Dual Impact of Tolvaptan on Intracellular and Extracellular Water in Chronic Kidney Disease Patients with Fluid Retention.

Objective Tolvaptan, an oral selective V2-receptor antagonist, is a water diuretic that ameliorates fluid retention with a lower risk of a worsening renal function than conventional loop diuretics. Although loop diuretics predominantly decrease extracellular water (ECW) compared with intracellular water (ICW), the effect of tolvaptan on fluid distribution remains unclear. We therefore examined how tolvaptan changes ICW and ECW in accordance with the renal function. Methods Six advanced chronic kidney disease patients (stage 4 or 5) with fluid retention were enrolled in this study. Tolvaptan (7.5 mg/day) added to conventional diuretic treatment was administered to remove fluid retention. The fluid volume was measured using a bioimpedance analysis device before (day 0) and after (day 5 or 6) tolvaptan treatment. Results Body weight decreased by 2.6%±1.3% (64.4±6.5 vs. 62.8±6.3 kg, p=0.06), and urine volume increased by 54.8%±23.9% (1,215±169 vs. 1,709±137 mL/day, p=0.03) between before and after tolvaptan treatment. Tolvaptan significantly decreased ICW (6.5%±1.5%, p=0.01) and ECW (7.5%±1.4%, p=0.02), which had similar reduction rates (p=0.32). The estimated glomerular filtration rate remained unchanged during the treatment (14.6±2.8 vs. 14.9±2.7 mL/min/1.732 m, p=0.35). Conclusion Tolvaptan ameliorates body fluid retention, and induces an equivalent reduction rate of ICW and ECW without a worsening renal function. Tolvaptan is a novel water diuretic that has a different effect on fluid distribution compared with conventional loop diuretics.

[Comparison of benefits to non-dialysis CKD patients between darbepoetin alpha and epoetin beta pegol].

BACKGROUND: Erythropoiesis-stimulating agents (ESAs) are the mainstay of treatment for renal anemia in chronic kidney disease (CKD) patients. However, the difference in hematopoietic effect between darbepoetin alfa (DA) and continuous erythropoiesis receptor activator (CERA) has remained unclear in non-dialysis CKD patients. Another purpose of this study was to analyze the red blood cells indices under treatment with these two ESAs in ESA-naïve CKD patients. METHODS: This study was designed as a multicenter retrospective observational investigation, and included 61 patients receiving DA (group DA) and 36 patients receiving CERA (group CERA) for at least six months. Relative effect of these ESAs was determined by comparing means of the individual monthly average of the area under the curve above the initial level of hemoglobin (Hb), hematocrit (Hct), and red blood cell count (RBC) with the trapezoidal rule, which are maintenance ratios. Serial changes in mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC) were also evaluated. RESULTS: No differences were found in the mean ratios of Hb, Hct, and RBC, and maintenance ratios of these parameters. The ratio of MCH in group CERA was decreased compared with that in group DA. Subsequent decrease in MCV was also remarkable in group CERA. CONCLUSIONS: It is speculated that iron demand increased during the administration of CERA, which was suggested by changes in the red cell indices. Reticulocyte indices and iron-related parameters could provide a more detailed explanation and the significance of iron supplementation during administration of CERA should be clarified when compared with other types of ESA.