Alfacalcidol in Prevention and Treatment of all Major Forms of Osteoporosis and Renal Osteopathy

The term Vitamin D designates a group of closely related seco-steroids with antirachitic activity. The two most important members of these are ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3). About 80 per cent of the vitamin D supply in man is produced in the skin and only 20 per cent is provided by nutrition. The first analogue of Vitamin D, dihydrotachysterol, was developed in the 1930s and used in the treatment of primary or secondary hypoparathyroidism. It then took 40 years to learn that Vitamin D was not the biologically active principle for healing bone disease. It has to be hydroxylated in the liver at position 25 to build 25-hydroxycholecalciferol and then finally in the kidney at position 1a to become 1a, 25-dihydroxycholecalciferol [= 1a, 25-(OH)2-D3]. Further generations of Vitamin D analogues have since been developed. The most important of these are the so-called D hormone 1a, 25-(OH)2-D3 (= calcitriol) and its analogue alfacalcidol (= 1a-OH-D3) which are highly effective drugs for the treatment of renal bone disease. Further successful indications for active Vitamin D analogues include hypoparathyroidism and osteomalacia.
With regards osteoporosis, the role of an insufficient Vitamin D supply or impairment in activation was underestimated for a long time. A breakthrough was achieved with studies showing that the prevalence of mild to moderate vitamin D deficiency was very high and increasing with age.