Product Information
Registration Status: ActiveMEDITROL is approved to be sold in Singapore with effective from 2008-04-25. It is marketed by GOLDPLUS UNIVERSAL PTE LTD, with the registration number of SIN13449P.
This product contains Calcitriol 0.25mcg in the form of CAPSULE, LIQUID FILLED. It is approved for ORAL use.
This product is manufactured by Mega Lifesciences Public Company LTD in THAILAND.
It is a Prescription Only Medicine that can only be obtained from a doctor or a dentist, or a pharmacist with a prescription from a Singapore-registered doctor or dentist.
Description
Calcitriol or 1,25-dihydroxycholecalciferol (abbreviated 1,25-(OH)2-D3) is the active form of vitamin D found in the body (vitamin D3). Calcitriol is marketed under various trade names including Rocaltrol (Roche), Calcijex (Abbott) and Decostriol (Mibe, Jesalis). It is produced in the kidneys via 25-hydroxyvitamin D-1 α-hydroxylase by conversion from 25-hydroxycholecalciferol (calcidiol). This is stimulated by a decrease in serum calcium, phosphate (PO43−) and parathyroid hormone (PTH) levels. It regulates calcium levels by increasing the absorption of calcium and phosphate from the gastrointestinal tract, increasing calcium and phosphate reabsorption in the kidneys and inhibiting the release of PTH. Calcitriol is also commonly used as a medication in the treatment of hypocalcemia and osteoporosis.
Indication
Used to treat vitamin D deficiency or insufficiency, refractory rickets (vitamin D resistant rickets), familial hypophosphatemia and hypoparathyroidism, and in the management of hypocalcemia and renal osteodystrophy in patients with chronic renal failure undergoing dialysis. Also used in conjunction with calcium in the management and prevention of primary or corticosteroid-induced osteoporosis.
Mechanism of Action
The mechanism of action of calcitriol in the treatment of psoriasis is accounted for by their antiproliferative activity for keratinocytes and their stimulation of epidermal cell differentiation. The anticarcinogenic activity of the active form of Calcitriol appears to be correlated with cellular vitamin D receptor (VDR) levels. Vitamin D receptors belong to the superfamily of steroid-hormone zinc-finger receptors. VDRs selectively bind 1,25-(OH)2-D3 and retinoic acid X receptor (RXR) to form a heterodimeric complex that interacts with specific DNA sequences known as vitamin D-responsive elements. VDRs are ligand-activated transcription factors. The receptors activate or repress the transcription of target genes upon binding their respective ligands. It is thought that the anticarcinogenic effect of Calcitriol is mediated via VDRs in cancer cells. The immunomodulatory activity of calcitriol is thought to be mediated by vitamin D receptors (VDRs) which are expressed constitutively in monocytes but induced upon activation of T and B lymphocytes. 1,25-(OH)2-D3 has also been found to enhance the activity of some vitamin D-receptor positive immune cells and to enhance the sensitivity of certain target cells to various cytokines secreted by immune cells.
Pharmacokinetics
- Absorption
- Rapidly absorbed from the intestine.
- Distribution
- Metabolism
- The first pathway involves 24-hydroxylase activity in the kidney; this enzyme is also present in many target tissues which possess the vitamin D receptor such as the intestine. The end product of this pathway is a side chain shortened metabolite, calcitroic acid. The second pathway involves the conversion of calcitriol via the stepwise hydroxylation of carbon-26 and carbon-23, and cyclization to yield ultimately 1a,25R(OH)2-26,23S-lactone D3. The lactone appears to be the major metabolite circulating in humans.
- Elimination
Clearance
* 15.3 mL/hr/kg [pediatric patients (age range: 1.8 to 16 years) undergoing peritoneal dialysis receiving dose of 10.2 ng/kg (SD 5.5 ng/kg) for 2 months]
Toxicity
LD50 (oral, rat) = 620 μg/kg; LD50 (intraperitoneal, rat) > 5 mg/kg; Overdose evident in elevated blood calcium levels causing symptoms of anorexia, nausea and vomiting, polyuria, polydipsia, weakness, pruritus, and nervousness, potentially with irreversible calcification of soft tissue in the kidney and liver.
Active Ingredient/Synonyms
(1S,3R,5Z,7E)-9,10-secocholesta-5,7,10-triene-1,3,25-triol | (1α,3β,5Z,7E)-9,10-secocholesta-5,7,10(19)-triene-1,3,25-triol | (5Z,7E)-(1S,3R)-9,10-secocholesta-5,7,10(19)-triene-1,3,25-triol | 1-alpha-25-Dihydroxyvitamin D3 | 1,25-DHCC | 1,25-dihydroxycholecalciferol | 1α,25-dihydroxycholecalciferol | 1α,25-dihydroxyvitamin D3 | 1α,25(OH)2D3 | Calcitriol | Calcitriolum | Calcitriol |
Source of information: Drugbank (External Link). Last updated on: 3rd July 18. *Trade Name used in the content below may not be the same as the HSA-registered product.