Intervention: Cannabidiol
Trial phase: Phase 2
ATC code: N03AX24
SMILES: C=C(C)[C@@H]1CCC(C)=C[C@H]1c1c(O)cc(CCCCC)cc1O
Sex: All
Age groups: Adult | Older Adult
Healthy volunteers: No
Participants at risk: 43
Group description: Participants received GWP42003 (100 mg/mL), 5 mL BID administered orally, 5 mL in the morning and 5 mL in the evening for 6 weeks.
Eligibility criteria:
Inclusion Criteria (all must be fulfilled):

Participant gave written informed consent for participation in the study and did not require involuntary treatment.
Participant was male or female aged 18 to 65 years.
Participant was able (in the investigator's opinion) and willing to comply with all study requirements.
Participant was diagnosed with schizophrenia or a related psychotic disorder (such as schizoaffective or schizophreniform disorder) as defined by the Diagnostic and Statistical Manual of Mental Disorders Version 4.
Participant was treated for a minimum of four-weeks and was on a stable dose of his or her current anti-psychotic (AP) medication.
Participant showed the capacity to respond at least partially to first line AP medication in the opinion of the investigator.
Participant remained stable on his or her dose of AP and concomitant medications for the duration of the study, in the opinion of the investigator.
Participant was willing for his or her name to be notified to the responsible authorities for participation in this study, as applicable in individual countries.
Participant was willing to allow his or her primary care practitioner and consultant, if appropriate, to be notified of participation in the study.

Exclusion Criteria (any of the following):

Participant had any known or suspected hypersensitivity to cannabinoids or any of the excipients of the Investigational Medicinal Product (IMP).
Participant had a Positive and Negative Symptom Scale total score of <60 at Day 1.

Participant presented with a current clinical picture and/or history that is consistent with:

i. delirium or dementia. ii. acute drug induced psychosis. iii. bipolar disorder.

Participant was taking more the one AP medication during the study.
Female participants of child bearing potential and male participants whose partner was of child bearing potential, unless willing to ensure that they or their partner used effective contraception, for example, oral contraception, double barrier, intra-uterine device, during the study and for three months thereafter (a male condom was not used in conjunction with a female condom).
Female participant who was pregnant, lactating, or planning pregnancy during the course of the study and for three months thereafter.
Participants who had received an IMP within 30 days prior to the screening visit.
Participants who had any other significant disease or disorder which, in the opinion of the investigator, either put the participant at risk because of participation in the study, or may have influenced the result of the study, or the participant's ability to participate in the study.
Participant had any abnormalities following a physical examination that, in the opinion of the investigator, prevented the participant from safe participation in the study.
Participant was unwilling to abstain from donation of blood during the study.
Participant had travelled outside the country of residence during the study.
Participant previously randomized into this study.