Haloperidol Dose Equivalent to 25mg Loxapine
Based on the available evidence, approximately 5-9 mg of haloperidol is equivalent to 25 mg of loxapine, using a dosage ratio of approximately 2.7:1 to 4.4:1 (loxapine:haloperidol). 1
Direct Comparative Evidence
The most relevant evidence comes from a head-to-head comparison study that directly evaluated loxapine versus haloperidol in acutely psychotic schizophrenic patients 1:
- Dosage ratios ranged from 2.7:1 to 4.4:1 (loxapine to haloperidol) 1
- Using the lower ratio (2.7:1): 25 mg loxapine ÷ 2.7 = approximately 9 mg haloperidol
- Using the higher ratio (4.4:1): 25 mg loxapine ÷ 4.4 = approximately 5.7 mg haloperidol
Both medications showed comparable efficacy and adverse effect profiles at these ratios, with loxapine demonstrating at least equivalent effectiveness to haloperidol in managing hostile and aggressive symptoms 1.
Clinical Context for Haloperidol Dosing
The recommended haloperidol dose range aligns well with this equivalence calculation 2:
- Standard haloperidol dose for acute agitation is 5 mg intramuscularly, which can be repeated based on clinical response 2
- Efficacy shows a dose-response relationship up to 10-15 mg; above this dose, there is diminished improvement 2
- For acute schizophrenia, doses in the range of 3-7.5 mg/day maintain efficacy while reducing extrapyramidal side effects compared to higher doses 3
Practical Application
For converting 25 mg loxapine to haloperidol, use 5-10 mg haloperidol 1:
- Start with 5 mg haloperidol as the initial equivalent dose 2, 1
- This falls within the standard therapeutic range and minimizes extrapyramidal adverse effects 3
- If inadequate response, titrate up to 10 mg, which remains within the optimal efficacy range 2