Comparative efficacy and tolerability of antidopaminergic and muscarinic antipsychotics for acute schizophrenia: a network meta-analysis of randomised controlled trials indexed in international English and Chinese databases

BACKGROUND: Antipsychotic drugs are the established treatment for acute schizophrenia but differ in receptor-binding profiles. In 2024, a new-in-class muscarinic receptor agonist (xanomeline-trospium) was licenced, acting upstream of antidopaminergic agents, and providing hope to decrease the adverse effects burden of antipsychotics. We aimed to compare the efficacy and tolerability of antipsychotics by performing network meta-analysis of randomised controlled trials (RCTs). METHODS: This systematic review (PROSPERO, CRD42022380708) included blinded and open RCTs investigating antipsychotic drugs in participants of any age with acute psychotic symptoms of schizophrenia over 3 weeks to 3 months. Included antipsychotics comprised 23 primarily dopamine-receptor blocking medications and the muscarinic receptor agonist xanomeline-trospium in different applications. We searched Cochrane Schizophrenia group's register, previous reviews, and five Chinese databases for trials published from database inception until July 26, 2024 and contacted authors to assess trials' methodological quality; only trials with appropriate randomisation indicated were included. The primary outcome was rating scale-measured overall symptoms of schizophrenia (efficacy) analysed with random-effects frequentist network meta-analysis. Secondary outcomes comprised 32 further efficacy and tolerability outcomes. The confidence in the estimates was assessed using the Confidence in Network Meta-Analysis approach. FINDINGS: After screening 18 859 references and contacting authors of 5428 trials, we included 438 RCTs. Of those, 388 RCTs with 78 193 participants (28 448 women and 49 745 men) provided usable data for at least one outcome. 5117 Chinese trials were identified but most were excluded because authors did not reply or reported serious methodological concerns. 256 double-blind studies with 58 948 participants provided usable data for the primary outcome. All antipsychotics reduced symptoms more than placebo with standardised mean differences ranging from -0·90 (95% CI -1·03 to -0·77) to -0·23 (-0·39 to -0·06). Particularly clozapine, as well as amisulpride, olanzapine, and risperidone were more efficacious than at least three other antipsychotics (confidence in estimates were low-to-moderate). Adverse effects varied across medications. INTERPRETATION: This network meta-analysis provides evidence for small-to-medium clinically relevant differences between antipsychotics in efficacy; this finding warrants stronger and more specific emphasis in clinical guidelines. Nonetheless, important differences in tolerability need to be considered for individualised drug choice, with partial dopamine agonists having overall better tolerability and xanomeline-trospium lacking adverse effects of dopamine-blocking agents but resulting in cholinergic and anticholinergic adverse events. Future research should directly compare xanomeline-trospium with other antipsychotics to confirm its efficacy; modern trials using clozapine early in schizophrenia are needed to establish whether it improves outcomes and prevents chronification. FUNDING: German Research Foundation, German Ministry of Research, Technology and Space, and National Natural Science Foundation of China.