“The defined daily dose DDD is the assumed average maintenance dose per day for a drug used for its mainindication in adults.” 4 DDDs are produced by the WHOCollaborative Center for Drug Statistics Methodologyfor all drugs listed in the Anatomical Therapeutic Chemical (ATC) classification system (http://www.whocc.no/). The following principles are important: thereference point for DDDs is a 70-kg adult, and they arebased on the main indication of a drug, which in thecase of antipsychotics is “psychosis.”
Olanzapine 1mg Equivalents Based on DDDs, the Minimum Effective Dose Method, the Classical Mean Dose Method, and an International Consensus
| DDD method | Leucht S et al. | Gardner DM et al. | |
| Amisulpride | 40 | 38.33 | 34.48 |
| Aripiprazole | 1.5 | 1.41 | 1.49 |
| Chlorpromazine | 30 | 38.88 | 30.3 |
| Clozapine | 30 | 30.62 | 20 |
| Haloperidol | 0.8 | 0.74 | 0.5 |
| Lurasidone | 6 | ||
| Olanzapine | 1 | 1 | 1 |
| Paliperidone | 0.6 | 0.45 | |
| Perphenazine | 3 | 1.49 | |
| Quetiapine | 40 | 32.27 | 37.04 |
| Risperidone | 0.5 | 0.38 | 0.3 |
| Sulpiride | 80 | 40 | |
| Ziprasidone | 8 | 7.92 | 8 |
| Zotepine | 20 | 13.24 | 14.93 |
- Leucht S, Samara M, Heres S, DAvis JM. Dose equivalents for antipsychotic drugs: the DDD method. Schizophr Bull. 2016;42.suppl_1: S90-S94.
- Leucht S, Samara M, Heres S, et al. Dose equivalents for second-generation antipsychotic drugs: the classical mean dose method. Schizophr Bull. 2015;41:1397–1402.
- Gardner DM, Murphy AL, O’Donnell H, Centorrino F, Baldessarini RJ. International consensus study of antipsychotic dosing. Am J Psychiatry. 2010;167:686–693.