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| Clinical data | |
|---|---|
| Trade names | Didronel, others |
| Other names | 1-Hydroxyethylidene-1,1-diphosphonic acid; HEDP |
| AHFS/Drugs.com | International Drug Names |
| License data | |
| Routes of administration | Oral,intravenous |
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| Pharmacokinetic data | |
| Bioavailability | 3% |
| Metabolism | Nil |
| Eliminationhalf-life | 1 to 6 hours |
| Excretion | Renal and fecal |
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| ECHA InfoCard | 100.018.684 |
| Chemical and physical data | |
| Formula | C2H8O7P2 |
| Molar mass | 206.027 g·mol−1 |
| 3D model (JSmol) | |
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Etidronic acid, also known asetidronate, is abisphosphonate drug.[1] It is non-nitrogenous bisphosphonate. It was patented in 1966 and approved for medical use in 1977.[2] For medicinal purposes, etidronic acid has been obsolete since the early 2010's.[3]
Etidronic acid is a bisphosphonate once used to strengthenbone, treatosteoporosis, and treatPaget's disease of bone.
Bisphosphonates primarily reduceosteoclastic activity, which preventsbone resorption, and thus moves the bone resorption/formation equilibrium toward the formation side and hence makes bone denser in the long run. Etidronate, unlike other bisphosphonates, also prevents bonecalcification. For this reason, other bisphosphonates, such asalendronate, are preferred when fighting osteoporosis. To prevent bone resorption without affecting too much bone calcification, etidronate is 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 was in fact used this way to fightheterotopic ossification. But in the long run, if used on a continuous basis, it will causeosteomalacia.
HEDP is a versatile phosphonate compound known for itscorrosion inhibition,chelating, and stabilizing properties, making it valuable across a range of industrial and consumer applications.
In industrial contexts, HEDP acts as a retardant ofcement hydration in concrete, extending the dormant period before hardening begins.[4] It is also used as a scale and corrosion inhibitor in circulating cooling water systems,oil fields, and low-pressure boilers, serving industries such as electric power, chemical manufacturing,metallurgy, and fertilizer production.
Beyond these applications, HEDP is utilized in thedyeing industry as aperoxide stabilizer and dye-fixing agent, and in non-cyanideelectroplating where it functions as a chelating agent. In the light woven industry, it serves as a detergent for cleaning metal and non-metal surfaces and is often combined withpolycarboxylic acids (superplasticizers) as a reducing agent. Typical dosages range from 1–10 mg/L for scale inhibition, 10–50 mg/L for corrosion inhibition, and 1000–2000 mg/L for detergent use.
As a chelating agent, HEDP binds to calcium, iron, and other metal ions, helping to reduce their potential environmental impact, particularly throughgreywater discharge intogroundwater. Its phosphonate structure also imparts corrosion resistance to unalloyed steel, and it retardsrancidification and oxidation offatty acids.
In detergents and cleaning agents, HEDP and its salts help mitigate the adverse effects ofhard water and stabilize peroxides duringbleaching by inhibiting degradation caused bytransition metals. Within the cosmetics industry, HEDP is used as a radical formation suppressant,emulsion stabilizer, and viscosity control agent. Although approved for use in cosmetic products, it is recommended that products containing HEDP, particularly soaps, be thoroughly rinsed from the skin after use.
HEDP also finds application in swimming pool maintenance, where it functions as a stain inhibitor by preventing metal ions from precipitating and staining pool surfaces.
| Bisphosphonate | Relative potency |
|---|---|
| Etidronate | 1 |
| Tiludronate | 10 |
| Pamidronate | 100 |
| Alendronate | 100-500 |
| Ibandronate | 500-1000 |
| Risedronate | 1000 |
| Zoledronate | 5000 |
Etidronic acid can be prepared by reactions of dialkylphosphites andcarboxylic acid anhydrides.[6] Other precursors includephosphorus trichloride andphosphorous acid.[7]
