This variance raises practical considerations, for example, in declaring a failed second-generation antipsychotics trial in the process of defining treatment-resistant schizophrenia. The wide variation challenges the validity of using chlorpromazine equivalents to compare across antipsychotics. The reported near-maximal effective dose of chlorpromazine was 400–450 mg, not 600–1,000 mg, and there appears to be little evidence to support high doses in treatment-resistant schizophrenia (4). In addition, the high doses calculated raise serious safety concerns and fly in the face of regulatory dosing recommendations. Accordingly, adopting chlorpromazine equivalents may not be appropriate for evaluating an adequate dosage for specific second-generation antipsychotics, and we suggest that a more appropriate means to confirm a failed clinical trial is suboptimal response at the maximum recommended dosage range for a specific second-generation antipsychotics, as per product monograph.