Olanzapine Time to Clinical Response
Olanzapine can show measurable antipsychotic effects within hours for some patients with acute psychosis. [1]
Clinical response is often assessed over weeks. In a randomized 8-week trial in early-onset schizophrenia spectrum disorders, the median time to clinical response for olanzapine was about 4.0 weeks (interquartile range ± 4.0). [2]
Earliest Observable Effects
In a multicenter, double-blind, placebo-controlled study of schizophrenia spectrum disorder patients with acute exacerbation treated with intramuscular olanzapine, symptom improvement beyond placebo was evident as early as 2 hours, and independent change in “core psychosis” was observed within the first 24 hours. [1]
Typical Time Course to Clinical Response
In the Treatment of Early Onset Schizophrenia Spectrum Disorders Study (TEOSS), among clinical responders, median time to clinical response was 4.0 weeks for olanzapine (± 4.0 weeks) within an 8-week treatment window. [2]
Early Nonresponse as a Timing Signal
In TEOSS, lack of at-least-minimal symptom improvement by about 3 weeks (CGI-I ≥ 4) predicted clinical nonresponse at week 8. [2]
Practical Interpretation of “Start Working”
For acute symptom improvement, effects may be detectable within 24 hours in some cases. [1]
For sustained clinical response, improvement is commonly judged over several weeks, with a median around 4 weeks in early-onset schizophrenia spectrum disorders. [2]