Alendronate Sodium

Alendronate Sodium
INN
Drug class
Routes of administration	Oral
Pregnancy category
Bioavailability	0.6–1.8%
Metabolism	Nil
Elimination half-life	10 years (in bone)
Excretion	Renal
Legal status
CAS Number	121268-17-5
PubChem	2089
DrugBank	DB00630
ChemSpider	2006
KEGG	D07482

Alendronate sodium is a bisphosphonate medication primarily used to treat and prevent osteoporosis in postmenopausal women and to increase bone mass in men with osteoporosis. It is also used to treat Paget's disease of bone and to manage glucocorticoid-induced osteoporosis. Alendronate sodium works by inhibiting osteoclast-mediated bone resorption, thereby leading to an overall increase in bone mineral density.

Pharmacology

Alendronate sodium is a nitrogen-containing bisphosphonate, which makes it more potent than non-nitrogenous bisphosphonates. It binds to hydroxyapatite found in bone, and its primary mechanism of action is the inhibition of the enzyme farnesyl pyrophosphate synthase in osteoclasts. This inhibition prevents the prenylation of small GTPase signaling proteins, which are essential for osteoclast function and survival, leading to decreased bone resorption.

Indications

Alendronate sodium is indicated for:

• Treatment and prevention of osteoporosis in postmenopausal women.
• Treatment to increase bone mass in men with osteoporosis.
• Treatment of glucocorticoid-induced osteoporosis in men and women receiving glucocorticoids in a daily dose equivalent to 7.5 mg or greater of prednisone and who have low bone mineral density.
• Treatment of Paget's disease of bone in men and women.

Dosage and Administration

Alendronate sodium is typically administered orally. For the treatment of osteoporosis, the recommended dose is 10 mg once daily or 70 mg once weekly. For the prevention of osteoporosis, the dose is 5 mg once daily or 35 mg once weekly. It is important to take alendronate sodium with a full glass of water at least 30 minutes before the first food, beverage, or medication of the day to enhance absorption and reduce the risk of esophageal irritation.

Side Effects

Common side effects of alendronate sodium include gastrointestinal issues such as abdominal pain, dyspepsia, and nausea. More serious side effects can include esophageal irritation, esophagitis, esophageal ulcers, and osteonecrosis of the jaw. Patients are advised to remain upright for at least 30 minutes after taking the medication to minimize the risk of esophageal irritation.

Contraindications

Alendronate sodium is contraindicated in patients with:

• Abnormalities of the esophagus which delay esophageal emptying such as stricture or achalasia.
• Inability to stand or sit upright for at least 30 minutes.
• Hypocalcemia.
• Known hypersensitivity to alendronate sodium or any of its components.

Mechanism of Action

Alendronate sodium acts by inhibiting osteoclast-mediated bone resorption. It does this by binding to bone hydroxyapatite and inhibiting the enzyme farnesyl pyrophosphate synthase, which is crucial for the prenylation of small GTPase signaling proteins in osteoclasts. This leads to decreased osteoclast activity and apoptosis, resulting in reduced bone resorption and turnover.

Clinical Studies

Clinical trials have demonstrated that alendronate sodium significantly increases bone mineral density and reduces the incidence of vertebral and hip fractures in postmenopausal women with osteoporosis. Studies have also shown its efficacy in increasing bone mass in men with osteoporosis and in treating glucocorticoid-induced osteoporosis.

Also see

• Bisphosphonates
• Osteoporosis
• Paget's disease of bone
• Bone mineral density