<qa>  What is the biologically active form of vitamin D found in dairy products?DN-101 is an experimental drug that has not been approved by the Food and Drug Administration FDA. It is a newly formulated pill that contains high amounts of calcitriol, a naturally occurring hormone and the biologically active form of vitamin D. The natural vitamin D found in dairy products or in typical vitamin pills, must be chemically changed by the liver and kidney into calcitriol before it is biologically active. The body normally uses small amounts of calcitriol to regulate its blood calcium levels. However, for any possible therapeutic effect, MDS patients require much higher levels of calcitriol than the body can produce from dietary vitamin D. DN-101 provides MDS patients with high doses of calcitriol in a pill form. 