Dosage and Administration
Ergocalciferol is usually administered orally once daily. Patients with GI, liver, or biliary disease associated with malabsorption of vitamin D analogs may require IM administration of ergocalciferol and, according to the manufacturers, should not be given oral ergocalciferol.
Each mg of ergocalciferol is equivalent to 40,000 USP units; each mcg of the drug is equivalent to 40 USP units. The manufacturers state that use of the dropper provided with the 200-mcg/mL oral solution delivers about 5 mcg/drop.
Dosage is expressed by weight (mg, mcg) or in terms of units.
During therapy with ergocalciferol, dosage depends on the nature and severity of the patient's hypocalcemia and must be individualized to maintain serum calcium concentrations of 9-10 mg/dL. Determinations of serum calcium, phosphorus, and BUN should be made every 2 weeks or more frequently as needed. In patients with familial hypophosphatemia or hypoparathyroidism, the manufacturers of ergocalciferol recommend that radiographic examination of the bones be performed every month until the condition stabilizes or is corrected; however, some clinicians believe that this is unnecessary.
Nutritional Rickets and Osteomalacia
In adults and children with nutritional rickets or osteomalacia and normal GI absorption, oral administration of 25 mcg of ergocalciferol daily results in normal serum calcium and phosphate concentrations in about 10 days, radiographic evidence of healing of bone within 2-4 weeks, and complete healing in about 6 months. However, 50-125 mcg daily for 6-12 weeks is commonly administered for more prompt healing. Diet should be corrected and, after healing has occurred, supplemental doses of ergocalciferol may be discontinued in patients with normal GI absorption. In adults with severe malabsorption and vitamin D deficiency, dosages of 250 mcg to 7.5 mg orally or 250 mcg IM daily have been given to correct osteomalacia. In children with malabsorption, oral ergocalciferol dosages of 250-625 mcg daily have been recommended. In vitamin D-deficient infants with tetany and rickets, calcium should be administered orally or IV to control tetany. Vitamin D deficiency is then treated orally with 50-125 mcg of ergocalciferol daily until the bones have healed, or 250 mcg may be given daily for about 3 weeks. Rarely, when compliance with ergocalciferol therapy is not predictable, a single 7.5- to 15-mg oral dose of ergocalciferol in oil solution has been used to treat rickets in children.
In children with familial hypophosphatemia (vitamin D-resistant rickets), the usual initial oral dosage of ergocalciferol is 1-2 mg daily with phosphate supplements; daily dosage is increased in 250- to 500-mcg increments at 3- to 4-month intervals until an adequate response is obtained. After growth is complete, dosage of ergocalciferol can often be reduced. In adults, oral ergocalciferol dosages of 250 mcg to 1.5 mg daily have been given with phosphate supplements.
In adults with Fanconi syndrome, oral ergocalciferol dosages of 1.25-5 mg (and in some patients 10 mg) daily have been given along with treatment of acidosis. In children with Fanconi syndrome, oral ergocalciferol dosages of 625 mcg to 1.25 mg daily have been used.
Vitamin D-Dependent Rickets
For the treatment of vitamin D-dependent rickets in adults, oral ergocalciferol dosages of 250 mcg to 1.5 mg daily have been recommended; some patients may require up to 12.5 mg daily. However, prolonged administration of dosages greater than 2.5 mg daily is likely to result in toxicity. Children may respond to oral dosages of 75-125 mcg daily; however, some require up to 1.5 mg daily.
Anticonvulsant-Induced Rickets and Osteomalacia
In patients with rickets or osteomalacia secondary to anticonvulsant therapy, oral ergocalciferol dosages of 50 mcg to 1.25 mg daily may be required. Some clinicians recommend prophylactic administration of 25 mcg of ergocalciferol daily or 250 mcg weekly in patients receiving long-term anticonvulsant therapy.
In patients with osteoporosis, oral ergocalciferol dosages of 25-250 mcg daily or 1.25 mg 2 times weekly have been used with calcium and fluoride supplements.
Hypoparathyroidism and Pseudohypoparathyroidism
For the management of hypoparathyroidism or pseudohypoparathyroidism in adults, oral ergocalciferol dosages of 625 mcg to 5 mg (and in some patients up to 10 mg) daily may be required with calcium supplements and/or IM or IV parathyroid hormone. Children with hypoparathyroidism or pseudohypoparathyroidism are usually treated with 1.25-5 mg of oral ergocalciferol daily and calcium supplements. Prolonged administration of ergocalciferol dosages greater than 2.5 mg daily in adults or children is likely to result in toxicity. Dosage should be gradually decreased as serum calcium concentrations approach normal.
To treat early renal osteodystrophy in adults with renal failure, an initial oral ergocalciferol dosage of 500 mcg daily has been recommended. Dosage is then adjusted according to the serum calcium concentration. To maintain normal serum calcium concentrations, oral ergocalciferol dosages of 250 mcg to 7.5 mg of ergocalciferol have been recommended; however, some patients have required up to 12.5 mg daily. In children with renal failure, oral ergocalciferol dosages of 100 mcg to 1 mg daily have been used to maintain normal serum calcium concentrations.
Dietary and Replacement Requirements
The American Academy of Pediatrics (AAP) recommends that all infants, children, and adolescents have a minimum daily intake of vitamin D of 400 units. This recommendation replaces the previous recommendation of a minimum daily intake (Adequate Intake) of vitamin D of 200 units.
The Adequate Intake (AI) of vitamin D (in terms of cholecalciferol or ergocalciferol) currently recommended by the National Academy of Sciences (NAS) in healthy adults 19-50 years of age is 5 mcg (200 units) daily. For healthy adults 51-70 or older than 70 years of age, NAS recommends an AI of 10 or 15 mcg (400 or 600 units) daily, respectively.
For breast-fed or partially breast-fed infants, AAP recommends a supplemental dosage of 400 units of vitamin D daily starting in the first few days of life; vitamin D supplementation is continued throughout childhood until the child is weaned and consumes at least 1 L or quart of vitamin D-fortified formula or milk daily.
Infants and older children who consume less than 1 L of vitamin D-fortified formula or milk daily should receive a supplemental dosage of 400 units of vitamin D daily. Other dietary sources of vitamin D may be included in the dietary intake of the child.
Adolescents who do not consume 400 units of vitamin D daily from vitamin D-fortified milk or foods should receive a supplemental dosage of 400 units of vitamin D daily.
Children at increased risk for vitamin D deficiency (e.g., those with fat malabsorption, those receiving anticonvulsant therapy) may need higher dosages of supplemental vitamin D to achieve normal vitamin D status.
Because exposure to sunlight is decreased markedly during the winter, young and middle-aged adults 19-50 years of age who live in northern latitudes (above 40° N) can become vitamin D deficient. Therefore, to cover the needs of nearly all adults 19-50 years of age, NAS recommends an AI of vitamin D of 5 mcg (200 units) daily.
Adults 51-70 years of age also depend on sunlight for most of their vitamin D requirement, but this age group is more prone to developing vitamin D deficiency because of a variety of factors that reduce cutaneous production of the vitamin. Dietary intakes of vitamin D exceeding 2.5 mcg (200 units) daily appear necessary to prevent higher rates of bone loss during periods of low sun exposure in adults 51-70 years of age. At vitamin D intakes exceeding 5.5 mcg (220 units) daily in this age group, there was no seasonal variation in serum parathyroid hormone (PTH) concentrations, an indicator of vitamin D status. Therefore, to cover the needs of nearly all adults 51-70 years of age, NAS recommends an AI of vitamin D of 10 mcg (400 units) daily.
Current evidence is strong that geriatric adults are at high risk for vitamin D deficiency, resulting in secondary hyperparathyroidism, osteomalacia, exacerbation of osteoporosis, and increased skeletal fractures, and that supplementation with dosages of 10-20 mcg (400-800 units) daily can be beneficial. Based on available evidence, NAS concluded that a vitamin D intake of 7.5 mcg (300 units) daily would be prudent for adults older than 70 years of age with limited sun exposure and body stores of the vitamin. Therefore, to cover the needs of nearly all adults in this age group, NAS recommends an AI of vitamin D of 15 mcg (600 units) daily for adults older than 70 years of age, regardless of extent of exposure to sunlight or body stores of the vitamin.
In adults with severe malabsorption syndromes, at least a 5- to 10-fold increase in the physiologic dose of ergocalciferol is usually needed to prevent osteomalacia, and some clinicians have recommended oral ergocalciferol dosages of 250 mcg to 2.5 mg daily. In some patients, IM administration of the drug may be preferred.
Pregnant and Lactating Women
The NAS states that women, whether pregnant or not, do not require vitamin D supplementation if they receive adequate sun exposure. Therefore, NAS states that the AI of vitamin D does not need to be increased during pregnancy; instead, pregnant women can receive the usual AI appropriate for their age. However, the 10 mcg (400 units) daily that is supplied by prenatal vitamins would not be excessive. Lactating women also do not appear to have an increased requirement for vitamin D. Therefore, NAS concluded that it is reasonable to extrapolate from observations in nonlactating women that an AI of 5 mcg (200 units) daily is needed when sun exposure is inadequate. However, the 10 mcg (400 units) daily that is supplied by postnatal vitamins would not be excessive.
For additional information of adequate intakes of vitamin D,