Calcitriol
| 證據等級: L5 | 預測適應症: 10 個 |
目錄
Calcitriol: From Hypoparathyroidism to Hereditary Hypophosphatemic Rickets
Multi-Indication Analysis Report Candidate ID: TW-DB00136-multi Data Cutoff: 2026-04-05
One-Sentence Summary
Calcitriol (1,25-dihydroxyvitamin D₃, DrugBank DB00136) is the biologically active terminal metabolite of the vitamin D activation pathway, globally established for managing hypocalcaemia in hypoparathyroidism and renal osteodystrophy, but currently not registered in Singapore. The TxGNN model identifies 10 predicted indications spanning genetic rickets syndromes, metabolic bone diseases, and renal tubular disorders — with Hereditary Hypophosphatemic Rickets (Rank 7) carrying the strongest actionable evidence: 7 clinical trials (including a direct Phase 1 calcitriol monotherapy trial and a Phase 4 dosing comparison) and 20 publications (including 2 Tier-1 clinical guidelines in The Lancet and Calcified Tissue International). The highest TxGNN-scored prediction (Rank 1: Vitamin D Deficiency, 99.96%) uses an obsolete ontology term with no corresponding trial evidence, but the underlying clinical concept is inherently supported by calcitriol's mechanism of action.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Not registered in Singapore; globally established for hypoparathyroidism, renal osteodystrophy (CKD), and vitamin D-dependent rickets type 1A |
| Predicted New Indication (Top-Ranked) | Vitamin D Deficiency (obsolete ontology term → ICD E55) |
| TxGNN Prediction Score | 99.96% (Rank 1) |
| Evidence Level | L4 (Rank 1: no trials or literature); L2 (Rank 7 — Hereditary Hypophosphatemic Rickets: strongest actionable evidence) |
| Singapore Market Status | Not marketed |
| Number of Registrations | 0 |
| Recommended Decision | Proceed with Guardrails (Hereditary Hypophosphatemic Rickets, Ranks 7–8) |
Multi-Indication Summary
| Rank | Predicted Disease | TxGNN Score | Evidence Level | Decision |
|---|---|---|---|---|
| 1 | Vitamin D Deficiency (obsolete term → ICD E55) | 99.96% | L4 | Research Question |
| 2 | Renal Tubular Acidosis | 99.93% | L3 | Research Question |
| 3 | Familial Isolated Hypoparathyroidism (impaired PTH secretion) | 99.81% | L4 | Research Question |
| 4 | Acromesomelic Dysplasia, Campailla-Martinelli type | 99.79% | L5 | Hold |
| 5 | Craniofacial Conodysplasia | 99.78% | L5 | Hold |
| 6 | Dahlberg-Borer-Newcomer Syndrome (HDR/Barakat) | 99.76% | L4 | Research Question |
| 7 | Hereditary Hypophosphatemic Rickets | 99.28% | L2 | Proceed with Guardrails |
| 8 | Hypophosphatemic Rickets | 98.08% | L2 | Proceed with Guardrails |
| 9 | Osteomalacia | 97.68% | L3 | Proceed with Guardrails |
| 10 | Vitamin D-Dependent Rickets | 97.42% | L3 | Proceed with Guardrails |
Why is This Prediction Reasonable?
Calcitriol is the biologically active form of vitamin D, produced in the proximal convoluted tubule of the kidney via CYP27B1 (1α-hydroxylase) acting on 25-hydroxyvitamin D. It binds the vitamin D receptor (VDR), a nuclear transcription factor expressed in intestinal epithelium, bone osteoblasts, renal tubular cells, and parathyroid gland chief cells. Through VDR activation, calcitriol enhances intestinal calcium absorption (from ~15% to 30–40%), promotes distal renal tubular calcium reabsorption, suppresses PTH synthesis, and enables adequate mineralisation of the osteoid bone matrix — making it a master regulator of calcium-phosphate homeostasis.
The 10 predicted indications cluster around two mechanistically coherent themes. The first is conditions where endogenous calcitriol synthesis is impaired: in hereditary hypophosphatemic rickets (particularly X-linked hypophosphataemia, XLH), FGF23 excess from PHEX mutations simultaneously drives renal phosphate wasting and suppresses CYP27B1 activity, creating a state of relative calcitriol deficiency; exogenous calcitriol directly restores VDR signalling and corrects the bone mineralisation deficit. The second theme is conditions where PTH deficiency reduces CYP27B1 stimulation: in hypoparathyroid syndromes (familial isolated hypoparathyroidism, HDR/Barakat syndrome), PTH-driven 1α-hydroxylation is lost, and calcitriol substitution functions as a precision enzyme-product replacement therapy.
For the top-ranked indication (Rank 1: "obsolete vitamin D deficiency"), the ontology term is marked deprecated in current biomedical databases, which explains the absence of trial registrations under this label. The clinically equivalent current term — Vitamin D Deficiency (ICD E55) — is an area where calcitriol's role is theoretically complete, as it is the deficient product itself. Re-querying evidence databases under ICD E55 terminology is strongly recommended before drawing conclusions about evidence absence.
Clinical Trial Evidence
Focus: Hereditary Hypophosphatemic Rickets / Hypophosphatemic Rickets (Ranks 7–8 — highest evidence)
| Trial Number | Phase | Status | Enrollment | Key Findings |
|---|---|---|---|---|
| NCT03748966 | Early Phase 1 | Active, Not Recruiting | 20 | Direct calcitriol monotherapy for XLH — dose escalation over 3 months; primary hypothesis: calcitriol alone (without phosphate) will improve serum phosphate levels and skeletal mineralisation in children and adults without increasing kidney calcifications |
| NCT03820518 | Phase 4 | Unknown | 100 | Compares high vs. low dose active vitamin D (calcitriol/alfacalcidol) combined with neutral phosphate in children with XLH; aims to establish evidence-based weight-dependent dosing for routine clinical practice |
| NCT04846647 | N/A (Observational) | Completed | 260 | Study of inappropriate FGF23 hypersecretion in hospitalised hypophosphataemia patients; confirms FGF23's dual role in suppressing renal phosphate reabsorption and inhibiting calcitriol synthesis — mechanistic underpinning for calcitriol supplementation |
| NCT06046820 | Phase 3 | Active, Not Recruiting | 27 | ENERGY 3 Study — evaluates INZ-701 in ENPP1 deficiency; contextualises calcitriol's evolving position within the current treatment landscape of hereditary hypophosphataemia |
| NCT01526304 | N/A (Cross-sectional) | Unknown | 150 | Cross-sectional study of FGF23, Klotho, and Sclerostin in kidney stone formers; provides background data on phosphate metabolism dysregulation relevant to calcitriol's role |
| NCT00844740 | N/A | Withdrawn (n=0) | 0 | Cinacalcet in familial hypophosphatemic rickets — withdrawn; abstract explicitly identifies oral phosphate + 1,25(OH)₂D (calcitriol) as the current standard of care, validating calcitriol's benchmark status |
| NCT06921720 | N/A (Diagnostic) | Not Yet Recruiting | 65 | ATP measurement by ³¹P-spectroscopy in phosphate diabetes (XLH); diagnostic study evaluating intracellular phosphate deficit, indirectly supporting rationale for calcitriol + phosphate supplementation |
Literature Evidence
Priority: Tier-1 guidelines and direct calcitriol treatment studies; selected from Ranks 7–10 evidence pools
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 39181153 | 2024 | Systematic Review | The Lancet | XLH comprehensive review: PHEX mutation → FGF23 excess → renal phosphate wasting + decreased calcitriol synthesis → hypophosphataemic rickets and osteomalacia; first-line conventional treatment confirmed as phosphate + active vitamin D metabolites |
| 40295317 | 2025 | Clinical Guideline | Calcified Tissue International | Current XLH diagnosis and therapy guideline; calcitriol confirmed as a core treatment component; discusses monitoring for hypercalcaemia and nephrocalcinosis |
| 2157942 | 1990 | Clinical Trial (non-RCT) | Metabolism | Direct calcitriol treatment evidence: complete metabolic correction achieved in VDDR type 1 with physiological calcitriol doses; partial improvement in XLH with supraphysiological doses combined with phosphate |
| 3839245 | 1985 | Clinical Trial (non-RCT) | J Clin Investigation | Key historical study: high-dose calcitriol (mean 68.2 ng/kg/day) induces and maintains healing of XLH-associated osteomalacia; conventional therapy heals rickets but fails to resolve osteomalacia without calcitriol |
| 40565034 | 2025 | Review | Int J Mol Sci | Renal and extrarenal calcitriol synthesis regulation; low circulating calcitriol documented in nutritional rickets, osteomalacia, obesity, and preeclampsia; outlines clinical implications |
| 34492747 | 2021 | Systematic Review + Case Series | J Pediatr Endocrinol Metab | VDDR1A (CYP27B1 mutations): genotype-phenotype spectrum; calcitriol is the definitive treatment, with complete clinical remission achievable at physiological replacement doses |
| 32204545 | 2020 | Review | Metabolites | Vitamin D's protective role in renal tubulopathies; proximal tubule mitochondria identified as primary site of calcitriol production; documents anti-inflammatory and antioxidative functions relevant to tubular acidosis management |
| 7970647 | 1994 | Clinical Study (non-RCT) | Orvosi Hetilap | Calcitriol improves osteomalacia complicating distal renal tubular acidosis; case report documenting bone disease progression and calcitriol response over 7 years of follow-up |
| 30454743 | 2019 | Review | Pediatric Clinics of North America | Hypophosphatemic rickets: conventional PO₄ + calcitriol treatment reviewed; monitoring protocol for nephrocalcinosis and nephrolithiasis as treatment-emergent complications |
| 29292875 | 2017 | Cohort Study | Pediatric Endocrinology Reviews | Spontaneous growth and effect of early calcitriol + phosphate therapy in 127 XLH patients from 49 centres; highlights importance of early initiation and consistent monitoring |
Singapore Market Information
Calcitriol is currently not registered in Singapore. No licensed products or approved indication texts are available in the HSA regulatory database.
| Authorization Number | Product Name | Dosage Form | Approved Indication |
|---|---|---|---|
| — | Not registered | — | No Singapore regulatory data available |
International reference: Calcitriol is registered and commercially available in multiple markets under brand names including Rocaltrol® (Roche) in oral capsule form (0.25 µg, 0.5 µg) and intravenous solution for haemodialysis patients. Registration in Singapore would require a full product registration application to the Health Sciences Authority (HSA) under the Therapeutic Products Regulations.
Safety Considerations
Please refer to the package insert for safety information.
Supplementary note from published literature (not from Singapore regulatory records; formal review required):
- Hypercalcaemia: The principal dose-limiting toxicity of calcitriol; requires routine monitoring of serum total and ionised calcium, especially during dose escalation
- Nephrocalcinosis / Nephrolithiasis: Particularly relevant in hypophosphatemic rickets treatment contexts; renal ultrasound monitoring recommended every 6–12 months
- PTH over-suppression: Excess calcitriol may cause adynamic bone disease via oversuppression of PTH; monitor intact PTH periodically
- Drug interaction consideration: Thiazide diuretics may potentiate hypercalcaemia risk; corticosteroids may partially antagonise calcitriol effects on intestinal calcium absorption
Conclusion and Next Steps
Decision: Proceed with Guardrails (Hereditary Hypophosphatemic Rickets, Ranks 7–8)
Rationale: Calcitriol combined with phosphate supplementation is the established conventional treatment for hereditary hypophosphatemic rickets (particularly XLH), endorsed by multiple Tier-1 clinical guidelines including a 2024 Lancet systematic review; an active Phase 1 monotherapy trial (NCT03748966) and a Phase 4 dosing optimisation trial (NCT03820518) both directly evaluate calcitriol in this indication, confirming ongoing clinical relevance even in the era of burosumab.
To proceed, the following is needed:
- [Blocking] Obtain formal HSA-approved package insert data for Singapore market registration, including approved warnings, contraindications, and product monograph (currently absent — identified as a blocking data gap DG001)
- [High Priority] Complete DrugBank MOA documentation query for calcitriol (DB00136) to formally characterise VDR-mediated mechanism for regulatory submissions (data gap DG002)
- [Evidence Gap] Re-query clinical trial and literature databases for Rank 1 indication using current ICD E55 terminology ("Vitamin D deficiency") rather than the obsolete ontology term, to accurately capture existing evidence
- [Regulatory] Initiate HSA product registration application for calcitriol in Singapore (oral capsule and/or IV formulation); currently no locally registered product
- [Safety Protocol] Develop Singapore-specific monitoring protocol: serum calcium and phosphate (monthly during dose titration, then quarterly), intact PTH (every 6 months), renal ultrasound for nephrocalcinosis (every 12 months), 24-hour urinary calcium
- [Dose Optimisation] Await completion of NCT03748966 (calcitriol monotherapy, XLH) and NCT03820518 (dose comparison, Phase 4) results before finalising dosing recommendations for Singapore clinical practice
Research Priority Note: Indications at Ranks 4 and 5 (acromesomelic dysplasia, craniofacial conodysplasia) are rated Hold (L5) and should not be advanced without new mechanistic or clinical evidence. Ranks 3 and 6 (familial isolated hypoparathyroidism, Dahlberg-Borer-Newcomer syndrome) represent mechanistically valid but evidence-sparse applications; these merit targeted literature searches under current disease terminology before further evaluation.
This report is generated for research reference purposes only and does not constitute medical advice. Drug repurposing candidates require clinical validation before application.
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.