| Level I | Good quality evidence |
Systematic review of RCTs with consistent findings High quality individual RCT |
| Level II |
Limited quality patient orientated evidence |
Systematic review of lower quality studies or studies with inconsistent findings Low quality clinical trial Cohort studies Case-control studies |
| Level III | Other |
Consensus guidelines, extrapolations from bench research, usual practice, opinion, disease-oriented evidence (intermediate or physiologic outcomes only), or case series |
[13] Promethazine, IM: Huf G, Alexander J, Gandhi P, Allen MH. Haloperidol plus promethazine for psychosis-induced aggression. Cochrane Database Syst Rev. 2016 Nov25;11:CD005146. https://www.ncbi.nlm.nih.gov/pubmed/27885664
Promethazine, IM: Huf G, Coutinho ES, Adams CE; TREC Collaborative Group. Rapid tranquillisation in psychiatric emergency settings in Brazil: pragmatic randomised controlled trial of intramuscular haloperidol versus intramuscular haloperidol plus promethazine. BMJ. 2007 Oct 27;335(7625):869. http://www.ncbi.nlm.nih.gov/pubmed/17954515