Use of Paricalcitol as Adjunctive Therapy to Renin-Angiotensin-Aldosterone System Inhibition for Diabetic Nephropathy: A Systematic Review of the Literature.

Purpose: Diabetic nephropathy (DN) is a major complication of diabetes. Paricalcitol is a vitamin D analog that is typically used for secondary hyperparathyroidism in patients with chronic kidney disease but may have some beneficial effect on DN. This review evaluates the effect of paricalcitol in combination with renin-angiotensin-aldosterone system inhibitor therapy in managing DN.

Methods: A literature search was conducted of PubMed and ClinicalTrials.gov. Limits were set to include only clinical trials in humans written in English. The search terms used were paricalcitol and diabetic nephropathy. The following outcomes of kidney function and damage as well as adverse drug events were assessed and included: 24-h urine albumin excretion, serum phosphorus and calcium concentrations, urinary albumin excretion rates, estimated glomerular filtration rate, and markers of inflammation and endothelial function.

Findings: Four studies with a total of 389 patients were identified for review through the process described above. Two of the 6 studies provide evidence of the effect of paricalcitol on DN by way of reduction in urine albumin to creatinine ratio and urinary albumin excretion rate when compared with placebo. One study reported an increase in serum phosphorous, 1 study observed a decrease in estimated glomerular filtration rate, and 1 study reported no effect on inflammatory markers or endothelial function.

Implications: The number of clinical trials examining the effect of paricalcitol in DN is small. The studies that have been completed enrolled <300 patients. Paricalcitol can reduce protein in the urine, but there is no compelling evidence that it preserves kidney function.