Overview
DESCRIPTION Calcitriol Oral Solution is a synthetic vitamin D analog which is active in the regulation of the absorption of calcium from the gastrointestinal tract and its utilization in the body. Calcitriol oral solution contains 1 mcg/mL of calcitriol. Calcitriol Oral Solution contains butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) as antioxidants.
Mechanism of Action
CLINICAL PHARMACOLOGY Man's natural supply of vitamin D depends mainly on exposure to the ultraviolet rays of the sun for conversion of 7-dehydrocholesterol in the skin to vitamin D 3 (cholecalciferol). Vitamin D 3 must be metabolically activated in the liver and the kidney before it is fully active as a regulator of calcium and phosphorus metabolism at target tissues. The initial transformation of vitamin D 3 is catalyzed by a vitamin D 3 -25-hydroxylase enzyme (25-OHase) present in the liver, and the product of this reaction is 25-hydroxyvitamin D 3 [25-(OH)D 3 ]. Hydroxylation of 25-(OH)D 3 occurs in the mitochondria of kidney tissue, activated by the renal 25-hydroxyvitamin D 3 -1 alpha-hydroxylase (alpha-OHase), to produce 1,25-(OH) 2 D 3 (calcitriol), the active form of vitamin D 3 .
Indications
- INDICATIONS AND USAGE Predialysis Patients Calcitriol Oral Solution is indicated in the management of secondary hyperparathyroidism and resultant metabolic bone disease in patients with moderate to severe chronic renal failure (Ccr 15 to 55 mL/min) not yet on dialysis. In children, the creatinine clearance value must be corrected for a surface area of 1.73 square meters. A serum iPTH level of ≥ 100 pg/mL is strongly suggestive of secondary hyperparathyroidism.
Common Doses
- 1 mcg
- 600 mg
- 800 mg
- 1200 mg
Dosage
DOSAGE AND ADMINISTRATION The optimal daily dose of Calcitriol Oral Solution must be carefully determined for each patient. Calcitriol Oral Solution can be administered as an oral solution (1 mcg/mL). Calcitriol Oral Solution therapy should always be started at the lowest possible dose and should not be increased without careful monitoring of serum calcium. The effectiveness of Calcitriol Oral Solution therapy is predicated on the assumption that each patient is receiving an adequate but not excessive daily intake of calcium.
Contraindications
- CONTRAINDICATIONS Calcitriol Oral Solution should not be given to patients with hypercalcemia or evidence of vitamin D toxicity. Use of Calcitriol Oral Solution in patients with known hypersensitivity to Calcitriol Oral Solution (or drugs of the same class) or any of the inactive ingredients is contraindicated.
Side Effects
- ADVERSE REACTIONS Since Calcitriol Oral Solution is believed to be the active hormone which exerts vitamin D activity in the body, adverse effects are, in general, similar to those encountered with excessive vitamin D intake, ie, hypercalcemia syndrome or calcium intoxication (depending on the severity and duration of hypercalcemia) (see WARNINGS ). Because of the short biological half-life of calcitriol, pharmacokinetic investigations have shown normalization of elevated serum calcium within a few days of treatment withdrawal, ie, much faster than in treatment with vitamin D 3 preparations.
Interactions
- No major interactions listed on the FDA label. Always consult a healthcare professional.