Effect of Oral Isosorbide Mononitrate Therapy on Proteinuria in Patients with Nephrotic Syndrome

Abstract

Objective: Proteinuria is the most important causitive factor in the progression of renal failure Angiotensin- converting enzyme inhibitors (ACEIs) and angiotensin- receptor blockers (ARBs) are shown to reduce proteinuria however in some patients, these drugs are not adequately effective. Oral nitrates may reduce proteinuria by way of glomerular vasodilation with resultant decrease in intraglomerular pressure. In this study the possible effects of oral isosorbide mononitrate (IMN) on proteinuria in patients with nephrotic syndrome was investigated. Material and Methods: A total of 36 patients with nephrotic syndrome (proteinuria >1 g/day) requiring oral IMN for symptomatic ischemic heart disease were enrolled. Results: Proteinuria was significantly decreased with the initiation of IMN (p=0.02) in all patients. In patients on combined ACEI and ARB treatment, IMN was effective in reducing proteinuria (p=0.01) however it was not effective in patients on single agent therapy as ACEI or ARB; (p=0.15). IMN was also effective in diabetic patients (p=0.02), but not effective in non-diabetic patients (p=0.33). IMN was ineffective in patients on calcium channel blocker treatment (CCB), (p=0.96). Decrease in proteinuria was associated with baseline proteinuria (p<0.001). Patients who responded to IMN therapy were significantly younger (p=0.01). In the logistic regression analysis for predicting the effectiveness of IMN, age, baseline proteinuria, ACEI, ARB, CCB use, presence of diabetes were included as independent variables. Only age and ACEI use were significant parametres. Conclusion: Oral nitrates may be effective for reducing proteinuria in patients with nephrotic syndrome. This favorable effect seemed to be more prominent in younger, diabetic patients using both ACEI and ARB.