Psychiatry · Year 3 · from Psychiatry

Case 2: Antipsychotic Selection and Metabolic Monitoring

Patient Demographics

• Age: 24 years old
• Sex: Male
• Occupation: College student (on medical leave)

Chief Complaint

"The voices are telling me people are plotting against me."

History of Present Illness

The patient is a 24-year-old man with a 6-month history of auditory hallucinations, paranoid delusions, social withdrawal, and declining function. He was recently diagnosed with schizophrenia, first episode. He was started on risperidone 2 mg BID in the hospital but developed significant akathisia and elevated prolactin causing gynecomastia. He is being transitioned to a different antipsychotic.

Baseline metabolic panel prior to any antipsychotic:

• Weight: 165 lbs, BMI 24.5
• Fasting glucose: 92 mg/dL
• HbA1c: 5.4%
• Lipid panel: Total cholesterol 178, LDL 105, HDL 48, TG 125
• Blood pressure: 118/76

Family history significant for type 2 diabetes (father, paternal grandmother) and obesity.

Antipsychotic Comparison Discussion

First-Generation vs Second-Generation:

• First-generation (typical): Higher risk of EPS and tardive dyskinesia, but lower metabolic risk
• Second-generation (atypical): Lower EPS risk, but variable metabolic risk

Second-Generation Antipsychotics - Metabolic Risk Hierarchy:

• HIGHEST: Olanzapine, clozapine
• MODERATE: Quetiapine, risperidone
• LOWER: Aripiprazole, ziprasidone, lurasidone

Agent Selection Considerations:

Given his:

• EPS/akathisia with risperidone
• Hyperprolactinemia
• Family history of diabetes
• Young age (decades of exposure ahead)

Aripiprazole selected:

• Lower EPS risk (D2 partial agonist)
• No prolactin elevation (unlike risperidone)
• Weight-neutral to modest weight gain
• Lower metabolic risk
• May cause akathisia (monitor closely)

Pharmacodynamic Teaching Points

Mechanism of Action (Aripiprazole):

• Dopamine D2 receptor partial agonist
• Acts as antagonist when dopamine is high (mesolimbic - treats positive symptoms)
• Acts as functional agonist when dopamine is low (mesocortical - may help negative symptoms)
• Optimal D2 occupancy: 65-80% for efficacy without EPS
• 5-HT2A antagonist (contributes to atypical profile)
• 5-HT1A partial agonist (may reduce anxiety)

Why Lower EPS:

• Partial agonism means less complete blockade
• Doesn't "overshoot" into extrapyramidal range
• But can still cause akathisia (most common side effect)

Why No Prolactin Elevation:

• Partial agonism maintains some dopaminergic tone in tuberoinfundibular pathway
• Prolactin remains normal (unlike risperidone, which causes marked elevation)

Prescribing Plan

Transition:

• Start aripiprazole 5 mg daily while tapering risperidone over 1 week
• Increase aripiprazole to 10 mg daily after 3-5 days if tolerated
• Target dose: 10-15 mg daily

Monitoring for Efficacy:

• Positive symptoms (hallucinations, delusions)
• Negative symptoms (flat affect, avolition)
• BPRS or PANSS if available

Monitoring for Side Effects:

• Akathisia (most common) - assess with BARS scale
• Activation, insomnia
• Nausea (transient)
• Headache

Metabolic Monitoring Protocol

Required Monitoring Schedule (per ADA/APA Consensus):

*Every 5 years if normal

Weight Management:

• Counsel about healthy diet and exercise at initiation
• Refer to nutritionist if >7% weight gain
• Consider metformin if significant weight gain
• Consider switching agents if severe metabolic effects

This Patient's Monitoring Plan:

• Baseline: Weight 165 lbs, BMI 24.5 (healthy)
• Given family history of diabetes, will check HbA1c at baseline and 12 weeks
• Monthly weight checks for first 3 months
• Fasting glucose and lipids at 12 weeks
• If significant metabolic changes, prioritize lifestyle interventions
• Aripiprazole's favorable metabolic profile chosen specifically given his risk factors

Follow-up Plan

Week 1: Phone check - tolerability, akathisia Week 2: In-person - adjust dose if needed, weight check Week 4: Efficacy assessment, weight check Week 12: Full metabolic panel, efficacy assessment

All cases for this lecture as Markdown