Conditions: Chronic Kidney Disease Vitamin D Deficiency Coronary Calcification Disorders of Calcium and Bone Metabolism
Keywords: Secondary Hyperparathryoidism Chronic Kidney Disease Vitamin D Coronary Calcification Bone metabolism
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 44
Healthy volunteers: no

Brief summary:
Patients with chronic kidney disease (CKD) have a higher mortality rate than the general population, with cardiovascular disease (CVD) accounting for approximately 50% of deaths. Vascular calcification is a common finding in patients with CKD. Furthermore, patients with CKD develop secondary hyperparathyroidism, partly because of a decrease of calcitriol synthesis on the kidney. Treatment of secondary hyperparathyroidism includes use of activated vitamin D including calcitriol and paricalcitol. Recent evidence in dialysis patients suggest an improved survival in patients using paricalcitol compared to calcitriol.

Studies in uremic rats suggests that there are differential effects of calcitriol and paricalcitol in expression of markers of soft-tissue calcification independent of calcium-phosphorus product. Calcitriol increased calcification of vascular smooth muscle cells cultured in calcification media. There was also significant increase in pulse pressure in animals treated with calcitriol.

The investigators hypothesize that these different forms of vitamin D may have differential effects in vascular calcification progression in CKD patients.

Detailed description:
Coronary artery calcification (CAC) is a risk marker for CVD and mortality. In animal models, calcitriol significantly increased the serum calcium-phosphate product and aortic calcium content, while paricalcitol had no effect. The objective of this randomized, blinded single-center is to determine the differential effect of oral calcitriol and paracalcitol on vascular calcification in patients with chronic kidney disease (CKD).

We performed a total of 89 screening visits and randomized 44 participants. Forty participants completed the final visit. Diagram 1 presents the recruitment schematic.

Arms:
arm 1: Calcitriol is a synthetic vitamin D analog which is active in the regulation of the absorption of calcium from the gastrointestinal tract and its utilization in the body. Calcitriol is available as capsules containing 0.25 mcg or 0.5 mcg calcitriol and as an oral solution containing 1 mcg/ml of calcitriol. All dosage forms contain butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) as antioxidants.

Subjects taking calcitriol started at 0.25 mcg 3x/week and titrated up during the next visit according to PTH levels. arm 2: Paricalcitol, USP, the active ingredient in Zemplar® Capsules, is a synthetically manufactured analog of calcitriol, the metabolically active form of vitamin D indicated for the prevention and treatment of secondary hyperparathyroidism in chronic kidney disease. Zemplar is available as soft gelatin capsules for oral administration containing 1 mcg, 2 mcg or 4 mcg of paricalcitol. Each capsule also contains medium chain triglycerides, alcohol, and butylated hydroxytoluene.

Subjects taking paricalcitol will be started at 2 mcg 3x/week and titrated up during the next visit according to PTH levels.

Interventions: intervention 1: Calcitriol (Rocaltrol®) intervention 2: Paricalcitol
Intervention descriptions: intervention 1: Subjects taking calcitriol will be started at 0.25 mcg 3x/week and titrated up during the next visit according to PTH levels. If at the 12 week visit, PTH is still not at goal, then calcitriol will be increased to 0.5 mcg 3x/week. intervention 2: Subjects taking paricalcitol will be started at 2 mcg 3x/week and titrated up during the next visit according to PTH levels. If at the 12 week visit, PTH is still not at goal, then paricalcitol will be increased to 4 mcg 3x/week.

Protocol document: