Defrol OS50 ml

Defrol OS is indicated for the following:

Established / FDA-approved uses

• Prevention and treatment of vitamin D deficiency in children and adults, including deficiency confirmed by low serum 25-hydroxyvitamin D levels.
• Prevention of rickets in infants and children and treatment of nutritional rickets.
• Treatment of osteomalacia due to vitamin D deficiency.
• Adjunctive therapy in hypoparathyroidism, to help maintain normal calcium levels.

Guideline-supported / adjunct uses

• Adjunct to calcium supplementation for the prevention and treatment of osteoporosis, particularly in postmenopausal women and older adults, to reduce fracture risk.
• Supportive therapy in chronic kidney disease-related metabolic bone disease and malabsorption syndromes causing vitamin D deficiency (used alongside other measures as directed by a physician).
• General maintenance of bone health and prevention of deficiency in individuals with limited sun exposure, dark skin, obesity, or malabsorptive conditions, as advised by a physician.

The specific dose and duration depend on baseline vitamin D status, age, and underlying condition, and should be determined by a physician.

Each formulation of Cholecalciferol [Vitamin D3] contains cholecalciferol (vitamin D3) as the active ingredient, available in various strengths and dosage forms, including tablets, capsules, oral drops/solution, and injections. Strength is commonly expressed in International Units (IU) or micrograms (mcg); 1 mcg cholecalciferol = 40 IU vitamin D3. Common available strengths include low-dose daily formulations (e.g., 400 IU, 1000 IU) as well as high-dose weekly/monthly formulations (e.g., 20,000 IU, 40,000 IU, 50,000 IU, 100,000 IU). Excipients vary by manufacturer and formulation.

Defrol OS is a fat-soluble secosteroid and the naturally occurring form of vitamin D, produced in human skin upon exposure to ultraviolet-B (UV-B) sunlight and also obtained from dietary sources and supplements. It is biologically inactive until it undergoes sequential hydroxylation in the liver (to 25-hydroxyvitamin D, calcifediol) and then in the kidney (to 1,25-dihydroxyvitamin D, calcitriol), the active hormonal form.

Defrol OS plays a central role in calcium and phosphate homeostasis, supporting intestinal absorption of calcium and phosphorus, normal bone mineralization, and neuromuscular function. It is widely used as a dietary supplement and therapeutic agent for the prevention and treatment of vitamin D deficiency and associated bone disorders.

Defrol OS belongs to the therapeutic class of Vitamins, specifically fat-soluble vitamin D analogues/supplements, used for the prevention and treatment of vitamin D deficiency and related bone metabolism disorders.

Mechanism of action: Cholecalciferol [Vitamin D3] is converted in the liver to 25-hydroxyvitamin D (calcifediol), the major circulating and storage form, and then in the kidney to the biologically active hormone 1,25-dihydroxyvitamin D (calcitriol). Calcitriol binds to the vitamin D receptor (VDR) in target tissues (intestine, bone, kidney, parathyroid gland), regulating gene transcription to:

• Increase intestinal absorption of calcium and phosphate.
• Promote renal tubular reabsorption of calcium.
• Mobilize calcium from bone in coordination with parathyroid hormone (PTH) to maintain serum calcium levels.
• Support normal mineralization of bone matrix (osteoid).

Pharmacokinetics: Cholecalciferol [Vitamin D3] is absorbed in the small intestine (absorption is enhanced by dietary fat and bile) and undergoes enterohepatic circulation. It is transported bound to vitamin D-binding protein, stored mainly in adipose tissue and muscle, and has a long half-life (serum 25-hydroxyvitamin D half-life is approximately 2-3 weeks), which allows for both daily and intermittent (weekly/monthly) high-dose regimens. It is metabolized in the liver and kidney and eliminated primarily in bile/feces.

Defrol OS is generally administered orally as tablets, capsules, or oral drops, taken with or without food (preferably with a meal containing fat to enhance absorption). High-dose weekly/monthly products must be taken exactly at the prescribed interval — not more frequently. Injectable forms are given intramuscularly by a healthcare provider. Do not chew or crush formulations unless specifically labeled for that use.

Defrol OS has the following clinically significant interactions:

• Thiazide diuretics: Concurrent use can increase the risk of hypercalcemia, as thiazides reduce urinary calcium excretion while Defrol OS increases calcium absorption; calcium levels should be monitored.
• Digoxin and other cardiac glycosides: Vitamin D-induced hypercalcemia can potentiate digoxin toxicity and increase the risk of cardiac arrhythmias; caution and monitoring are advised with concurrent use.
• Corticosteroids: Chronic corticosteroid use can impair calcium absorption and vitamin D metabolism, potentially increasing Defrol OS dose requirements.
• Cholestyramine, colestipol, orlistat, and mineral oil: These agents can reduce intestinal absorption of Defrol OS (a fat-soluble vitamin); doses should be separated in time where co-administration is necessary.
• Phenytoin, phenobarbital, and other enzyme-inducing anticonvulsants: May increase hepatic metabolism of Defrol OS, reducing its effectiveness and potentially requiring dose adjustment.
• Other vitamin D analogues or calcium supplements: Concurrent high-dose use increases the risk of hypercalcemia and vitamin D toxicity; combined intake should be monitored by a physician.

At recommended doses, Defrol OS is generally well tolerated and side effects are uncommon. Adverse effects are primarily associated with excessive intake leading to hypercalcemia. Reported effects include:

• Nausea, vomiting, constipation, decreased appetite, or dry mouth (with excessive dosing).
• Headache, fatigue, weakness, or metallic taste.
• Symptoms of hypercalcemia with overdose/toxicity: polyuria, polydipsia, confusion, muscle weakness, and, rarely, kidney impairment or arrhythmias (see Overdose).
• Mild allergic-type reactions (rash, pruritus) have rarely been reported.

Defrol OS at recommended dietary allowance (RDA) doses is generally considered safe during pregnancy and lactation and is often recommended as part of routine prenatal supplementation. However, high-dose supplementation beyond physician-recommended amounts should be avoided, as excessive maternal vitamin D intake has been associated with fetal harm (hypercalcemia) in animal studies at high doses. Defrol OS should be used during pregnancy and breastfeeding only in doses recommended by a physician; use only if clearly needed, with the dose individualized based on baseline vitamin D status and clinical judgment. Defrol OS is excreted in breast milk; a physician should guide dosing in nursing mothers and their infants.

The following precautions apply to the use of Defrol OS:

• Risk of vitamin D toxicity/hypercalcemia: Defrol OS is a fat-soluble vitamin that can accumulate in the body with excessive or prolonged high-dose use, particularly with unsupervised use of high-dose weekly or monthly mega-dose formulations. Doses should not exceed those prescribed, and the interval between high-dose formulations must be respected. Periodic monitoring of serum calcium and 25-hydroxyvitamin D levels is advised during high-dose or prolonged therapy.
• Granulomatous disorders: Use with caution in patients with sarcoidosis, tuberculosis, or other granulomatous diseases, as macrophages in granulomas can produce active vitamin D independent of parathyroid hormone regulation, increasing the risk of hypercalcemia.
• Renal impairment: Patients with significant renal impairment have reduced capacity to convert Defrol OS to its active form and are at increased risk of hyperphosphatemia; use requires physician supervision, and active vitamin D analogues may be preferred in such patients.
• Hyperparathyroidism: Use with caution, as it may worsen hypercalcemia.
• Existing hypercalcemia or hypercalciuria: Use with caution and only under close medical supervision, as it is otherwise contraindicated at toxic levels (see Contraindications).
• Avoid self-adjusting or exceeding the prescribed dose; excessive supplementation is a recognized and preventable cause of vitamin toxicity.

Overdose of Defrol OS can cause vitamin D toxicity, primarily manifesting as hypercalcemia. Symptoms may include nausea, vomiting, decreased appetite, constipation, weakness, fatigue, confusion, excessive thirst, increased urination, and, in severe or prolonged cases, kidney injury, nephrocalcinosis, or cardiac arrhythmias. If overdose is suspected, seek immediate medical attention or contact a poison control center/emergency services. Treatment is supportive and may include discontinuation of vitamin D and calcium intake, hydration, and other measures directed by a physician in a medical facility; do not attempt specific home treatment beyond seeking urgent medical care.

Store at room temperature (below 30°C), away from light and moisture. Keep out of reach of children.

Renal impairment: Use Defrol OS with caution in patients with significant renal impairment; conversion to active vitamin D is reduced and there is increased risk of hyperphosphatemia and hypercalcemia. Physician supervision and monitoring are advised.

Hepatic impairment: Since hepatic 25-hydroxylation is required for activation, patients with significant liver disease may have reduced efficacy and should be monitored; dose adjustment may be needed under physician guidance.

Elderly: Commonly used in older adults for bone health and fracture-risk reduction; standard doses are generally well tolerated, but periodic monitoring is reasonable, especially with high-dose regimens or concurrent calcium supplementation.

Obesity/malabsorption: Individuals with obesity, malabsorption syndromes, or after bariatric surgery may require higher doses of Defrol OS under physician supervision due to sequestration in fat tissue or reduced absorption.

Duration of therapy with Defrol OS depends on the indication: short, defined high-dose replacement courses (e.g., 6-8 weeks) are typically used to correct confirmed deficiency, followed by long-term (often indefinite) maintenance dosing to prevent recurrence, particularly in individuals with ongoing risk factors. For general bone health maintenance, low-dose daily or equivalent weekly/monthly supplementation may be continued long-term as advised by a physician, with periodic reassessment of vitamin D status.

Cholecalciferol [Vitamin D3] is classified as a fat-soluble vitamin (Vitamin D analogue), used therapeutically as a vitamin D supplement/bone metabolism agent.

Cholecalciferol [Vitamin D3] is hydroxylated in the liver to 25-hydroxyvitamin D and subsequently in the kidney to the active hormone 1,25-dihydroxyvitamin D (calcitriol), which binds nuclear vitamin D receptors to increase intestinal calcium and phosphate absorption, promote renal calcium reabsorption, and support normal bone mineralization, thereby maintaining calcium-phosphate homeostasis and skeletal health.

Defrol OS is approved for use in infants, children, and adolescents for the prevention and treatment of vitamin D deficiency and rickets. The American Academy of Pediatrics (AAP) recommends 400 IU/day for all breastfed and partially breastfed infants beginning shortly after birth, continued until the infant is weaned to at least 1 liter/day of vitamin D-fortified formula or milk, and 400-600 IU/day for older infants, children, and adolescents depending on dietary intake. Higher, physician-directed replacement doses are used for confirmed deficiency or rickets, followed by maintenance dosing. Dosing should always be guided by a pediatrician, particularly for high-dose or injectable formulations, which are not routinely used in young infants without specific medical indication.