A Clinically Oriented Review of New Antipsychotics for Schizophrenia

Currently available antipsychotics, mainly targeting the dopaminergic pathway, fail to address the complexity of schizophrenic symptoms and can lead to burdening adverse events. The need for innovative pharmacological options remains critical and research is now focusing on the development of non-dopaminergic antipsychotics. This review aims to summarize the current literature on the most promising non-dopaminergic new APs (muscarinic agonists, Trace Amine Associated Receptor 1 agonists, Glycine Transporter Type 1 inhibitors and 5-HT2A antagonists) and provide a clinically oriented overview of their efficacy, safety and potential use in schizophrenia.

A preliminary search was conducted through the Clinical Trials Database, in order to identify a representative (at late-stage clinical development) for each pharmacological class. The following drugs were selected: bitopertin (GlyT-1 inhibitor), pimavanserin (5-HT2A antagonist), ulotaront (TAAR1 agonist) and xanomeline-trospium (muscarinic agonist). Then, a literature search was conducted through PubMed, in order to retrieve current literature focusing on the efficacy and safety of these drugs.

The clinical development of bitopertin and pimavanserin was halted despite the early promises. Xanomeline-trospium chloride was recently approved by the FDA for the treatment of schizophrenia. Ulotaront showed mixed results, although analysis is ongoing.

The findings of our review indicate that research on the treatment of schizophrenia is gaining momentum. However, it is crucial to remain cautious about over-optimism, as many compounds have failed to deliver the expected results. A balanced approach is recommended when dealing with new APs, whether under investigation or approved. In the latter case, clinicians should carefully evaluate the cost-benefit ratio. Since several agents are still being tested, there is hope that additional data may present new therapeutic opportunities.