What is the best urgent oral treatment for drug-induced psychosis?

Best Urgent Oral Treatment for Drug-Induced Psychosis

For drug-induced psychosis requiring urgent oral treatment, second-generation antipsychotics, particularly olanzapine 5-10 mg or risperidone 0.5-2 mg, are recommended as first-line options due to their efficacy and favorable side effect profiles. 1

First-Line Treatment Options

Olanzapine

• Initial dose: 5-10 mg orally once daily 2, 3
• Can be given as orally disintegrating tablet (ODT) for faster absorption and in patients refusing standard tablets 2
• Particularly effective for agitation and psychosis with rapid onset of action 4
• May cause drowsiness, orthostatic hypotension, and metabolic effects with long-term use 2
• Caution: Avoid combining with benzodiazepines due to risk of oversedation and respiratory depression 2

Risperidone

• Initial dose: 0.5 mg orally, can be repeated up to every 12 hours if needed 2
• Available as orally disintegrating tablet (ODT) 2
• Lower risk of sedation compared to olanzapine but higher risk of extrapyramidal symptoms (EPS) at doses >6 mg/24h 2
• May cause insomnia, agitation, anxiety, drowsiness, and orthostatic hypotension 2

Quetiapine

• Initial dose: 25 mg (immediate release) orally 2
• Can be given every 12 hours if scheduled dosing required 2
• More sedating than risperidone but less likely to cause extrapyramidal side effects 2
• May cause orthostatic hypotension and dizziness 2

Special Considerations

Patient-Specific Factors

• Elderly or debilitated patients: Start with lower doses (olanzapine 2.5 mg, risperidone 0.25-0.5 mg, quetiapine 12.5-25 mg) 2, 1
• Hepatic/renal impairment: Reduce doses and monitor closely 2
• Parkinson's disease patients: Avoid typical antipsychotics and olanzapine as they may worsen motor symptoms; quetiapine is preferred 5

Combination Therapy for Severe Agitation

• For severe agitation not controlled by antipsychotics alone, consider adding lorazepam 1-2 mg orally 2, 1
• The combination of haloperidol and lorazepam has shown efficacy for rapid tranquilization 2, 1
• Caution: Avoid combining benzodiazepines with high-dose olanzapine due to risk of respiratory depression 2

Treatment Algorithm

1. Identify the causative substance and eliminate exposure if possible 6
2. Rule out medical causes of psychosis (infections, metabolic disorders, etc.) 6
3. Initial treatment:
   • For most patients: Olanzapine 5-10 mg orally
   • For elderly/frail patients: Olanzapine 2.5 mg or risperidone 0.5 mg
   • For patients with Parkinson's disease: Quetiapine 25 mg
4. If inadequate response after 1-2 hours:
   • Consider additional dose of the same medication
   • Or add lorazepam 1-2 mg orally for severe agitation
5. Monitor for:
   • Response to treatment
   • Vital signs (particularly with combined therapy)
   • Side effects (sedation, orthostatic hypotension, extrapyramidal symptoms)

Duration of Treatment

• Antipsychotics should be used for the shortest period necessary 6
• Drug-induced psychosis typically resolves within 30 days of sobriety 6
• Gradual tapering of antipsychotics once the patient is stable 6
• Long-term monitoring is recommended as substance-induced psychosis carries a high risk of conversion to schizophrenia or bipolar disorder (up to one in three individuals) 6

Common Pitfalls and Caveats

• Misdiagnosis: Distinguishing between primary psychotic disorders and substance-induced psychosis can be challenging 7
• Medication interactions: Be aware of potential interactions between antipsychotics and substances of abuse 8
• Benzodiazepines alone: Should only be used as monotherapy for alcohol or benzodiazepine withdrawal-related psychosis 2
• Inadequate dosing: Starting with too low a dose may result in continued agitation and risk to patient and staff
• Excessive sedation: High doses or combinations of sedating medications can lead to respiratory depression
• QTc prolongation: Monitor for QTc prolongation, especially when combining multiple antipsychotics or in patients with cardiac risk factors 1

Remember that while medication is important for acute management, addressing the underlying substance use disorder is essential for long-term outcomes and prevention of recurrence.