Article: Calcitriol

Calcitriol
Systematic (IUPAC) name
(1R,3S)- 5-[2-[(1R,3aR,7aS)-1- [(2R)-6-hydroxy-6-methyl-heptan-2-yl]- 7a-methyl-2,3,3a,5,6,7-hexahydro-1H- inden-4-ylidene]ethylidene]- 4-methylidene-cyclohexane-1,3-diol
Identifiers
CAS number	32222-06-3
ATC code	A11CC04 D05AX03
PubChem	134070
DrugBank	APRD00246
Chemical data
Formula	C27H44O3
Mol. weight	416.64 g.mol-1
Pharmacokinetic data
Bioavailability	?
Metabolism	Renal
Half life	5–8 hours
Excretion	Renal
Therapeutic considerations
Pregnancy cat.	B3 (Au), C (U.S.)
Legal status	S4 (Au), POM (UK)
Routes	Oral, IV, topical

Calcitriol (INN) (IPA: [kælsɪˈtraɪɒl, kælˈsɪtrɪɒl]) or 1,25-dihydroxycholecalciferol (abbreviated 1,25-(OH)₂D₃) is the active form of vitamin D found in the body (vitamin D₃). It is produced in the kidneys by conversion from 25-hydroxycholecalciferol (calcidiol) and regulates calcium levels by increasing the absorption of calcium from the gastrointestinal tract. Calcitriol is also commonly used as a medication in the treament of hypocalcaemia and osteoporosis. Calcitriol is marketed under various trade names including Rocaltrol (Roche) and Calcijex (Abbott).

Indications

Calcitriol is indicated for:^[1]

• Treatment of hypocalcaemia – hypoparathyroidism, osteomalacia (rickets), renal osteodystrophy, chronic renal dialysis
• Treatment of osteoporosis
• Prevention of corticosteroid-induced osteoporosis

Calcitriol is also sometimes used topically in the treament of psoriasis, however the evidence to support its efficacy is inconclusive.^[2] The vitamin D analogue calcipotriol is more commonly used for psoriasis.

Adverse effects

The main adverse drug reaction associated with calcitriol therapy is hypercalcaemia – early symptoms include: nausea, vomiting, constipation, anorexia, apathy, headache, thirst, sweating, and/or polyuria). Compared to other vitamin D compounds in clinical use (cholecalciferol, ergocalciferol), calcitriol has a higher risk of inducing hypercalcaemia. However, such episodes may be shorter and easier to treat due to its relatively short half-life.^[1]