Dosing regimens for depot antipsychotics range from two-to twelve-weekly administration. There are limited meta-analytic data regarding the effect of different injection frequencies of the same depot antipsychotic at the equivalent dose on psychiatric outcomes and adverse effects. This study investigated differences in psychiatric outcomes and adverse effects between different frequencies of depot antipsychotics through a systematic review and meta-analysis. We performed a systematic search of MEDLINE, EMBASE, Cochrane database, PsycINFO and two Chinese databases for RCTs that compared the frequency of depot antipsychotic administration. The primary outcome was psychiatric symptomatology, with secondary outcomes of quality of life, admission rates, adverse drug reactions, cost-effectiveness and compliance. Twelve studies were included in the meta-analysis. Most studies compared two- and four-weekly injections (n = 10). Different injection frequencies did not lead to differences in clinical outcomes or adverse events. However, two-weekly injections led to significantly greater improvements on the CGI-S scale than four-weekly administration. A sensitivity analysis by removing low quality studies showed lower incidence of somnolence and injection site pain for 2-weekly compared with 4-weekly injections. There were limited data on admission rates and no RCT data on cost-effectiveness or compliance. While there is limited evidence on secondary measures to support 2-weekly over 4-weekly injections, patient choice and convenience should remain the priority when considering certain antipsychotics. Cost-effectiveness and adherence should also be considered, although further studies are required to further evaluate these parameters.
Keywords: Adverse reactions; Depot antipsychotic; Dosing frequency; Long acting injectables; Psychiatric outcomes.
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