double-blind controlled trial to compare effectiveness of intramuscular olanzapine and ketamine as first medication to fast sedation of patients with agitation caused by psychiatric conditions. Randomization will be performed by permuted blocks allocation in which ketiamine or olanzapine standard treatment will be assigned to blocks of five patients and distributed in this order: olanzapine and ketiamine. This assignment will be repeated until the total number of subjects (500) be reached.