Etidronic acid

Etidronic acid

File:Etidronic acid.svg
Systematic (IUPAC) name
(1-hydroxy-1-phosphono-ethyl)phosphonic acid
Clinical data
[[Regulation of therapeutic goods |Template:Engvar data]]	US FDA: Etidronate+disodium
Pregnancy category	US: C (Risk not ruled out)
Routes of administration	Oral, intravenous
Legal status
Legal status	℞ (Prescription only)
Pharmacokinetic data
Bioavailability	3%
Metabolism	Nil
Biological half-life	1 to 6 hours
Excretion	Renal and fecal
Identifiers
CAS Number	2809-21-4
ATC code	M05BA01 (WHO) M05BB01
PubChem	CID 3305
DrugBank	APRD00964
Chemical data
Formula	C2H8O7P2
Molar mass	206.028 g/mol[[]]
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Etidronic acid (INN) or 1-hydroxyethane 1,1-diphosphonic acid (HEDP) is a bisphosphonate used in detergents, water treatment, cosmetics and pharmaceutical treatment.

An etidronate is a salt of etidronic acid, abbeviated M_nHEDP (M: is a cation, n: number of M maximum 4).

Chelating Agent and Anti-oxidant

Etidronic acid is a chelating agent and may be added to bind or, to some extent, counter the effects of substances, such as calcium, iron or other metal ions, which may be discharged as a component of grey wastewater and could conceivably contaminate groundwater supplies. As a phosphonate it has corrosion inhibiting properties on unnalloyed steel. Etidronic acid also acts to retard rancidification and oxidation of fatty acids.

HEDP and its salts are added to detergents and other cleaning agents to prevent the effects of hard water. It is also used in peroxide bleaching to prevent degradation of peroxides by transition metals.

Etidronic acid is listed as an ingredient of several cosmetic formulations where it is used for suppressing radical formation, emulsion stabilser and viscosity control. While etidronic acid has not been limited from inclusion in cosmetics and does have legitimate uses, it is recommended that, as with most cosmetic products (particularly soaps), the product should be thoroughly rinsed from the skin after use.

Etidronic acid is also included among swimming pool chemicals. It is used as a stain inhibitor to prevent metal ions coming out of solution and staining the sides of swimming pools.

Pharmaceutical use

Etidronic acid (trade name Didronel) is a bisphosphonate used to strengthen bone, treat osteoporosis, and treat Paget's disease of bone.

Bisphosphonates primarily reduce osteoclastic activity, which prevents bone resorption, and thus moves the bone resorption/formation equilibrium toward the formation side and hence makes bone stronger on the long run. Etidronate, unlike other bisphosphonates, also prevents bone calcification. For this reason, other bisphosphonates, like alendronate, are preferred when fighting osteoporosis. To prevent bone resorption without affecting too much bone calcification, etidronate must be administered only for a short time once in a while, for example for two weeks every 3 months. When given on a continuous basis, say every day, etidronate will altogether prevent bone calcification. This effect may be useful and etidronate is in fact used this way to fight heterotopic ossification. But in the long run, if used on a continuous basis, it will cause osteomalacia.

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