REVIEW OF: Terao I et al, J Psychopharmacology2023;37(10);953–959

STUDY TYPE: Meta-analysis

Quetiapine is widely used in varying doses and formulations to manage schizophrenia. Given its extensive dose range in both immediate-release (IR) and extended-release (ER) forms, it can be challenging to determine which formulation is most appropriate to prescribe. This research offers a valuable comparison of IR and ER quetiapine across different dosages.

The study synthesized data from six double-blind, randomized, placebo-controlled trials involving 2,456 patients using a dose-response network meta-analysis. This analytical tool allows researchers to evaluate multiple doses within the same analysis, avoiding common issues found in traditional meta-analyses that mix different doses. The main outcomes were scores on the Positive and Negative Syndrome Scale and/or the Brief Psychiatric Rating Scale.

Both IR and ER quetiapine were more effective than placebo, which was not a surprise. However, there were significant differences across formulations and doses. IR quetiapine had a bell-shaped dose-response curve up to 500 mg, which peaked at a maximally effective dose of about 300 mg. ER quetiapine only had increasing efficacy above 300 mg, increasing linearly to a maximally effective dose around 550 mg and then decreasing somewhat to 800 mg (the highest dose studied). Superimposing these dose-response curves showed IR significantly outperforming ER at doses between 100 and 300 mg, with ER better in the 600–700 mg range.

The authors summarized their findings on quetiapine for schizophrenia with the following recommendations:

• Begin with an IR formulation for doses up to 300 mg.
• If the clinical response at 300 mg of IR is inadequate, switch to ER to titrate further. 

CARLAT TAKE

This meta-analysis provides us with some updated recommendations for prescribing quetiapine for schizophrenia. It suggests using IR quetiapine for doses up to 300 mg. For higher doses, ER is likely more effective, but may have diminishing returns above 550 mg.