Psychiatric Pharmacology Flashcards
What is the rationale behind SSRIs?
Selective Serotonin Reuptake Inhibitors
Deficiency in serotonergic activity in depressed patients
Give three indications for commencing SSRIs
- Mild to Moderate depression where low intensity psychosocial interventions have not helped
- Patients with subthreshold depression
- Mod to Severe depression with concomitant high intensity psychological intervention
Describe the efficacy of SSRIs
Same efficacy as TCAs
Fewer Anti-muscarinic Side Effects
Less Cardiotoxic
What is the SSRI licensed for Major Depression?
Paroxetine
What is the SSRI licensed for Bulimia Nervosa?
Fluoxetine
Name two contraindications to SSRIs
Children (unless seen by psychiatrist)
Mania
Name two instances in which SSRIs should be cautioned
Epilepsy
Suicidal Ideation
Name two DDIs of SSRIs
Some platelet interference
NSAIDs
Warfarin/Heparin
Name three side effects of SSRIs
Decreased alertness
Suicidal feelings
Dyspepsia
Name four causes of Serotonin Syndrome
- Drug is started too high/Dose escalated
- Addition of another serotinergic
- Replacement of antidepressants without long enough clearance period
- SSRI and MAOI
How does Serotonin Syndrome present?
Neuromuscular Hyperactivity
Autonomic Dysfunction (tachycardia, hyperthermia, shivering)
Altered mental state
How is Serotonin Syndrome managed?
Withdrawal of medication
State three pieces of advice that should be given to patients when starting SSRIs
May take a few weeks to work
Must stop if they develop a rash
After remission of symptoms, needs to be continued for another 4-6 months
When should patients on SSRIs be reviewed
After 1-2 weeks of starting
After 4-8 weeks to determine response
What is the first line SSRI for children?
Fluoxetine
What is the first line SSRI for patients post MI?
Sertraline
What is the max dose of Fluoxetine, Sertraline, Citalopram and Paroxetine?
Fluoxetine - 60mg
Sertraline - 200mg
Citalopram - 40mg
Paroxetine - 50mg
How should SSRIs be withdrawn?
Reduce dose gradually over a four week period
Any abrupt stop - Discontinuation Syndrome (restlessness, problems sleeping, sweating)
Which SSRI commonly causes weight gain?
Paroxetine
Give three indications for SNRIs
Major depressive disorder
Anxiety Disorder
OCD
When should SNRIs be taken?
Recommend to take in the morning as can cause insomnia in some patients if taken at night
Name two contraindications to SNRIs
If they have taken MAOI in the past two weeks
NSAIDs
Name three general Side Effects
Loss of Appetite
Increased suicidal thoughts
Sexual Dysfunction (Low libido, anorgasmia)
How should SNRIs be withdrawn?
Slowly taper to avoid discontinuation syndrome
This is common with Venlafaxine due to short half life
Name an indication and contraindication for Venlafaxine as a choice of SNRI
Good for Geriatrics
CI - High Arrhythmic Risk, Uncontrolled Htn
Give an advantage and disadvantage to Duloxetine as a choice of SNRI
Effective for physical depression symptoms
Can’t break capsules due to instability in stomach
Name three populations unsuitable to take Mirtazepine as a choice of SNRI
Elderly
Hypertensive
Urinary retention
Name two SE of Mirtazepine
Weight Gain
Sedative
What is the mechanism of action of TCAs? Give two examples
Blocks Serotonin and Noradrenaline reuptake (first generation as opposed to SNRIs)
Amitryptyline, Imipramine
Name three indications for TCAs
Depression
Anxiety
Chronic Bed Wetting
Describe some interactions of TCAs
CYP450
TCAs can cause weight gain and colnvulsions. Give three other categories of side effects
Antimuscarinic
Antihistaminic
Antiadrenergic
Name two cautions and two contraindications for TCAs
Caution: Epilepsy, Cardiac Disease
Contraindication: Mania, Recent MI
How quickly does a TCA overdose become apparent?
Within the first hour due to easy absorption from small intestine
Name five effects of TCA overdose
Confusion Hypotension Syncope Hypo ventilations Decreased/Absent bowel sounds
How is TCA overdose managed?
IV Sodium Bicarbonate
Name the two types of MAOI
Irreversible - Phenelzine, Isocarboxazid
Reversible - Moclobamide (MAOI- A selective)
Name three indications for MAOI
3rd line for depression
Social Phobia
Panic Disorder
Name some interactions of MAOI
Lethal - SSRIs, TCA
May potentiate cigarette effects
How should MAOI be stopped?
Withdrawn over a four week period with a two week washout
Name three side effects of MAOI
Orthostatic Hypotension
Dry Mouth
Anorgasmia
What is a Hypertensive Crisis with MAOI?
Excess tyramine causes release of Norepinephrine (causing continuous vasoconstriction)
Avoid tyramine rich foods (Alcohol, cheese, fermented foods)
Not required with Moclobamide
When are Antipsychotics required?
Any psychiatric conditions where patient has Delusions and/or Hallucinations
Describe the four dopamine pathways in the CNS
Mesolimbic - too much dopamine in psychosis
Mesocortical - too little dopamine in psychosis
Nigrostriatal - Dopamine dependent movement
Tuberoinfundibular - the pathway that can result in hyperprolactinaemia
What is the MOA of typical antipsychotics?
D2 Receptor Antagonists
Name the three types of typical antipsychotics and give an example of each
High Potency - Haloperidol
Mid Potency - Perphenazine
Low Potency - Chlorpromazine
High potency has much higher risk of Extra Pyramidal SE than Low Potency
Name three side effects of Haloperidol
Akathisia
Parkinsonism
Dystonia
All EPS
Name three contraindications to Haloperidol
Acute stroke
Severe intoxication
Known cardiac disease
How would an overdose of Haloperidol present?
Often just severe forms of the classical side effects
How is a Haloperidol overdose managed?
Activated charcoal if within first hour
Monitor for Long QT
Ropinorole/Bromocriptine for EPS
What should be monitored with Haloperidol?
BMI
BP
Fasting BGC
Name three SE to Chlorpromazine
Dose dependent increase in seizure risk
Weight Gain
Sedation
Name two interactions of Chlorpromazine
Decreased absorption if full stomach/alcohol
Can inhibit own metabolism as it is a CYP2D6 substrate AND inhibitor
What is the MOA of a Atypical Antipsychotics?
Serotonin Dopamine 2 Antagonists
Name three effects more likely with Atypical Antipsychotics (than typical)
Metabolic Syndrome
Weight Gain
T2DM
How long should Atypical Antipsychotics be continued for?
Up to 5 years
If stopping antipsychotics, how long should they be tapered over?
3 months
Describe three side effects of Risperidone
Hyperprolactinaemia
Weight Gain
In doses over 6mg it functions more like a typical - Extrapyramidal
Describe three side effects of Olanzepine
Weight Gain
Hyperprolactinaemia
Hypertriglyceridaemia
How are the effects of Olanzepine monitored?
Fasting BGC at baseline
Then every 4-6 monthly
Then yearly