Pamidronate Disodium (Mechanism of Action)

In this article, we will discuss Pamidronate Disodium (Mechanism of Action). So, let’s get started.

Mechanism of Action

The principal pharmacologic action of pamidronate disodium is inhibition of bone
resorption. Although the mechanism of antiresorptive action is not completely understood, several factors are thought to contribute to this action. Pamidronate disodium adsorbs to calcium phosphate (hydroxyapatite) crystals in bone and may block dissolution of this mineral component of bone. In vitro, pamidronate disodium inhibited osteoclast activity. In animal studies, pamidronate disodium inhibited bone resorption, but did not inhibit bone formation and mineralization. In animal tumor models, pamidronate disodium inhibited the increased osteoclast activity induced by tumors.

Pharmacodynamics

Serum phosphate levels have been noted to decrease after administration of pamidronate disodium, presumably because of decreased release of phosphate from bone and increased renal excretion as parathyroid hormone levels, which are usually suppressed in hypercalcemia associated with malignancy, return toward normal. Phosphate therapy was
administered in 30% of the patients in response to a decrease in serum phosphate levels. Phosphate levels usually returned toward normal within 7 to 10 days. Urinary calcium/creatinine and urinary hydroxyproline/creatinine ratios decrease and usually return to within or below normal after treatment with pamidronate disodium. These changes occur within the first week after treatment, as do decreases in serum calcium levels, and are consistent with an antiresorptive pharmacologic action.

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