Vitamin D is synthesized in the skin from 7-dehydrocholesterol under UVB light and is also obtained from the diet. It is first converted to 25-hydroxyvitamin D (25OHD) by enzymes like CYP2R1, and then to the active form 1,25-dihydroxyvitamin D (1,25(OH)₂D) by CYP27B1 in the kidneys. 1,25(OH)₂D binds to the vitamin D receptor (VDR), a transcription factor, to regulate gene expression. Vitamin D analogs are being developed to target specific diseases with minimal side effects. These analogs differ in their affinity for the VDR, their metabolism, and their interaction with other proteins like the retinoid X receptor (RXR). The metabolism of vitamin D involves several enzymes, including CYP24A1, which catabolizes both 25OHD and 1,25(OH)₂D. Vitamin D has various clinical applications, including the treatment of psoriasis, secondary hyperparathyroidism, and osteoporosis. It also plays a role in bone health, immune function, and the prevention of cardiovascular diseases. The development of vitamin D analogs aims to enhance its therapeutic potential while minimizing side effects. The mechanisms of action of vitamin D and its analogs are complex, involving both genomic and nongenomic pathways. Understanding these mechanisms is crucial for the development of targeted therapies.Vitamin D is synthesized in the skin from 7-dehydrocholesterol under UVB light and is also obtained from the diet. It is first converted to 25-hydroxyvitamin D (25OHD) by enzymes like CYP2R1, and then to the active form 1,25-dihydroxyvitamin D (1,25(OH)₂D) by CYP27B1 in the kidneys. 1,25(OH)₂D binds to the vitamin D receptor (VDR), a transcription factor, to regulate gene expression. Vitamin D analogs are being developed to target specific diseases with minimal side effects. These analogs differ in their affinity for the VDR, their metabolism, and their interaction with other proteins like the retinoid X receptor (RXR). The metabolism of vitamin D involves several enzymes, including CYP24A1, which catabolizes both 25OHD and 1,25(OH)₂D. Vitamin D has various clinical applications, including the treatment of psoriasis, secondary hyperparathyroidism, and osteoporosis. It also plays a role in bone health, immune function, and the prevention of cardiovascular diseases. The development of vitamin D analogs aims to enhance its therapeutic potential while minimizing side effects. The mechanisms of action of vitamin D and its analogs are complex, involving both genomic and nongenomic pathways. Understanding these mechanisms is crucial for the development of targeted therapies.