Pyridoxamine: A novel treatment for schizophrenia with enhanced carbonyl stress.

AIM: The aim of this clinical trial was to obtain proof of concept for high-dose pyridoxamine as a novel treatment for schizophrenia with enhanced carbonyl stress. METHODS: Ten Japanese schizophrenia patients with high plasma pentosidine, which is a representative biomarker of enhanced carbonyl stress, were recruited in a 24-week, open trial in which high-dose pyridoxamine (ranging from 1200 to 2400 mg/day) was administered using a conventional antipsychotic regimen. Main outcomes were the total change in Positive and Negative Syndrome Scale score and the Brief Psychiatric Rating Scale score from baseline to end of treatment at week 24 (or at withdrawal). RESULTS: Decreased plasma pentosidine levels were observed in eight patients. Two patients showed marked improvement in their psychological symptoms. A patient who harbors a frameshift mutation in the Glyoxalase 1 gene also showed considerable reduction in psychosis accompanied with a moderate decrease in plasma pentosidine levels. A reduction of greater than 20% in the assessment scale of drug-induced Parkinsonism occurred in four patients. Although there was no severe suicide-related ideation or behavior, Wernicke's encephalopathy-like adverse drug reactions occurred in two patients and were completely suppressed by thiamine supplementation. CONCLUSION: High-dose pyridoxamine add-on treatment was, in part, effective for a subpopulation of schizophrenia patients with enhanced carbonyl stress. Further randomized, placebo-controlled trials with careful monitoring will be required to validate the efficacy of high-dose pyridoxamine for these patients.

Adverse renal effects of the AGE inhibitor pyridoxamine in combination with ACEi in non-diabetic adriamycin-induced renal damage in rats.

BACKGROUND/AIMS: Advanced glycation end products (AGEs) are involved in diabetic nephropathy. The AGE inhibitor pyridoxamine (PM) is renoprotective in experimental chronic allograft nephropathy supporting its potential in non-diabetic renal damage. METHODS: We studied the effects of PM in adriamycin nephropathy (AN; 1.5 mg/kg i.v.). Six weeks after disease induction, treatment started with vehicle (VEH), lisinopril (ACEi; 75 mg/l drinking water), PM (2 g/l) and PM + lisinopril (PM/ACEi) (n = 12 per group) for 18 weeks. Age-matched healthy rats (n = 6) served as controls (CON). RESULTS: ACEi reduced proteinuria, blood pressure, and renal damage. PM gradually increased blood pressure and not affected proteinuria. In PM/ACEi the antiproteinuric and blood pressure-lowering effects of ACEi were abrogated during long-term treatment. Remarkably, creatinine, focal glomerulosclerosis and interstitial fibrosis were considerably increased under PM/ACEi. Pronounced hypercholesterolemia, which occurred in both PM-treated groups, was accompanied by marked glomerular lipid deposition. CONCLUSION: PM was not renoprotective in AN. By contrast, renal damage was aggravated when PM was combined with ACEi. Despite the fact that there is no current evidence that these findings apply to the drug as used in human diabetic nephropathy, we emphasize the importance of close monitoring of blood pressure, lipids and possible direct toxic effects in future studies with PM in renal patients, especially when combining PM with ACEi.