Calcitriol

Introduction

Calcitriol (1,25-dihydroxylcholecaldiferol) is a steroid hormone with three hydroxyl groups, which is an active metabolite and the most effective form of vitamin D. It is produced primarily in the kidney when the blood calcium level and parathyroid hormone are low. Calcitriol promotes the calcium and phosphorus absorption in the intestine, reabsorption in the kidneys. Along with parathyroid hormone, it regulates bone growth for building and keeping strong bones. Calcitriol is used to treat and prevent low levels of calcium and bone disease in patients whose kidneys or parathyroid glands are not working normally, to treat secondary hyperparathyroidism and metabolic bone disease in people with kidney disease. Calcitriol may also be chemopreventive for colon and prostate cancers as it induces cell cycle arrest, cell differentiation, and apoptosis.

References

1. https://pubchem.ncbi.nlm.nih.gov
2. https://medlineplus.gov
3. http://flexikon.doccheck.com/en/Calcitriol
4. https://en.wikipedia.org/wiki/Calcitriol
5. https://www.webmd.com

Description

Calcitriol is the active form of vitamin D and is also a kind of hormones in the body. It plays an important role in the regulation of calcium and phosphorus concentration. It can increase the blood calcium level by increasing the intestinal absorption of calcium and can also increase the release of the bone calcium release for increasing the blood calcium levels. This study was first conducted and reported by Michael F. Holick in 1971. The basic principle of action model of calcitriol in many cases is through binding with the vitamin D receptor (the VDR), e.g., the ligand-receptor complex forming between calcitriol and its receptor in the intestinal epithelial cells cytoplasm can be transferred to the nucleus for being as the transcriptional factor in promoting the expression of calcium-binding protein. The increased level of calcium-binding proteins can help the cell to actively transport of more calcium ions, thereby increasing the calcium absorption level. Calcium absorption while maintaining electrical neutrality also requires transporting anions, mainly the absorption of inorganic phosphate ions, so calcitriol also promote the absorption of phosphorus.
Clinically, this drug can be used in the treatment of hypocalcemia, hypoparathyroidism (adult), osteomalacia, rickets (infants), chronic kidney disease, renal osteodystrophy, osteoporosis, as well as the prevention of glucocorticoid induced osteoporosis.

Calcitriol-dimensional molecular structure
The above information is edited by the chemicalbook of Dai Xiongfeng.

Description

Calcitriol is synthesized from 7-dehydro cholesterol in humans via a non-enzymatic photochemical reaction with 290-310 nm UV light in the skin. Hydroxylation of the resulting cholecalciferol in the liver produces 25-hydroxy vitamin D₃, the principal circulating form of vitamin D. A second, tightly regulated hydroxylation in the kidney produces calcitriol. Plasma calcitriol levels range from 10-70 pg/ml and are influenced by numerous dietary and hormonal factors. The main physiologic effects of calcitriol are to increase the absorption of calcium at the level of the intestinal epithelium, and to increase the mineralization of bone via the direct stimulation of osteoblasts.

Chemical Properties

White Crystalline Powder

Originator

Rocaltrol,Roche,US,1978

Uses

Calcium regulator, anti-psoriatic

Uses

The biologically active form of vitamin D3. Calcium regulator; vitamin (antirachitic); antihyperparathyroid; antineoplastic; antipsoriatic

Uses

Calcitriol (1α,25-dihydroxy Vitamin D3) is synthesized from 7-dehydrocholesterol in humans via a non-enzymatic photochemical reaction with 290-310 nm UV light in the skin. Hydroxylation of the resulting cholecalciferol in the liver produces 25-hydroxy Vitamin D3, the principal circulating form of Vitamin D. A second, tightly regulated hydroxylation in the kidney produces calcitriol. Plasma calcitriol levels range from 10-70 pg/ml and are influenced by numerous dietary and hormonal factors. The main physiologic effects of calcitriol are to increase the absorption of calcium at the level of the intestinal epithelium, and to increase the mineralization of bone via the direct stimulation of osteoblasts.[Cayman Chemical]

Uses

Vitamin medicines; it can be used for treating the renal bone malnutrition of patients with chronic renal failure;

Definition

ChEBI: A hydroxycalciol that is calcidiol in which the pro-S hydrogen of calcidiol is replaced by a hydroxy group. It is the active form of vitamin D3, produced fom calciol via hydoxylation in the li er to form calcidiol, which is subsequently oxidised in the kidney to give calcitriol.

Manufacturing Process

1α,25-Dihydroxyprecholecalciferol: A solution of 1α,25- diacetoxyprecholecalciferol (0.712 g, 1.42 mmols), potassium hydroxide (2.0 g, 35.6 mmols) and methanol (40 ml) was stirred at room temperature under argon for 30 hours. The reaction mixture was concentrated under reduced pressure. Water (50 ml) was added to the residue and the mixture was extracted with methylene chloride (3 x 100 ml). The combined organic extracts were washed with saturated sodium chloride solution (3 x 50 ml), dried over anhydrous sodium sulfate, filtered and evaporated under reduced pressure to give 0.619 g of 1alpha,25-dihydroxyprecholecalciferol as a thick oil.
1α,25-Dihydroxycholecalciferol: A solution of 1α,25-dihydroxyprecholecalciferol [0.619 g in dioxane (30 ml)] was heated under reflux for 30 minutes under an atmosphere of argon. The reaction mixture was concentrated under reduced pressure and the residue was purified with a Waters Associates liquid chromatograph model 202 using a 8 foot * 3/8 inch Porasil A column and a 5:1 mixture of ethyl acetate-n-hexane as the eluent to give 0.474 g (80% yield based on 1α,25-diacetoxyprecholecalciferol) of pure 1α,25- dihydroxycholecalciferol. Recrystallization from methyl formate afforded 0.340 g of 1α,25-dihydroxcholecalciferol as colorless crystals, MP 113°-114°C.

brand name

Calcijex (Abbott); Rocaltrol (Roche.

Therapeutic Function

Calcium regulator

General Description

1α,25-Dihydroxyvitamin D₃, also referred as calcitriol, is a calcitrophic hormone. It is the most biologically active metabolite of vitamin D produced in proximal tubular cells in the kidney.

Biological Activity

Active metabolite of vitamin D 3 that activates the vitamin D receptor (VDR). Displays calcemic actions; stimulates intestinal and renal Ca 2+ absorption and regulates bone Ca 2+ turnover. Exhibits antitumor activity; inhibits in vivo and in vitro cell proliferation in a wide range of cells including breast, prostate, colon, skin and brain carcinomas and myeloid leukemia cells.

Biochem/physiol Actions

Biologically active form of vitamin D3 in calcium absorption and deposition. 1α,25-Dihydroxyvitamin D3 has widespread effects on cellular differentiation and proliferation, and can modulate immune responsiveness, and central nervous system function. Recent studies suggest that 1α,25-dihydroxyvitamin D3 acts as a chemopreventive agent against several malignancies including cancers of the prostate and colon and shows synergy with other anticancer compounds.

Clinical Use

Vitamin D analogue:

Promotes intestinal calcium absorption

Suppresses PTH production and release

Veterinary Drugs and Treatments

Calcitriol may be potentially beneficial in the adjunctive treatment of chronic renal disease in dogs and cats but its use is somewhat controversial, particularly the decision on how soon in the course of chronic renal insufficiency it should employed. It may also be of benefit in treating some types of dermatopathies (primary idiopathic seborrhea).

Drug interactions

Potentially hazardous interactions with other drugs
Antiepileptics: the effects of vitamin D may be reduced in patients taking barbiturates or anticonvulsants.
Diuretics: increased risk of hypercalcaemia with thiazides.
Sevelamer: absorption may be impaired by sevelamer

Metabolism

During transport in the blood at physiological concentrations, calcitriol is mostly bound to a specific vitamin D binding protein (DBP), but also, to a lesser degree, to lipoproteins and albumin. At higher blood calcitriol concentrations, DBP appears to become saturated, and increased binding to lipoproteins and albumin occurs. Calcitriol is inactivated in both the kidney and the intestine, through the formation of a number of intermediates including the formation of the 1,24,25-trihydroxy derivatives. It is excreted in the bile and faeces and is subject to enterohepatic circulation.

storage

Desiccate at -20°C