indication

For the management of hypercalcemia of malignancy and as an adjunct in the management of osteolysis resulting from bone metastases of malignant tumors.

pharmacology

Clodronate is a first generation (non-nitrogenous) bisphosphonate in the same family as etidronate and tiludronate. Clodronate affects calcium metabolism and inhibits bone resorption and soft tissue calcification. Of the clodronate 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. Clodronate 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.

mechanism of action

The bisphosphonate group binds strongly to the bone mineral, hydroxyapatite. This explains the specific pharmacological action of these compounds on mineralized tissues, especially bone. The exact mechanism of action of clodronate is not known, however it is known that it does not inhibit protein isoprenylation but can be metabolized intracellularly to a β-γ-methylene (AppCp-type) analog of ATP (AppCCl2p), which is cytotoxic to macrophages in vitro. Inhibition of the ADP/ATP translocase by the metabolite AppCCl2p is a likely route by which clodronate causes osteoclast apoptosis and inhibits bone resorption. Recently, the slime mold Dictyostelium discoideum was shown to take up bisphosphonates by pinocytosis. In these cells, clodronate, but not other pharmacologically active bisphosphonates, was incorporated into adenine nucleotides, which could potentially explain why this bisphosphonate sometimes seems to act differently than the other bisphosphonates. Clodronate, like all biphosphonates, also binds protein-tyrosine-phosphatase.

toxicity

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.

biotransformation

Clodronate is not metabolized in humans.

absorption

After oral administration, absorption is estimated at 1–3% of the ingested dose because of the low uptake from the gastrointestinal tract.

half life

Approximately 13 hours.

drug interactions

Aluminium: Formation of non-absorbable complexes

Calcium: Formation of non-absorbable complexes

Calcium Acetate: Calcium Salts may decrease the serum concentration of Bisphosphonate Derivatives such as clodronate. Avoid administration of oral calcium supplements within 2 hours before or after tiludronate/clodronate/etidronate.

Calcium Chloride: Calcium salts may decrease the serum concentration of bisphosphonate derivatives. Avoid administration of oral calcium supplements within 2 hours before or after tiludronate/clodronate/etidronate.

Dihydroxyaluminium: Formation of non-absorbable complexes

Estramustine: Clodronate may increase the levels of estramustine.

Iron: Formation of non-absorbable complexes

Iron Dextran: Formation of non-absorbable complexes

Magnesium: Formation of non-absorbable complexes

Magnesium oxide: Formation of non-absorbable complexes

Sucralfate: Formation of non-absorbable complexes