Calcifediol

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Cat Number

API19356173

CAS Number

19356-17-3

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Product Detail Description Scientific Support Customer Q&A

CAS Number

19356-17-3

EINECS

242-990-9

Storage

Store at 2-8℃

Synonyms

25-hydroxyvitamin D3; Calcifediol anhydrous; Didrogyl; Calcifediolum; Rayaldee; 5,6-cis-25-Hydroxyvitamin D3

Molecular Formula

C27H44O2

Molecular Weight

400.6

Smiles

C[C@H](CCCC(C)(C)O)[C@H]1CC[C@@H]\\2[C@@]1(CCC/C2=C\\C=C/3\\C[C@H](CCC3=C)O)C

Appearance

White to off-white powder

Melting Point

74-76℃

Boiling Point

529.2℃

General Description

Calcifediol, also known as 25-hydroxyvitamin D3, is the major circulating metabolite of vitamin D3 produced by hepatic hydroxylation. It serves as the immediate precursor to the active hormone calcitriol and is used therapeutically to correct vitamin D deficiency. This agent is available in oral formulations and offers a more direct pathway to raising vitamin D stores than unhydroxylated vitamin D.

Mechanism of Action

Following absorption, calcifediol undergoes further hydroxylation in the kidney by the enzyme 1-alpha-hydroxylase to form calcitriol, the active form of vitamin D. Calcitriol binds to the vitamin D receptor in target tissues, regulating gene transcription involved in calcium and phosphate homeostasis. This includes enhancing intestinal absorption of calcium, promoting renal tubular reabsorption, and modulating bone remodeling processes.

Application

It is approved for the management of secondary hyperparathyroidism in patients with chronic kidney disease stages 3 through 5, where renal conversion of vitamin D to its active form is impaired. It is also utilized for the treatment of vitamin D deficiency in patients with malabsorption syndromes or hepatic insufficiency. Unlike cholecalciferol, it does not require hepatic hydroxylation, making it particularly useful in patients with compromised liver function.

A 3‑arm double‑blind randomized trial compared daily calcifediol 20 µg, cholecalciferol 3200 IU, and placebo in 152 postmenopausal women (age 50‑70) with osteopenia/osteoporosis and baseline 25(OH)D <30 ng/mL. The primary endpoint was a composite measure of lower extremity function (gait speed, knee flexor/extensor strength, sit‑to‑stand) assessed as the probability of improvement or maintenance across eight tests at 3 and 6 months. Adjusted probabilities of success were 53.6% for calcifediol, 55.5% for vitamin D3, and 61.4% for placebo—no significant differences. Neither calcifediol nor high‑dose vitamin D3 improved or maintained lower extremity function in younger postmenopausal women with vitamin D insufficiency.

Fig. 1 Flow of participants in the trial. (Bischoff-Ferrari HA, et al., 2025)

References

Bischoff-Ferrari HA, et al. Effect of calcifediol and cholecalciferol on muscle function in postmenopausal women: a randomized controlled trial. Osteoporos Int. 2025; 36(6):1007-1018.

Does Calcifediol require extreme protection from light, heat, and oxygen?

Yes, as a vitamin D metabolite, it is highly sensitive to light, heat, and air. Storage under inert atmosphere in light-resistant, sealed containers at 2-8°C is essential.

What is the recommended storage temperature for Calcifediol?

Store at 2-8°C (refrigerated). Thermal degradation is a significant concern at room temperature, leading to loss of potency and formation of trans-isomers.

Is Calcifediol susceptible to isomerization during long-term storage?

Yes, it can undergo cis-trans isomerization upon light or heat exposure.

How is the stability of Calcifediol verified in soft gelatin capsule formulations?

We provide compatibility data for lipid-based formulations and recommend the use of antioxidants (such as tocopherol) to protect against oxidative degradation.