Ergocalciferol is usually administered orally once daily. Ergocalciferol has been administered IM† in some patients (e.g., those with GI, liver, or biliary disease associated with malabsorption of vitamin D analogs); however, ergocalciferol injection is no longer commercially available in the US.
When ergocalciferol is administered as an oral solution, the oral syringe provided by the manufacturer should be used to measure the dose and administer the solution directly into the patient's mouth.101
Each mg of ergocalciferol is equivalent to 40,000 USP units; each mcg of the drug is equivalent to 40 USP units.
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. In patients with familial hypophosphatemia (vitamin D-resistant rickets) or hypoparathyroidism, determinations of serum calcium and phosphorus concentrations should be made every 2 weeks or more frequently as needed.100 In these patients, the manufacturers of ergocalciferol recommend that radiographic examination of the bones be performed every month until the condition stabilizes or is corrected;100 however, some clinicians believe that this is unnecessary.
The manufacturers state that patients with malabsorption syndrome should not receive oral ergocalciferol.100,101
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 (injection no longer commercially available in the US) 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.
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.
Dietary and Replacement Requirements
The American Academy of Pediatrics (AAP) recommends a minimum daily intake of 400 units of vitamin D in all infants, children, and adolescents.124
Because of insufficient data to establish estimated average requirements (EARs) and recommended dietary allowances (RDAs) in infants younger than 1 year of age, the National Academy of Sciences (NAS) uses adequate intake (AI) for vitamin D requirements in this age group.153 In infants younger than 1 year of age, NAS recommends an AI of 400 units (10 mcg) daily of vitamin D.153 (For more information on dietary reference values established by NAS, see Uses: Dietary Requirements, in the Vitamin D Analogs General Statement 88:16.)
Ensuring normal healthy bone accretion is the primary consideration when establishing dietary reference values for older children and adolescents 1-18 years of age.153 Based on this consideration, NAS recommends an EAR of 400 units (10 mcg) daily of vitamin D in children and adolescents 1-18 years of age, and an RDA of 600 units (15 mcg) daily to cover the needs of nearly all children in this age group assuming minimal sun exposure.153
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.124
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.124 Other dietary sources of vitamin D may be included in the dietary intake of the child.124
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.124
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.124
Bone maintenance is the primary concern in adults 19-50 years of age.153 Although data on bone health outcomes related to vitamin D generally are more limited in adults 19-50 years of age, NAS recommends an EAR of 400 units (10 mcg) daily of vitamin D and an RDA of 600 units (15 mcg) daily to cover the needs of nearly all adults in this age group assuming minimal sun exposure.153
Maintenance of bone mass and reduction of bone loss are essential factors in developing dietary reference intakes for vitamin D in adults 51-70 years of age.153 The majority of women in this life stage group will experience some degree of bone loss due to menopause, but findings generally have not supported an effect of vitamin D alone (without calcium) on bone outcomes.153 Because the available data do not suggest that average vitamin D intake requirements increase with aging, the same dietary reference values are recommended for older adults 51-70 years of age as for younger adults (19-50 years of age).153 These values include an EAR of 400 units (10 mcg) daily and an RDA of 600 units (15 mcg) daily assuming minimal sun exposure.153
Because risk of skeletal fractures is increased with aging, particularly for adults older than 70 years of age, reduction in fracture risk is the most important indicator in setting a reference standard for this age group.153 However, there are a number of unknown factors associated with the physiology of normal aging that can affect intake estimates for this population.153 There is compelling evidence indicating that calcium alone in this age group can modestly reduce the risk of fracture, but vitamin D alone generally does not have a substantial effect on fracture risk reduction.153 Therefore, based on available evidence, NAS recommends an average vitamin D intake of 400 units (10 mcg) daily in adults older than 70 years of age and an intake of 800 units (20 mcg) daily to cover the needs of nearly all adults in this age group assuming minimal sun exposure.153 However, these recommendations are made in light of the uncertainties that have been identified in this older age group.153
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 has been preferred; however, ergocalciferol injection is no longer commercially available in the US.
Maternal 25-hydroxyvitamin D concentrations do not appear to affect fetal calcium homeostasis or skeletal outcomes.153 Therefore, NAS states that intake requirements of vitamin D for pregnant women are the same as for women who are not pregnant.153
Current evidence indicates that increased maternal intake of vitamin D has no effect on neonatal serum 25-hydroxyvitamin D concentrations unless maternal intake is excessive.153 Therefore, NAS states that it is reasonable to use the same dietary reference values for vitamin D in lactating and nonlactating women.153
For additional information on adequate intakes of vitamin D, see Dosage: Dietary and Replacement Requirements, in the Vitamin D Analogs General Statement 88:16.