title: Systematic review of the efficacy and tolerability of clozapine in the treatment of youth with early onset schizophrenia.
abstract: BACKGROUND
  The use of clozapine (CLZ) for treatment-resistant schizophrenia is well established in adults. However, it is seldom used in youth with early onset schizophrenia (EOS) largely because of lack of clarity about its risk benefit ratio. This review synthesises and evaluates available evidence regarding the efficacy and tolerability of CLZ in EOS with the aim to assist clinical decision-making.
  
  
  METHODS
  We conducted a systematic review of the primary literature on the clinical efficacy and adverse drug reactions (ADRs) observed during CLZ treatment in EOS. We also identified relevant practice guidelines and summarised current guidance.
  
  
  RESULTS
  CLZ showed superior efficacy than other antipsychotics in treating refractory EOS patients; short-term clinical trials suggest an average improvement of 69% on the Brief Psychiatric Rating Scale that was sustained during long-term follow-up (up to 9 years). No fatalities linked to CLZ treatment were reported. Sedation and hypersalivation were the most common complaints, reported by over 90% of patients. Other common ADRs (reported in 10-60% of patients) were enuresis, constipation, weight gain, and non-specific EEG changes. Less common ADRs (reported in 10-30% of patients) were akathisia, tachycardia and changes in blood pressure. Neutropenia was reported in 6-15% of cases but was usually transient while agranulocytosis was rare (<0.1%). Seizures were also uncommon (<3%). Metabolic changes were relatively common (8-22%) but emergent diabetes was not frequently observed (<6%). Overall the rate of discontinuation was low (3-6%). Current guidelines recommend the use of CLZ in EOS patients who have failed to respond to two adequate trials with different antipsychotics and provide detailed schedules of assessments to evaluate and assess potential ADRs both prior to initiation and throughout CLZ treatment.
  
  
  CONCLUSIONS
  Available data although limited in terms of number of studies are consistent in demonstrating that CLZ is effective and generally safe in the treatment of refractory EOS provided patients are regularly monitored.
authors.affiliation: Child and Adolescent Mental Health Services, South London and Maudsley NHS Foundation Trust, London, UK.
authors.forename: C
authors.initials: C
authors.lastname: Schneider
authors.affiliation: Child and Adolescent Mental Health Services, South London and Maudsley NHS Foundation Trust, London, UK.
authors.forename: R
authors.initials: R
authors.lastname: Corrigall
authors.affiliation: Child and Adolescent Mental Health Services, South London and Maudsley NHS Foundation Trust, London, UK.
authors.forename: D
authors.initials: D
authors.lastname: Hayes
authors.affiliation: Child and Adolescent Mental Health Services, South London and Maudsley NHS Foundation Trust, London, UK.
authors.forename: M
authors.initials: M
authors.lastname: Kyriakopoulos
authors.affiliation: Department of Psychiatry, Icahn School of Medicine at Mount Sinai, Box 1230, 1425, Madison Avenue, New York, NY 10029, USA. Electronic address: sophia.frangou@mssm.edu.
authors.forename: S
authors.initials: S
authors.lastname: Frangou
mesh_terms: D000293:Adolescent; D014150:Antipsychotic Agents / Q000009:adverse effects / Q000494:pharmacology / Q000627:therapeutic use*; D003024:Clozapine / Q000009:adverse effects / Q000494:pharmacology / Q000627:therapeutic use*; D042241:Early Diagnosis; D006801:Humans; D012559:Schizophrenia / Q000175:diagnosis / Q000188:drug therapy*
chemical_list: D014150:Antipsychotic Agents; D003024:Clozapine
keywords: Clozapine; Early onset; Efficacy; Paediatric; Schizophrenia; Tolerability