Vitamin D receptor
Vitamin D receptor (VDR) agonist [1].

In mice undergoing nephrectomy, doxercalciferol (100 or 300 pg/g b.w.) restores serum calcium and parathyroid hormone (PTH) levels to normal. In mice undergoing nephrectomy, doxercalciferol (300 pg/g b.w.) significantly lowers osteitis fibrosa. In rats given a high-salt (HS) diet, doxercalciferol significantly reduces cardiac hypertrophy and enhances cardiac function. In rats fed a high salt (HS) diet, doxercalciferol treatment results in a significant decrease in tissue atrial natriuretic factor (ANF) mRNA level and plasma brain natriuretic peptide (BNP) level. Additionally, doxercalciferol dramatically lowers protein kinase C-α (PKCα) levels, indicating a possible link between vitamin D deficiency and PKC-mediated cardiac hypertrophy. In diet-induced obese (DIO) mice, doxercalciferol reduces proteinuria, podocyte damage, mesangial growth, and extracellular matrix protein accumulation. In DIO mice, doxercalciferol also reduces profibrotic growth factors, proinflammatory cytokines, oxidative stress, and macrophage infiltration. Moreover, doxercalciferol inhibits the DIO mice's renin-angiotensin-aldosterone system activation, which includes the angiotensin II type 1 receptor and the mineralocorticoid receptor. In mice, the combination of doxercalciferol and losartan most effectively prevents albuminuria, restores the structure of the glomerular filtration barrier, and significantly lowers glomerulosclerosis in a dose-dependent manner. Mice's diabetic kidneys show virtually no morphological or molecular changes when doxercalciferol and losartan are combined.

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In 5/6 nephrectomized (NX) rats, Doxercalciferol (0.083, 0.167, or 0.333 μg/kg, i.p.) raises serum phosphorus at Week 6. In addition, doxercalciferol (0.167 and 0.333 μg/kg) enhances increased pulse wave velocity (PWV) in 5/6 nephrectomized (NX) rats at Week 6 and raises serum calcium and Ca × P at Weeks 2 and 6. Doxercalciferol decreases serum PTH to the SHAM level and prevents PTH from rising at 0.083 μg/kg[1]. In NON mice fed a high-fat diet, doxercalciferol (125 ng/kg, i.p., three times a week) increases the expression of VDR mRNA level and renal expression of TRPV5. In mice given an HF diet, doxercalciferol also reduces proteinuria, stops podocyte loss, and reduces the buildup of extracellular matrix proteins. In mice fed an HF diet, doxercalciferol blocks increased expression of the renin-angiotensin-aldosterone system and inhibits the expression of profibrotic growth factors (TGF-β, PAI-1, and connective tissue growth factor (CTGF)). In addition, Doxercalciferol inhibits the infiltration of macrophages, lowers NF-κb activity, stops the expression of proinflammatory cytokines, and stops the accumulation of renal lipids in mice given a high-fat diet[2]. When administered intraperitoneally (i.p.) three times a week to streptozotocin-induced diabetic mice, doxercalciferol (30 ng/kg) significantly attenuates podocyte loss and apoptosis and decreases glomerular fibrosis[3].
In male NON/LJ mice fed a high-fat (HF) diet (60 kcal% fat) for 28 weeks, treatment with Doxercalciferol (125 ng/kg body wt, intraperitoneal injection, 3 times per week) significantly decreased urinary albumin-to-creatinine ratio (proteinuria) compared with vehicle-treated HF controls [1].
Doxercalciferol prevented podocyte injury, as evidenced by restored protein expression of WT1 and podocin, and restored synaptopodin immunostaining in HF-fed mice [1].
Doxercalciferol reduced mesangial expansion and matrix accumulation (decreased PAS staining intensity) and decreased glomerular and tubulointerstitial accumulation of fibronectin (mRNA and immunostaining) in HF-fed mice [1].
Doxercalciferol decreased macrophage infiltration (CD68 immunostaining), NF-κB DNA binding activity, and mRNA expression of proinflammatory cytokines including Cox-2, RAGE, TLR-4, and MCP-1 in kidneys of HF-fed mice [1].
Doxercalciferol reduced renal oxidative stress as shown by decreased mRNA expression of Nox-4, p47-phox, Nox2, and decreased oxidized protein levels (ELISA) in HF-fed mice [1].
Doxercalciferol decreased renal accumulation of neutral lipids (triglycerides and cholesterol) and adipophilin mRNA expression (oil red O staining) in HF-fed mice [1].
Doxercalciferol downregulated mRNA expression of SREBP-1c, ACC, FAS, and ACL (fatty acid synthesis), increased PPAR-α (fatty acid oxidation), and decreased CD36 (fatty acid uptake) in kidneys of HF-fed mice [1].
Doxercalciferol downregulated mRNA expression of SREBP-2, LDLR, and HMG CoA reductase (cholesterol synthesis and uptake) in kidneys of HF-fed mice [1].
Doxercalciferol increased mRNA expression of farnesoid X receptor (FXR) in kidneys of HF-fed mice [1].
Doxercalciferol prevented the activation of the renin-angiotensin-aldosterone system (including angiotensin II type 1 receptor and mineralocorticoid receptor) in HF-fed mice [1].

Rats: One week following nephrectomy, male Sprague-Dawley 5/6 nephrectomized (NX) rats (∼200 mg) are used. A typical surgical ablation procedure consisting of two steps is used to perform the nephrectomy. Rats are kept on a high-phosphorus diet (0.9% phosphorus and 0.6% calcium) for the duration of the study starting two weeks after nephrectomy in order to cause secondary hyperparathyroidism. Day 0: Vehicle (5% EtOH/95% propylene glycol; 0.4 mL/kg; i.p.) or VDRA (paricalcitol or Doxercalciferol; 0.083, 0.167, or 0.333 μg/kg; intraperitoneally) is given three times a week for 41 days (n = 6–10 per group) to SHAM and 5/6 NX rats (n = 7–10 per group). These dosages were selected because, in this CKD model, after two or six weeks of treatment, lower doses (0.021 and 0.042 μg/kg; i.p.) of either compound do not suppress PTH. Days 0 through 41 are when blood is drawn (24 hours after the dose). Animals are given ketamine (50 mg/kg) anesthesia on Days 0, 13, and 41 (24 h post-dose), and blood is drawn from the tail vein for measurements of PTH and serum blood chemistry[1].

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Male NON/LJ mice (obtained from The Jackson Laboratories) were fed a control low-fat diet (LF; 10 kcal% fat) or a high-fat diet (HF; 60 kcal% fat) for 28 weeks. Mice were treated intraperitoneally with either vehicle (80% propylene glycol/20% PBS) or Doxercalciferol at 125 ng/kg body weight, three times per week. For biochemical studies, n=12 mice per group (kidneys from 2 mice were combined for RNA and protein studies). For histology and immunofluorescence, n=6 mice per group. Blood glucose was measured with a glucometer. Plasma triglyceride and cholesterol were measured with kits. Urine albumin and creatinine were measured using kits, and results expressed as urine albumin-to-creatinine ratio (μg/mg). After sacrifice, kidneys were harvested for RNA extraction (quantitative real-time PCR), protein extraction (Western blotting), lipid extraction (triglyceride and cholesterol measurement), NF-κB transcriptional activity assay, oxidized protein analysis (ELISA), histology (PAS staining, oil red O staining), and immunofluorescence microscopy (synaptopodin, fibronectin, CD68) [1].
Preliminary dose-ranging studies showed that Doxercalciferol at 125 ng/kg did not increase serum calcium or phosphorus (Table 1: serum Ca 8.37±1.37 mg/dl vs vehicle 9.14±1.26 mg/dl; serum Pi 9.75±0.39 vs 9.89±0.42 mg/dl) while inducing renal VDR gene expression and expected changes in vitamin D-metabolizing enzymes (decreased 1-α-hydroxylase, increased 24-α-hydroxylase) [1].

Metabolism / Metabolites
After absorption from the gastrointestinal tract, docecalciferol is activated in the liver via CYP27 to produce 1α,25-(OH)2D2 (major metabolite) and 1α,24-dihydroxyvitamin D2 (minor metabolite). Activation of docecalciferol does not require renal involvement.
Biological half-life
32 to 37 hours.

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Doxercalciferol is a prodrug (1α-hydroxyvitamin D2) that requires hepatic metabolism to the active metabolite 1,25-dihydroxyvitamin D2. The half-life of 1,25-dihydroxyvitamin D2 is longer than that of calcitriol or paricalcitol in human subjects (reference cited) [1].
In this study, Doxercalciferol treatment increased renal VDR mRNA expression and induced the feedback regulatory loop: suppression of 1-α-hydroxylase mRNA and stimulation of 24-α-hydroxylase mRNA [1].
No other ADME parameters (e.g., Cmax, AUC, bioavailability) are reported [1].

Doxercalciferol at 125 ng/kg (3 times/week) did not cause significant increases in serum calcium or phosphorus compared to vehicle in NON/LJ mice. Serum calcium: vehicle 9.14±1.26 mg/dl, doxercalciferol 8.37±1.37 mg/dl; serum phosphorus: vehicle 9.89±0.42 mg/dl, doxercalciferol 9.75±0.39 mg/dl [1].
Doxercalciferol at 25 ng/kg and 500 ng/kg also showed no significant changes in serum calcium or phosphorus (Table 1) [1].
No other toxicity data (e.g., LD50, organ toxicity) are reported [1].

[1]. Differential effects of vitamin D receptor activators on aortic calcification and pulse wave velocity in uraemic rats. Nephrol Dial Transplant. 2008 Dec;23(12):3824-30.

[2]. Vitamin D receptor agonist doxercalciferol modulates dietary fat-induced renal disease and renal lipid metabolism. Am J Physiol Renal Physiol. 2011 Mar;300(3):F801-10.

[3]. Vitamin D receptor signaling in podocytes protects against diabetic nephropathy. J Am Soc Nephrol. 2012 Dec;23(12):1977-86.

Docecalciferol is a hydroxysteroid and a synthetic vitamin D2 analog. Upon activation in the body, it is metabolized to produce 1α,25-dihydroxyvitamin D2 (1α,25-(OH)2D2), a naturally occurring, biologically active form of vitamin D2. It is used to treat secondary hyperparathyroidism, a condition in which patients with chronic kidney disease produce excessive parathyroid hormone (PTH; a natural substance that controls calcium levels in the blood). It acts as a provitamin, bone mineral density protectant, and hormone precursor. It is both a vitamin D and a hydroxysteroid. Docecalciferol is indicated for the treatment of secondary hyperparathyroidism in patients with chronic kidney disease undergoing dialysis, as well as in patients with stage 3 or 4 chronic kidney disease. Docecalciferol is marketed by Genzyme Corporation under the brand name Hectoral and manufactured by Catalent Pharma Solutions, Inc.
Dcecalciferol is a vitamin D2 analog.
Doccecalciferol is a synthetic vitamin D analog with potential antitumor activity. In the liver, docecalciferol is converted into biologically active vitamin D metabolites. These metabolites control the intestinal absorption of dietary calcium, the renal tubular reabsorption of calcium, and work in conjunction with parathyroid hormone (PTH) to promote calcium mobilization from bones. These vitamin D metabolites act directly on osteoblasts through interaction with specific receptor proteins in target tissues, stimulating bone growth; they also act on the parathyroid glands, inhibiting the synthesis and secretion of parathyroid hormone (PTH). This drug has also been shown to inhibit the growth of retinoblastoma and may have some antiproliferative activity against prostate cancer cells.
Drug Indications

Doccecalciferol is indicated for the treatment of secondary hyperparathyroidism in patients with chronic kidney disease undergoing dialysis, and for the treatment of secondary hyperparathyroidism in patients with stage 3 or 4 chronic kidney disease.
FDA Label

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Mechanism of Action
Calcitriol (1α,25-(OH)2D3) and 1α,25-(OH)2D2 regulate serum calcium levels, maintaining them at levels necessary for essential bodily functions. Specifically, bioactive vitamin D metabolites control intestinal absorption of dietary calcium, renal tubular reabsorption of calcium, and work with parathyroid hormone (PTH) to promote calcium mobilization from bones. They act directly on osteoblasts to stimulate bone growth and on the parathyroid glands to inhibit the synthesis and secretion of PTH. These functions are achieved through the interaction of these bioactive metabolites with specific receptor proteins in various target tissues. In patients with chronic kidney disease (CKD), insufficient production of bioactive vitamin D metabolites due to deficiency or inadequate 25-hydroxyvitamin D-1α-hydroxylase activity leads to secondary hyperparathyroidism, thereby promoting the development of metabolic bone disease.

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Doxercalciferol is a vitamin D receptor (VDR) agonist. Among clinically used VDR agonists, doxercalciferol and paricalcitol have a lower propensity to cause hypercalcemia and hypercalciuria than calcitriol, allowing use of higher tolerable doses [1].
The study demonstrates that VDR activation with Doxercalciferol prevents diet-induced obesity (DIO) nephropathy in NON mice through multiple mechanisms: decreasing proteinuria, podocyte injury, mesangial expansion, extracellular matrix accumulation, macrophage infiltration, oxidative stress, inflammation, fibrosis, and modulating renal lipid metabolism (decreasing fatty acid and cholesterol synthesis, increasing fatty acid oxidation, decreasing lipid uptake) [1].
Doxercalciferol also downregulates the renin-angiotensin-aldosterone system (including AT1 receptor and mineralocorticoid receptor) in the kidney [1].
The study suggests cross-talk between VDR and farnesoid X receptor (FXR), as doxercalciferol treatment increased FXR expression in the kidney [1].

C28H44O2

412.65

412.334

C, 81.50; H, 10.75; O, 7.75

54573-75-0

trans-Doxercalciferol;74007-20-8;Impurity of Doxercalciferol;127516-23-8

5281107

White to yellow/brown solid powder

1.0±0.1 g/cm3

538.7±50.0 °C at 760 mmHg

138-140ºC

224.0±24.7 °C

0.0±3.3 mmHg at 25°C

1.541

8.15

2

2

5

30

712

7

C=C1[C@H](C[C@@H](C/C1=C/C=C2[C@]3([C@@](C)([C@H](CC3)[C@@H](/C=C/[C@@H](C(C)C)C)C)CCC/2)[H])O)O

HKXBNHCUPKIYDM-CGMHZMFXSA-N

InChI=1S/C28H44O2/c1-18(2)19(3)9-10-20(4)25-13-14-26-22(8-7-15-28(25,26)6)11-12-23-16-24(29)17-27(30)21(23)5/h9-12,18-20,24-27,29-30H,5,7-8,13-17H2,1-4,6H3/b10-9+,22-11+,23-12-/t19-,20+,24+,25+,26-,27-,28+/m0/s1

(1R,3S,5Z)-5-[(2E)-2-[(1R,3aS,7aR)-1-[(E,2R,5R)-5,6-dimethylhept-3-en-2-yl]-7a-methyl-2,3,3a,5,6,7-hexahydro-1H-inden-4-ylidene]ethylidene]-4-methylidenecyclohexane-1,3-diol

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: (1). This product requires protection from light (avoid light exposure) during transportation and storage.  (2). This product is not stable in solution, please use freshly prepared working solution for optimal results.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Solubility in Formulation 1: ≥ 2.5 mg/mL (6.06 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (6.06 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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 (Please use freshly prepared in vivo formulations for optimal results.)