Overview

Cholecalciferol is also known as Vitamin D3. Vitamin D3 is a form of Vitamin D. Cholecalciferol is the raw form of the nutrient that humans obtain through exposure to sunlight. It is the form the nutrient takes after it has been processed for use by the body. Cholecalciferol is made in the skin following UVB light exposure It is structurally similar to steroids such as testosterone, cholesterol, and cortisol (though vitamin D3 itself is a secosteroid). Excessive doses in humans can result in vomiting, constipation, weakness, and confusion Vitamin D is an essential nutrient that plays an important role in calcium metabolism and bone health. In recent years, biomarkers like PTH, calcium absorption have been used to define relevant biological indices of vitamin D nutritional status. Vitamin D3 supports calcium in your body in order to develop and maintain strong bones and healthy teeth.
it is also found in some foods and can be taken as a dietary supplement. It is used to treat and prevent vitamin D deficiency and associated diseases, including rickets

Indications

Vitamin D3 (Cholecalciferol) is indicated in the treatment and prevention of bone disorders including osteomalacia, rickets and so on, which are caused by low levels of vitamin D in the body.It is also used for familial hypophosphatemia, hypoparathyroidism that is causing low blood calcium, and Fanconi syndrome.

Pharmacology

Mechanism of action:

Cholecalciferol is inactive by itself. It is converted to its active form by two hydroxylations: the first in the liver, by CYP2R1 or CYP27A1, to form 25-hydroxycholecalciferol (calcifediol, 25-OH vitamin D3). The second hydroxylation occurs mainly in the kidney through the action of CYP27B1 to convert 25-OH vitamin D3 into 1,25-dihydroxycholecalciferol (All these metabolites are bound in blood to the vitamin D-binding protein. The action of calcitriol is mediated by the vitamin D receptor, a nuclear receptor which regulates the synthesis of hundreds of proteins and is present in virtually every cell in the body.

Pharmacodynamics:

Cholecalciferol (Vitamin D3) is a steroid hormone that has long been known for its important role in regulating body levels of calcium and phosphorus, in mineralization of bone, and for the assimilation of Vitamin A. The classical manifestations of vitamin D deficiency are rickets, which is seen in children and results in bony deformaties including bowed long bones. Deficiency in adults leads to the disease osteomalacia. Both rickets and osteomalacia reflect impaired mineralization of newly synthesized bone matrix, and usually result from a combination of inadequate exposure to sunlight and decreased dietary intake of vitamin D. Common causes of vitamin D deficiency include genetic defects in the vitamin D receptor, severe liver or kidney disease, and insufficient exposure to sunlight. Vitamin D plays an important role in maintaining calcium balance and in the regulation of parathyroid hormone (PTH). It promotes renal reabsorption of calcium, increases intestinal absorption of calcium and phosphorus, and increases calcium and phosphorus mobilization from bone to plasma.

Pharmacokinetics:

ABSORPTION: Cholecalciferol is readily absorbed from the small intestine if fat absorption is normal . Bile is necessary for absorption as well.
PROTEIN BINDING: 50% to 80%, in the plasma, vitamin D3 (from either diet or the skin) is bound to vitamin D-binding protein (DBP) produced in the liver, for transport to the liver.
METABOLISM: Within the liver, cholecalciferal is hydroxylated to calcidiol (25-hydroxycholecalciferol) by the enzyme 25-hydroxylase. Within the kidney, calcidiol serves as a substrate for 1-alpha-hydroxylase, yielding calcitriol (1, 25-dihydroxycholecalciferol), the biologically active form of vitamin D3.
ELIMINATION: Vitamin D is excreted in faeces and urine.

Side Effects

• Allergic reactions.
• swelling of the face, lips, or tongue.
• Bone pain
• Increased thirst
• Increased urination
• Irregular heartbeat, high blood pressure
• Seizures
• Unexpected weight loss

Contraindication

Cholecalciferol is contraindicated in:

• Nephrolithiasis / nephrocalcinosis
• Severe renal impairment and renal failure
• Hypervitaminosis D
• Hypersensitivity to the active substances or to any of the excipients sarcoidosis.
• high amount of phosphate in the blood, high amount of calcium in the blood.
• blockage of the arteries called arteriosclerosis,kidney stones.

Pregnancy and Lactation: Vitamin D3 film-coated tablets can be used during breast-feeding. Calcium and vitamin D pass into breast milk. This should be considered when giving additional vitamin D to the child.