Calcitriol Injection

Calcitriol Injection is synthetically manufactured calcitriol and is available as a sterile, isotonic, clear, colorless to yellow, aqueous solution for intravenous injection. Calcitriol is available in 1 mL ampules. Each 1 mL contains: Calcitriol 1 mcg; Polysorbate 20, 4 mg; Sodium Chloride 1.5 mg; Sodium Ascorbate 10 mg added; Dibasic Sodium Phosphate, Anhydrous 7.6 mg; Monobasic Sodium Phosphate, Monohydrate 1.8 mg; Edetate Disodium, Dihydrate 1.1 mg added; Water for Injection q.s. pH range 6.7-7.7.

Calcitriol is a crystalline compound which occurs naturally in humans. It is soluble in organic solvents but relatively insoluble in water. Calcitriol is chemically designated (5Z,7E)-9,10-secocholesta-5,7,10(19)-triene-1α,3β,25-triol and has the following structural formula:

Molecular Formula: C27H44O3

The other names frequently used for calcitriol are 1α,25-dihydroxycholecalciferol, 1α,25-dihydroxyvitamin D3, 1,25-DHCC, 1,25(OH)2D3 and 1,25-diOHC.

Since calcitriol is the most potent metabolite of vitamin D available, vitamin D and its derivatives should be withheld during treatment.

A non-aluminum phosphate-binding compound should be used to control serum phosphorus levels in patients undergoing dialysis.

Overdosage of any form of vitamin D is dangerous (see also OVERDOSAGE). Progressive hypercalcemia due to overdosage of vitamin D and its metabolites may be so severe as to require emergency attention. Chronic hypercalcemia can lead to generalized vascular calcification, nephrocalcinosis and other soft-tissue calcification. The serum calcium times phosphate (Ca x P) product should not be allowed to exceed 70. Radiographic evaluation of suspect anatomical regions may be useful in the early detection of this condition.

1.  General

Excessive dosage of Calcitriol Injection induces hypercalcemia and in some instances hypercalciuria; therefore, early in treatment during dosage adjustment, serum calcium and phosphorus should be determined at least twice weekly. Should hypercalcemia develop, the drug should be discontinued immediately.

Calcitriol Injection should be given cautiously to patients on digitalis, because hypercalcemia in such patients may precipitate cardiac arrhythmias.

2.  Information for Patients

The patient and his or her parents should be informed about adherence to instructions about diet and calcium supplementation and avoidance of the use of unapproved non-prescription drugs, including magnesium-containing antacids. Patients should also be carefully informed about the symptoms of hypercalcemia (see ADVERSE REACTIONS).

3.  Essential Laboratory Tests

Serum calcium, phosphorus, magnesium and alkaline phosphatase and 24-hour urinary calcium and phosphorus should be determined periodically. During the initial phase of the medication, serum calcium and phosphorus should be determined more frequently (twice weekly).

Adynamic bone disease may develop if PTH  levels are suppressed to abnormal levels. If biopsy is not being done for other (diagnostic) reasons, PTH levels may be used to indicate the rate of bone turnover. If PTH levels fall below recommended target range (1.5 to 3 times the upper limit of normal), in patients treated with Calcitriol Injection, the Calcitriol Injection dose should be reduced or therapy discontinued. Discontinuation of Calcitriol Injection therapy may result in rebound effect, therefore, appropriate titration downward to a maintenance dose is recommended.

4.  Drug Interactions

Magnesium-containing antacid and Calcitriol Injection should not be used concomitantly, because such use may lead to the development of hypermagnesemia.

5.  Carcinogenesis, Mutagenesis, Impairment of Fertility

Long-term studies in animals have not been conducted to evaluate the carcinogenic potential of Calcitriol Injection. Calcitriol was not mutagenic in vitro in the Ames test nor was oral calcitriol genotoxic in vivo in the Mouse Micronucleus Test. No significant effects on fertility and/or general reproductive performances were observed in a Segment I study in rats using oral calcitriol at doses of up to 0.3 mcg/kg.

6.  Pregnancy

Pregnancy Category C:

Calcitriol has been found to be teratogenic in rabbits when given orally at doses of 0.08 and 0.3 mcg/kg. All 15 fetuses in 3 litters at these doses showed external and skeletal abnormalities. However, none of the other 23 litters (156 fetuses) showed external and skeletal abnormalities compared with controls. Teratogenicity studies in rats at doses up to 0.45 mcg/kg orally showed no evidence of teratogenic potential. There are no adequate and well-controlled studies in pregnant women. Calcitriol Injection should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Nonteratogenic Effects: In the rabbit, oral dosages of 0.3 mcg/kg/day administered on days 7 to 18 of gestation resulted in 19% maternal mortality, a decrease in mean fetal body weight and a reduced number of newborns surviving to 24 hours. A study of the effects on orally administered calcitriol on peri- and postnatal development in rats resulted in hypercalcemia in the offspring of dams given calcitriol at doses of 0.08 or 0.3 mcg/kg/day, hypercalcemia and hypophosphatemia in dams given calcitriol at a dose of 0.08 or 0.3 mcg/kg/day and increased serum urea nitrogen in dams given calcitriol at a dose of 0.3 mcg/kg/day. In another study in rats, maternal weight gain was slightly reduced at an oral dose of 0.3 mcg/kg/day administered on days 7 to 15 of gestation.

The offspring of a woman administered oral calcitriol at 17 to 36 mcg/day during pregnancy manifested mild hypercalcemia in the first 2 days of life which returned to normal at day 3.

7.  Nursing Mothers

It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants from calcitriol, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.

8.  Pediatric Use

The safety and effectiveness of Calcitriol Injection were examined in a 12-week randomized, double-blind, placebo-controlled study of 35 pediatric patients, aged 13-18 years, with end-stage renal disease on hemodialysis.  Sixty-six percent of the patients were male, 57% were African-American, and nearly all had received some form of vitamin D therapy prior to the study.  The initial dose of Calcitriol Injection was 0.5 mcg, 1 mcg, or 1.5 mcg, 3 times per week, based on baseline iPTH level of less than 500 pg/mL, 500-1000 pg/mL, or greater than 1000 pg/mL, respectively.  The dose of Calcitriol Injection was adjusted in 0.25 mcg increments based on the levels of serum iPTH, calcium, and Ca x P.  The mean baseline levels of iPTH were 769 pg/mL for the 16 Calcitriol Injection-treated patients and 897 pg/mL for the 19 placebo-treated subjects.  The mean weekly dose of Calcitriol Injection ranged from 1 mcg to 1.4 mcg.  In the primary efficacy analysis, 7 of 16 (44%) subjects in the Calcitriol Injection group had 2 consecutive 30% decreases from baseline iPTH compared with 3 of 19 (16%) patients in the placebo group (95% CI for the difference between groups -6%, 62%).  One Calcitriol Injection-treated patient experienced transient hypercalcemia (>11 mg/dL), while 6 of 16 (38%) Calcitriol Injection-treated patients vs. 2 of 19 (11%) placebo-treated patients experienced Ca x P >75.

9.  Geriatric Use

Clinical studies of Calcitriol Injection did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences  in responses between the elderly and younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosage range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.

The optimal dose Calcitriol Injection must be carefully determined for each patient.

The effectiveness of Calcitriol Injection therapy is predicated on the assumption that each patient is receiving an adequate and appropriate daily intake of calcium. The RDA for calcium in adults is 800 mg. To ensure that each patient receives an adequate daily intake of calcium, the physician should either prescribe a calcium supplement or instruct the patient in proper dietary measures.

The recommended initial dose of Calcitriol Injection, depending on the severity of the hypocalcemia and/or secondary hyperparathyroidism, is 1 mcg (0.02 mcg/kg) to 2 mcg administered three times weekly, approximately every other day. Doses as small as 0.5 mcg and as large as 4 mcg three times weekly have been used as an initial dose. If a satisfactory response is not observed, the dose may be increased by 0.5 to 1 mcg at two to four week intervals. During this titration period, serum calcium and phosphorus levels should be obtained at least twice weekly. If hypercalcemia or a serum calcium times phosphate product greater than 70 is noted, the drug should be immediately discontinued until these parameters are appropriate. Then, the Calcitriol Injection dose should be reinitiated at a lower dose. Doses may need to be reduced as the PTH levels decrease in response to the therapy. Thus, incremental dosing must be individualized and commensurate with PTH, serum calcium and phosphorus levels.

The following is a suggested approach in dose titration:

Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.

Discard unused portion

WARNING: PROTECT FROM LIGHT. RETAIN IN CARTON UNTIL TIME OF USE.

Store at 20°-25°C (68°-77°F); excursions permitted to 15°-30°C (59°-86°F) (See USP Controlled Room Temperature).

Calcitriol Injection

NDC 0517-0132-25       1 mcg/mL       1 mL ampules         Boxed in 25

AMERICAN REGENT, INC.
SHIRLEY, NY  11967

IN0132
Rev. 6/08
MG #15726

PRINCIPAL DISPLAY PANEL – 1 mL Container

NDC 0517-0132-25

CALCITRIOL
INJECTION
1 mcg/mL

1 mL AMPULE

FOR IV USE

Rx Only

WARNING: PROTECT FROM LIGHT.

AMERICAN REGENT, INC.
SHIRLEY, NY  11967

Rev. 1/05