Molecule

Drug Groups

approved

Description

A diphosphonate which affects calcium metabolism. It inhibits ectopic calcification and slows down bone resorption and bone turnover. [PubChem]

Indication

For the treatment of symptomatic Paget's disease of bone and in the prevention and treatment of heterotopic ossification following total hip replacement or due to spinal cord injury.

Pharmacology

Etidronic acid is a first generation (non-nitrogenous) bisphosphonate in the same family as clodronate and tiludronate. Etidronic acid affects calcium metabolism and inhibits bone resorption and soft tissue calcification. Of the etidronic acid that is resorbed (from oral preparation) or infused (for intravenous drugs), about 50% is excreted unchanged by the kidney. The remainder has a very high affinity for bone tissue, and is rapidly absorbed onto the bone surface. Etidronic acid has been shown to prevent or delay skeletal-related events and decrease bone pain as well as normalize calcium levels in the presence of hypercalcemia.

Toxicity

Clinical experience with acute etidronic acid overdosage is extremely limited. Decreases in serum calcium following substantial overdosage may be expected in some patients. Signs and symptoms of hypocalcemia also may occur in some of these patients. Some patients may develop vomiting. In one event, an 18-year-old female who ingested an estimated single dose of 4800 to 6000 mg (67 to 100 mg/kg) of etidronate was reported to be mildly hypocalcemic (7 .5 2 mg/ dl) and experienced paresthesia of the fingers.

Affected Organisms

Biotransformation

Not metabolized.

Absorption

The amount of drug absorbed after an oral dose is approximately 3%.

Half Life

In normal subjects, plasma half-life of etidronic acid, based on non-compartmental pharmacokinetics is 1 to 6 hours.

Elimination

Etidronate disodium is not metabolized. Within 24 hours, approximately half the absorbed dose is excreted in urine; the remainder is distributed to bone compartments from which it is slowly eliminated. Unabsorbed drug is excreted intact in the feces.

External Links