Zuclopenthixol Acetate Dosing for Acute Psychosis
For acutely disturbed psychotic patients, administer 50-150 mg intramuscularly as a single injection, with most patients adequately controlled on 50-100 mg. 1
Initial Dosing Strategy
- Start with 50 mg IM for most patients, as this dose has been shown to adequately manage severely disturbed psychotic patients for the first 3 days 2
- The dose range of 50-150 mg per injection is sufficient for controlling acute symptoms in most acutely disturbed psychotic patients 1
- Asian patients may require lower doses (50 mg) as they achieve higher serum concentrations compared to Caucasian patients with equivalent dosing 2
Repeat Dosing Protocol
- Repeat injections can be given at 2-3 day intervals if symptoms persist, as the duration of effect is typically 2-3 days 1
- Most patients (15 of 19 in one study) required only one injection, while some needed 2-3 injections with 3-day intervals 1
- In clinical practice, the protocol allows for repeat injections at Day 3 and Day 6, with an additional injection at Day 1 permitted if initial efficacy is insufficient 3
- Mean dosage per injection in clinical studies ranged from 126-138 mg 3
Pharmacokinetic Profile
- Peak serum concentration occurs at approximately 36 hours after a 100 mg dose, reaching 41 ng/mL, then decreasing to 15 ng/mL by 72 hours 1
- For 50 mg doses in Asian patients, serum concentrations at 24,48, and 72 hours were 19.9,31.5, and 17.8 micrograms/L respectively 2
- The onset of action begins from the second day of injection, with statistically significant reduction in psychotic anxiety evident within 24 hours 4, 3
Dose-Response Considerations
- Higher doses (50-100 mg/injection) do not appear more effective than lower doses (25-50 mg/injection) based on available evidence 5
- Significant correlations exist between dose and maximal serum concentration, as well as between dose and area under the curve 1
- Patients receiving identical doses achieve serum concentrations of approximately the same order 1
Comparative Efficacy
- Zuclopenthixol acetate results in fewer total injections over 7 days compared to haloperidol IM (NNT 4), reducing the number of coercive interventions 5
- Supplementary benzodiazepine use is significantly reduced compared to haloperidol (RR 0.03) 5
- No significant difference exists in sedation at 2 hours or adverse effects compared to haloperidol 5
Safety Profile
- Adverse effects are generally few and mild, with low frequency of extrapyramidal reactions 1, 2
- Movement disorders occur in less than 20% of patients, similar to haloperidol 5
- Local tolerance at the injection site is excellent 1, 4
- Common side effects include blurred vision, dry mouth, and dizziness, occurring at similar rates to haloperidol 5
Clinical Caveats
- The evidence base consists primarily of small trials with methodological limitations, so recommendations should be applied with appropriate clinical judgment 5
- Onset of action is not truly "rapid" - significant effects begin at 24 hours, not within minutes to hours like some alternatives 3, 5
- Consider ethnic differences in drug metabolism when dosing, particularly for Asian patients who may require lower doses 2