A total of 320 newly admitted schizophrenic men were randomly assigned to either an aliphatic, piperidine, or piperazine phenothiazine. Physicians chose drugs within the class assigned and used them to maximal clinical advantage. None of the drug classes was superior to another in total efficacy.
Finer differences were that piperazines were more effective in patients who were older and who were categorized as having "core" or "nonparanoid" types of schizophrenia, characterized chiefly by thought disorders. The prevailing belief that these drugs are more specific antipsychotic agents was given some support.
Past difficulties in replicating specific indications for antipsychotic drugs, as well as the few differences found in this study, force the clinician still to choose drugs empirically. Differing reactions of individual patients to various drugs are more likely due to differences in drug kinetics than to any important pharmacological differences.
Hollister LE, Overall JE, Kimbell I, Pokorny A. Specific Indications for Different Classes of Phenothiazines. Arch Gen Psychiatry. 1974;30(1):94-99. doi:10.1001/archpsyc.1974.01760070072011