Ergocalciferol capsules for hypoparathyroidism and vitamin D resistant rickets

Ergocalciferol is a synthetic form of vitamin D2 used to regulate calcium levels in the body. It is administered orally in capsule form and specifically prescribed for treating certain disorders related to calcium and phosphorus imbalances, such as hypoparathyroidism and vitamin D resistant rickets. The medication requires close medical supervision due to its narrow therapeutic index and potential for serious toxicity.

Ergocalciferol capsules are approved for the following conditions:

• Treatment of hypoparathyroidism—a condition where the parathyroid glands produce insufficient hormone to regulate calcium levels.
• Management of refractory rickets (vitamin D resistant rickets), which is a form of rickets not responsive to regular vitamin D therapy.
• Treatment of familial hypophosphatemia, a genetic disorder characterized by low phosphate levels affecting bone health.

Ergocalciferol

Ergocalciferol (vitamin D2) undergoes two hydroxylation steps in the body to form its active metabolites. First, the liver converts it to 25-hydroxyvitamin D, then the kidneys further hydroxylate it to the biologically active 1,25-dihydroxyvitamin D. These metabolites promote the absorption of calcium and phosphorus from the small intestine, increase mineral release from bones, and enhance calcium reabsorption in the kidneys. This action raises serum calcium and phosphate levels, helping to normalize bone mineralization.

There is a delay of 10 to 24 hours before effects begin after oral administration due to the time required for metabolic activation.

Dosing must be individualized and closely monitored under medical supervision. The therapeutic dose range is narrow, requiring frequent blood calcium and phosphorus tests.

Vitamin D Resistant Rickets:

Doses can range from 12,000 to 500,000 IU daily depending on patient response.

Hypoparathyroidism:

Doses typically range from 50,000 to 200,000 IU daily, administered together with calcium lactate 4 g six times per day.

Monitoring: Blood calcium and phosphorus should be measured at least every two weeks, and X-rays of bones taken monthly until stable correction is achieved.

Calcium intake: Should be adequate to ensure clinical efficacy.

• Hypercalcemia (high blood calcium levels).
• Malabsorption syndrome affecting vitamin D absorption.
• Known hypersensitivity to vitamin D or any component of the product.
• Hypervitaminosis D (excess vitamin D levels).

• Hypersensitivity reactions may occur, especially in infants with idiopathic hypercalcemia; vitamin D must be strictly restricted in these cases.
• Serious toxicities including hypercalcemia, renal impairment, vascular and soft tissue calcifications can occur with overdose or improper dosing.
• Use caution in patients receiving thiazide diuretics as these may increase the risk of hypercalcemia.
• Keep medication out of reach of children due to risk of overdose.
• This product contains FD&C Yellow No. 5 (tartrazine), which can cause allergic-type reactions, especially in those sensitive to aspirin.
• Protect the capsules from light to prevent degradation.

Signs of hypervitaminosis D and toxicity include:

• Renal effects: polyuria, nocturia, polydipsia, hypercalciuria, azotemia, hypertension, nephrocalcinosis, irreversible renal insufficiency.
• Central nervous system: mental retardation, weakness, vague aches, stiffness.
• Soft tissues: widespread calcification including heart, blood vessels, renal tubules, lungs.
• Skeletal: bone demineralization (osteoporosis), stunted growth in children.
• Gastrointestinal: nausea, anorexia, constipation.
• Metabolic: mild acidosis, anemia, weight loss.

• Mineral oil can reduce absorption of ergocalciferol by interfering with fat-soluble vitamin absorption.
• Thiazide diuretics may lead to dangerous hypercalcemia in patients treated concurrently with ergocalciferol.

Pregnancy

Animal studies associate vitamin D excess with fetal abnormalities resembling supravalvular aortic stenosis syndrome. Use of vitamin D above recommended levels during pregnancy should be avoided unless benefits outweigh risks. Safety above 400 IU daily in pregnancy is not established.

Nursing Mothers

Caution is advised; large maternal doses can cause elevated vitamin D metabolites in breast milk, resulting in hypercalcemia in nursing infants. Monitoring infant serum calcium is recommended if high doses are used.

Overdose effects can last for two or more months due to storage in body tissues.

Symptoms of overdose include hypercalcemia with anorexia, nausea, weakness, constipation, mental retardation, anemia, renal impairment, widespread soft tissue calcification, bone demineralization, and stunted growth in children.

Treatment involves immediate cessation of vitamin D, low calcium diet, hydration, and symptomatic care. Severe hypercalcemia may require intravenous saline, loop diuretics, dialysis, or other therapies like corticosteroids and EDTA. Deaths from renal or cardiovascular failure have been reported with untreated severe toxicity.

Store at 77°F (25°C) with permitted excursions between 59° to 86°F (15° to 30°C) as per USP Controlled Room Temperature guidelines. Dispense in a tight, light-resistant container to protect from light.