Paricalcitol 131918-61-1

S.Impurity<0.05%, 99% up, PMDA, DMF

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Product Information

Product name	Paricalcitol
CAS No.	131918-61-1
Molecular Formula	C₂₇H₄₄O₃
Molecular Weight	416.64
Quality Standard	S.Impurity<0.05%, 99% up, PMDA, DMF
Appearance	White to almost white powder

COA

Test Items	Specifications	Results
Appearance	White to almost white powder	White powder
Identification	(1) IR: Identical versus reference spectrum	Conforms
Identification	(2) The retention time of the major peak in the chromatogram of the assay preparation corresponds to that in the chromatogram of the standard preparation, as obtained in the Assay.	Conforms
Solubility	Soluble in anhydrous alcohol, insoluble in water.	Conforms
Loss on drying	≤ 2.0%	0.04%
Related substances (Report Threshold 0.05%)	22Z-Paricalcitol ≤ 0.15%	ND
	Any individual impurity ≤0.10%	ND
	Total impurities ≤0.15%	ND
Residual solvents	Isopropyl acetate ≤5000ppm	325ppm
Residual solvents	2-Propanol ≤5000ppm	< 23.9ppm(LOD)
Microbial limits	TAMC ≤5 cfu/mg	<1cfu/mg
	TYMC ≤5 cfu/mg	<1cfu/mg
	E.coli: should be absence in 1mg	Absent
Bacterial endotoxins	< 5 EU/μg	< 5 EU/μg
Assay (Calculated on the dried basis)	97.0% - 103.0%	100.0%
Conclusion	It conforms to USP2024 including in-house standard.

Usage

Paricalcitol (19-nor-1α,25-dihydroxyvitamin D₂; CAS 131918-61-1; C27H44O3; MW 416.64; ATC H05BX02) is a synthetic vitamin D receptor activator for secondary hyperparathyroidism in chronic kidney disease. Its advantage is not stronger PTH suppression — it is the separation of PTH suppression from calcemic and phosphatemic effects, achieved through the 19-nor A-ring modification and the retained vitamin D₂ side chain.

Why paricalcitol stands out

1. Faster, more reliable PTH control

PTH reduction ≥30% in 91% of patients versus 13% on placebo (P < 0.001). Median time to ≥40% PTH suppression was 8 weeks versus 12 weeks for calcitriol (P = 0.02), and the therapeutic PTH range was reached at 18 weeks in patients who had never reached it on calcitriol.

2. A wider calcemic and phosphatemic margin

Hypercalcemic episodes were 18% versus 33% on calcitriol (P = 0.008). Fractional intestinal calcium absorption was lower (0.135 vs 0.158; P = 0.022). In a two-year crossover study (n = 73), switching from calcitriol to paricalcitol at a 1:3 ratio lowered serum calcium (P = 0.0003), phosphorus (P = 0.027), Ca × P product (P = 0.003), PTH (P = 0.001) and alkaline phosphatase (P = 0.0005), with far fewer missed doses (P < 0.0001).

3. Lower treatment burden

Oral and intravenous presentations are both marketed, covering dialysis and non-dialysis settings. A 1:3 conversion ratio applies when switching from calcitriol. Pill burden over 24 weeks was 240 versus 292 tablets (P = 0.01).

4. Evidence at a glance

Endpoint	Paricalcitol	Comparator	P value
≥30% PTH reduction, CKD stage 3–4, 24 wk	91%	13% (placebo)	< 0.001
Median time to ≥40% PTH suppression	8 weeks	12 weeks (calcitriol)	0.02
Hypercalcemic episodes, dialysis	18%	33% (calcitriol)	0.008
Fractional intestinal Ca absorption	0.135	0.158 (calcitriol)	0.022
Ca × P product, 2-yr crossover	Lower	Calcitriol baseline	0.003

5. Scope of the evidence

In non-dialysis CKD stage 3–4 patients, the difference in confirmed hypercalcemia was not statistically significant (3 vs 1 event; P = 0.36), and a small oral head-to-head dialysis trial (n = 66) found similar efficacy and safety (iPTH −48.4% vs −41.9%; P = 0.6). A 2016 systematic review concluded that the evidence is insufficient to demonstrate an advantage over non-selective vitamin D derivatives. Defensible positioning: faster attainment of the PTH target, lower intestinal calcium absorption, lower Ca × P product, lower pill burden — not a blanket claim of superiority.