indication

For the treatment and prevention of osteoporosis in postmenopausal women.

pharmacology

Ibandronate is a nitrogen-containing bisphosphonate in the same class as alendronate and risedronate. Ibandronate inhibits osteoclast-mediated bone resorption. All of the bisphosphonates prevent the breakdown of bone by bone cells called osteoclasts. In persons who are at high risk for osteoporosis, bisphosphonates not only result in increased amounts of bone and bone strength, they also reduce the risk of hip fractures and other bone fractures.

mechanism of action

The action of ibandronate on bone tissue is based partly on its affinity for hydroxyapatite, which is part of the mineral matrix of bone. Nitrogen-containing bisphosphonates (such as pamidronate, alendronate, risedronate, ibandronate and zoledronate) appear to act as analogues of isoprenoid diphosphate lipids, thereby inhibiting farnesyl pyrophosphate (FPP) synthase, an enzyme in the mevalonate pathway. Inhibition of this enzyme in osteoclasts prevents the biosynthesis of isoprenoid lipids (FPP and GGPP) that are essential for the post-translational farnesylation and geranylgeranylation of small GTPase signalling proteins. This activity inhibits osteoclast activity and reduces bone resorption and turnover. In postmenopausal women, it reduces the elevated rate of bone turnover, leading to, on average, a net gain in bone mass.

toxicity

LD₅₀ = 811 mg/kg (rat, oral), side effects include bronchitis, pneumonia and urinary tract infections.

biotransformation

No evidence of ibandronate being metabolized in humans.

absorption

Poorly absorbed (mean bioavailability following a 2.5 mg oral dose is about 0.6% compared to intravenous dosing). Absorption is impaired by any kind of food or drink other than plain water.

half life

10-60 hours

route of elimination

Ibandronate is eliminated by renal excretion. Unabsorbed ibandronate is eliminated unchanged in the feces.

drug interactions

Aluminium: Formation of non absorbable complexes

Calcium: Formation of non-absorbable complexes

Calcium Acetate: Calcium Salts may decrease the serum concentration of Bisphosphonate Derivatives such as ibandronate. Avoid administration of oral calcium supplements within 60 minutes after oral ibandronate.

Calcium Chloride: Calcium salts may decrease the serum concentration of bisphosphonate derivatives. Avoid administration of oral calcium supplements within 60 minutes after oral ibandronate.

Iron: Formation of non absorbable complexes

Iron Dextran: Formation of non-absorbable complexes

Magnesium: Formation of non-absorbable complexes

Magnesium oxide: Formation of non absorbable complexes

Sucralfate: Formation of non absorbable complexes