Overview
11 DESCRIPTION Calcifediol, USP, the active ingredient in RAYALDEE, is synthetically manufactured as calcifediol monohydrate. Calcifediol is also known as calcidiol, 25-hydroxycholecalciferol or 25-hydroxyvitamin D 3 . Calcifediol monohydrate is a white crystalline powder, has a calculated molecular weight of 418.65 and is soluble in alcohol and fatty oils but practically insoluble in water.
Mechanism of Action
12 CLINICAL PHARMACOLOGY 12.1 Mechanism of Action Calcifediol (25-hydroxyvitamin D 3 ) is a prohormone of the active form of vitamin D 3 , calcitriol (1,25‑dihydroxyvitamin D 3 ). Calcifediol is converted to calcitriol by cytochrome P450 27B1 (CYP27B1), also called 1-alpha hydroxylase, primarily in the kidney. Calcitriol binds to the vitamin D receptor in target tissues and activates vitamin D responsive pathways that result in increased intestinal absorption of calcium and phosphorus and reduced parathyroid hormone synthesis. 12.2 Pharmacodynamics In repeat-dose clinical studies with RAYALDEE, increased levels of serum total 25-hydroxyvitamin D were associated with corresponding increases in serum total 1,25‑dihydroxyvitamin D concentrations and reductions in circulating plasma intact...
Indications
- 1 INDICATIONS AND USAGE RAYALDEE is a vitamin D 3 analog indicated for the treatment of secondary hyperparathyroidism in adult patients with stage 3 or 4 chronic kidney disease and serum total 25-hydroxyvitamin D levels less than 30 ng/mL. Limitations of Use RAYALDEE is not indicated for the treatment of secondary hyperparathyroidism in patients with stage 5 chronic kidney disease or in patients with end-stage renal disease on dialysis.
Common Doses
- 30 mcg
- 9.8 mg
- 60 mcg
- 5.5 mg
Dosage
2 DOSAGE AND ADMINISTRATION • The initial dose of RAYALDEE is 30 mcg administered orally once daily at bedtime. Serum calcium should be below 9.8 mg/dL before initiating treatment. ( 2 ) • Monitor serum calcium, phosphorus, 25-hydroxyvitamin D and intact parathyroid hormone (PTH) 3 months after starting therapy or changing dose. ( 2.2 , 5.3 ) • Increase the dose to 60 mcg once daily after 3 months if intact PTH is above the treatment goal. Ensure serum calcium is below 9.8 mg/dL, phosphorus is below 5.5 mg/dL and 25-hydroxyvitamin D is below 100 ng/mL before increasing the dose. ( 2.
Contraindications
- 4 CONTRAINDICATIONS None. None ( 4 )
Side Effects
- 6 ADVERSE REACTIONS The following important adverse reactions are discussed in greater detail in other sections of the label: • Hypercalcemia [ see Warnings and Precautions ( 5.1 ) ] • Adynamic Bone Disease [ see Warnings and Precautions ( 5.3 ) ] The most common adverse reactions (≥3% and more frequent than placebo) were anemia, nasopharyngitis, increased blood creatinine, dyspnea, cough, congestive heart failure and constipation. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact OPKO Pharmaceuticals, LLC at 1-844-729-2539 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.
Interactions
- 7 DRUG INTERACTIONS • Co-administration of cytochrome P450 inhibitors, such as ketoconazole, may alter serum levels of calcifediol. ( 7.1 ) • Co-administration of thiazides may cause hypercalcemia. ( 7.2 ) • Cholestyramine may impair the absorption of calcifediol. ( 7.3 ) • The half-life of calcifediol is reduced by drugs stimulating microsomal hydroxylation, such as phenobarbital or other anticonvulsants. ( 7.4 ) 7.1 CYP3A Inhibitors Cytochrome P450 inhibitors, such as ketoconazole, atazanavir, clarithromycin, indinavir, itraconazole, nefazodone, nelfinavir, ritonavir, saquinavir,...