Clodronic acid

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Clodronic acid
Clodronic acid.png
Systematic (IUPAC) name
(dichloro-phosphono-methyl)phosphonic acid
Clinical data
AHFS/ International Drug Names
CAS Registry Number 10596-23-3 YesY
ATC code M05BA02
PubChem CID: 25419
DrugBank DB00720 YesY
ChemSpider 23731 YesY
UNII 0813BZ6866 YesY
KEGG D03545 YesY
ChEBI CHEBI:110423 YesY
Chemical data
Formula CH4Cl2O6P2
Molecular mass 244.892 g/mol
 YesY (what is this?)  (verify)

Clodronic acid (INN) or clodronate disodium (USAN) is a first generation (non-nitrogenous) bisphosphonate. It is an anti-osteoporotic drug approved for the prevention and treatment of osteoporosis in post-menopausal women and men to reduce vertebral fractures, hyperparathyroidism, hypercalcemia in malignancy, multiple myeloma and fracture related pain because of its potent anti-inflammatory and analgesic effects shown as a reduction in inflammatory markers like IL-1β, IL-6, and TNF-alfa.

An Italian study compared the analgesic effect of clodronic acid versus acetaminophen in rheumatic condition related pain. Study result show a reduction in pain in favor of clodronic acid that provided more analgesia than 3 grams/day of acetaminophen. Clodronate is also used in experimental medicine to selectively deplete macrophages.

Clodronic acid is approved for human use in Canada and Australia, the United Kingdom, where it is marketed as Bonefos, Loron, Clodron and in Italy as Clasteon, Difosfonal, Osteostab and several generics. In other countries is prescribed as a bone resorption inhibitor and antihypercalcemic agent.

Use in equine medicine[edit]

Clodronic acid is approved for use in horses under the trade name Osphos, for treatment of navicular syndrome. It is given by intramuscular injection, with the total dose divided into 3 sites on the horse. Clinical effects may not be seen for up to 2 months, and horses may need treatments repeated every 3 to 6 months.

Adverse reactions and contraindications[edit]

Osphos has been shown to have several adverse effects. These include:[1]

  • Signs of discomfort, agitation, or colic, usually within 2 hours of treatment.
  • Head shaking
  • Lip licking


  1. ^ U.S. Food and Drug Administration. "FDA Provides Equine Veterinarians with Important Information about TILDREN and OSPHOS for Navicular Syndrome in Horses".