Indicated for the treatment of postmenopausal osteoporosis. It also reduces the risk of vertebral and hip fractures. Alendronic acid (as sodium alendronate trihydrate) is a potent bisphosphonate which inhibits osteoclastic bone resorption.
Alendronate is a bisphosphonate that binds to bone hydroxyapatite and specifically inhibits the activity of osteoclasts, the bone-resorbing cells. Alendronate reduces bone resorption with no direct effect on bone formation, although the latter process is ultimately reduced because bone resorption and formation are coupled during bone turnover.
Animal studies have indicated the following mode of action. At the cellular level, alendronate shows preferential localization to sites of bone resorption, specifically under osteoclasts. The osteoclasts adhere normally to the bone surface but lack the ruffled border that is indicative of active resorption. Alendronate does not interfere with osteoclast recruitment or attachment, but it does inhibit osteoclast activity. Studies in mice on the localization of radioactive [3H] alendronate in bone showed about 10-fold higher uptake on osteoclast surfaces than on osteoblast surfaces. Bones examined 6 and 49 days after [3H] alendronate administration in rats and mice, respectively, showed that normal bone was formed on top of the alendronate, which was incorporated inside the matrix. While incorporated in bone matrix, alendronate is not pharmacologically active. Thus, alendronate must be continuously administered to suppress osteoclasts on newly formed resorption surfaces. Histomorphometry in baboons and rats showed that alendronate treatment reduces bone turnover (i.e., the number of sites at which bone is remodeled). In addition, bone formation exceeds bone resorption at these remodeling sites, leading to progressive gains in bone mass.
ORAL Osteopetrosis: Adult: 10 mg daily or 70 mg once wkly. Paget’s disease of bone: Adult: 40 mg daily for 6 mth; may be repeated if necessary after 6-mth post-treatment evaluation period. Prophylaxis of postmenopausal osteoporosis: Adult: 5 mg once daily or 35mg once wkly. Corticosteroid-induced osteoporosis: Adult: Treatment & prevention: 5 mg daily; may increase to 10 mg daily in women who do not receive HRT.
The incidence of upper gastrointestinal side effects are increased with the concomitant use of non-steroidal anti-inflammatory agents and aspirin. Absorption of Alendronate is reduced in the presence of antacids and calcium supplements.
Hypocalcaemia; oesophageal abnormalities & factors which delay oesophageal emptying; severe renal impairment; hypersensitivity; inability to stand or sit upright for 30 mm. Pregnancy, lactation. Upper GI disorders (discontinue if symptoms worsen); history of ulcers, active GI bleeding. Correct vitD&Ca deficiency before starting therapy. To be taken 1/2 an hr before breakfast & remain upright for at least 30 mmns after admin. Not recommended for use in patients w/ CrCI <35 mI/min.
Oesophagitis, oesophageal ulcers & erosions, dysphagia, heartburn, retrosternal pain, abdominal pain, distension, diarrhoea, constipation, flatulence, headache, rash, erythema, musculoskeletal pain, transient decreases in serum phosphate.
Alendronic acid should not be used during pregnancy. It is not known whether alendronic acid is excreted into human breast milk.
Store in a well-closed container at room temperature, 15-30°C
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