Administering a combination of promethazine and chlorpromazine to patients with a "galloping psychosis" has an antipsychotic and tranquilizing effect which calms them down to a more manageable and less aggressive state. The drugs are chemically similar; promethazine's actions are strongly potentiated in the combination, so large doses must be given under careful supervision. Case histories demonstrate successful short term management of acutely psychotic, aggressive patients who were a danger to themselves and others.
Favazza, Armando R.
"Promethazine-Chlorpromazine Combination in the Treatment of Unmanageable Psychotic Patients,"
Henry Ford Hospital Medical Journal
: Vol. 17
Available at: https://scholarlycommons.henryford.com/hfhmedjournal/vol17/iss4/10