Psychopharmacology

Question 1

ANTIDEPRESSANTS

Question 2

Selective Serotonin Reuptake Inhibitors (SSRI)
- Side effects
- Interactions
- Cessation

Answer 2

Side effects:
- GI symptoms
- Upper GI bleed
- Increased anxiety and agitation
- Citalopram: prolonged QT segment
- Fluoxetine and paroxetine: have a higher propensity for drug interactions
Interactions:
- NSAIDS: co-prescribe omeprazole
- Warfarin/heparin: use mirtazepine instead
- MOI and TCA: serotonin syndrome
- Aspirin
Cessation:
- Continue for a least 6 months after remission to reduce risk for relapse
- Should be gradually reduced over a 4 week period (except fluoxetine). Paroxetine has a higher incidence of discontinuation symptoms.
- Discontinuation symptoms
= increased mood change
= restlessness
= difficulty sleeping
= unsteadiness
= sweating
= gastrointestinal symptoms: pain, cramping, diarrhoea, vomiting
= paraesthesia

Question 3

Serotonin and noradrenaline reuptake inhibitors e.g. Venlafaxine and duloxetine
- Side effects
- Contraindicaitons

Answer 3

Side effects:
- May increase blood pressure
- Nausea
- Sexual dyfunction (Venlafaxine)
- Dizziness
CI:
- Conditions assosciated with high risk of cardiac arrhythmias, uncontrolled HTN

Question 4

Noradrenaline-Serotonin Specific Antidepressants (NASSAs) e.g. Mirtazapine
- Side effects
- Contraindications

Answer 4

Side effects:
- Sedation
- Dry mouth
- Increased appetite
- Weight gain
CI:
- Px with history of closed angle glaucoma, pregnancy, breastfeeding, hepatic impairment

Question 5

Tricyclic Antidepressants (TCAs) e.g. Amitriptyline, Clomipramine
- Side effects
- Overdose

Answer 5

Side effects:
- Antihistamine effects- sedation, weight gain, confusion (esp. in elderly)
- Anti-cholinergic (muscarinic)- blurry vison, constipation, dry mouth, urinary retention
- Alpha-1 block- orthostatic hypotension
Overdose:
- Develop seizures, hyperthermia, coma
- Tx: SODIUM BICARBONATE

Question 6

Monoamine Oxidase Inhibitors (MAOIs) e.g. Selegiline
- Side effects
- CI

Answer 6

Side effects:
- Hypertensive crisis with tyramine
- Arrythmias
- Increase appetite
- Weight gain
CI:
- Serotonin syndrome
- Cheese effect: eating foods containing tyrannies can cause hypertensive crisis (cheese, red wine, meats)

Question 7

ANTIPSYCHOTICS

Question 8

Typical antipsychotics
- Examples
- MOI
- Side effects
- WARNING

Answer 8

Examples: Haloperidol, Chlorpromazine
MOI: Dopamine D2 receptor antagonists
Side effects:
- Extrapyramidal side-effects
= Parkinsonism
= Acute dystonia: sustained muscle contraction e.g. torticollis, oculogyric crisis managed with procyclidine
= Akathisia (severe restlessness)
= Tardive dyskinesia (late onset of choreoathetoid movements, abnormal, involuntary) e.g chewing, pouting of jaw
- Antimusc: dry mouth, blurred vision, urinary retention, constipation
- Impaired glucose tolerance
- Neuroleptic malignant syndrome
- Prolonged QT: especially haloperidol
WARNING:
- Increased risk of stroke
- Increased risk of venous thromboembolism

Question 9

Atypical antipsychotics
- MOA
- Side effects
- WARNING

Answer 9

MOA: Act on a variety of receptors (D2, D3, D4, 5-HT)
Side effects:
- Extrapyramidal side-effects and hyperprolactinaemia less common
- Weight gain
- CLOZAPINE
= agranulocytosis
= neutropaenia
= reduced seizure threshold
= constipation
= myocarditis: a baseline ECG should be taken before starting treatment
= hypersalivation
= Dose adjustment of clozapine might be necessary if smoking is started or stopped during treatment.
WARNING
- Increased risk of stroke
- Increased risk of venous thromboembolism

Question 10

MOOD STABILISERS

Question 11

Lithium
- Side effects
- Monitoring
- CI

Answer 11

Side effects:
- nausea/vomiting,
- diarrhoea
- fine tremor
- nephrotoxicity: polyuria, secondary to nephrogenic diabetes insipidus
- thyroid enlargement, may lead to hypothyroidism
- ECG: T wave flattening/inversion
- weight gain
- idiopathic intracranial hypertension
- leucocytosis
- hyperparathyroidism and resultant hypercalcaemia
Monitoring patients on lithium:
- Blood sample 12 hours post dose
- After starting lithium levels should be performed weekly until concentrations are stable
- Once established, lithium blood level should ‘normally’ be checked every 3 months
- After a change in dose, lithium levels should be taken a week later and weekly until the levels are stable.
- Thyroid and renal function should be checked every 6 months
CI:
- Pregnancy: Teratogenic = Ebsteins anomaly

Question 12

Sodium Valporate
- Side effects

Answer 12

• GI disturbances,
• Weight gain,
• Aggression,
• Thrombocytopenia,
• Reversible hair loss,
• Peripheral oedema,
• Ataxia,
• Tremor

Question 13

Carbamazepine

Answer 13

• GI disturbances,
• Dermatitis,
• Dizziness,
• Hyponatraemia,
• Agranulocytosis

Question 14

ANXIOLYTICS AND HYPNOTICS

Question 15

Benzodiadepines
- MOA
- Side effects

Answer 15

MOA: enhance the effect of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) by increasing the frequency of chloride channels.
Side effects:
- Drowsiness
- Light headedness
- Next day confusion and ataxia

Question 16

Z drugs
- MOA
- Side effects

Answer 16

MOA: They act on the α2-subunit of the GABA receptor.
Side effects:
- Similar to benzodiazepines
- Increase the risk of falls in the elderly