SEROQUEL Dosing for Substance-Induced Psychosis
For substance-induced psychosis, start quetiapine at 12.5 mg twice daily and titrate cautiously to a maximum of 200 mg twice daily, monitoring closely for sedation and orthostatic hypotension. 1
Initial Dosing Strategy
- Begin with 12.5 mg twice daily as the starting dose for quetiapine in psychotic presentations 1
- This conservative approach minimizes side effects while establishing tolerability, particularly important given quetiapine's sedating properties 1
- Monitor for transient orthostatic hypotension, which is a notable concern with quetiapine initiation 1
Dose Titration
- Increase doses only at widely spaced intervals of 14-21 days after initial titration, and only if response has been inadequate 2
- Titrate within the limits of sedation and emergence of side effects 2
- Maximum dose is 200 mg twice daily (400 mg total daily) 1
- Research supports that quetiapine can be effectively dosed twice daily rather than three times daily despite its 7-hour half-life 3
Clinical Context for Substance-Induced Psychosis
While the available guidelines primarily address first-episode psychosis and schizophrenia rather than substance-induced psychosis specifically, the dosing principles remain applicable with important caveats:
- Use the lower end of the dosing range given that substance-induced psychosis may resolve with abstinence and supportive care
- The sedating properties of quetiapine 1 may be beneficial for agitation but require careful monitoring in patients with active substance use
- Rule out ongoing substance intoxication or withdrawal before attributing symptoms solely to psychosis and initiating antipsychotic treatment 2
Key Safety Considerations
- Quetiapine is more sedating than other atypical antipsychotics like risperidone or olanzapine 1
- Watch for orthostatic hypotension, particularly during dose initiation and escalation 1
- Quetiapine produces minimal extrapyramidal symptoms and does not cause sustained prolactin elevation 3, 4
- Avoid exceeding maximum recommended doses, as this increases side effects without improving efficacy 2
Alternative Considerations
If quetiapine is poorly tolerated or ineffective, consider switching to:
- Risperidone 2 mg/day (maximum 4 mg/day in first-episode psychosis) 2
- Olanzapine 7.5-10 mg/day (maximum 20 mg/day) 2
These alternatives have more robust evidence for acute psychosis but may have different side effect profiles that are less desirable in substance-induced presentations.