Pyridoxamine: a Novel Treatment for Schizophrenia with Enhanced Carbonyl Stress
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Psychiatry and Clinical Neurosciences 2018; 72:35–44 doi:10.1111/pcn.12613 Regular Article Pyridoxamine: A novel treatment for schizophrenia with enhanced carbonyl stress , ,† ,† Masanari Itokawa, MD, PhD,1,2,3 * Mitsuhiro Miyashita, MD, PhD ,1,2,4 Makoto Arai, PhD,1 Takashi Dan, MD, PhD,5 Katsuyoshi Takahashi, MD, PhD,2 Taro Tokunaga, MD,2 Kayo Ishimoto, MD,2 Kazuya Toriumi, PhD,1 Tomoe Ichikawa, PhD,1 Yasue Horiuchi, PhD,1 Akiko Kobori, MS,1 Satoshi Usami, PhD,6 Takeo Yoshikawa, MD, PhD,3 Naoji Amano, MD, PhD,4 Shinsuke Washizuka, MD, PhD,4 Yuji Okazaki, MD2 and Toshio Miyata, MD, PhD5 1Project for Schizophrenia Research, Tokyo Metropolitan Institute of Medical Science, 2Department of Psychiatry, Tokyo Metropolitan Matsuzawa Hospital, Tokyo, 3Laboratory for Molecular Psychiatry, RIKEN Brain Science Institute, Wako, 4Department of Psychiatry, Shinshu University School of Medicine, Matsumoto, 5Division of Molecular Medicine and Therapy, Tohoku University Graduate School of Medicine, Sendai, and 6Graduate School of Education, University of Tokyo, Tokyo, Japan Aim: The aim of this clinical trial was to obtain considerable reduction in psychosis accompanied proof of concept for high-dose pyridoxamine as a with a moderate decrease in plasma pentosidine novel treatment for schizophrenia with enhanced levels. A reduction of greater than 20% in the carbonyl stress. assessment scale of drug-induced Parkinsonism occurred in four patients. Although there was no Methods: Ten Japanese schizophrenia patients with severe suicide-related ideation or behavior, Wer- high plasma pentosidine, which is a representative nicke’s encephalopathy-like adverse drug reactions biomarker of enhanced carbonyl stress, were recruited occurred in two patients and were completely sup- in a 24-week, open trial in which high-dose pyridox- pressed by thiamine supplementation. amine (ranging from 1200 to 2400 mg/day) was administered using a conventional antipsychotic regi- Conclusion: High-dose pyridoxamine add-on treat- men. Main outcomes were the total change in Positive ment was, in part, effective for a subpopulation of and Negative Syndrome Scale score and the Brief Psy- schizophrenia patients with enhanced carbonyl chiatric Rating Scale score from baseline to end of stress. Further randomized, placebo-controlled trials treatment at week 24 (or at withdrawal). with careful monitoring will be required to validate the efficacy of high-dose pyridoxamine for these Results: Decreased plasma pentosidine levels were patients. observed in eight patients. Two patients showed marked improvement in their psychological symp- toms. A patient who harbors a frameshift muta- Key words: advanced glycation end-products, car- tion in the Glyoxalase 1 gene also showed bonyl stress, pentosidine, pyridoxamine, schizophrenia. CHIZOPHRENIA IS A devastating disorder char- S acterized by positive symptoms, including audi- *Correspondence: Masanari Itokawa, MD, PhD, Center for Medical tory hallucinations and delusions, and negative Research Cooperation, Tokyo Metropolitan Institute of Medical Science, symptoms, including blunted affect, anhedonia, and 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan. cognitive deficits. The lifetime prevalence ranges Email: [email protected] † from approximately 0.3% to 0.7%, and disease Both authors contributed equally to this manuscript. Received 11 June 2017; revised 7 September 2017; onset frequently occurs during puberty or early ado- accepted 18 October 2017. lescence. Adequate psychosocial support as well as © 2017 The Authors 35 Psychiatry and Clinical Neurosciences © 2017 Japanese Society of Psychiatry and Neurology 36 M. Itokawa et al. Psychiatry and Clinical Neurosciences 2018; 72:35–44 psychopharmacologic treatment is needed to achieve In contrast, clinical interventions, such as pyridox- and maintain recovery. Although many studies have amine supplementation, aimed at reducing carbonyl been conducted to clarify the underlying mechanism stress, may provide a safe and effective treatment for of the disease, the main cause and pathophysiology schizophrenia patients with enhanced carbonyl of schizophrenia still remains elusive since there is stress. To test this hypothesis, we conducted a 24- considerable heterogeneity in symptoms, and long- week, open-label clinical trial with high-dose pyri- term clinical courses differ substantially from patient doxamine supplementation in schizophrenia to patient. patients. In this study, two patients showed marked Carbonyl stress is an abnormal metabolic state improvement in clinical symptoms, and one patient resulting from either increased production of reac- showed considerable improvement in psychological tive carbonyl compounds (RCO) or decreased detox- symptoms accompanied by a moderate decrease in ification of RCO.1 Advanced glycation end products plasma pentosidine levels. Additionally, four partici- (AGE) are generated as a consequence of elevated pants showed improvements in drug-induced Par- carbonyl stress, and numerous experimental studies kinsonism and two patients experienced Wernicke’s in animals and humans implicate increased AGE in encephalopathy, which was completely alleviated – a variety of diseases, including diabetes mellitus,2 4 following thiamine supplementation. chronic kidney disease,1 cardiovascular diseases5 and cognitive impairment with or without – METHODS dementia.6 8 Pyridoxamine, one of the three forms of vitamin B6, is capable of scavenging certain RCO, Subjects thereby inhibiting the formation of AGE and allevi- Inclusion criteria for this clinical trial were patients ating their unfavorable physiological effects. The with schizophrenia or schizoaffective disorder aged other forms of vitamin B6, pyridoxine and pyridoxal, 20–65 years who were hospitalized in Matsuzawa fi lack this therapeutic bene t. However, pyridoxamine Metropolitan Hospital. Diagnoses were made by at is synthesized from both pyridoxal and pyridoxine least two experienced psychiatrists according to the in vivo, so that depleting pyridoxamine to combat DSM-IV-TR. Patients with diabetes mellitus or chronic enhanced carbonyl stress eventually leads to kidney disease were excluded, since both diseases decreases in both pyridoxal and pyridoxine. occasionally induce increased plasma pentosidine We previously reported that enhanced carbonyl levels. Other exclusion criteria included: organic men- stress is associated with a subpopulation of patients tal diseases, substance dependence, past history of 9 suffering from schizophrenia. In addition, a close substance dependence, comorbid malignant tumors, relationship between schizophrenia and carbonyl pregnancy, modified electroconvulsive therapy within 10 stress was also found in a larger cohort, and a 3 months, prescription to theophylline, choline the- drug-naïve patient with high pentosidine levels has ophylline, aminophylline and levodopa (which are 11 been reported. Clinical features of patients with contraindicated with pyridoxamine), and severe phys- enhanced carbonyl stress are similar to those with ical conditions that made study participation inappro- treatment-resistant schizophrenia, and negative cor- priate. Eligible patients exhibited enhanced carbonyl relations between psychological symptoms of stress defined as elevated plasma pentosidine levels schizophrenia and serum pyridoxal levels have been according to a previous report9 (>55.2 ng/mL; defined 12 reported. Likewise, a recent study suggests that above 2 SD of healthy control subjects). In this study, pyridoxal levels could be a possible biomarker to serum pyridoxal levels could not be used as an inclu- predict the clinical course in a subset of schizophre- sion criterion because the number of patients fulfilling 13 nia patients. Clozapine is the most effective agent both high pentosidine and low pyridoxal were so few among various antipsychotics for patients with that sufficient participants could not be recruited. 14,15 treatment-resistant schizophrenia. However, the After patient selection, 10 eligible patients were identi- use of clozapine is restricted because of serious and fied for this clinical trial. lethal adverse effects, including granulocytopenia,16 which require strict and frequent monitoring of white blood cell counts. Thus, clozapine treatment Study design causes problems for both patients as well as health- A 24-week, open-label design was adopted. Pyridox- care providers. amine was initiated with a dose of 1200 mg/day © 2017 The Authors Psychiatry and Clinical Neurosciences © 2017 Japanese Society of Psychiatry and Neurology Psychiatry and Clinical Neurosciences 2018; 72:35–44 Pyridoxamine treatment for schizophrenia 37 supplementing the existing antipsychotic regimen, phosphate-buffered saline. A sample (corresponding with the responsible doctor setting the daily dose to 25 μg of protein) was injected into an HPLC sys- (1200, 1800, or 2400 mg/day) during the trial. The tem and fractionated on a C18 reverse-phase col- dose was determined according to phase I clinical umn. Eluent was monitored at excitation-emission trials. To avoid degradation, we stored pyridoxamine wavelengths of 335/385 nm using a fluorescence in powder form in a light-blocking box and dis- detector (RF-10A; Shimadzu, Kyoto, Japan). Syn- solved it in water and syrup (to reduce sourness) for thetic pentosidine was used to obtain a standard three daily oral administrations. Treatment adher- curve. Three forms of vitamin B6 (pyridoxine, pyri- ence and the general condition of all participants doxal,