Calcitriol (Rocaltrol / Calcijex)
calcitriol — 1,25-dihydroxyvitamin D3
Indications
| Indication | Approved Population | Therapy Type | Status |
|---|---|---|---|
| Secondary HPT and metabolic bone disease in CKD on dialysis | Adults (oral & IV) | Monotherapy or adjunctive (with phosphate binders, calcium supplements) | FDA Approved |
| Secondary HPT and metabolic bone disease in predialysis CKD | Adults and pediatric patients (CrCl 15–55 mL/min; iPTH ≥100 pg/mL) | Monotherapy or adjunctive | FDA Approved |
| Hypocalcemia in hypoparathyroidism | Adults and pediatric patients ≥1 year (postsurgical, idiopathic, pseudohypoparathyroidism) | Monotherapy (with calcium supplementation) | FDA Approved |
Calcitriol is the biologically active form of vitamin D3 (1,25-dihydroxycholecalciferol), which plays a central role in calcium and phosphorus homeostasis. In healthy individuals, the kidneys produce calcitriol from 25-hydroxyvitamin D3 via 1-alpha-hydroxylase. Patients with CKD lose this capacity, leading to calcitriol deficiency, hypocalcemia, and secondary hyperparathyroidism. Exogenous calcitriol replacement restores intestinal calcium absorption, suppresses PTH secretion through vitamin D receptor (VDR) activation on parathyroid cells, and improves the histological features of renal osteodystrophy. In hypoparathyroidism, calcitriol compensates for the absence of PTH-driven renal 1-alpha-hydroxylation. The physiological daily production of calcitriol is approximately 0.5 to 1.0 mcg (FDA PI).
Prevention of corticosteroid-induced osteoporosis: Calcitriol 0.5–1 mcg/day has shown benefit in preventing bone loss at the lumbar spine in patients on chronic corticosteroids. Evidence quality: Moderate.
Vitamin D-resistant rickets / osteomalacia: Used when standard vitamin D is ineffective. Evidence quality: Low (case series).
Plaque psoriasis (topical formulation): Calcitriol 3 mcg/g ointment (Vectical) is FDA-approved for mild-to-moderate plaque psoriasis. This is a separate topical formulation and is not covered in this systemic monograph.
Dosing
Adult Dosing by Clinical Scenario
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| CKD on dialysis — oral therapy for secondary HPT | 0.25 mcg PO daily | 0.5–1 mcg PO daily | Individualized | Titrate by 0.25 mcg at 4–8 wk intervals; some patients respond to 0.25 mcg every other day Serum Ca twice weekly during titration |
| CKD on dialysis — IV pulse therapy for secondary HPT (Calcijex) | 1–2 mcg (0.02 mcg/kg) IV TIW | 0.5–4 mcg IV TIW | Individualized (doses up to 4 mcg TIW used) | Administer IV bolus at end of hemodialysis; titrate by 0.5–1 mcg at 2–4 wk intervals Serum Ca and P twice weekly during titration |
| Predialysis CKD — secondary HPT (adults and peds ≥3 yr) | 0.25 mcg PO daily | 0.25–0.5 mcg PO daily | 0.5 mcg PO daily | May increase to 0.5 mcg if needed; reduce or stop if hypercalcemia occurs Peds <3 yr: 10–15 ng/kg/day |
| Hypoparathyroidism — adult (postsurgical, idiopathic, or pseudo) | 0.25 mcg PO daily (morning) | 0.5–2 mcg PO daily | Individualized (most respond to 0.5–2 mcg/day) | Titrate at 2–4 wk intervals; monitor 24-hr urine Ca periodically Larger doses may be needed if malabsorption present |
| Hypoparathyroidism — pediatric (ages 1–5 yr) | 0.25 mcg PO daily | 0.25–0.75 mcg PO daily | 0.75 mcg PO daily | Limited data in children <1 yr; dosing guidelines not established for pseudohypoparathyroidism <6 yr |
| Hypoparathyroidism — pediatric (≥6 yr) | 0.25 mcg PO daily | 0.5–2 mcg PO daily | Individualized (same range as adults) | Titrate per adult protocol with age-appropriate calcium supplementation |
Calcitriol effectiveness depends on adequate daily calcium intake. The FDA PI recommends a minimum dietary calcium of 600 mg/day (US RDA 800–1,200 mg for adults). Because calcitriol enhances GI calcium absorption, some patients may actually need less supplemental calcium over time. Conversely, sudden increases in dietary calcium (e.g., increased dairy) or uncontrolled calcium supplement use can precipitate hypercalcemia. Always assess dietary calcium intake before adjusting the calcitriol dose.
If serum calcium exceeds the upper limit of normal by >1 mg/dL: (1) immediately stop calcitriol, (2) institute low-calcium diet and withdraw calcium supplements, (3) check serum calcium daily until normalized (usually 2–7 days), then (4) reinitiate calcitriol at a dose 0.25 mcg/day lower than previous (or 0.5 mcg lower for IV formulation). The Ca × P product should not exceed 70 mg²/dL².
Pharmacology
Mechanism of Action
Calcitriol is the endogenous, hormonally active form of vitamin D3, produced physiologically through sequential hydroxylation of cholecalciferol: first at C-25 in the liver by 25-hydroxylase, then at C-1 in the kidney by 1-alpha-hydroxylase. Synthetic calcitriol bypasses both hydroxylation steps, delivering the fully active hormone directly. Calcitriol binds to the intracellular vitamin D receptor (VDR), a nuclear transcription factor present in intestine, bone, parathyroid gland, and kidney. In the intestine, VDR activation upregulates calcium-binding proteins (calbindins) that mediate transcellular calcium and phosphorus absorption. In the parathyroid gland, calcitriol suppresses PTH gene transcription, directly reducing PTH synthesis and secretion. In bone, calcitriol promotes both osteoblast differentiation and osteoclast-mediated bone resorption depending on the ambient calcium milieu, contributing to mineral homeostasis and skeletal remodeling.
ADME Profile
| Parameter | Value | Clinical Implication |
|---|---|---|
| Absorption | Rapidly absorbed orally; Tmax 3–6 h; after 0.5 mcg PO, serum rose from 40 to 60 pg/mL at 2 h; steady state within 7 days of repeated dosing | Fast onset permits daily oral dosing; food does not significantly impair absorption; response assessable within 1 week |
| Distribution | 99.9% bound to alpha-globulin vitamin D binding protein (DBP) in blood; crosses the placenta; excreted in breast milk at low levels (~2.2 pg/mL) | Very high protein binding limits free drug fraction; fetal and neonatal exposure possible |
| Metabolism | Two catabolic pathways: (1) 24-hydroxylase → calcitroic acid (side-chain cleavage); (2) C-26/C-23 hydroxylation and cyclization → 1α,25(OH)&sub2;-26,23-lactone D&sub3; (major circulating metabolite, ~131 pg/mL). Not CYP3A4-dependent in the classical hepatic sense, but ketoconazole may inhibit catabolic enzymes. | Short-lived active compound with rapid inactivation; metabolic pathways are regulated by PTH, calcium, and phosphorus — forming a feedback loop |
| Elimination | t½ 5–8 h (normal subjects); 16.2 h (nephrotic syndrome), 21.9 h (hemodialysis); enterohepatic recycling occurs; IV: 27% feces, 7% urine within 24 h; cumulative by day 6: 49% feces, 16% urine | Short t½ in normal subjects means hypercalcemia resolves within days of stopping; prolonged t½ in CKD necessitates closer monitoring |
Side Effects
Adverse effects of calcitriol are essentially those of vitamin D excess and are directly related to its calcium-raising action. The primary safety concern is hypercalcemia, which is dose-dependent and reversible upon discontinuation. The short biological half-life of calcitriol means that elevated serum calcium normalizes much faster (within days) than with ergocalciferol or cholecalciferol preparations.
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Hypercalcemia | ~33% (1 in 3) | From hypoparathyroidism studies; the defining dose-limiting toxicity; usually detected by routine monitoring before symptoms develop |
| Hypercalciuria | ~14% (1 in 7) | From hypoparathyroidism studies; may increase nephrolithiasis risk; monitor 24-hr urine calcium periodically |
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Nausea, vomiting, anorexia | Common | Early warning signs of hypercalcemia; prompt calcium level check required |
| Constipation, dry mouth | Common | Calcium-mediated reduction in GI motility; ensure adequate hydration |
| Weakness, somnolence, headache | Common | CNS manifestations of hypercalcemia; reversible with dose reduction |
| Muscle pain, bone pain | Common | May also occur early in treatment as part of bone remodeling; distinguish from hypercalcemia |
| Metallic taste | Common | Considered an early marker of calcium elevation; may precede laboratory-detected hypercalcemia |
| Elevated serum creatinine | ~17% (1 in 6) | From hypoparathyroidism studies; approximately half had normal baseline; usually reversible; indicates renal vasoconstriction from hypercalcemia |
| Adverse Effect | Estimated Frequency | Typical Onset | Required Action |
|---|---|---|---|
| Severe hypercalcemia (Ca >12 mg/dL) | Dose-dependent; may require emergency attention (FDA PI) | Days to weeks after initiation or dose increase | Immediately stop calcitriol; low-calcium diet; withdraw calcium supplements; check Ca daily until normalized (2–7 days); consider dialysis against Ca-free dialysate if persistent |
| Nephrocalcinosis / soft tissue calcification | Uncommon; related to chronic hypercalcemia | Weeks to months of uncontrolled Ca × P product >70 | Monitor Ca × P product (must not exceed 70 mg²/dL²); use phosphate binders; radiographic evaluation of suspect regions; discontinue calcitriol |
| Cardiac arrhythmias (digitalis-treated patients) | Rare; occurs in setting of hypercalcemia + digitalis | Variable; precipitated by elevated calcium levels | Use calcitriol cautiously in digitalis-treated patients; monitor calcium closely; may need to withhold digitalis temporarily |
| Pancreatitis | Rare; late sign of vitamin D intoxication | Late; after prolonged hypercalcemia | Stop calcitriol; supportive care; investigate for alternative causes |
| Hypersensitivity reactions (pruritus, rash, urticaria, erythema multiforme) | Rare; confirmed by rechallenge in at least one case | Any time during treatment | Discontinue permanently; provide appropriate treatment |
Early signs (act promptly): weakness, headache, somnolence, nausea, vomiting, dry mouth, constipation, muscle/bone pain, metallic taste, anorexia. Late signs (indicates prolonged toxicity): polyuria, polydipsia, weight loss, nocturia, calcific conjunctivitis, pancreatitis, hypertension, cardiac arrhythmias, nephrocalcinosis, ectopic calcification, elevated BUN, and rarely overt psychosis. Patients and caregivers should be educated to report early signs immediately.
Drug Interactions
Calcitriol is the most potent naturally occurring form of vitamin D. Its primary interaction risk is pharmacodynamic — any agent that raises or lowers calcium can either augment toxicity or reduce efficacy. Calcitriol undergoes catabolism through kidney-based 24-hydroxylase; ketoconazole and similar azole antifungals may inhibit this pathway. Calcitriol is not a significant CYP3A4 substrate in the traditional hepatic sense, but its catabolic enzymes can be affected by broad-spectrum enzyme inhibitors and inducers.
Monitoring
-
Serum Calcium
Twice weekly during titration; monthly once stable; without tourniquet
Routine The single most critical monitoring parameter. Stop calcitriol immediately if Ca exceeds ULN by >1 mg/dL. A fall in serum alkaline phosphatase often precedes hypercalcemia and can serve as an early warning signal in dialysis patients. -
Serum Phosphorus
Periodically (dialysis); monthly for 6 months, then periodically (predialysis)
Routine Calcitriol increases phosphorus absorption. Maintain Ca × P product below 70 mg²/dL². Use non-aluminum phosphate binders to control hyperphosphatemia in dialysis patients. -
iPTH
Baseline; then every 3–4 months (predialysis)
Routine Target range per KDIGO guidelines. Excessive PTH suppression risks adynamic bone disease. -
Alkaline Phosphatase
Periodically (dialysis and predialysis)
Routine Falling ALP in dialysis patients may herald impending hypercalcemia. Also serves as marker for bone disease activity. -
Serum Magnesium
Periodically (dialysis patients)
Routine Calcitriol increases Mg absorption; critically important if patient is using Mg-containing antacids (contraindicated in dialysis). -
Serum Creatinine
Monthly for 6 months, then periodically (predialysis)
Routine Chronic hypercalcemia may elevate creatinine, usually reversible. Not relevant for patients already on dialysis. -
24-Hour Urine Calcium
Periodically (hypoparathyroidism patients)
Routine Detect hypercalciuria that may precede nephrolithiasis or nephrocalcinosis. Target urine Ca excretion within reference range. -
Ca × P Product
At each Ca/P measurement
Trigger-based Must not exceed 70 mg²/dL². Sustained elevation increases risk of metastatic calcification, nephrocalcinosis, and soft tissue damage. Radiographic evaluation if elevated.
Contraindications & Cautions
Absolute Contraindications
- Hypercalcemia — calcitriol will further increase calcium, potentially to life-threatening levels (FDA PI).
- Evidence of vitamin D toxicity — calcitriol is the most potent vitamin D metabolite and will amplify existing toxicity.
- Known hypersensitivity to calcitriol, other vitamin D analogs, or any inactive ingredients.
Relative Contraindications (Specialist Input Recommended)
- Concurrent pharmacologic-dose vitamin D therapy — risk of additive hypercalcemia; if switching from ergocalciferol, allow several months for washout before stable calcitriol dosing can be established.
- Patients on digitalis glycosides — hypercalcemia potentiates digitalis toxicity; use calcitriol only with close calcium monitoring.
- Patients with granulomatous diseases (sarcoidosis, tuberculosis) — macrophage-derived 1-alpha-hydroxylase may cause unregulated calcitriol production, amplifying the risk of hypercalcemia.
Use with Caution
- Immobilized patients (e.g., postoperative) — increased risk of hypercalcemia due to bone resorption plus reduced renal clearance.
- Patients with hyperphosphatemia — calcitriol increases phosphorus absorption; elevated Ca × P product (>70) risks ectopic calcification.
- Patients with hepatic impairment — calcitriol metabolism via hepatic pathways not formally studied; use with caution.
- Patients at risk for nephrolithiasis — hypercalciuria from calcitriol increases stone risk; monitor 24-hr urine calcium.
Overdosage of any form of vitamin D is dangerous. 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 × P) product should not be allowed to exceed 70 mg²/dL². Calcitriol is the most potent metabolite of vitamin D available.
Patient Counselling
Purpose of Therapy
Calcitriol is the active form of vitamin D that your body normally makes in the kidneys. When your kidneys are not working well, or when your parathyroid glands are underactive, your body cannot make enough of this hormone on its own. Calcitriol helps your body absorb calcium from food and keeps your bones healthy. It also helps control parathyroid hormone levels, which protects your bones and blood vessels from damage.
How to Take
Take calcitriol capsules or solution by mouth as directed, usually once daily. It can be taken with or without food. Take it at the same time each day to maintain steady levels. Take the calcium supplements your doctor has prescribed alongside calcitriol, but do not take extra calcium, vitamin D, or antacids without consulting your doctor. If you miss a dose, take it as soon as you remember unless it is close to the time for your next dose — do not double up.
Sources
- Rocaltrol (calcitriol) Capsules and Oral Solution — Full Prescribing Information. Validus Pharmaceuticals LLC. Drugs.com Primary regulatory source for oral calcitriol: indications, dosing, adverse reactions, pharmacokinetics, drug interactions, and contraindications.
- Calcijex (calcitriol injection) — Full Prescribing Information. FDA FDA-approved label for IV calcitriol in hemodialysis patients; source of IV dosing data and pediatric clinical trial results.
- Calcitriol Capsules — Generic Prescribing Information. Drugs.com Generic label confirming identical indications, dosing, and safety profile as Rocaltrol.
- Baker LR, Abrams SM, Roe CJ, et al. 1,25(OH)2D3 administration in moderate renal failure: a prospective double-blind trial. Kidney Int. 1989;35(2):661–669. doi:10.1038/ki.1989.36 Early RCT establishing calcitriol efficacy in predialysis CKD patients for improving calcium homeostasis and PTH suppression.
- Greenbaum LA, Benador N, Goldstein SL, et al. Intravenous calcitriol for treatment of hyperparathyroidism in children on hemodialysis. Pediatr Nephrol. 2005;20(5):622–630. doi:10.1007/s00467-004-1746-8 Placebo-controlled study (n=35) of IV calcitriol in pediatric HD patients showing effective PTH reduction with manageable hypercalcemia.
- Coburn JW, Maung HM, Elangovan L, et al. Doxercalciferol safely suppresses PTH levels in patients with secondary hyperparathyroidism associated with chronic kidney disease stages 3 and 4. Am J Kidney Dis. 2004;43(5):877–890. doi:10.1053/j.ajkd.2004.01.012 Comparative study providing context for calcitriol versus newer vitamin D analogs in PTH suppression efficacy and hypercalcemia rates.
- KDIGO 2017 Clinical Practice Guideline Update for the Diagnosis, Evaluation, Prevention, and Treatment of CKD-MBD. Kidney Int Suppl. 2017;7(1):1–59. doi:10.1016/j.kisu.2017.04.001 International guideline recommending calcitriol, vitamin D analogs, or calcimimetics for CKD G5D patients requiring PTH-lowering therapy (Rec 4.2.4, 2B).
- Ketteler M, et al. Chronic kidney disease–mineral and bone disorder: conclusions from a KDIGO Controversies Conference. Kidney Int. 2025;107(3):405–423. doi:10.1016/j.kint.2024.11.013 Most recent KDIGO update; updated guidance no longer recommends routine calcitriol use in non-dialysis CKD; reserves for severe and progressive sHPT.
- DeLuca HF. Overview of general physiologic features and functions of vitamin D. Am J Clin Nutr. 2004;80(6 Suppl):1689S–1696S. doi:10.1093/ajcn/80.6.1689S Comprehensive review of vitamin D metabolism, 1-alpha-hydroxylation, VDR signaling, and the physiological role of calcitriol in calcium homeostasis.
- Junaid SZS, Patel P, Patel JB. Calcitriol. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; updated March 2025. NCBI Bookshelf Comprehensive review of calcitriol pharmacology, indications, dosing, adverse events, and interprofessional management considerations.
- Salusky IB, Goodman WG. Calcitriol in the management of renal osteodystrophy. Semin Nephrol. 1997;17(6):517–525. Reviews the PK behavior of calcitriol in CKD patients including prolonged half-life, dose-response relationships, and pediatric dosing considerations.
- Brown AJ, Dusso A, Slatopolsky E. Vitamin D. Am J Physiol. 1999;277(2):F157–F175. doi:10.1152/ajprenal.1999.277.2.F157 Landmark review of vitamin D metabolism in the kidney, including calcitriol synthesis regulation, feedback mechanisms, and pharmacological implications in renal failure.