Vitamin D analogues: how do they differ and what is their clinical role?

The development of vitamin D analogues capable of effective parathyroid suppression whilst avoiding undesirable low bone turnover, hypercalcaemia and hyperphosphataemia has received considerable attention over the last decade w1x. Much in vitro and animal work has been undertaken with frustrating disparity emerging between therapeutic potential in the experimental setting and performance in available clinical trials. The biology and, in particular, gene regulatory properties of vitamin D are now more fully understood w2x and provide useful insights into the mechanisms underpinning the selective properties encountered experimentally. The formulation of ‘designer’ compounds possessing distinct physiological characteristics that will afford them an advantage in the clinical arena remains an enticing prospect.