Methods	Allocation: random, no further details. Blindness: double, no further details. Duration: 8 weeks. Design: parallel. Location: single centre.
Participants	Diagnosis: (CCMD-3) schizophrenia. N=63. Gender: not reported. Age: mean clozapine=30 years, mean quetiapine=28 years. History: duration ill mean clozapine=0.63 years, mean quetiapine=0.65 years, age at onset not reported. Setting: in- and outpatient.
Interventions	Clozapine: flexible dose. Allowed dose range: 25-750 mg/day. Mean dose: 270.5 mg/day. N=31. Quetiapine: flexible dose. Allowed dose range: 25-750 mg/day. Mean dose: 478.5 mg/day. N=32
Outcomes	Leaving the study early: any reason. Global State: CGI. Mental State: PANSS total score. Adverse effects: open interviews, cardiac effects (palpitation), EPS (akathisia, rigor, tremor), sedation, weight gain, laboratory (white blood cell count) Unable to use - Leaving the study early: due to adverse events (not fully reported)
Notes
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	Random, no further details.
Allocation concealment?	Unclear	No further details
Blinding? Subjective outcomes	Unclear	Double, probably identical capsules. Whether blinding was successful has not been examined, but both compounds differ quite substantially in side effects. This can be a problem for blinding
Blinding? Objective outcomes	Yes	Objective outcomes such as laboratory measures or death are unlikely to have been much affected by problems of blinding
Incomplete outcome data addressed? All outcomes	Unclear	Two participants left the study early due to adverse events in the clozapine group. There is some doubt whether all data on leaving the study early have been presented
Free of selective reporting?	Yes	We did not find evidence for selective reporting.
Free of other bias?	Unclear	There were no data on pre study medication, therefore baseline imbalance can not be excluded