Official Title

Studies With 1,25-Dihydroxycholecalciferol
  • Phase

    Phase 2
  • Study Type

  • Intervention/Treatment

    calcitriol ...
  • Study Participants

Vitamin D in the diet undergoes changes in the liver and kidneys to several forms. Patients suffering from disorders with Vitamin D resistance are unable to absorb calcium from food. Patients diagnosed with these disorders will be evaluated and treated with high doses of another form of Vitamin D (1,25-dihydroxyvitamin D3). Patients will be monitored and observed throughout the study to avoid experiencing side effects from the medication.
Patients with extreme resistance to 1,25-dihydroxyvitamin D will be evaluated and treated with high doses of 1,25-dihydroxyvitamin D3.

Plan: In previously untreated patients the study will be divided into a control and one or more treatment periods. During the control period, parathyroid status will be assessed by parameters nos. 1& 2 (below). In previously treated patients maintenance vitamin D will be gradually replaced with 1,25(OH)2D3. This will be accomplished by withdrawal of vitamin D and institution of 1,25(OH)2D3 when the serum calcium shows a downward trend.

1,25(OH)2D3 as 0.25 or 0.5 ug capsules (though IND 20,889) or as a solution of I microgram per ml will be administered orally. In most cases, because of consideration of time and expense, the cooperation of the patient's local physician will be enlisted. The following will be monitored:

Serum calcium, phosphorus,alkaline phosphatase,creatinine at twice weekly intervals. After a maintenance dose has been established, this will be decreased to a monthly, and subsequently 3-6 monthly interval.
Urine calcium, phosphorus,creatinine and cAMP before therapy and, when appropriate, during therapy.

The dose of 1,25(OH)2D3 will be 0.125 to 50.0 ug/day. Serum calcium will not be allowed to rise above the normal range (2.0 -2.4 mM at NIH). Should hypercalcemia occur, appropriate treatment will be initiated and the drug dosage will be decreased.
Study Started
Mar 31
Primary Completion
Oct 31
Study Completion
Oct 31
Results Posted
Nov 25
Last Update
Nov 25

Drug 1,25-Dihydroxycholecalciferol

Usual doses of 1,25-dihydroycholecalciferol are 0.25-1 ug per day. All patients in this study received very high doses or 5-20 ug per day.

Drug treatment Experimental

1,25-Dihydroxycholecalciferol 5 ug orally per day for 2 years



Patients with hereditary resistance to calcitrol.


Group 1

All Events

Event Type Organ System Event Term

Number of Participants With Normal Serum Calcium Concentrations

Normal calcium concentration 8.2-10.6 mg/dL

Group 1


Age, Continuous

years (Mean)
Full Range: 5.0 to 50.0

Region of Enrollment

Sex: Female, Male

Overall Study

Group 1