ROCALTROL
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ROCALTROL (ROCALTROL).
Calcitriol, the active form of vitamin D, binds to vitamin D receptors in target tissues, increasing intestinal absorption of calcium and phosphate, promoting renal tubular reabsorption of calcium, and stimulating bone mineralization.
| Metabolism | Primarily metabolized in the kidney and liver via 24-hydroxylation by CYP24A1, with minor pathways involving glucuronidation and oxidation. |
| Excretion | Primarily biliary/fecal; approximately 50% of dose recovered in feces within 24 hours. Renal excretion accounts for <5% of unchanged drug. |
| Half-life | Terminal elimination half-life is approximately 25–35 hours after oral administration. Clinical context: Once-weekly or thrice-weekly dosing achieves steady state in 1–2 weeks. |
| Protein binding | Approximately 99.9% bound to specific vitamin D binding protein (DBP) and albumin in plasma. |
| Volume of Distribution | Vd is approximately 0.5–0.7 L/kg, indicating distribution into extracellular fluid and tissues. |
| Bioavailability | Oral bioavailability is approximately 70–80% from the capsule formulation, with no significant food effect. |
| Onset of Action | Oral: Onset of effect on calcium absorption occurs within 2–6 hours; peak serum calcium increase observed at 8–12 hours. |
| Duration of Action | Duration of effect on serum calcium is approximately 24–48 hours after a single oral dose. Clinical note: Dosing interval is typically once daily to thrice weekly depending on indication. |
| Molecular Weight | 416.64 |
Oral, 0.25 mcg once daily; may increase to 0.5 mcg once daily based on response. Typical adult dose is 0.25-0.5 mcg/day.
| Dosage form | SOLUTION |
| Renal impairment | Calcitriol is contraindicated in patients with hypercalcemia or evidence of vitamin D toxicity. In chronic kidney disease (CKD) stages 3-4, start with 0.25 mcg/day; monitor serum calcium and phosphate. For CKD stage 5 on dialysis, dose may be increased to 0.5-1 mcg/day. No specific GFR-based adjustment guidelines; use with caution in severe impairment. |
| Liver impairment | No specific adjustment for Child-Pugh class; monitor calcium levels in severe hepatic impairment due to potential altered vitamin D metabolism. |
| Pediatric use | For pediatric chronic kidney disease or hypoparathyroidism: starting dose 0.25 mcg/day or 15 ng/kg/day orally; may adjust based on serum calcium. For rickets, 1 mcg/day for 2-4 weeks. |
| Geriatric use | No specific dose adjustment; start at lower end of dosing range (0.25 mcg/day) due to potential renal impairment; monitor serum calcium and creatinine regularly. |
| 1st trimester | Teratogenic risk: limited human data; animal studies show teratogenicity at high doses. Use only if clearly needed. |
| 2nd trimester | Monitor maternal serum calcium and renal function; adjust dose to avoid hypercalcemia which may affect fetal development. |
| 3rd trimester | Use with caution; high doses may cause maternal hypercalcemia leading to fetal hypoparathyroidism, tetany, and seizures. |
Clinical note
Comprehensive clinical and safety monograph for ROCALTROL (ROCALTROL).
| Placental transfer | Calcitriol crosses the placenta; fetal serum levels are about 50-80% of maternal levels. |
| Breastfeeding | Excreted in human milk in low amounts; monitor infant serum calcium if used in breastfeeding women. |
| Lactation Rating |
■ FDA Black Box Warning
None.
| Serious Effects |
HypercalcemiaVitamin D toxicityKnown hypersensitivity to calcitriol or any component of the formulation
| Precautions | Hypercalcemia: Risk of hypercalcemia and hypercalciuria; monitor serum calcium, phosphate, and creatinine regularly., Adynamic bone disease: May occur with oversuppression of PTH in dialysis patients., Aluminum toxicity: Concomitant use with aluminum-containing antacids increases aluminum absorption and risk of toxicity., Digitalis toxicity: Hypercalcemia increases risk of cardiac arrhythmias in patients on digitalis. |
| Food/Dietary | Maintain a consistent intake of calcium and avoid high‑calcium foods (e.g., dairy) unless directed. Do not consume phosphate‑rich foods excessively. Avoid grapefruit juice as it may increase calcitriol absorption. |
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| Teratogenic Risk | ROCALTROL (calcitriol) is classified as FDA Pregnancy Category C. Adequate studies in pregnant women are not available. In animal studies, calcitriol administered at doses 1-5 times the human therapeutic dose resulted in fetal abnormalities including skeletal deformities and reduced fetal weight. Use during pregnancy only if clearly needed and potential benefit justifies risk to fetus. First trimester: theoretical risk of teratogenicity based on animal data; avoid unless essential. Second and third trimesters: may be used for maternal indication (e.g., hypocalcemia) with careful monitoring; high doses may cause hypercalcemia in fetus leading to adverse effects. |
| Fetal Monitoring | Monitor maternal serum calcium, phosphate, magnesium, and alkaline phosphatase levels regularly. Monitor fetal growth and well-being via ultrasound. Assess for fetal hypercalcemia (e.g., polyhydramnios, nephrocalcinosis) in cases of high maternal dosing. Monitor maternal renal function. |
| Fertility Effects | No specific data on effects on human fertility. In animal studies, no adverse effects on fertility were observed. Calcitriol is a naturally occurring hormone; disturbances in calcium homeostasis may affect reproductive physiology. |
| Clinical Pearls | ROCALTROL (calcitriol) is the active form of vitamin D; no hepatic conversion required. Monitor serum calcium, phosphate, and creatinine regularly. Avoid concomitant use of thiazide diuretics (hypercalcemia risk). Use with caution in patients with sarcoidosis or renal impairment. Dosage adjustments needed with enzyme-inducing anticonvulsants (e.g., phenytoin) or bile acid sequestrants (e.g., cholestyramine). |
| Patient Advice | Take exactly as prescribed, do not change dose without consulting your doctor. · Avoid self‑medicating with calcium or vitamin D supplements. · Report symptoms of hypercalcemia: nausea, vomiting, constipation, weakness, or confusion. · Adhere to prescribed dietary restrictions on calcium and phosphate intake. · Do not take magnesium‑containing antacids. · Attend all scheduled blood tests to monitor calcium levels. |