Bisphosphonates and
Alendronate
Fulya
KARAMUSTAFA*, Nevin ÇELEBÝ°,*
* Gazi University, Faculty of Pharmacy, Department of
Pharmacautical Technology, Etiler - 06330 - Ankara
oCorresponding Author
Summary
Bisphosphonates are a class of drugs used in the management
of disorders of calcium and bone metabolism. Treatment with
bisphosphonates causes early reduction in bone resorption
and then a later reduction in bone formation. They bind
strongly to bone mineral, and inhibit the bone resorption
and crystal dissolution. Alendronate, like other
bisphosphonates, is a bone resorption inhibitor being used
in the prevention and treatment of bone diseases. It is used
in the prevention and treatment of postmenopausal
osteoporosis, osteoporosis in men, corticosteroidinduced
osteoporosis, Paget’s disease, primary hyperparathyroidism,
malignant hypercalcemia and metastatic bone diseases. The
bioavailability of alendronate is low. It is primarily
absorbed across the gastrointestinal tract paracellularly
because of the polar and charged structure at physiological
pH. It is better absorbed from the segments of the
gastrointestinal tract with larger surface areas. Following
the administration of intravenous 14C alendronate,
the drug distributes in the calcified and noncalcified
tissues. Albumin is the predominant protein that binds
alendronate. It appears not to be metabolized in mammals.
The renal route is the only means for its elimination.
Terminal elimination half-life in women with post-menopausal
osteoporosis is 10 years, while it is 200 days in rats and
1000 days in dogs. Alendronate is generally well-tolerated
after short- or long-term usage, but adverse effects like
esophagitis and gastric damage have also been reported. It
can behave like a topical irritant and can affect the
gastric epithelium directly or indirectly by increasing
esophageal irritation that was present before. It can
increase esophageal abnormalities caused from low pH.
The direct chromatographic analysis of trihydrate of
alendronate sodium is complicated due to the lack of a
suitable UV chromophore for conventional high-performance
liquid chromatographic analysis and insufficient volatility
for gas chromatographic analysis.
Key Words: .
Key Words :
Bisphosphonates, alendronate, therapeutic
use, pharmacokinetics, adverse effects, analysis.
