Strategies for Switching between Oral Postsynaptic Antidopaminergic Antipsychotics in Patients with Schizophrenia: A...

Antipsychotic switching is common in the treatment of schizophrenia. Pharmacokinetic and pharmacodynamic properties of antipsychotics can inform switch strategies, as switching from shorter to longer half-life antipsychotics and switching from more antagonistic to less antagonistic or partial agonist agents at dopaminergic, histaminergic, and cholinergic receptors can lead to withdrawal or rebound symptoms, potentially complicating switch results. This systematic literature review of studies investigated switching strategies between oral antipsychotics. Pharmacokinetic and pharmacodynamic characteristics of antipsychotics that can influence switch outcomes were also extracted from publications and prescribing information.

MEDLINE, Embase, Cochrane Central Register of Controlled Trials, and PubMed databases were queried (last search 13 May 2024) for articles published from 1 June 2010 to 1 April 2024, with keywords (schizophr* OR schizoaff*) AND (antipsychotic*) AND (switch*). Randomized controlled trials, open-label studies, meta-analyses, and reviews of oral antipsychotic switching were included. Records were excluded if they investigated a disease other than schizophrenia or schizoaffective disorder or focused on long-acting injectable or non-approved antipsychotics. Data on switch strategies investigated and study outcomes were manually extracted from randomized controlled trials and open-label switch studies of oral antipsychotics in schizophrenia or schizoaffective disorder. Meta-analyses and review articles were summarized. There was no assessment for risk of bias or specific method to synthesize results.

Of the 579 records identified during the systematic review, 80 articles investigated switching of oral antipsychotics in adult patients with schizophrenia, including 58 randomized and non-randomized studies (9 of which investigated ≥ 1 antipsychotic) and 22 review articles or meta-analyses. The antipsychotics investigated during this period were: aripiprazole (studies = 18); paliperidone, ziprasidone, olanzapine, and risperidone (studies = 7 each); brexpiprazole, clozapine and lurasidone (studies = 4 each); amisulpride, (studies = 3); quetiapine and iloperidone (studies = 2 each); and asenapine and lumateperone (1 study each). Most studies that reported a switch method employed cross-titration switching (studies = 39; 69.6%), while abrupt switching (studies = 10; 17.9%) and switching at investigator's discretion (studies = 7; 12.5%) were rare. A total of 24 studies (N = 3440 patients) had statistical comparisons between treatment groups, but few studies specifically statistically compared outcomes between different switch strategies (1 trial each for aripiprazole, clozapine, iloperidone, and ziprasidone; N = 666 patients), with mixed outcomes. Frequencies of sedative rescue treatments, which could have attenuated potential withdrawal symptoms, were rarely disclosed.

Despite the importance and frequency of antipsychotic switching, few studies have specifically investigated outcomes of different switch strategies. General clinical preference appears to utilize gradual switching approaches to avoid potential rebound symptoms. Future research with current and emerging antipsychotics is needed, especially for switching between antipsychotics with different receptor profiles and for switches that are potentially vulnerable to rebound and withdrawal symptoms.