Can you provide a concise overview of psychiatric medications commonly tested on the Canadian MCCQE for quick reference?

Psychiatric Medications Overview for Canadian MCCQE

Antidepressants

For major depressive disorder, SSRIs (escitalopram, sertraline, paroxetine, fluvoxamine) and SNRIs (venlafaxine) are first-line treatments in Canada. 1

Key Points:

• SSRIs are most commonly used: Escitalopram and sertraline preferred as first-line due to efficacy and tolerability
• SNRIs (venlafaxine): Alternative first-line option, particularly useful for patients with comorbid pain or fatigue
• Newer agents: Vortioxetine (first-line), levomilnacipran ER and vilazodone (second-line) 2
• St. John's wort: Shows similar efficacy to low-dose antidepressants but fewer side effects; not typically recommended due to drug interactions 3

Clinical Pearls:

• SSRIs have lower rates of sexual dysfunction with vortioxetine and vilazodone
• Nausea is the most common side effect across most antidepressants
• Gradual discontinuation recommended for SNRIs to avoid discontinuation syndrome
• Monitor for suicidality, especially in youth

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Antipsychotics

Typical (First-Generation) Antipsychotics

Haloperidol and chlorpromazine are standard typical antipsychotics, but atypical agents are generally preferred due to lower extrapyramidal side effects. 4

• Haloperidol: High-potency, more extrapyramidal symptoms (EPS), less sedating
• Chlorpromazine: Low-potency, more sedating, fewer EPS
• Major risk: Tardive dyskinesia (50% of elderly after 2 years of continuous use) 5

Atypical (Second-Generation) Antipsychotics

Atypical antipsychotics (risperidone, olanzapine, quetiapine, aripiprazole) are preferred first-line for schizophrenia and acute psychosis due to lower EPS risk. 4, 5

Specific Agents:

• Risperidone: Start 0.25-0.5 mg; EPS risk increases >6 mg/day; available as oral disintegrating tablet (ODT)
• Olanzapine: Start 2.5-5 mg; generally well-tolerated; metabolic effects with long-term use; available as ODT
• Quetiapine: Start 25 mg; more sedating; less EPS; oral only
• Aripiprazole: Start 5 mg; partial dopamine agonist; less EPS; less metabolic effects; available IM 6
• Clozapine: Reserved for treatment-refractory cases; requires regular lab monitoring 4

Acute Agitation Management

For acute agitation, use benzodiazepines (lorazepam, midazolam) OR typical antipsychotics (haloperidol, droperidol) as monotherapy. 7

• Combination therapy: Oral lorazepam + oral risperidone for cooperative patients 7
• Parenteral combination: Benzodiazepine + haloperidol may produce faster sedation 7
• Droperidol: Faster sedation than haloperidol but QT prolongation concerns 7

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Mood Stabilizers

Bipolar Disorder

Lithium, valproate, or atypical antipsychotics are first-line for acute mania; lithium or valproate for maintenance. 8, 4, 8

Acute Mania:

• Lithium: FDA-approved age ≥12 years; requires close monitoring (therapeutic level, renal, thyroid)
• Valproate/Divalproex: Effective for acute mania; avoid in pregnancy (teratogenic); therapeutic level 40-90 mcg/mL
• Carbamazepine: Alternative mood stabilizer; requires CBC and liver monitoring; therapeutic level 4-8 mcg/mL 5
• Atypical antipsychotics: Aripiprazole, olanzapine, risperidone, quetiapine, ziprasidone all approved for acute mania 8

Bipolar Depression:

• Olanzapine + fluoxetine: FDA-approved combination 8
• Lamotrigine: Approved for maintenance therapy 8

Maintenance:

• Lithium or valproate: Continue ≥12 months after remission 4
• Lamotrigine or olanzapine: Also approved for maintenance 8

Critical Warnings:

• Antidepressants in bipolar: May trigger mania; always use with mood stabilizer 8
• Valproate in pregnancy: Avoid if possible; use folic acid supplementation 4
• Polytherapy: Often required but avoid unnecessary combinations 8

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Benzodiazepines

Lorazepam and midazolam are preferred benzodiazepines for acute agitation and anxiety due to predictable pharmacokinetics. 9, 6

Specific Agents:

• Lorazepam: 0.5-2 mg PO/SC/IV; fast onset, no active metabolites, complete absorption
• Midazolam: 0.5-2.5 mg SC/IV; faster onset but shorter duration than lorazepam
• Diazepam: Longer half-life; erratic IM absorption; less preferred

Clinical Use:

• Acute agitation: Effective monotherapy or combined with antipsychotics 7
• Alcohol/benzodiazepine withdrawal: Treatment of choice as monotherapy 6
• Caution: Risk of falls in elderly, respiratory depression (especially with olanzapine), paradoxical agitation, may cause delirium 6

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Anticonvulsants in Psychiatry

Epilepsy:

• First-line: Phenobarbital (cost-effective) or carbamazepine (preferred for partial seizures) 4
• Avoid routine use after first unprovoked seizure 4
• Discontinuation: Consider after 2 seizure-free years 4

Mood Stabilization:

• Carbamazepine: 100 mg BID initially; monitor CBC and liver enzymes; problematic side effects 5
• Valproate: Better tolerated than carbamazepine for agitation 5
• Gabapentin/Topiramate: NOT effective for bipolar disorder 8

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Special Populations

Children/Adolescents:

• Lithium: Only agent FDA-approved for bipolar disorder age ≥12 years 8
• Antidepressants: Limited efficacy evidence; monitor closely for suicidality 8
• SSRIs: Most commonly used (17.8% with past-year depression use antidepressants) 10

Elderly/Dementia:

• Atypical antipsychotics preferred over typical agents for behavioral disturbances 5
• Avoid typical antipsychotics when possible due to 50% tardive dyskinesia risk after 2 years 5
• Trazodone: 25 mg/day starting dose for agitation; safer alternative 5
• Avoid anticholinergics (benztropine, trihexyphenidyl) for EPS in elderly 5

Pregnancy:

• Avoid valproate if possible; use folic acid with all antiepileptics 4
• Antiepileptic monotherapy at minimum effective dose preferred 4

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Key Side Effects to Remember

Extrapyramidal Symptoms (EPS):

• Higher with typical antipsychotics (especially high-potency like haloperidol)
• Lower with atypical antipsychotics (except risperidone >6 mg/day)
• Management: Reduce dose, switch agents; avoid routine anticholinergic prophylaxis 4

Metabolic Effects:

• Olanzapine and quetiapine: highest risk
• Monitor weight, glucose, lipids with long-term atypical antipsychotic use

QT Prolongation:

• Droperidol, haloperidol, ziprasidone
• Consider ECG monitoring in high-risk patients

Discontinuation Syndromes:

• SNRIs: gradual taper required
• Benzodiazepines: gradual taper to avoid withdrawal/seizures
• Antipsychotics: continue ≥12 months after remission before considering withdrawal 4