Bisphosphonates

Bisphosphonates are used to treat osteoporosis and severe hypercalcemia.  

Osteoporosis is caused by low calcium levels in the bone.  As you remember osteoclasts are cells that resorb bone and increase serum calcium. The drugs discussed in this section are nitrogen containing bisphosphonates and work by inhibiting farnesyl pyrophosphate synthase, which is an enzyme that promotes attachment of the osteoclast to the bone. Removing osteoclasts from the bone reduces bone resorption and lowers serum calcium levels. Lowering of serum calcium levels is the reason that these medications are used in the treatment of severe hypercalcemia.  

Class Drugs

• Alendronate

• Ibandronate

• Risedronate

• Zoledronic Acid

Class Mechanism of Action

Inhibits farnesyl pyrophosphate synthase

• Farnesyl pyrophosphate promotes attachment of osteoclasts to bone, which allows for bone resorption

• Reduced bone resorption treats osteoporosis and lowers serum calcium levels

Class Applications

Osteoporosis

• Increases bone mass

Hypercalcemia of malignancy

Class Adverse Effects

Avoid in severe renal failure

• Renal elimination

Poor oral absorption

• Do not take with food

Esophagitis, stomach ulcers

• Patients must remain upright for 30 minutes after dosing

Osteonecrosis of the jaw

Drug Table

Drug Name	Application	Comments	Image
Alendronate			"Allen Wrench" "Drone"
Ibandronate			"Band" "Ron Ate"
Risedronate			"Riser" "Drone"
Zoledronic Acid			"Z - Hole" "Drone"