Alfacalcidol (1-hydroxycholecalciferol)   中文名称: 阿法骨化醇

Vitamin D Receptor (VDR) [1][3][4]

阿法骨化醇（Alfacalcidol, 1-羟基胆钙化醇）促进原代大鼠成骨细胞分化和功能。1-10 nM浓度下，7天后使碱性磷酸酶（ALP）活性分别提高~35%（1 nM）和~60%（10 nM），通过激活VDR上调成骨标志物（骨钙素、I型胶原）表达~45-70%[3][4]
- 抑制RAW264.7细胞分化形成的破骨细胞活性。5 nM 阿法骨化醇（Alfacalcidol, 1-羟基胆钙化醇）使抗酒石酸酸性磷酸酶（TRAP）阳性破骨细胞数量减少~52%，抑制破骨细胞介导的骨吸收~48%（与对照组相比）[3]
- 增强成骨细胞胶原合成：10 nM处理14天后，I型胶原生成增加~55%，胶原交联改善（通过羟脯氨酸含量检测和胶原溶解度实验证实）[4]

乙醇的作用至少部分独立于钙的作用。阿法骨化醇（0.025-0.1 mg/kg；通道；每周 5 次；持续 3 个月）可增强这方面的维生素 D 并具有骨质预防作用。

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在绝经后骨质疏松女性临床研究中，口服阿法骨化醇（Alfacalcidol, 1-羟基胆钙化醇）（0.5 μg/天，每日1次，持续12个月）使腰椎骨密度（BMD）增加~6.2%，股骨颈BMD增加~4.8%，年椎体骨折风险较基线降低~42%[1]
- 在卵巢切除（OVX）大鼠骨质疏松模型中，口服阿法骨化醇（Alfacalcidol, 1-羟基胆钙化醇）（0.2 μg/kg/天，每日1次，持续16周）增强骨胶原质量：股骨羟脯氨酸含量增加~30%，胶原交联密度提高~25%，骨极限强度（三点弯曲实验）增加~35%（与OVX对照组相比）[4]
- 与维生素D₃对比，阿法骨化醇（Alfacalcidol, 1-羟基胆钙化醇）（0.1 μg/kg/天，口服12周）在OVX大鼠中疗效更优：腰椎BMD增加~8.5%（维生素D₃组为~4.2%），骨小梁体积分数（BV/TV）改善~32%（维生素D₃组为~18%）[3]
- 在继发性甲状旁腺功能亢进患者中，口服阿法骨化醇（Alfacalcidol, 1-羟基胆钙化醇）（0.25-1 μg/天）8周后使血清甲状旁腺激素（PTH）水平降低~38%，疗效与非选择性VDR激活剂相当，但高钙血症发生率更低[2]

VDR转录活性实验：转染VDR表达质粒和VDR响应性荧光素酶报告基因质粒的HEK293细胞，用0.1-100 nM 阿法骨化醇（Alfacalcidol, 1-羟基胆钙化醇）处理24小时，检测荧光素酶活性量化VDR激活，证实剂量依赖性增强VDR介导的转录[3][4]
- 碱性磷酸酶（ALP）活性实验：原代大鼠成骨细胞用0.1-10 nM 阿法骨化醇（Alfacalcidol, 1-羟基胆钙化醇）培养7天，细胞裂解后，以对硝基苯基磷酸酯为底物，比色法测定ALP活性[3]
- 胶原交联实验：成骨细胞培养上清液在1-10 nM 阿法骨化醇（Alfacalcidol, 1-羟基胆钙化醇）处理14天后收集，傅里叶变换红外光谱（FTIR）检测胶原交联密度[4]

成骨细胞分化实验：原代大鼠成骨细胞接种于96孔板，用0.1-10 nM 阿法骨化醇（Alfacalcidol, 1-羟基胆钙化醇）处理7-14天。比色法检测ALP活性；PCR分析骨钙素和I型胶原mRNA表达；茜素红染色评估矿化[3][4]
- 破骨细胞形成实验：RAW264.7细胞用RANKL诱导分化为破骨细胞，同时用0.1-10 nM 阿法骨化醇（Alfacalcidol, 1-羟基胆钙化醇）处理5天。计数TRAP阳性多核细胞；骨片陷窝形成实验评估骨吸收[3]

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.

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OVX rat osteoporosis model: Female Sprague-Dawley rats were ovariectomized to induce osteoporosis. Two weeks post-surgery, Alfacalcidol (1-hydroxycholecalciferol) was dissolved in corn oil and administered by oral gavage at 0.1-0.2 μg/kg/day for 12-16 weeks. Rats were sacrificed; femur and lumbar spine were collected for BMD measurement (DEXA), bone histomorphometry, collagen quality analysis (hydroxyproline assay, FTIR), and bone strength testing (three-point bending) [3][4]

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.

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Oral administration of Alfacalcidol (1-hydroxycholecalciferol) shows good bioavailability (~70-80% in humans) [1][3]
- It is metabolized in the liver to 1,25-dihydroxycholecalciferol (active form) via 25-hydroxylation, with a plasma elimination half-life of ~2-3 hours [1][3]
- It distributes widely to bone, liver, kidney, and intestinal tissues, with bone tissue/plasma concentration ratio of ~4.0 at 4 hours post-administration [3]

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

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In vitro, Alfacalcidol (1-hydroxycholecalciferol) showed no significant cytotoxicity to primary osteoblasts or hepatocytes at concentrations up to 100 nM [3][4]
- In vivo, administration of Alfacalcidol (1-hydroxycholecalciferol) at doses up to 1 μg/kg/day for 16 weeks (OVX rats) did not cause hypercalcemia or hypercalciuria (serum calcium and urinary calcium levels within normal range) [3][4]
- Clinical data showed mild adverse effects: gastrointestinal discomfort (nausea, constipation, incidence ~3-5%), hypercalcemia (~2% at high doses), and hypercalciuria (~1%) [1][2]

[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.

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Alfacalcidol (1-hydroxycholecalciferol) is a synthetic analog of vitamin D₃, acting as a prodrug that requires only hepatic 25-hydroxylation to form the active 1,25-dihydroxycholecalciferol [1][3]
- Its core mechanism involves binding to and activating VDR, regulating transcription of genes involved in calcium metabolism, osteoblast differentiation, osteoclast inhibition, and collagen synthesis [3][4]
- It is indicated for the treatment of postmenopausal osteoporosis, senile osteoporosis, and secondary hyperparathyroidism (especially in patients with impaired renal function, as it bypasses renal 1-hydroxylation) [1][2][3]
- Compared to vitamin D₃, it has faster onset of action and superior efficacy in improving BMD and reducing fracture risk, due to direct activation of VDR without relying on renal hydroxylation [3]
- It is administered orally (capsules or drops) with a recommended daily dose of 0.25-1 μg for adults [1][2]

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

40.46

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

注意： (1). 本产品在运输和储存过程中需避光。  (2). 请将本产品存放在密封且受保护的环境中（例如氮气保护），避免吸湿/受潮。  (3). 该产品在溶液状态不稳定，请现配现用。

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

配方 1 中的溶解度: ≥ 2.5 mg/mL (6.24 mM) (饱和度未知) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (这些助溶剂从左到右依次添加，逐一添加), 澄清溶液。
例如，若需制备1 mL的工作液，可将100 μL 25.0 mg/mL澄清DMSO储备液加入到400 μL PEG300中，混匀；然后向上述溶液中加入50 μL Tween-80，混匀；加入450 μL生理盐水定容至1 mL。
*生理盐水的制备：将 0.9 g 氯化钠溶解在 100 mL ddH₂O中，得到澄清溶液。

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配方 2 中的溶解度: 2.5 mg/mL (6.24 mM) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (这些助溶剂从左到右依次添加，逐一添加), 悬浊液; 超声助溶。
例如，若需制备1 mL的工作液，可将 100 μL 25.0 mg/mL澄清DMSO储备液加入900 μL 20% SBE-β-CD生理盐水溶液中，混匀。
*20% SBE-β-CD 生理盐水溶液的制备（4°C，1 周）：将 2 g SBE-β-CD 溶解于 10 mL 生理盐水中，得到澄清溶液。

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配方 3 中的溶解度: ≥ 2.5 mg/mL (6.24 mM) (饱和度未知) in 10% DMSO + 90% Corn Oil (这些助溶剂从左到右依次添加，逐一添加), 澄清溶液。
例如，若需制备1 mL的工作液，可将 100 μL 25.0 mg/mL 澄清 DMSO 储备液加入到 900 μL 玉米油中并混合均匀。

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请根据您的实验动物和给药方式选择适当的溶解配方/方案：
1、请先配制澄清的储备液(如：用DMSO配置50 或 100 mg/mL母液(储备液));
2、取适量母液，按从左到右的顺序依次添加助溶剂，澄清后再加入下一助溶剂。以 下列配方为例说明 (注意此配方只用于说明，并不一定代表此产品 的实际溶解配方):
10% DMSO → 40% PEG300 → 5% Tween-80 → 45% ddH2O (或 saline);
假设最终工作液的体积为 1 mL, 浓度为5 mg/mL: 取 100 μL 50 mg/mL 的澄清 DMSO 储备液加到 400 μL PEG300 中，混合均匀/澄清；向上述体系中加入50 μL Tween-80，混合均匀/澄清；然后继续加入450 μL ddH2O (或 saline)定容至 1 mL；
3、溶剂前显示的百分比是指该溶剂在最终溶液/工作液中的体积所占比例;
4、 如产品在配制过程中出现沉淀/析出，可通过加热(≤50℃)或超声的方式助溶;
5、为保证最佳实验结果，工作液请现配现用！
6、如不确定怎么将母液配置成体内动物实验的工作液，请查看说明书或联系我们;
7、 以上所有助溶剂都可在 Invivochem.cn网站购买。