N-acetylcysteine (NAC) in schizophrenia resistant to clozapine: a double blind randomised placebo controlled trial targeting negative symptoms

BMC Psychiatry, Sep 2016

Background Clozapine is an effective treatment for a proportion of people with schizophrenia (SZ) who are resistant to the beneficial effects of other antipsychotic drugs. However, anything from 40–60 % of people on clozapine experience residual symptoms even on adequate doses of the medication, and thus could be considered ‘clozapine resistant’. Agents that could work alongside clozapine to improve efficacy whilst not increasing the adverse effect burden are both desired and necessary to improve the lives of individuals with clozapine-resistant SZ. N-Acetylcysteine (NAC) is one such possible agent. Previous research from our research group provided promising pilot data suggesting the efficacy of NAC in this patient population. The aim of the study reported here is to expand this work by conducting a large scale clinical trial of NAC in the treatment of clozapine-resistant SZ. Methods This study is an investigator initiated, multi-site, randomised, placebo-controlled trial. It aims to include 168 patients with clozapine-resistant SZ, divided into an intervention group (NAC) and a control group (placebo). Participants in the intervention group will receive 2 g daily of NAC. The primary outcome measures will be the negative symptom scores of the Positive and Negative Syndrome Scale (PANSS). Secondary outcome measures will include: changes in quality of life (QoL) as measured by the Lancashire Quality of Life Profile (LQoLP) and cognitive functioning as measured by the total score on the MATRICS. Additionally we will examine peripheral and cortical glutathione (GSH) concentrations as process outcomes. Discussion This large scale clinical trial will investigate the efficacy of NAC as an adjunctive medication to clozapine. This trial, if successful, will establish a cheap, safe and easy-to-use agent (NAC) as a ‘go to’ adjunct in patients that are only partly responsive to clozapine. Trial registration Australian and New Zealand Clinical Trials Registration Number: Current Randomised Controlled Trial ACTRN12615001273572. The date of registration 23 November 2015.

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N-acetylcysteine (NAC) in schizophrenia resistant to clozapine: a double blind randomised placebo controlled trial targeting negative symptoms

Rossell et al. BMC Psychiatry N-acetylcysteine (NAC) in schizophrenia resistant to clozapine: a double blind randomised placebo controlled trial targeting negative symptoms Susan L. Rossell 0 1 8 9 Paul S. Francis 14 Cherrie Galletly 12 13 Anthony Harris 11 16 Dan Siskind 15 Michael Berk 10 Kiymet Bozaoglu 6 Frances Dark 7 Olivia Dean 10 Dennis Liu 12 13 Denny Meyer 1 4 Erica Neill 0 9 Andrea Phillipou 0 9 Jerome Sarris 2 5 David J. Castle 0 3 9 0 St Vincent's Mental Health Service, St Vincent's Hospital , Melbourne, VIC , Australia 1 Centre for Mental Health, Faculty of Health, Arts and Design, Swinburne University of Technology , Melbourne, VIC , Australia 2 Centre for Human Psychopharmacology, Swinburne University of Technology , Melbourne, VIC , Australia 3 Department of Psychiatry, University of Melbourne , Melbourne, VIC , Australia 4 Department of Statistics, Data Science and Epidemiology, Swinburne University of Technology , Melbourne, VIC , Australia 5 ARCADIA Mental Health Research Group, Professorial Unit, The Melbourne Clinic, Department of Psychiatry, The University of Melbourne , Melbourne, VIC , Australia 6 Baker IDI Heart & Diabetes Institute , Melbourne, VIC , Australia 7 Metro South Addiction and Mental Health Service , Brisbane, QLD , Australia 8 Monash Alfred Psychiatry Research Centre and The Voices Clinic , The Alfred, Melbourne, VIC , Australia 9 St Vincent's Mental Health Service, St Vincent's Hospital , Melbourne, VIC , Australia 10 IMPACT Strategic Research Centre , Barwon Health , Deakin University , Geelong, VIC , Australia 11 Discipline of Psychiatry, Sydney Medical School, University of Sydney , Sydney, NSW , Australia 12 Northern Adelaide Health Local Network , Adelaide, South Australia , Australia 13 Psychiatry Department, University of Adelaide , Adelaide, South Australia , Australia 14 Centre for Chemistry and Biotechnology, School of Life & Environmental Sciences, Deakin University , Geelong, VIC , Australia 15 School of Medicine, University of Queensland , Brisbane, QLD , Australia 16 Brain Dynamics Centre, The Westmead Institute for Medical Research, University of Sydney , Sydney, NSW , Australia Background: Clozapine is an effective treatment for a proportion of people with schizophrenia (SZ) who are resistant to the beneficial effects of other antipsychotic drugs. However, anything from 40-60 % of people on clozapine experience residual symptoms even on adequate doses of the medication, and thus could be considered 'clozapine resistant'. Agents that could work alongside clozapine to improve efficacy whilst not increasing the adverse effect burden are both desired and necessary to improve the lives of individuals with clozapine-resistant SZ. N-Acetylcysteine (NAC) is one such possible agent. Previous research from our research group provided promising pilot data suggesting the efficacy of NAC in this patient population. The aim of the study reported here is to expand this work by conducting a large scale clinical trial of NAC in the treatment of clozapine-resistant SZ. Methods: This study is an investigator initiated, multi-site, randomised, placebo-controlled trial. It aims to include 168 patients with clozapine-resistant SZ, divided into an intervention group (NAC) and a control group (placebo). Participants in the intervention group will receive 2 g daily of NAC. The primary outcome measures will be the negative symptom scores of the Positive and Negative Syndrome Scale (PANSS). Secondary outcome measures will include: changes in quality of life (QoL) as measured by the Lancashire Quality of Life Profile (LQoLP) and cognitive functioning as measured by the total score on the MATRICS. Additionally we will examine peripheral and cortical glutathione (GSH) concentrations as process outcomes. Discussion: This large scale clinical trial will investigate the efficacy of NAC as an adjunctive medication to clozapine. This trial, if successful, will establish a cheap, safe and easy-to-use agent (NAC) as a 'go to' adjunct in patients that are only partly responsive to clozapine. N-Acetylcysteine; Clozapine; Schizophrenia; Negative Symptoms; Cognition; Biomarkers - Trial registration: Australian and New Zealand Clinical Trials Registration Number: Current Randomised Controlled Trial ACTRN12615001273572. The date of registration 23 November 2015. Background Schizophrenia Schizophrenia (SZ) is a severe and enduring mental illness, afflicting 1 % of the population. Despite some treatment advances, most notably the discovery of the antipsychotic drugs, many people with SZ continue to suffer substantial disability associated with ongoing distressing symptoms. For example, in Australia (where this trial will take place) the recent Survey of High Impact Psychosis (SHIP) found that 41.3 % of the 1825 participants with a psychotic illness were, despite treatment, experiencing persistent psychotic symptoms [ 1 ]. Negative symptoms and cognitive deficits are the most poorly re (...truncated)


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Susan Rossell, Paul Francis, Cherrie Galletly, Anthony Harris, Dan Siskind, Michael Berk, Kiymet Bozaoglu, Frances Dark, Olivia Dean, Dennis Liu, Denny Meyer, Erica Neill, Andrea Phillipou, Jerome Sarris, David Castle. N-acetylcysteine (NAC) in schizophrenia resistant to clozapine: a double blind randomised placebo controlled trial targeting negative symptoms, BMC Psychiatry, 2016, pp. 320, 16, DOI: 10.1186/s12888-016-1030-3