Mechanism of action:

Alendronate monosodium trihydrate, is a bisphosphonate that inhibits osteoclastic bone resorption with no direct effect on bone formation. 

Pharmacokinetics:

Absorption: The mean oral bioavailability of alendronate in women was (%0.64) for doses ranging from 5 to 70 mg when administered after an overnight fast and two hours before a breakfast. Oral bioavailability of the 10 mg tablet in men (%0.59) was similar to that in women. Bioavailability was decreased (by approximately %40) when 10 mg alendronate was administered either 0.5 or 1 hour before a breakfast, when compared to dosing 2 hours before eating. Concomitant administration of alendronate with coffee or orange juice reduced bioavailability by approximately %60. 

Distribution: Protein binding in human plasma is approximately %78. 

Metabolism: There is no evidence that alendronate is metabolized in animals or humans.

Elimination: The terminal half-life in humans is estimated to exceed 10 years, probably reflecting release of alendronate from the skeleton. Although no clinical information is available, it is likely that, as in animals, elimination of alendronate via the kidney will be reduced in patients with impaired renal function. Therefore, greater accumulation of alendronate in bone might be expected in these patients. No dosage adjustment is necessary for patients with mild-to-moderate renal insufficiency (creatinine clearance 35 to 60 mL/min). 

No dosage adjustment is necessary for patients with hepatic impairment.