Effects of tolvaptan on renal function in chronic kidney disease patients with volume overload.

Background: Fluid overload in chronic kidney disease (CKD) is generally controlled by diuretics, with potentially harmful effects on renal function. The efficacy of tolvaptan, a vasopressin V2-receptor antagonist and aquaretic, has not been evaluated for fluid control in CKD with reduced renal function.

Methods: Each patient from a group of 24 CKD patients on tolvaptan 15 mg/d plus conventional diuretics (T group) was matched by age and sex with a patient from a group of 24 CKD patients on conventional nonaquaretic diuretics alone not associated to tolvaptan other than tolvaptan (C group). Changes in renal function were compared between the groups for 1 year.

Results: There were no significant differences in blood pressure, hemoglobin levels, cardiac function, urine specific gravity, and urinary sodium concentration between the 2 groups at the beginning of the follow-up period and 1 year after. The estimated glomerular filtration rate (eGFR) by the formula developed by Japanese Society of Nephrology (in mL/min/1.73 m2 ) decreased: C group (from 28.3±13.6 to 23.0±12.3, p =0.09), T group (from 22.7±12.4 to 19.4±12.2, p =0.18), but both did not reach significance. A 50% reduction in eGFR was observed in 4 patients in the C group and 1 in the T group ( p <0.05). A subgroup analysis performed on the patients with stage 3-4 CKD demonstrated a significant reduction in eGFR in the C group (n=17, p =0.04), but not in T group (n=17, p =0.07).

Conclusion: These results suggest that tolvaptan may have less effects on CKD progression among stage 3-4 CKD patients who are on conventional diuretics.