Psychiatry Drugs Flashcards
Give 3 examples of 1st generation (typical) antipsychotics
- Haloperidol
- Chlorpromazine
- Prochlorperazine
Mechanism of action of 1st generation (typical) antipsychotics?
Block post-synaptic dopamine receptors (particularly D2)
What neurotransmitter is implicated in psychosis?
Dopamine
How is dopamine implicated in psychosis?
Psychosis is associated with increased dopamine release in striatal regions.
What class of dopamine receptors do antipsychotics primarily work on?
D2 receptors
What 2 other receptors can antipsychotics work on?
Serotinergic and histaminic but degree varies from drug to drug.
Antipsychotics act on which neural pathways to produce antipsychotic effect?
Mesolimbic/mesocortical pathways
Antipsychotics act on which neural pathways to produce EPSEs?
Nigrostriatal pathway
Antipsychotics act on which neural pathways to result in increased prolactin?
Tuberohypophyseal pathway
What does the tuberohypophyseal pathway connect? How does this impact prolactin levels?
Connects hypothalamus and pituitary gland
Pituitary gland responsible for prolactin regulation
Blockage leads to increased prolactin levels
Why can antipsychotics also be used in N&V?
D2 receptors are also found in the chemoreceptor trigger zone
Clinical indication for antipsychotics?
- Used to treat ACUTE psychotic illness by reducing delusions, hallucinations, thought disorder and agitation.
- Also used PROPHYLACTICALLY to prevent relapse of psychosis
- Urgent treatment of severe psychomotor agitation
- Schizophrenia
- Bipolar Disorder - particularly in acute episode of mania or
hypomania - N&V
Give 5 examples of 2nd generation (atypical) antipsychotics
- Olanzapine
- Quetiapine
- Risperidone
- Clozapine
- Aripiprazole
Are typical or atypical antispychotics typically prescribed as 1st line?
Atypical (2nd generation)
Does the MOA differ between 1st and 2nd generation antipsychotics?
No
How do 2nd generation antipsychotics differ from 1st?
- Improved efficacy in ‘treatment resistant’ schizophrenia
- Wider therapeutic range
- Improved risk against negative symptoms
- Lower risk of extrapyramidal side effects
Which atypical antipsychotic is particularly effective in the management of ‘treatment resistant’ schizophrenia?
Clozapine
Give some side effects of 1st generation antipsychotics
- Extra-pyramidal side effects (EPSEs)
- Drowsiness (all antipsychotics have sedative effect)
- Anti-adrenergic side effects
- Hyperprolactinaemia
- Antimuscarinic effects
- Antihistamine effects –> sedative
What causes EPSEs in antipsychotics?
Due to D2 blockade in the nigrostriatal pathway
What is the main drawback of 1st generation antipsychotics?
EPSEs
When would 1st line antipsychotics be indicated over 2nd line in the management of schizophrenia?
Particularly when the METABOLIC side effects of second generation (atypical) antipsychotics are likely to be problematic
Give 3 contraindications for 1st line antipsychotics
- Elderly
- Dementia
- Parkinson’s
Why are typical antipsychotics contraindicated in the elderly?
o Particularly sensitive
o Increased risk of stroke and VTE
Why are typical antipsychotics contraindicated in dementia patients?
o Avoid –> may INCREASE risk of stroke and death
o Can worsen Parkinsonism in LBD
In which type of dementia can typical antipsychotics worsen parkinsonism?
Dementia with Lewy Bodies
Why are typical antipsychotics contraindicated in Parkinson’s patients?
o Avoid if possible –> cause EPSEs
o Small dose of lorazepam might be alternative in distress
What is an alternative to typical antipsychotics for Parkinson’s patients?
Small dose of lorazepam might be alternative in distress
Blockade in which pathway leads to EPSE’s in 1st line antipsychotics?
Due to D2 blockade in the nigrostriatal pathway
Give some examples of EPSE’s seen in 1st line (typical) antipsychotics
- Acute dystonic reactions
- Akathisia
- Neuroleptic malignant syndrome
- Tardive dyskinesia
What are acute dystonic reactions?
▪ Involuntary parkinsonian movements
▪ Muscle spasms
E.g. Torticollis – stiffness in neck / when your neck muscles spasm and your neck twists to the side
E.g. Oculogyric crisis
What is oculogyric crisis?
spasmodic movements of the eyeballs into a fixed position, usually upwards
Management of acute dystonia?
Anticholinergics e.g. procyclidine
What is akathisia?
▪ State of inner restlessness
▪ Can’t stop moving, may be extremely
distressing
Management of akathisia?
Beta blockers e.g. Propranolol
What is neuroleptic malignant syndrome (NMS)?
A life-threatening idiosyncratic reaction to (often 1st line) antipsychotic drugs (rare).
Can happen after change in dose, treatment commencing or suddenly stopping
What happens in neuroleptic malignant syndrome?
Rigidity –> muscle breakdown –>
rhabdomyolysis –> kidney failure
Give some symptoms seen in NMS
- Fever
- Altered mental status
- Autonomic dysfunction
- Neuromuscular excitability –> hypertonia, hyperreflexia
- Confusion
- Autonomic dysregulation –> tachycardia, hyperthermia, unstable BP
Give some risk factors for NMS
- Usually YOUNG MALE patients
- Higher antipsychotic doses
- High-potency antipsychotics
- Concomitant drug use (e.g. lithium)
- Depot formulations (i.e. long-acting)
- Acute medical illness (e.g. trauma, infection)
- Acute catatonia (state or immobility)
- Previous NMS
Management for NMS?
- Stop antipsychotic
- IV fluids
- Sodium bicarbonate
- Codeine
- Dantrolene (muscle relaxant)
- Bromocriptine (dopamine agonist)
When would tardive dyskinesia typically appear after antipsychotic use?
Late adverse effect after months or years of therapy
What is tardive dyskinesia?
Movements that are:
* Pointless
* Involuntary
* Repetitive
Most common is chewing and
pouting of jaw
Can be irreversible
Management of tardive dyskinesia?
Tetrabenazine
What are the anti-adrenergic side effects of 1st line antipsychotics?
CVS effects –> prolonged QT interval, arrhythmias
Hypotension
Erectile dysfunction
Which 1st line antipsychotics particularly causes QT interval prolongation?
Haloperidol
Blockade in which pathway by 1st line antipsychotics leads to hyperprolactinaemia?
tuberohypophyseal pathway blockade
Give some symptoms of hyperprolactinaemia
▪ Menstrual disturbance
▪ Galactorrhoea
▪ Breast pain
What are antimuscarinics?
Antimuscarinics are a subtype of anticholinergic drugs.
Anticholinergics refer to agents that block cholinergic receptors, or acetylcholine receptors.
Anticholinergics are divided into 2 categories: antimuscarinics, which block muscarinic receptors, and antinicotinics, which block nicotinic receptors.
Give some antimuscarinic side effects of 1st line antipsychotics
▪ Dry mouth – can’t spit
▪ Urinary retention – can’t pee
▪ Constipation – can’t shit
▪ Eye problems – can’t see
What are some antihistamine side effects of antipsychotics?
▪ Weight gain
▪ Sedation
▪ Anti-emetic
Why should haloperidol not be prescribed with metoclopramide?
Treatment with either medication alone can cause Parkinson-like symptoms and abnormal muscle movements, and combining them may increase that risk.
What investigations should be done in schizophrenia?
Bedside:
- Blood sugar
- Urine dipstick (+/- MSU)
- ECG (evaluate for long QT if considering antipsychotics)
Bloods:
- FBC
- LFT
- Thyroid function tests
- Syphilis serology
- Bloodborne virus screen
- Autoimmune screen (e.g. ANA, anti-DS DNA for Lupus)
What investigations should be done before starting antipsychotics?
- Baseline bloods – FBC, U&Es, LFTs, lipids, fasting blood glucose, prolactin
- Weight, BP, pulse
- ECG – baseline QTc
Via what 2 routes are 1st line antipsychotics typically taken?
o Orally
o Slow release (depot) injection
In an emergency, what 1st line antipsychotic is typically given?
Haloperidol can be given via rapid acting IM injection
What is significant issue with taking antipsychotics?
Adherence
What are some risk factors for antipsychotics NOT working
o Presence of persistent symptoms
o Poor adherence to regimen
o Lack of insight
o Substance abuse
N.B. In schizophrenia, chance about 1/3 of those on placebo
What investigations are required 3 MONTHS after starting 1st line antipsychotics?
- Weight
- Lipids
Then annually.
What investigations are required 6 MONTHS after starting 1st line antipsychotics?
Fasting blood glucose.
Then annually.
What monitoring investigations are needed with 1st line antipsychotics?
- Frequent review of symptoms essential
- Dose may be adjusted
- Weight, lipids – at 3 months, then annually
- Fasting blood glucose – at 6 months, annually
- FBC, U&Es, LFTs – annually
- Repeat ECG/monitoring - annual
- Annual CV risk assessment
Which 2nd line (atypical) antipsychotic is associated with weight gain and hypercholesterolaemia?
Olanzapine
Which 2nd line (atypical) antipsychotic is LEAST likely to help with SLEEP?
Risperidone
Which 2nd line (atypical) antipsychotic has the MOST TOLERABLE side effect profile, particularly for prolactin elevation?
Aripiprazole
Before starting 2nd line (atypical) antipsychotics, what investigations should be done?
- Bloods – FBC, U&E, LFTs, RBS/HbA1c, Prolactin, lipids and cholesterol
- ECG
Give some indications for 2nd line (atypical) antipsychotics
- Urgent treatment of severe psychomotor agitation
o Leading to dangerous or violent behaviour
o Or to calm patients to permit assessment - Schizophrenia
- Bipolar Disorder
o Particularly in acute episode of mania or
hypomania
When would 2nd line (atypical) antipsychotics be indicated OVER 1st line in the management of schizophrenia?
o Particularly when EPSEs have complicated the use of 1st generation antipsychotics
o Or when NEGATIVE symptoms are prominent
Which class of antipsychotics should be used in schizophrenia where NEGATIVE symptoms are prominent?
2nd line (atypical)
What are 2 major contraindications of clozapine?
- Severe heart disease
- History of neutropenia
How do the side effects of 2nd line (atypical) antipsychotics differ from 1st line?
Similar side effects to 1st line
Often tolerated a lot better – less EPSEs, but more endocrine side effects
What metabolic side effects are seen in 2nd line antipsychotics?
o Weight gain – more than typical
o Diabetes
o Lipid changes
What is a severe side effect of clozapine?
Severe deficiency in neutrophils
–> Agranulocytosis
Give some drug interactions for 2nd line antipsychotics
- Other dopamine blocking anti-emetics
- Drugs which prolong the QT interval
- Other sedating drugs
Which antipsychotic is chosen when other treatment for schizophrenia have proven intolerable or ineffective?
Clozapine
What investigation is needed if taking clozapine?
Regular FBC needed – initially weekly
Why can carbamazepine (anti-epileptic) not be prescribed with clozapine?
Both affect bone marrow function
Symptoms of agranulocytosis?
o Myocarditis
o Weight gain
o Excessive salivation – sleep sitting up/towels
o Seizures
What monitoring is required when taking 2nd line antipsychotics?
Monitor for metabolic and CV side effects
o Weight
o Lipid
o ECG
Clozapine
o Regular blood monitoring needed – initially weekly
o Report infective symptoms immediately
What class of drug is lithium?
A mood stabiliser
What is lithium used to treat?
A variety of mood disorders e.g. bipolar disorder, recurrent depressive episodes (haven’t responded to anti-depressants)
MOA of lithium?
Inhibits the formation of cAMP affecting a wide range of neurotransmitter pathways.
Leads to mood stabilisation
Indications for lithium?
- Acute treatment of moderate to severe mania
- Prophylaxis in recurrent depression and bipolar mood disorder
- Augmentation therapy in resistant depression
- Prevention of aggression in patients with learning disability
How is lithium excreted?
Renally
Clearance depends on renal function, fluid intake, sodium intake
What side effects can be seen in lithium use at a therapeutic dose?
Initial adverse effects:
- GI disturbance –> N&D
- Vertigo
- Muscle weakness
- Similar to diabetes –> fine hand tremors, polyuria, polydipsia (thirst due to dry mouth), metallic taste
Longer term effects:
- Hypothyroidism – 20%
- Hyperparathyroidism
- Nephrotoxicity
- Renal tumours
How does hyperparathyroidism affect calcium levels?
Hypercalcaemia
What are calcium levels like in lithium use?
The presence of mild hypercalcaemia with elevated PTH is consistent with lithium-induced hyperparathyroidism
What renal complications can be seen with lithium use?
A small reduction in GFR is seen in 20% of people taking lithium.
- In the vast majority of these people this effect is benign.
- A very small number of people taking lithium may develop interstitial nephritis.
Long-term use can cause nephrogenic diabetes insipidus (symptoms of thirst and polyuria)
Over many years Li can cause decline in tubular function and associated with increased risk of CKD
What clinical features can be seen in lithium TOXICITY?
Toxicity (a bit like alcohol):
- Coarse tremor
- CNS disturbance e.g. seizures, impaired coordination, dysarthria
- Cardiac arrhythmias
- Visual disturbance
Severe toxicity (>2 mmol/l):
- Hyperreflexia
- Convulsions
- Psychosis
- Syncope
- Renal insufficiency
- Death
What is dysarthria?
Difficulty speaking because the muscles you use for speech are weak.
At what concentrations does lithium toxicity typically occur?
> 1.2 mmol/L
Differentials for lithium toxicity?
- Neurological conditions e.g. Parkinson’s disease, cerebellar disorders
- Endocrine disorders e.g. diabetes insipidus or diabetes mellitus
- Cardiaac conditions (due to arrhythmias)
- Substance intoxication or withdrawal
Investigations in suspected lithium toxicity?
Serum lithium levels –> This is the gold standard for diagnosing lithium toxicity.
Electrolyte levels: To assess for any electrolyte imbalance.
Thyroid function tests: Given the potential for thyroid dysfunction.
Renal function tests: Given lithium’s potential to cause renal impairment.
ECG: To assess for arrhythmias.
Management of lithium toxicity?
- Stop lithium
- Maintain electrolyte balance
- IV fluids and urine alkalisation (enhances excretion of drug)
- Monitor renal function (diuresis/dialysis)
Contraindications/warnings for lithium?
- Cardiac disease or Addison’s Disease
- Severe renal insufficiency
- Hypothyroidism
- Possibly teratogenic – risk of Epstein’s anomaly, but very rare
Why is lithium contraindicated in Cardiac disease or Addison’s disease?
Causes sodium depletion (HF)
What can increase risk of lithium toxicity?
- NSAIDs, diuretics
- Renal failure, UTI, dehydration
- D&V
- Alcohol
- Hot weather
- Age >50 y/o
- Abnormal thyroid function
Give 4 examples of SSRIs
- Sertraline
- Citalopram
- Fluoxetine
- Escitalopram
What class of drug is fluoxetine?
SSRI (antidepressant)
Indications of SSRIs?
- 1st line treatment for moderate to severe depression, and in mild depression if psychological treatments alone are insufficient
- Panic disorder
- Obsessive compulsive disorder (OCD)
MOA of SSRIs?
SSRIs preferentially inhibit neuronal reuptake of 5-HT (serotonin) from the synaptic cleft, increasing its availability for neurotransmission
This improves mood and physical symptoms in depression & anxiety
Why are SSRIs generally preferred over tricyclic antidepressants despite both classes having similar efficacy?
SSRIs do NOT inhibit noradrenaline uptake and cause less blockade of other receptors –> have fewer side effects and less dangerous in overdose
Which SSRI is licensed in bulimia nervosa?
Fluoxetine
Give some side effects of SSRIs
Common:
- GI upset
- Changes in appetite/weight (loss/gain)
- Hypersensitivity reactions e.g. rash
Other:
- Hyponatraemia
- Suicidal thoughts and behaviours may be increased
- May lower seizure threshold
- Sexual problems
- Serotonin syndrome
- Increased risk of bleeding
- Citalopram can prolong the QT interval and predispose to arrhythmias
Who is hyponatraeima (as a side effect of SSRIs) most common in?
Particularly in elderly and may present with confusion and reduced consciousness