The effects of ethanol are at least partially independent of calcium action. Alfacalcidol (0.025-0.1 mg/kg; channel; 5 times weekly; for 3 months) boosts vitamin D in this aspect and has bone preventive effects.

Animal/Disease Models: Female Wistar-Imamichi rat (8 months old), ovariectomized [3]
Doses: 0.025mg/kg, 0.05mg/kg, 0.1mg/kg
Route of Administration: oral; Inhibition of PTH[3]. Five times a week; lasted for 3 months.
Experimental Results: exerted bone protective effects, independent of calcium-related effects.

Absorption, Distribution and Excretion
Alfacalcidol is absorbed passively and almost completely in the small intestine.

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Metabolism / Metabolites
Alfacalcidol is rapidly converted in the liver to 1,25-dihydroxyvitamin D, which is essentially the metabolite of vitamin D that regulates calcium and phosphate metabolism. Alfacalcidol is further metabolized to other polar inactive metabolites, excreted primarily through the bile.

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Biological Half-Life
The half-life of alfacalcidol ranges from three to four hours.

Protein Binding
The active metabolite of alfacalcidol, 1,25-dihydroxyvitamin D, is transported to tissues via globulin, a specific transport protein.

[1]. [Postmenopausal osteoporosis. Digital Rx radiogrammetry in the diagnosis and follow-up of treatment with alfacalcidol]. Rev Med Chir Soc Med Nat Iasi. 2006 Oct-Dec;110(4):833-41.

[2]. Cost Effectiveness of Paricalcitol versus a Non-Selective Vitamin D Receptor Activator for Secondary Hyperparathyroidism in the UK. Clin Drug Investig. 2010;30(8):545-57.

[3]. The advantage of alfacalcidol over vitamin D in the treatment of osteoporosis. Calcif Tissue Int. 1999 Oct;65(4):311-6.

[4]. Alfacalcidol enhances collagen quality in ovariectomized rat bones. J Orthop Res. 2014 Aug;32(8):1030-6.

Alfacalcidol is a member of the class of D3 vitamins that is calciol in which the hydrogen at the 1alpha position is replaced by a hydroxy group. It is an active metabolite of cholecalciferol, which performs important functions in regulation of the calcium balance and the bone metabolism. It has a role as a bone density conservation agent. It is a member of D3 vitamins, a seco-cholestane, a hydroxycalciol and a diol. It is functionally related to a calciol.
Alfacalcidol, or 1-alpha-hydroxycholecalciferol or 1-alpha-hydroxyvitamin D3, is a non-endogenous analogue of [vitamin D]. It plays an essential function in calcium homeostasis and bone metabolism. Alfacaldisol is activated by the enzyme 25-hydroxylase in the liver to mediate its effects in the body, or most importantly, the kidneys and bones. The pharmacological actions of alfacalcidol are prolonged than vitamin D because a negative feedback mechanism regulates the final activation step of vitamin D in the kidneys. Alfacalcidol is available in oral and intravenous formulations. In Canada, it is marketed as ONE-ALPHA, which manages hypocalcemia, secondary hyperparathyroidism, and osteodystrophy in adults with chronic renal failure. In approving European countries, alfacalcidol is also indicated for managing nutritional and malabsorptive rickets and osteomalacia, vitamin D-dependent rickets and osteomalacia, and hypophosphataemic vitamin D resistant rickets and osteomalacia.

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Drug Indication
Alfacalcidol is indicated in adult patients with chronic renal failure for the management of hypocalcemia, secondary hyperparathyroidism, or osteodystrophy. Alfacalcidol is indicated in the management of nutritional and malabsorptive rickets and osteomalacia, vitamin D-dependent rickets and osteomalacia, and hypophosphataemic vitamin D resistant rickets and osteomalacia.
FDA Label

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Mechanism of Action
In conditions like chronic renal failure, renal bone disease, hypoparathyroidism, and vitamin D dependent rickets, the kidneys' capacity for 1α-hydroxylation is impaired, leading to reduced production of endogenous 1,25-dihydroxyvitamin D and aberrated mineral metabolism. As an active and potent analog of vitamin D, alfacalcidol works to restore the functions and activities of endogenous 1,25-dihydroxyvitamin D.

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Pharmacodynamics
Alfacalcidol works to increase serum levels of calcium by stimulating intestinal calcium absorption, reabsorption of calcium from bone, and possibly the renal reabsorption of calcium. It also modestly promotes intestinal phosphorus absorption. In patients with renal failure, alfacalcidol increased intestinal calcium and phosphorus absorption in a dose-related manner. This increase in calcium and phosphorus levels occurs within three days following drug administration: this effect was reversed within three days of drug discontinuation. In patients with chronic renal failure, serum calcium levels were elevated while parathyroid hormone and alkaline phosphatase levels returned to normal levels within five days following alfacalcidol administration. Since alfacalcidol suppresses parathyroid hormone, a reduction in parathyroid hormone levels is achieved more rapidly in patients on intermittent intravenous therapy, with significant reductions occurring within three months of therapy. In patients receiving daily oral therapy of alfacalcidol, the time it takes alfacalcidol to normalize plasma calcium levels may be up to several months, possibly reflecting calcium being utilized for bone mineralization. In patients with nutritional osteomalacia, alfacalcidol increased calcium absorption with six hours of oral administration and the effects peaked at 24 hours.

C27H44O2

400.64

400.334

C, 80.94; H, 11.07; O, 7.99

41294-56-8

5282181

White to off-white solid powder

1.0±0.1 g/cm3

531.5±50.0 °C at 760 mmHg

134-136°C

222.6±24.7 °C

0.0±3.2 mmHg at 25°C

1.534

8.31

2

2

6

29

643

6

O([H])[C@@]1([H])C([H])([H])[C@@]([H])(C(=C([H])[H])/C(/C1([H])[H])=C(\[H])/C(/[H])=C1/C([H])([H])C([H])([H])C([H])([H])[C@@]2(C([H])([H])[H])[C@]/1([H])C([H])([H])C([H])([H])[C@]2([H])[C@]([H])(C([H])([H])[H])C([H])([H])C([H])([H])C([H])([H])C([H])(C([H])([H])[H])C([H])([H])[H])O[H]

OFHCOWSQAMBJIW-AVJTYSNKSA-N

InChI=1S/C27H44O2/c1-18(2)8-6-9-19(3)24-13-14-25-21(10-7-15-27(24,25)5)11-12-22-16-23(28)17-26(29)20(22)4/h11-12,18-19,23-26,28-29H,4,6-10,13-17H2,1-3,5H3/b21-11+,22-12-/t19-,23-,24-,25+,26+,27-/m1/s1

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

Alfacalcidol; Alfarol; alpha-Calcidol; Alpha D 3; Bondiol; EB 644; Alpha-D3

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). Please store this product in a sealed and protected environment (e.g. under nitrogen), avoid exposure to moisture.  (3). 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 (6.24 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 (6.24 mM) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), suspension solution; with ultrasonication.
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 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (6.24 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.)