Indications

Vitamin D3 is indicated for the prevention and treatment of Vitamin D3 deficiency, which commonly occurs due to limited sunlight exposure or inadequate dietary intake.

• Bone & Dental Health: Vital for efficient absorption of calcium and phosphate required to maintain strong bones and teeth, preventing rickets, osteomalacia, and osteoporosis.

• Immune Support: Plays a key role in boosting overall immune system function.

• Maternal & Infant Care: Essential during pregnancy and breastfeeding to help prevent pre-eclampsia and support infant growth and development.

Pharmacology

• Mechanism of Action: Vitamin D3 is absorbed in the small intestine, bound to $\alpha$-globulins, and transported to the liver where it is converted into 25-hydroxyvitamin D3 (calcidiol). A second conversion in the kidneys creates 1,25-dihydroxyvitamin D3 (calcitriol)—the active form that binds to Vitamin D Receptors (VDRs) to facilitate calcium absorption.

• Pharmacokinetics: As a fat-soluble vitamin, unmetabolized Vitamin D3 is stored in fat and muscle tissue. It has a half-life of approximately 50 days and is eliminated via feces and urine.

Dosage & Administration

Note: Administer strictly as directed by a registered physician.

Capsules

• Adults:

  • Deficiency Treatment: 40,000 IU once weekly for 7 weeks.

  • Maintenance: 1,400–2,000 IU/day. (Check 25-hydroxyvitamin D levels 3–4 months after starting maintenance).

  • Prevention: 20,000 IU every 4 weeks (higher doses may be required in specific cases).

  • Osteoporosis Support: 20,000 IU once a month.

• Children (12–18 Years):

  • Deficiency Treatment: 20,000 IU once every 2 weeks for 6 weeks.

  • Prevention: 20,000 IU every 6 weeks.

Oral Tablets (Film-Coated, Oroflash, or Chewable)

• Film-Coated: 1,000 IU (1–2 tablets) daily with food or within 1 hour after a meal.

• Oroflash / Chewable: 1,000 IU to 2,000 IU daily with food or within 1 hour after a meal. Chew thoroughly before swallowing.

Oral Solution

• Under 1 Year: 400 IU once daily.

• 1 to 18 Years: 600 IU once daily.

Injection (Intramuscular or Oral Use)

• Treatment:

  • Rickets: 1 ampoule every 2 weeks for 1 month, then 1 ampoule every 4 months.

  • Osteoporosis / Osteomalacia: 1 ampoule every 2 weeks for 3 months.

  • Hypocalcemic Tetany: 1 ampoule every 4 months (up to 2 ampoules if directed).

  • Menopause: 1 ampoule every 6 months.

  • Deficiency: 1 ampoule, repeated 1 to 6 months later as indicated.

• Prevention:

  • Pregnancy: $\frac{1}{2}$ ampoule at the 6th or 7th month.

  • Breastfeeding / Children up to 5 yrs / Adolescents: 1 ampoule every 6 months ($\frac{1}{2}$ ampoule for breastfeeding if specified).

  • Elderly: $\frac{1}{2}$ ampoule every 3 months.

• Injection Administration Instructions:

  • Oral: Snap the narrow neck, pour contents into a spoon, and mix with water or milk before consuming.

  • IM Use: Snap the narrow neck and administer as an intramuscular injection.

Safety Information

Contraindications

Do not use in conditions associated with hypercalcemia, active Vitamin D3 toxicity, or known hypersensitivity to Vitamin D3 or its excipients.

Drug Interactions

• Reduced Effect: Phenytoin, barbiturates, glucocorticoids, cholestyramine, paraffin oil, actinomycin, and imidazole antifungals may reduce efficacy or absorption.

• Increased Risk: Calcium combined with Vitamin D3 can enhance the effects of digitalis/cardiac glycosides (requires ECG and calcium monitoring).

Precautions & Warnings

• Monitor plasma-calcium levels regularly during high-dose therapy, renal impairment, pregnancy, or lactation.

• Exercise caution and consult a physician if taking Digoxin, Thiazide Diuretics, or if suffering from liver/kidney disease, hyperparathyroidism, lymphoma, tuberculosis, or granulomatous disorders.

Side Effects & Overdose

• Side Effects: Generally well-tolerated. Occasional acute symptoms include headache, nausea, vomiting, stomach pain, loss of appetite, and constipation.

• Overdose Toxicity: Chronic or acute overdose leads to hypercalcemia, causing weakness, apathy, excessive thirst, polyuria, and potential tissue/vascular calcification. Treatment involves immediate cessation of Vitamin D and rehydration.

Pregnancy & Lactation

Daily intake of 400 IU is recommended (up to 4,000 IU is proven safe if deficiency is present). Excreted in breast milk; consider maternal intake when supplementing a nursing infant.

General Information

• Therapeutic Class: Bone formation vitamins / Vitamin D preparations.

• Storage: Store below 25°C in a cool, dry place protected from light. Keep out of reach of children.