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This study evaluates the addition of L-Arginine to the usual regimen in the treatment of schizophrenia in adults. As a requisite of crossover design, half of the participants started with L-Arginine and the other half with placebo and switched over after a three weeks use and one week of a washout period.
L-arginine is the precursor of nitric oxide (NO), a neuromodulator of dopamine, gamma-aminobutyrate (GABA) and glutamate systems. Nitric oxide donors which increase NO levels at the cellular level could improve N-methyl-D-aspartate (NMDA) receptor dysfunction. Using L-arginine could bypass the blocked NMDA receptors and improve the therapeutic efficacy by reversing the dysfunction.
The investigators proposed that using L-Arginine, a dietary supplement in most cultures, might constitute a safe option as an add-on treatment which may display beneficial effects on positive, negative, cognitive and affective symptoms associated with schizophrenia.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| L-Arginine-First | Experimental | For the first three weeks, L-Arginine 3 g bid (500mg capsules 6 x 2), one week wash-out, then for the next three weeks placebo capsules (6 x 2) |
|
| Placebo-First | Experimental | For the first three weeks, placebo capsules (6 x 2), one week wash-out, then for the next three weeks L-Arginine 3 g bid (500 mg capsules 6 x 2) |
|
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| L-Arginine | Dietary Supplement | Experimental supplement |
| |
| Measure | Description | Time Frame |
|---|---|---|
| Change from baseline in Positive and Negative Syndrome Scale | Evaluating change in Positive and Negative Syndrome Scale between baseline and Week 3, comparing subjects treated with L-Arginine for 3 weeks to subjects treated with placebo for 3 weeks. | baseline and week 3 |
| Measure | Description | Time Frame |
|---|---|---|
| Change from baseline in Neuropsychological Test Battery | Evaluating change in Neuropsychological Test Battery between baseline and Week 3, comparing subjects treated with L-Arginine for 3 weeks to subjects treated with placebo for 3 weeks. | baseline and week 3 |
| Change from baseline in the The Calgary Depression Scale for Schizophrenia |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Affiliation | Role |
|---|---|---|
| Kazım M Yazıcı, MD | Hacettepe University Faculty of Medicine Department of Psychiatry | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Hacettepe University Faculty of Medicine Department of Psychiatry | Ankara | 06100 | Turkey (Türkiye) |
| PubMed Identifier | Type | Citation | Retractions |
|---|---|---|---|
| 17513442 | Background | Boger RH. The pharmacodynamics of L-arginine. J Nutr. 2007 Jun;137(6 Suppl 2):1650S-1655S. doi: 10.1093/jn/137.6.1650S. | |
| 23429845 | Background | Maia-de-Oliveira JP, Trzesniak C, Oliveira IR, Kempton MJ, Rezende TM, Iego S, Baker GB, Dursun SM, Machado-de-Sousa JP, Hallak JE. Nitric oxide plasma/serum levels in patients with schizophrenia: a systematic review and meta-analysis. Braz J Psychiatry. 2012 Oct;34 Suppl 2:S149-55. doi: 10.1016/j.rbp.2012.07.001. English, Portuguese. |
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| ID | Term |
|---|---|
| D012559 | Schizophrenia |
| D011618 | Psychotic Disorders |
| ID | Term |
|---|---|
| D019967 | Schizophrenia Spectrum and Other Psychotic Disorders |
| D001523 | Mental Disorders |
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| ID | Term |
|---|---|
| D001120 | Arginine |
| ID | Term |
|---|---|
| D024361 | Amino Acids, Basic |
| D000596 | Amino Acids |
| D000602 | Amino Acids, Peptides, and Proteins |
| D000599 | Amino Acids, Diamino |
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| Placebo |
| Other |
Placebo capsules in the same color and shape with the experimental supplement |
|
Evaluating change in The Calgary Depression Scale for Schizophrenia between baseline and Week 3, comparing subjects treated with L-Arginine for 3 weeks to subjects treated with placebo for 3 weeks. |
| baseline and week 3 |
| Change from baseline in Clinical Global Impression - Severity | Evaluating change in Clinical Global Impression - Severity between baseline and Week 3, comparing subjects treated with L-Arginine for 3 weeks to subjects treated with placebo for 3 weeks. | baseline and week 3 |
| Change from baseline in Abnormal Involuntary Movement Scale | Evaluating change in Abnormal Involuntary Movement Scale between baseline and Week 3, comparing subjects treated with L-Arginine for 3 weeks to subjects treated with placebo for 3 weeks. | baseline and week 3 |
| Change from baseline in Uku Side Effects Rating Scale | Evaluating change in Uku Side Effects Rating Scale between baseline and Week 3, comparing subjects treated with L-Arginine for 3 weeks to subjects treated with placebo for 3 weeks. | baseline and week 3 |
| Change from baseline in blood pressure | baseline and week 7 |
| Change from baseline in heart rate | baseline and week 7 |
| Change from baseline in temperature | baseline and week 7 |
| Change from baseline in respiratory rate | baseline and week 7 |
| Change from baseline in weight | baseline and week 7 |
| Change from baseline in electrocardiogram | baseline and week 7 |
| Change from baseline in complete blood count | Composed of different measures. Change in any measure indicates impairment in the composite measure | baseline and week 7 |
| Change from baseline in alanine aminotransferase | baseline and week 7 |
| Change from baseline in aspartate aminotransferase | baseline and week 7 |
| Change from baseline in alkaline phosphatase | baseline and week 7 |
| Change from baseline in urea | baseline and week 7 |
| Change from baseline in creatinine | baseline and week 7 |
| Change from baseline in sodium | baseline and week 7 |
| Change from baseline in potassium | baseline and week 7 |
| Change from baseline in chloride | baseline and week 7 |
| Change from baseline in calcium | baseline and week 7 |
| Change from baseline in thyroid-stimulating hormone | baseline and week 7 |
| Change from baseline in free T4 | baseline and week 7 |
| Change from baseline in total cholesterol | baseline and week 7 |
| Change from baseline in HDL | baseline and week 7 |
| Change from baseline in LDL | baseline and week 7 |
| Change from baseline in triglycerides | baseline and week 7 |
| Change from baseline in human chorionic gonadotropin | Pregnancy test in women | baseline and week 7 |
| 23217729 | Background | Vayisoglu S, Anil Yagcioglu AE, Yagcioglu S, Karahan S, Karci O, Gurel SC, Yazici MK. Lamotrigine augmentation in patients with schizophrenia who show partial response to clozapine treatment. Schizophr Res. 2013 Jan;143(1):207-14. doi: 10.1016/j.schres.2012.11.006. Epub 2012 Dec 2. |
| 30260460 | Derived | Kocyigit Y, Yoca G, Karahan S, Ayhan Y, Yazici MK. [L-Arginine Add-On Treatment for Schizophrenia: A Randomized,Double-Blind, Placebo-Controlled, Crossover Study]. Turk Psikiyatri Derg. 2018 Fall;29(3):147-153. Turkish. |
| D000601 | Amino Acids, Essential |