Conditions: Schizophrenia
Allocation: RANDOMIZED | Intervention model: CROSSOVER
Enrollment: 13
Healthy volunteers: no

Brief summary:
STUDY OBJECTIVES: To determine whether the addition of L-arginine to treatment as usual (TAU) in schizophrenia further improves and enhances therapeutic efficacy (positive, negative and depressive symptoms) and effectiveness of antipsychotic treatment

STUDY POPULATION: Patients diagnosed (DSM-IV criteria) with schizophrenia or schizoaffective disorder

Total expected number of patients: 14

INVESTIGATIONAL COMPOUND: L-arginine capsules, 3 grams of L-arginine given twice a day (total daily dose of 6 grams/day)

DURATION OF ACTIVE TREATMENT: 3 weeks followed by wash-out phase of 5 days and 3 weeks of second treatment phase (cross-over design)

EVALUATION CRITERIA: Primary (efficacy) outcomes: PANSS scores. Secondary outcomes: Calgary Depression Scale for schizophrenia, CGI; AIMS, UKU-assessment of side-effects

ASSESSMENT SCHEDULE: Treatment arm 1: Baseline, weeks: 1,2,3, wash-out phase; week 4, cross-over phase: treatment phase-2; weeks 5,6,7

STATISTICAL CONSIDERATIONS: Analysis of variance of outcome measures with treatment as the between-subject factor and pre- and post-treatment scores as within- subjects factors.

DURATION OF STUDY PERIOD: Patient recruitment to be completed in 12 months, study full completion 18 months.

Detailed description:
In the current study, our goals were to examine the clinical benefits of the nitric oxide (NO) donor and main precursor of NO, L-arginine, to further improve the symptoms of schizophrenia with minimum or no additional side-effects. L-Arginine is classified as a semi-essential or conditionally essential amino acid depending on the developmental stage and health status of the individual. Glutamate N-methyl-D-aspartate (NMDA) receptors have functional connections to the NO system in the brain. Dysfunction of connectivity of the neuroregulators glutamate and NO have been implicated in mechanisms of psychosis. Therefore, any downstream effects of NMDA dysfunction in schizophrenia may be ultimately mediated by the NO system at a cellular level. As an augmenting treatment to antipsychotic therapy, we examined the ability of L-arginine to further improve residual symptoms in the illness.

Arms:
arm 1: Patients with diagnosis of schizophrenia will be randomised to receive L-arginine first/placebo second 3 grams bid (cross-over design) in addition to treatment as usual. The active treatment period will be 3 weeks, with a wash-out period of 5 days and re-commencing on the alternative arm of the randomization arm 2: Patients with diagnosis of schizophrenia will be randomised to receive placebo first/L-arginine second 3 grams bid (cross-over design) in addition to treatment as usual. The active treatment period will be 3 weeks, with a wash-out period of 5 days and re-commencing on the alternative arm of the randomization

Interventions: intervention 1: L-Arginine
Intervention descriptions: intervention 1: 3 grams, twice daily, oral administration

Protocol document: