How to switch from olanzapine (antipsychotic) to an alternative and start hydroxychloroquine (HCQ) (antimalarial) in a patient with psychosis on 10mg daily olanzapine who now meets the criteria for Systemic Lupus Erythematosus (SLE)?

Management of Olanzapine Transition and HCQ Initiation in SLE Patient with Psychosis

For a patient with psychosis on olanzapine 10mg daily who now meets criteria for SLE, a cross-titration approach should be used to switch to quetiapine while simultaneously initiating hydroxychloroquine at 5mg/kg/day real body weight for SLE management.

Rationale for Medication Change

• Olanzapine should be switched to an alternative antipsychotic due to increased risk of agranulocytosis in SLE patients, which can worsen morbidity and mortality 1
• Hydroxychloroquine (HCQ) is recommended for all patients with SLE as it reduces disease flares, prevents organ damage accrual, and improves long-term survival 2

Antipsychotic Transition Plan

1. Choose alternative antipsychotic:

   • Quetiapine is preferred as it has less reported interactions with SLE and fewer hematologic adverse effects 1, 3
   • Avoid chlorpromazine as it can induce lupus-like syndromes 3

2. Cross-titration schedule:

   • Week 1: Start quetiapine 100mg at bedtime while maintaining olanzapine 10mg
   • Week 2: Increase quetiapine to 200mg at bedtime, reduce olanzapine to 7.5mg
   • Week 3: Increase quetiapine to 300mg at bedtime, reduce olanzapine to 5mg
   • Week 4: Increase quetiapine to target dose (300-400mg), reduce olanzapine to 2.5mg
   • Week 5: Discontinue olanzapine, continue quetiapine at therapeutic dose 3, 4

3. Monitoring during transition:

   • Assess for psychotic symptoms weekly during transition 4, 5
   • Monitor for extrapyramidal symptoms, sedation, and metabolic effects 3
   • Complete blood count weekly during first month to monitor for hematologic abnormalities 1

Hydroxychloroquine Initiation

1. Dosing:

   • Start HCQ at 5mg/kg/day based on real body weight (not to exceed this threshold) 2
   • Daily dose can be divided into twice daily administration if gastrointestinal side effects occur 2

2. Pre-treatment assessments:

   • Measure G6PD levels in men, especially those of African, Asian, or Middle Eastern origin 2
   • Baseline renal function (if eGFR <30 ml/min/1.73m², reduce HCQ dose by 25%) 2
   • Baseline ophthalmologic examination is not mandatory before starting treatment 2

3. Monitoring:

   • Annual ophthalmologic examination starting after 5 years of therapy (or after 1 year if additional risk factors present) 2
   • Regular assessment of SLE disease activity 2
   • Monitor for psychiatric symptoms as antimalarials may rarely exacerbate psychiatric disorders 6, 3

Special Considerations

• Psychiatric manifestations in SLE:

  • Psychosis can be a manifestation of neuropsychiatric SLE rather than a primary psychiatric disorder 4, 5
  • Evaluate whether psychotic symptoms are due to SLE activity, medication effects, or primary psychiatric disorder 3

• Potential drug interactions:

  • HCQ generally has minimal interactions with antipsychotics 2
  • Avoid chloroquine as it has been reported to trigger psychiatric symptoms more frequently than HCQ 6

• Treatment goals:

  • Aim for remission or low disease activity in SLE 2
  • Maintain psychiatric stability throughout the transition 3, 4
  • Prevent SLE flares and organ damage with consistent HCQ therapy 2

Follow-up Plan

• Weekly psychiatric assessment during the first month of medication transition 4, 5
• Monthly follow-up for the next 3 months to assess both psychiatric symptoms and SLE activity 2
• Blood HCQ levels may be checked after 3 months to ensure adequate dosing (target >0.6 mg/L) 2
• Regular monitoring for potential side effects of both medications 2