This

study aimed to assess antipsychotic treatment prior to the initiation of polypharmacy and ascertained clinicians’ reasons for coprescribing long term. We also aimed to determine patterns of antipsychotic Protein Tyrosine Kinase inhibitor coprescription and associated outcome. Method: Prescription charts across a large mental health trust were reviewed to identify all patients coprescribed two or more antipsychotics excluding clozapine. For those receiving antipsychotic polypharmacy for at least 6 months, electronic patient records were examined to obtain demographic data, documented Inhibitors,research,lifescience,medical reasons for initiating polypharmacy and prior prescribing information. Sequence of prescribing, clinical outcome, adverse effects and prescriber considerations to revert to monotherapy were determined. Results: In all, 38 patients had been receiving two antipsychotics excluding clozapine for Inhibitors,research,lifescience,medical longer than

6 months. In 39% of cases patients had been prescribed no or only one antipsychotic before initiation of polypharmacy while 48% had been trialled on clozapine. The most frequently documented reason for coprescribing was that residual psychotic symptoms remained with monotherapy. An improvement in psychotic symptoms was documented in 26% of patients receiving polypharmacy. Prescribers considered stopping polypharmacy in 23 patients. Conclusion: Antipsychotics were Inhibitors,research,lifescience,medical coprescribed largely to improve symptoms and clinical outcome in patients with inadequate response to monotherapy. Polypharmacy was not solely reserved for patients in whom all other therapeutic Inhibitors,research,lifescience,medical options had failed. There was some evidence to suggest that patients did benefit from coprescription, albeit at the expense of an increased adverse effect burden. Prospective randomized trials of specific antipsychotic combinations are required to assess the therapeutic utility of this under-researched Inhibitors,research,lifescience,medical practice. Keywords: antipsychotics, polypharmacy, schizophrenia Introduction According to the National

Institute for Health and Clinical Excellence (NICE) guidelines for the treatment of schizophrenia, antipsychotic polypharmacy can only be justified in the context of cross-titration, to avoid relapse isothipendyl during switch over of medication [National Institute for Health and Clinical Excellence, 2009]. The addition of a second antipsychotic to clozapine is also cautiously recommended in treatment-refractory patients with an inadequate response to trials of at least two antipsychotics and clozapine. Despite stringent guidelines and limited evidence of efficacy, antipsychotic polypharmacy regimens including and excluding clozapine have steadily increased over the past two decades [Gilmer et al. 2007]. It appears that coprescription arises out of the desire to improve symptoms and reduce adverse effect burden [Taylor et al. 2002].