Cholecalciferol

Introduction Overview

Generic Name

cholecalciferol

Brand Name

Carlson D
Ddrops
Decara
Delta D3
Enfamil D-Vi-Sol
Replesta
Thera-D Rapid Repletion
Vitamin D3
D 1000 IU
D3-5
D3-50
D400
Maximum D3
D2000
Liquid Vitamin D-3
Thera-D 2000
Thera-D 4000
D-Vita Drops
Replesta NX
Replesta Children's
D3
Thera-D Sport
D3 1000
Celebrate Vitamin D3 Quick-Melt
Aqueous Vitamin D
UpSpringbaby D
Super-Strength D-5000
Super Daily D3
Optimal-D3
Optimal-D3 Pack
Optimal D3 M Pack
Optimal D3 M
Prevagen
VitaJoy Gummies Daily D
Kid's Super Daily D3
Prevagen Extra Strength
High Potency Vitamin D3
Zarbee's Baby Vitamin D
Happy Sunshine Vitamin D3
D3 Liquid
Vitamin D3 Gummies
Vitamin D3 Bone and Joint Health
Vitafusion Vitamin D3 Gummies
Vitafusion Vitamin D3 Extra Strength Gummies
Osteo-Vit3

Dosage Form

oral capsule
oral liquid
oral solution
oral tablet
oral tablet, chewable
oral tablet, disintegrating
oral wafer

Drug Class

Vitamins

Pharmacokinetics

Absorption:
Cholecalciferol (vitamin D3) is absorbed primarily in the small intestine, along with dietary fats, making its bioavailability dependent on the presence of bile and the digestive process of lipids. Following oral administration, cholecalciferol is incorporated into micelles and transported across the intestinal mucosa via passive diffusion. Factors such as malabsorption syndromes, bile acid deficiency, or fat malabsorption can significantly reduce absorption, necessitating adjusted dosages or alternative delivery methods. Peak serum concentrations occur several hours post-dose, with variable absorption depending on formulation and fat content of meals.

Distribution:
Once absorbed, cholecalciferol is transported in the bloodstream bound primarily to vitamin D-binding protein (DBP), which facilitates tissue distribution. It is distributed to liver and adipose tissue, where it is sequestered or metabolized. Due to its fat solubility, cholecalciferol accumulates in adipose tissue, serving as a reservoir that influences its plasma half-life and duration of action. The biological half-life reflects both the release from these stores and metabolic clearance rates.

Metabolism:
Cholecalciferol undergoes sequential hydroxylations to become active. It is first hydroxylated in the liver by 25-hydroxylase enzymes (mainly CYP2R1) to form 25-hydroxyvitamin D3 (calcidiol), the major circulating form and marker of vitamin D status. Further hydroxylation occurs primarily in the kidneys by 1α-hydroxylase to produce 1,25-dihydroxyvitamin D3 (calcitriol), the hormonally active form. This step is tightly regulated by serum calcium, phosphate, parathyroid hormone (PTH), and fibroblast growth factor 23 (FGF23). Extra-renal conversion in various tissues contributes to autocrine and paracrine functions of vitamin D.

Elimination:
Calcidiol and calcitriol are metabolized to inactive forms, such as calcitroic acid, which are excreted predominantly via the bile into feces, with minimal renal excretion. The elimination half-life of 25-hydroxyvitamin D3 is approximately 15 days, reflective of the vitamin’s storage in fat and slow release. Factors influencing elimination include liver and kidney function, and certain diseases or drugs can affect these metabolic pathways.

Dosage Forms

Available Dosage Forms:
Cholecalciferol is available in multiple forms designed to accommodate diverse patient needs and dosing regimens. These include:
- Oral capsules with strengths of 10 mcg (400 IU), 25 mcg (1000 IU), 50 mcg (2000 IU), 62.5 mcg (2500 IU), 125 mcg (5000 IU), 250 mcg (10,000 IU), 325 mcg, 350 mcg, 625 mcg, and 1250 mcg (50,000 IU).
- Oral liquids in various concentrations, including 10 mcg/0.25 mL (400 IU/0.25 mL), 10 mcg/drop, 10 mcg/mL, 125 mcg/0.5 mL, 125 mcg/mL, 1250 mcg/3 mL, and 25 mcg/10 mL.
- Oral solutions with 25 mcg/drop and 250 mcg/mL strengths.
- Oral tablets offered in 10 mcg, 25 mcg, 50 mcg, 100 mcg, 125 mcg, 250 mcg, and 1250 mcg strengths.
- Chewable tablets available in 10 mcg, 25 mcg, 37.5 mcg, and 50 mcg.
- Disintegrating (Quick-Melt) tablets in 50 mcg and 125 mcg formulations, designed for patients with swallowing difficulties.
- Oral wafers at 350 mcg and 1250 mcg strengths, often used for weekly or monthly dosing.

Dosages for Adults and Adolescents:
The standard recommended dietary allowance (RDA) for vitamin D is 15 mcg (600 IU) daily for individuals aged 18–70 years, increased to 20 mcg (800 IU) daily for those over 70 years to maintain bone health and calcium homeostasis. For supplementation, dosages may range up to 100 mcg (4000 IU) as tolerable upper intake levels to avoid toxicity. The dosing regimen may vary depending on baseline vitamin D status, indication, and patient factors.

Specific Patient Populations:
- Infants 0 to 6 months: 10 mcg (400 IU) daily with an upper intake limit of 25 mcg (1000 IU).
- Infants 7 to 12 months: 10 mcg (400 IU) daily, upper limit 38 mcg (1500 IU).
- Children 1–3 years: 15 mcg (600 IU) daily, upper limit 63 mcg (2500 IU).
- Children 4–8 years: 15 mcg (600 IU) daily, upper limit 75 mcg (3000 IU).
- Adolescents 9–18 years: 15 mcg (600 IU) daily, upper limit 100 mcg (4000 IU).
Dosage adjustments may be necessary in conditions such as malabsorption, chronic kidney disease, or during pregnancy and lactation. Liquid and disintegrating forms facilitate administration in pediatric and geriatric patients or those with swallowing difficulties, ensuring adherence and accurate dosing. The wafer formulations enable less frequent dosing, enhancing convenience.

Mechanism Of Action

Cholecalciferol, the natural form of vitamin D3, serves as a prohormone that undergoes sequential hydroxylations to yield the biologically active hormone calcitriol. The primary mechanism of action involves the regulation of calcium and phosphate homeostasis, essential for normal bone mineralization and cellular function.

At the molecular level, calcitriol binds with high affinity to the intracellular vitamin D receptor (VDR), a member of the nuclear receptor family. Upon ligand binding, the VDR forms a heterodimer with the retinoid X receptor (RXR), which then binds to vitamin D response elements (VDREs) in the promoter regions of target genes. This interaction modulates transcription of a myriad of genes linked to calcium transport proteins, phosphate metabolism, and cellular differentiation.

In the intestines, activation of VDR upregulates epithelial calcium channels and calcium-binding proteins such as calbindin, increasing the active absorption of dietary calcium and phosphate. In bones, calcitriol influences osteoblast and osteoclast differentiation and function, promoting bone remodeling and mineralization. Furthermore, it suppresses parathyroid hormone secretion through direct action on parathyroid cells, thereby indirectly modulating bone resorption.

Beyond bone and mineral metabolism, cholecalciferol exhibits pleiotropic effects impacting immune modulation, cell proliferation, and differentiation. Research has highlighted its role in reducing inflammatory cytokine production and supporting innate immunity, with potential implications for autoimmune and infectious diseases. Compared with ergocalciferol (vitamin D2), cholecalciferol has been demonstrated to generate higher and more sustained serum 25-hydroxyvitamin D levels, with superior efficacy in correcting deficiency states. Clinical trials underscore its safety and effectiveness in preventing fractures, falls, and vitamin D deficiency-related disorders, informing its widespread use as a dietary supplement and therapeutic agent.

Pharmacological Actions

Enhances calcium and phosphate absorption in the gastrointestinal tract to support bone mineralization.
Regulates bone remodeling by modulating osteoblast and osteoclast activity through the vitamin D receptor.
Suppresses parathyroid hormone secretion, thereby reducing bone resorption and maintaining serum calcium levels.
Modulates immune responses by regulating cytokine production and supporting innate immunity.
Supports cellular proliferation, differentiation, and apoptosis in various tissues.
Acts as a prohormone converted to calcitriol, the biologically active form of vitamin D.
Increases expression of calcium-binding proteins such as calbindin in the intestinal epithelium.
Influences phosphate homeostasis alongside calcium to prevent metabolic bone diseases.
Exhibits neuroprotective properties through regulation of neuronal calcium channels and neurotrophic factors.
May have antioxidant effects contributing to cellular protection.
Improves muscle function, potentially reducing the risk of falls in elderly patients.
Demonstrates superior potency and longer half-life compared to vitamin D2 (ergocalciferol).
Contributes to regulation of the renin-angiotensin system, impacting cardiovascular health.
Influences insulin secretion and glucose metabolism as part of endocrine pancreatic function.
Facilitates autocrine and paracrine signaling via local tissue conversion to active vitamin D metabolites.

Therapeutic Or Clinical Uses

Prevention and treatment of vitamin D deficiency and insufficiency.
Management of metabolic bone diseases such as osteoporosis and rickets.
Supplementation in populations with limited sun exposure or malabsorption syndromes.
Adjunct therapy in hypocalcemia resulting from hypoparathyroidism or chronic kidney disease.
Prevention of falls and fractures in elderly patients by enhancing musculoskeletal health.
Supportive treatment in conditions of impaired calcium and phosphate metabolism.
Used in pediatric populations to prevent nutritional rickets.
Correction of vitamin D insufficiency to improve immune function.
Supplementation during pregnancy and lactation to support maternal and fetal bone health.
Aid in management of diseases with secondary vitamin D deficiency, such as cystic fibrosis or liver disease.
Potential adjunct in autoimmune diseases through immunomodulatory effects.
Supportive therapy post bariatric surgery to counteract malabsorption.
Used in conjunction with calcium supplementation to optimize bone mineral density.
Prevention of falls in institutionalized elderly populations.
Helping maintain adequate 25-hydroxyvitamin D serum levels as part of a general health maintenance program.

Side Or Adverse Effects

Hypercalcemia characterized by symptoms such as nausea, vomiting, and constipation.
Metallic taste in the mouth as an early sign of vitamin D overdose.
Muscle weakness and bone pain relating to calcium imbalance.
Weight loss associated with chronic excessive intake.
Constipation and gastrointestinal discomfort including abdominal pain.
Nausea and occasional vomiting in cases of elevated serum vitamin D levels.
Allergic reactions including urticaria (hives), swelling of face, lips, tongue, or throat.
Rare instances of hypercalciuria leading to kidney stones.
Potential for vascular and soft tissue calcification with long-term overdose.
Headache and confusion secondary to hypercalcemia in severe cases.
Fatigue and lethargy related to electrolyte imbalances.
Increased thirst and polyuria signaling early vitamin D toxicity.
Irritability or mood changes occasionally reported.
Exacerbation of preexisting hypercalcemia or hypervitaminosis D conditions.
Rare reports of rash or skin reactions.

Precautions

Not to be used in patients with known hypersensitivity to vitamin D or its derivatives.
Avoid use in individuals with preexisting hypercalcemia or hypervitaminosis D.
Caution in patients with malabsorption syndromes as altered vitamin D metabolism may occur.
Monitoring serum calcium and 25-hydroxyvitamin D levels is advised during prolonged therapy.
Use with care in patients with kidney disease due to altered metabolism and risk of hypercalcemia.
Consider potential interactions with medications influencing calcium or vitamin D levels.
Patients with heart disease should be evaluated carefully prior to supplementation.
Pregnant and breastfeeding women should seek medical advice before use to prevent fetal or neonatal toxicity.
Do not exceed recommended dosages to minimize risk of toxicity.
Adjust dosages in pediatric populations based on age and weight.
Contains potential allergenic excipients such as peanut oil or soybean oil in some formulations.
Patients with phenylketonuria (PKU) should be cautious with formulations containing aspartame.
In diabetes, monitor blood glucose as vitamin D status can influence insulin sensitivity.
Avoid concurrent use with other vitamin D supplements unless directed by a physician.
Educational guidance on dietary calcium and vitamin D intake should accompany therapy.

Warnings

Contraindicated in patients with hypersensitivity to cholecalciferol or other forms of vitamin D.
Avoid use in hypercalcemia or evidence of vitamin D toxicity (hypervitaminosis D).
Risk of vitamin D overdose causing life-threatening hypercalcemia if dosing is excessive.
Patients with malabsorption disorders may have altered vitamin D kinetics requiring supervision.
Excessive intake during pregnancy or lactation may harm unborn or nursing infants.
Frequent monitoring with blood tests and possible imaging (e.g., x-rays) are necessary during treatment.
Use caution with formulations containing allergenic substances in patients with allergies.
Avoid concurrent high-dose vitamin A supplements which may exacerbate toxicity risks.
Potential drug interactions necessitate medication review before initiation.
Do not exceed tolerable upper intake levels to prevent adverse effects.
Monitoring is important in elderly patients to reduce risk of hypercalcemia and falls.
Risk of nephrolithiasis or soft tissue calcification with long-term high doses.
Keep out of reach of children to prevent accidental overdose.
Medical supervision is mandatory for dosing adjustments in chronic kidney disease or parathyroid disorders.
Discontinue and seek emergency care if signs of allergic reaction or overdose occur.

Contraindication

Known allergy or hypersensitivity to cholecalciferol or vitamin D preparations.
Hypercalcemia of any cause, as vitamin D may exacerbate elevated serum calcium.
Hypervitaminosis D – elevated vitamin D levels preclude further supplementation.
Conditions causing impaired vitamin D metabolism leading to toxicity risk.
Severe malabsorption syndromes with inability to process vitamin D adequately without monitoring.
Patients taking certain medications that contraindicate vitamin D use without specialist oversight.
History of vitamin D toxicity or granulomatous diseases such as sarcoidosis.
Severe renal impairment without medical supervision due to disturbed vitamin D metabolism.
Those with disorders leading to hypercalciuria and risk of nephrolithiasis.
Infants and children without medical advice to prevent dosing errors.
Concurrent use with other vitamin D analogs without clinical indication.
Pregnant or breastfeeding women without physician guidance due to fetal/neonatal risk.
Pre-existing hyperphosphatemia untreated before vitamin D administration.
Patients with disturbances in calcium-phosphate metabolism requiring specialized care.
Use contraindicated in some formulations containing allergenic excipients in sensitized individuals.

Drug Interactions

Antacids containing aluminum may impair absorption of cholecalciferol if taken concurrently.
Medications such as cholestyramine can reduce vitamin D absorption by binding bile acids.
Phenytoin and phenobarbital induce hepatic enzymes that accelerate vitamin D metabolism, reducing efficacy.
Rifampin increases hepatic metabolism of vitamin D, potentially leading to deficiency.
Thiazide diuretics increase serum calcium and, when combined with vitamin D, risk hypercalcemia.
Glucocorticoids decrease calcium absorption and impair vitamin D metabolism, reducing effectiveness.
Orlistat and other lipase inhibitors can reduce vitamin D absorption due to fat malabsorption.
Certain anticonvulsants modify vitamin D metabolism, necessitating dosage adjustments.
Ketoconazole inhibits vitamin D hydroxylation enzymes, altering activation.
Digitalis toxicity risk may increase with hypercalcemia induced by vitamin D overdose.
Calcium supplements combined with cholecalciferol may increase risk of hypercalcemia if not monitored.
Magnesium deficiency impairs vitamin D activation; co-administration may require monitoring.
Excessive vitamin D may interfere with the efficacy of some bisphosphonates.
Vitamin D enhances absorption of calcium, potentially altering the effect of certain cardiac glycosides.
Concurrent use with other vitamin D analogs may lead to additive toxicities.

Preparations Of The Drug

Oral capsules in multiple strengths ranging from 10 mcg (400 IU) to 1250 mcg (50,000 IU).
Oral liquid formulations for flexible dosing in infants, children, and adults.
Oral solutions providing high-potency vitamin D in drop form to facilitate administration.
Tablets including standard, chewable for ease of ingestion, disintegrating Quick-Melt tablets for patients with dysphagia.
Oral wafers designed for weekly or monthly dosing schedules.
Combination products with calcium and other vitamins minerals for comprehensive supplementation.
Various brands offering over-the-counter and prescription-strength formulations.
Drops formulated with peanut oil or soybean oil as carriers in some products.
Preparation options that include sugar-free, dye-free, and phenylalanine-free versions for sensitive patients.
Gummies and chewable tablets with added flavorings targeted at pediatric and adult populations.
Liquid vitamin D-3 concentrates designed for rapid correction of deficiency states.
Super-strength capsules and tablets for high-dose repletion therapy.
Formulations tailored for neonatal and pediatric supplementation requirements.
Sustained-release or delayed-release formulations potentially available for specialized clinical needs.
Pharmaceutical grade, USP standardized vitamin D3 ensuring quality and potency.