Addition of aliskiren to olmesartan ameliorates tubular injury in chronic kidney disease patients partly by reducing proteinuria.

Introduction: Tubular injury is more important than glomerulopathy for renal prognosis in chronic kidney disease (CKD) patients. Numerous studies have demonstrated the active participation of the renin-angiotensin system (RAS) in CKD. However, whether addition of aliskiren, a direct renin inhibitor, to olmesartan improves renal tubular injury in CKD patients is unknown.

Methods: This study compared the effects of aliskiren (300 mg daily), olmesartan (40 mg daily), and its combination therapy on urinary L-fatty acid binding protein (L-FABP), a marker of tubular injury in stage I or II CKD patients. It also examined which clinical variables were independently correlated with tubular damage.

Results: Olmesartan or aliskiren monotherapy for 6 months comparably decreased blood pressure (BP) and proteinuria. BP and proteinuria levels were reduced more by combination therapy than by either monotherapy. Olmesartan or aliskiren decreased urinary L-FABP level, and combination therapy produced more incremental reduction in L-FABP level relative to each monotherapy. Multiple stepwise regression analysis revealed that BMI, low-density lipoprotein (LDL)-cholesterol and proteinuria were independently related to urinary L-FABP level.

Conclusions: The present study demonstrated that addition of aliskiren to olmesartan decreased urinary L-FABP level partly via reduction of proteinuria in stage I or II CKD patients.