The FDA has approved paricalcitol injection (Zemplar®, Abbott Labs) for children and adolescents with secondary hyperparathyroidism who are undergoing hemodialysis. Zemplar® was initially introduced in 1998.
Because patients with kidney failure do not produce the active form of vitamin D, they have vitamin D deficiency and secondary hypoparathyroidism, in which the parathyroid glands produce excess amounts of parathyroid hormone (PTH).
Approximately 1,400 American children between ages 5 and 19 undergo hemodialysis.
Secondary hyperparathyroidism can lead to weak and brittle bones, anemia, and cardiac and neurological problems. Because bones and other organs are still developing in children, and because children are typically patients for longer periods of time, the disease can be more difficult to treat than in adults. Left untreated, secondary hyperparathyroidism can be a factor in growth retardation.
Zemplar® was tested in a 12-week randomized, double-blind, placebo-controlled study of 29 pediatric hemo-dialysis patients with chronic renal failure. Nearly all patients had received a form of vitamin D therapy before the study. Sixty percent of the Zemplar® patients showed two consecutive 30% decreases in PTH levels; only 21% of the placebo patients did. Fewer Zemplar® patients (23%) than placebo patients (31%) experienced elevated serum calcium levels.
The overall percentage of serum calcium measurements (defined as 10.3 mg/dl or greater) was 7% in the Zemplar® group and 7% in the placebo group. Hypercalcemia did not occur in either group during the study.