Ergocalciferol (vitamin D2 ) is a provitamin that is activated to calcitriol or 1,25-dihydroxy vitamin D 3 by sequential hydroxylation in the liver and kidneys. It is used as a dietary vitamin D supplement and in the treatment of hypoparathyroidism. However, since ergocalciferol requires activation before it is fully functional, alternative therapies like alfacalcidol and calcitriol are the preferred agents. It is also used (as off-label treatment) in the prevention of osteoporosis, vitamin D insufficiency and vitamin D deficiency including patients with chronic kidney disease.

Ergocalciferol (vitamin D2 ) Dose in Adults

Note: 1 mcg of ergocalciferol  = 40 units

Off-label use in the prevention of Osteoporosis:

• Adults 50 years of age or older:
  • 800 - 1,000 units/day orally.

Off label use in the treatment of Vitamin D deficiency & insufficiency:

• The optimal cut-offs have not been clearly defined. However, most experts recommend a range of 20 - 40 ng/ml as reasonable.
• For every 100 units/day of vitamin D ingested, the serum levels increase by 0.7 - 1 ng/ml in individuals with normal absorption.
• Dosing recommendations are as follows:
• Initial dosing (according to baseline serum vitamin D levels:

• Levels between 20 - 30 ng/mL:
  • 600 - 800 units orally once a day (repeat vitamin D level is not required) or
  • 1,000 - 2,000 units orally once a day (recheck vitamin D levels in 3 months)
• Levels between 10 - 20 ng/mL:
  • 800 - 1,000 units orally once a day or
  • 2,000 units once a day (repeat serum vitamin D levels after 3 months).
  • Patients who do not achieve a target vitamin D levels may be advised 2,000 units orally once a day or 50,000 units orally once a week for 6 - 8 weeks or
  • 5,000 - 7,000 units orally once a day for 8 weeks followed by decreased maintenance dosing to maintain the target vitamin D levels.
• Levels less than 10 ng/mL or symptomatic patients:
  • 50,000 units orally once a week or
  • 5,000 - 7,000 units once a day for 6 - 8 weeks to achieve the target levels ( recheck vitamin D levels after 3 months).
• Maintenance dosing:
  • 600 to 800 units/day but depends on the baseline vitamin D levels and is highly patient specific.
• Higher doses or longer durations may be required in obese patients, patients with gastrointestinal problems that impair its absorption, and patients on certain medications.

Off label use in the treatment of Vitamin D deficiency or insufficiency in patients with chronic kidney disease:

• Vitamin D dosing is the same as in the general population.

Use in the treatment of Hypoparathyroidism:

Patients with hypoparathyroidism requires supplementation of the active of vitamin D i.e. alfacalcidol and calcitriol in conjunction with calcium supplementation.

Ergocalciferol (vitamin D2) Dose in Childrens

Note: 1 mcg = 40 units

Adequate Intake in infants:

• 400 units/day orally

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Recommended Daily Allowance (RDA):

• Children and Adolescents: 600 units/day orally

Use in the treatment of Hypoparathyroidism:

• Infants, Children, and Adolescents:
  • 50,000 - 200,000 units orally once a day with calcium supplements

Use in the treatment of Vitamin D deficiency (as Rickets prevention):

• Fully or partially breastfed infants:
  • 400 units/day orally beginning in the first few days of life.
  • Supplementation should continue until the infant is weaned to 1,000 mL/day or more or 1 qt/day orally of vitamin D-fortified milk
  • Formula-fed infants ingesting less than 1,000 mL of vitamin D-fortified formula or milk: 400 units/day orally.
• Children and Adolescents without adequate intake:
  • 400 -  600 units/day orally.

Use in the treatment of Vitamin D deficiency:

• Infants:
  • 2,000 units orally once a day for 6 weeks to achieve serum vitamin D levels of more than 20 ng/mL followed by a maintenance dose of 400 - 1,000 units daily.

• Children and Adolescents:
  • 2,000 units orally once a day for 6 - 8 weeks to achieve a serum vitamin D of more than 20 ng/mL followed by a maintenance dose of 600 - 1,000 units daily.

Use in the treatment of Vitamin D insufficiency or deficiency associated with CKD (stages 2 to 5, 5D) and serum 25 hydroxyvitamin D level of less than 30 ng/mL: 

• Levels between 16 - 30 ng/mL:
  • 2,000 units/day orally for 3 months or 50,000 units every month for 3 months.
• Levels between 5 - 15 ng/mL:
  • 4,000 units/day orally for 12 weeks or 50,000 units every other week for 12 weeks.
• Level of less than 5 ng/mL:
  • 8,000 units/day orally for 4 weeks then 4,000 units/day for 2 months for a total therapy of 3 months or 50,000 units/week for 4 weeks followed by 50,000 units 2 times monthly for a total therapy of 3 months
• Maintenance dose:
  • • 200 - 1,000 units/day orally.

Use in the treatment of Rickets:

• Daily therapy (preferred):
  • Infants:
    • 2,000 units orally daily for 3 months or more followed by a maintenance dose of 400 units daily.
  • Children:
    • 3,000 - 6,000 units orally daily for 3 months or more followed by a maintenance dose of 600 units daily.
  • Adolescents:
    • 6,000 units orally daily for 3 months or more followed by a maintenance dose of 600 units daily.
• Single-dose therapy (alternative to cholecalciferol)
  • Infants 3 months or more:
    • 50,000 units orally once, or in divided doses over several days
    • Maintenance therapy of 400 units per day may be initiated after 3 months.
  • Children:
    • 150,000 units orally once, or in divided doses over several days
    • Maintenance therapy of 600 units per day may be initiated after 3 months
  • Adolescents:
    • 300,000 units orally once, or in divided doses over several days
    • Maintenance therapy of 600 units per day may be initiated after 3 months.

Ergocalciferol Pregnancy Risk Factor C

• Ergocalciferol crosses over the placental barrier, and maternal vitamin D levels correlate to fetal levels.
• Animal studies have shown adverse effects.
• Pregnant women require 1000 to 2000 units per day, but deficient patients may need higher doses.
• Vitamin D levels should be monitored, particularly for patients on high doses.

Ergocalciferol use during breastfeeding:

• Breastmilk may contain ergocalciferol or its metabolites, which can cause hypercalcemia in the infants breastfeeding.
• Lactating women should use it with caution
• Infants do not receive adequate vitamin D from mothers who supplement it.
• Vitamin D supplementation should be considered for all infants who are breastfed exclusively or partially.

Ergocalciferol (vitamin D2) Dose in Renal Disease: 

• Dose adjustment has not been recommended by the maufacturer in patients with renal disease.

Ergocalciferol (vitamin D2) Dose in Liver Disease:

• Dose adjustment has not been recommended by the maufacturer in patients with liver disease. 

Common Side Effects Of Ergocalciferol Include:

• Hypervitaminosis D
• Hyperphosphatemia
• Hypercalcemia (manifested by constipation, nausea, dehydration, altered mentation, drowsiness, renal stones, and abdominal pain).

Contraindication to Ergocalciferol (Vitamin D2) include:

• Hypercalcemia
• Hypervitaminosis D
• Malabsorption syndrome
• Allergies to vitamin D and its analogs

Warnings and Precautions

• Vitamin D toxicities:
  • Excessive doses can cause toxic effects such as nausea, vomiting and loss of appetite.
  • The effects of ergocalciferol may last up to 2 months after treatment is stopped.
• Hyperphosphatemia
  • Metastatic calcification may occur when hyperphosphatemia is present. Hyperphosphatemia patients should exercise caution.
• Obesity:
  • Vitamin D is stored in the adipose tissue.
  • This means that obese people with a BMI greater than 30 Kg/m2 may need higher doses. 
  • You should monitor your vitamin D intake when it exceeds the recommended RDA.
• Renal impairment
  • Patients with kidney disease especially ESRD require the active form of vitamin D in the form of calcitriol or alfacalidol.

Monitor:

• Signs and symptoms of vitamin D toxicity.
• Serum 25 (OH) Vitamin D levels 3 months after the initiation or adjustment in the dose.
• Depending on the severity of the deficiency, measure serum calcium, phosphorus, alkaline phosphatase, and PTH (Parathyroid hormone) levels.
• Young children with vitamin D deficiency may require more frequent dosing.
• Individuals at increased risk of vitamin D deficiency like those with chronic fat malabsorption and those using antiseizure medications should have vitamin D levels done at 3-months intervals. PTH and bone mineral density should be monitored at 6 months intervals.
• In patients with CKD, measure corrected calcium and phosphorus after one month and then at three months intervals.

How to take ergocalciferol?

• It may be administered orally without regard to meals.
• Administer with an accurate measuring device to avoid overdosage if an oral liquid formulation is used.

Mechanism of action of ergocalciferol:

• Ergocalciferol (vitamin D 2) is a provitamin activated to calcitriol and 1,25-dihydroxy vitamin D3 by sequential hydroxylation within the liver, kidneys, and liver.
• It increases calcium absorption from small intestine and renal tubules.

It is capable of initiating action at the rate of10-24 hours. After daily administration, the maximum effect can be seen in approximately a month. It is fat-soluble and absorbed in small intestines.

For absorption, it must be present with bile. The Half-lifeThe circulating 25(OH), vitamin D takes 2 - 3 week, while the activated (1,25-dihydroxy vitamin) takes about 4 hours. It is excreted mainly in the feces. 

International brands of ergocalciferol:

• D-Forte
• Osto-D2
• SANDOZ D-Forte
• Calcidol
• Calciferol
• Drisdol
• Adekon
• Aderowest
• AFI-D2 forte
• Aquasol AD
• Axed
• Biocatines D2
• Calciferol BD
• D-forte
• DePURA
• Devitol
• Endo-D
• Ergosterina
• Irradiata
• Farmobion D2
• Infadin
• Jekovit
• One-Alpha
• Ostelin
• Pharmaton Complex
• Raquiferol
• Raquiferol BC
• Raquiferol D2
• Sterogyl
• Sterogyl-15
• Vigantol
• Vigantolo
• Vitamina D2 Salf
• Vitaminol

Ergocalciferol (vitamin D2) Brands in Pakistan: