To study the in vivo effect of epalrestat (Epa), an aldose reductase inhibitor, on the generation of oxygen-derived free radicals by neutrophils from poorly controlled NIDDM patients (HbA1c > 10%).
A total of 31 diabetic patients were randomly divided into two groups: an Epa(+) group of 16 patients treated with 150 mg/day epalrestat and an Epa(−) group of 15 patients treated without epalrestat. A control group of 20 age- and sex-matched normal healthy subjects also participated. HbA1c, postprandial plasma glucose (PPG), and neutrophil bactericidal function were measured before and at the end of the drug treatment period (4 weeks). Neutrophil bactericidal function was measured as chemilu-minescence amplified by a Cypridina luciferin analog (CLA), which is dependent on O2− generation, and by luminol (L), which is highly dependent on OCl− generation, in response to formyl-methonyl-leucyl-phenylalanine (fMLP).
At the start of the experiment, both CLA-dependent chemiluminescence (CLA-DCL) and L-dependent chemiluminescence (L-DCL) were clearly decreased in diabetic subjects (64 and 54%, respectively; P < 0.05) compared with control subjects (2,182 ± 144 and 3,221 ± 173 kc · min−1 · 10−6 cells, respectively). At the end of the experiment, CLA-DCL and L-DCL in the Epa(+) group were significantly improved by 44 and 46%, respectively; however, these values were still lower than the corresponding results in the control group. HbA1c and PPG in both the Epa(+) and Epa (−) groups were significantly higher than in the control group, and treatment had no effect on either HbA1c or PPG.
These data suggest that epalrestat may be a useful drug to prevent infection by improving the impaired O2− and OCl− generation by neutrophils from poorly controlled NIDDM patients.
