Psychiatric Pharmacy Essentials: Antipsychotic Dose Equivalents | American Association of Psychiatric Pharmacists (AAPP)

Antipsychotic dose equivalents may be utilized when switching between or comparing different antipsychotics. Multiple methods have been used to calculate antipsychotic dose equivalences, each with their own strengths and limitations. Differences in receptor-binding profiles among newer agents, changes in clinical trial methodology over time, and limited dose-response data for older agents limit the applicability of any single dose-equivalency method across all antipsychotics. Furthermore, none of the available methods consider a patient’s acuity status, specific physical and medical condition(s), or history of previous antipsychotic exposure. Equivalent doses are difficult to determine and often incorrect; therefore, the information below should be paired with caution and clinical judgement. Methods which currently exist focus on schizophrenia or psychosis dosing and may not accurately translate to other psychiatric diagnoses. It should also be noted that equivalency guidance may not predict individual patient efficacy or tolerability. An awareness and comparison of multiple methods is required for clinical decision making and has been included in the table and references below.

How should I convert doses between different antipsychotics?

The table below presents several methods using oral olanzapine 10 mg/day as the common reference dose.^1-4 The DDD, MED, ED95 equivalent, and ICSAD-2 values represent the dose of each antipsychotic corresponding to olanzapine 10 mg/day according to the specified method. Note that ED95 equivalences are based off dose-response for predominant positive symptoms. Finally, the multi-method dose equivalent calculator referenced in Leucht et al. (2020)⁵ may aid in calculating equivalencies for medications or formulations not included in the table below.

Table. Oral Antipsychotic Dose Equivalents

Generic	Brand	DDD¹	MED²	ED95 Equivalent³	ICSAD-2 Equivalent⁴
First-Generation Antipsychotics
Chlorpromazine	Thorazine^©	300mg	N.A	N.A	N.A
Fluphenazine	Prolixin^©	10mg	N.A	N.A	N.A
Haloperidol	Haldol^©	8mg	5.3mg	7.9mg	5mg
Loxapine	Loxitane^©	100mg	N.A	N.A	N.A
Perphenazine	Trilafon^©	30mg	N.A	N.A	N.A
Thiothixene	Navane^©	30mg	N.A	N.A	N.A
Second-Generation Antipsychotics
Aripiprazole	Abilify^©	15mg	13.3mg	6.5mg	15mg
Asenapine	Saphris^©	20mg	13.3mg	6.8mg	10mg
Brexpiprazole	Rexulti^©	3mg	N.A	2.2mg	2mg
Cariprazine	Vraylar^©	3mg	N.A	3.9mg	3mg
Clozapine	Clozaril^©	300mg	400mg	361.3mg	N.A
Iloperidone	Fanapt^©	18mg	10.7mg	14.6mg	N.A
Lumateperone	Caplyta^©	N.A	N.A	22.2mg	21mg
Lurasidone	Latuda^©	60mg	53.3mg	132.2mg	60mg
Olanzapine	Zyprexa^©	10mg	10mg	10mg	10mg
Paliperidone	Invega^©	6mg	4mg	8.1mg	6mg
Quetiapine	Seroquel^©	400mg	200mg	650.6mg	375mg
Risperidone	Risperdal^©	5mg	2.7mg	2.5mg	3mg
Ziprasidone	Geodon^©	80mg	53.3mg	189.9mg	80mg

Abbreviations: DDD = Defined Daily Dose; ED95 = 95% Effective Dose; ICSAD-2 = Second International Consensus Study of Antipsychotic Dosing; MED = Minimum Effective Dose; N.A. = not available.

Definitions:

Defined Daily Dose: Assumed average maintenance dose per day for a drug used for its main indication in adults.1
Minimum Effective Dose: Lowest fixed dose consistently found to be more efficacious than placebo.²
ED95 Equivalent: Drug-specific dose estimated to achieve 95% of that antipsychotic's modeled maximum efficacy, converted to an olanzapine 10 mg/day equivalent using the ratio of the drug's ED95 to the olanzapine ED95 (15.7 mg/day).3
ICSAD-2 Equivalent: Expert-consensus estimate of a clinically equivalent antipsychotic dose. ICSAD-2 used olanzapine 20 mg/day as the reference; values in this table are normalized to olanzapine 10 mg/day by linear halving.⁴

Antipsychotic Dose Conversion Spreadsheet⁵

Reviewer 1: Maria Blaze, PharmD, BCPP
Reviewer 2: Angeleki Zecopoulos, PharmD
2026-2027 AAPP Resident and New Practitioner Committee

WHO Collaborating Centre for Drug Statistics Methodology. ATC/DD Index 2026. 2026 [cited 2026/09/07].
Leucht S, Samara M, Heres S, Patel MX, Woods SW, Davis JM. Dose Equivalents for Second-Generation Antipsychotics: The Minimum Effective Dose Method. Schizophrenia Bulletin. 2014 Mar 1;40(2):314-326. Oxford University Press (OUP). DOI: 10.1093/schbul/sbu001.
Furukawa Y, Lin X, Rodolico A, Tian J, Wu H, Schneider-Thoma J, et al. Antipsychotic dose and efficacy for acute schizophrenia spectrum disorders: an updated systematic review and dose-response meta-analysis. eClinicalMedicine. 2026 Apr;94:103847. Elsevier BV. DOI: 10.1016/j.eclinm.2026.103847.
McAdam MK, Baldessarini RJ, Murphy AL, Gardner DM. Second International Consensus Study of Antipsychotic Dosing (ICSAD-2). J Psychopharmacol. 2023 Oct;37(10):982-991. SAGE Publications. DOI: 10.1177/02698811231205688.
Leucht S, Crippa A, Siafis S, Patel MX, Orsini N, Davis JM. Dose-Response Meta-Analysis of Antipsychotic Drugs for Acute Schizophrenia. AJP. 2020 Apr 1;177(4):342-353. American Psychiatric Association Publishing. DOI: 10.1176/appi.ajp.2019.19010034.