activity
- more likely to cause diabetes and dyslipidaemia
Examples of antipsychotics
Typical - haloperidol - flupenthixol - zuclopenthixol - chlorpromazine - sulpride Atypical - clozapine - olanzapine - risperidone - quetiapine - amisulpride - aripirazole - partial D2 agonist
Side effects of antipsychotics
Sedation Weight gain QTc prolongation Typical - extra-pyramidal - bradykinesia - muscle stiffness and tremor - tardive dyskinesia - akathisia - dizziness - sexual dysfunction Atypical - weight gain - dyslipidaemia and diabetes
Monitoring required for antipsychotics
Baseline - FBC, lipids, LFTs, HbA1c, weight, ECG, BP and pulse Weekly - weight Others at 3 months then yearly
Features of clozapine
D2 antagonist and 5HT-2 antagonist
Most efficacious antipsychotic
Improvements can continue for several months
Used in schizophrenia after at least 2 other antipsychotics failed
Dose titrated slowly upward over 2 weeks and vital signs monitored due to potential for autonomic dyregulation
Side effects of clozapine
Agranulocytosis
- close monitoring of FBC - weekly for first 18 weeks then fortnightly then monthly
Gastrointestinal hypomobility
- constipation and potentially fatal bowel obstruction
Hypersalivation
Urinary incontinence
Treatment of clozapine induced agranulocytosis
Stop clozapine
Stop other marrow supressing drugs - sodium valproate
Avoid other antipsychotics for a couple of weeks where possible - if needed aripiprazole
Contact consultant haematologist
Avoid sources of infection - consider broad spec abx
Lithium - increased WCC and neutrophil count
Granulocyte colony-stimulating factor - injection
Define neuroleptic malignant syndrome
Rare, life-threatening reaction to antipsychotics
Features of neuroleptic malignant syndrome
Fever Confusion Muscle rigidity Sweating Autonomic instability Death due to - rhabdomyolysis - renal failure - seizures
Risk factor for neuroleptic malignant syndrome
High potency dopamine antagonists (typical antipsychotics)
Antipsychotic naïve patients
High doses
Young men
Treatment for neuroleptic malignant syndrome
Emergency referral to A&E
Stop antipsychotics
Fluid resuscitation
Reduced temperature
Treatment for extra pyramidal side effects of antipsychotics
Anticholinergics
- Ratio of dopamine: acetylcholine in nigrostriatal pathway more important than absolute quantities
- If too much acetylcholine in relation to dopamine - reduce acetylcholine activity
- not effective for tardive dyskinesia