SP395
SEVELAMER HYDROCHLORIDE IMPROVES OXIDATIVE STRESS IN MAINTENANCE HEMODIALYSIS PATIENTS Free

Introduction and Aims: Oxidative stress plays a key role in the pathogenesis of cardiovascular diseases. Superoxide dismutase (SOD) and malondialdehyde (MDA) are well-known antioxidant enzymes that detoxifies highly oxidant compounds as advanced glycation end products (AGEs). We thought that avoiding calcium intake and through pleiotropic effects, sevelamer hydrochloride might be a differential influence in terms of oxidative stress. The aim of this study is to evaluate the effects of phosphate binders (PBs) on the components of the oxidative stress and clinical and biochemical parameters including pulse wave velocity in our maintenance hemodialysis (MHD) patients.

Methods: A total of 111 patients (mean age: 52.2 ± 14.3 years; mean duration of dialysis: 9.7 ± 4.6 years) undergoing maintenance hemodialysis and using the same PBs at least one year were enrolled into the study. Patients were divided into two groups according to usage of PBs as sevelamer based PB (group 1; n: 84 and calcium based PB (group 2; n.27). Biochemical parameters as fasting plasma glucose (FPG), hemoglobin A1c (HbA1c), calcium, phosphorus, bicarbonate, C-reactive protein (CRP), lipid prophile, uric acid and urea reduction rate (URR) were assessed from monthly clinical visits in one year follow up period. Serum AGE, MDA and SOD levels were determined by ELISA method. Pulse wave velocity (PWv) was determined from pressure tracing over carotid and femoral arteries using the SphygmoCor system and change in PWv levels through 1 year was evaluated with ∆PWV. ∆PWV was calculated as (PWV2-PWV1)/PWV1.

Results: Groups were similar in means of demographic characteristics (age, gender, duration of dialysis, comorbidity score) and biochemical parameters as serum calcium, phosphorus, parathyroid hormone, uric acid, CRP, lipid profile and URR levels. Patients in group 1 had significantly lower AGE (3.6±2.2 u/mL vs 4.8±2.4 u/mL; p: 0.018), higher MDA (27.8 ± 14.8 µmol/L vs 21.3 ± 5.9 µmol/L, p: 0.027) and SOD (6.0 ± 1.5 U/ml vs 5.1 ± 1.6 U/ml; p: 0.012) levels. Although both baseline and first year PWv values were similar in two groups, PWv values significantly decreased in group 1 (p: 0.001) where increased in group 2 (p: 0.021) in the second year analysis. In linear regression analysis, serum AGE levels were detected as the unique predictor of ∆PWV (p: 0.005). For each 1 u/mL of increased level of AGE resulted in 0.53 cm/sec of increased level of PWv (p: 0.005, CI: 0.016-0.089).

Conclusions: Despite similar phosphorus levels and dialysis adequency, sevelamer decreases serum AGE and increases serum MDA and SOD levels as well as improves PWv. Thus, sevelamer improves the oxidative stress and cardiovascular risk by pleiotropic effects when compared to calcium based phosphate binders.