Current antipsychotic treatments of schizophrenia are only partially effective, and their use
is often associated with serious side effects. Cannabidiol is a natural counterpart of the
psychoactive component of marijuana, delta-9- tetrahydrocannabinol and has no psychotomimetic
or addictive properties. In a controlled clinical trial of cannabidiol versus amisulpride in
acute paranoid schizophrenia we showed a statistically significant clinical improvement in
all symptoms clusters of schizophrenia compared to baseline with either treatment.
Cannabidiol displayed a significantly superior side-effect profile in particular regarding
prolactin elevation, extrapyramidal symptoms and weight gain. The favorable side-effect
profile and potentially novel mechanism of action identify this molecule as a potential
antipsychotic. However, long-term safety and efficacy data is still lacking. This study is to
evaluate the efficacy and safety of the novel compound cannabidiol in the maintenance
treatment of schizophrenia in comparison to placebo as an add-on to an established treatment
with either amisulpride, aripiprazole, olanzapine, quetiapine or risperidone, in a 12-months,
double-blind, parallel-group, randomized, placebo-controlled clinical trial. Thereby,
relevant data on cannabidiol's antipsychotic potential will be gained.