Week 11 - Bisphosphonates Flashcards
Bisphosphonates: indications
- Osteoporosis
- High fracture risk
- Hypercalcemia
- Matastatic bone disease
- Paget disease
Bisphosphonates: MOA
Inhibit bone resorption by reducing osteoclast number and function (prevents bone breakdown)
Increases bone density
Bisphosphonates: pharmacokinetics
- Poorly absorbed orally
- Long half-life (will need to take ‘drug holidays’)
- Renally excreted: not recommended in moderate to severe kidney disease
Bisphosphonates: ADR
- Gastric irritation
- Atypical femur fractures
- Severe bone/joint/muscle pain
- Upper GI mucosa irritation (esophagitis, ulcers, dysphagia)
- Hypocalcemia
- Jaw osteonecrosis
Bisphosphonates: patient education
- Best given on empty stomach w/ 8 oz water to enhance absorption and stay upright for at least 30 minutes
- D/c before dental work
Bisphosphonates: contraindications
- ABSOLUTE contraindications
- Uncorrected hypocalcemia
- Delayed esophageal emptying (stricture, achalasia)
- Inability to stand or sit upright for at least 30 minutes
- Increased risk of aspiration
- Creatinine clearance <35 (renal impairment)
- UGI pathology (e.g. Barretts esophagus)
Bisphosphonates: examples
- Risedronate (Actonel)
- Alendronate (Fosamax)
- Ibandronate (Boniva)
- Zoledronic acid (Reclast)
Risedronate (Actonel): MOA
Inhibits bone resorption w/o inhibiting bone formation
Alendronate (Fosamax): MOA
Highly selective inhibitor of bone resorption
Ibandronate (Boniva): MOA
Lack of evidence for prevention of hip or non-vertebral fracture
Zoledronic acid (Reclast): ADR
More risk of renal toxicity
Zolecronic acid (Reclast): patient education
- Given IV
- Check creatinine before each dose
- Push fluids before and after each dose
- Acetaminophen after infusion may reduce acute phase reaction (influenza like)
Bisphosphonates: duration of therapy
- If fracture risk remains high after initial 5 years, consider changing to alternative therapy or extending oral bisphosphonate for up to 10 years
- Consider drug holiday after initial 5 years of therapy if bone mineral density is stable
- Optimal length of drug holiday is usually for up to 5 years
Osteoporosis is diagnosed when bone density is ___
2.5 standard deviations below average
Osteoporosis risk factors
- >70 years
- Slight build
- Fair complexion
- Low calcium and/or vitamin D diet
- Minimal sun exposure
- Weight <70 kg
Osteoporosis: ethnic differences
Young African American women have higher bone density, but risk increases with age
Asian women at high risk
Hispanic women have similar risk as white women
What effect does estrogen have on bones?
Estrogen prevents the bone resorption action of PTH
True/False: Selective estrogen receptor modulators (SERM) have an estrogenic effect on bones
True - example Raloxifene (Evista)
True/False: Starting bisphosphonates in osteopenia status is recommended for most patients
False - no longer considered good practice
True/False: There is no evidence of optimal time of duration w/ bisphosphonate therapy
True - some molecules have a 10 year half-life
Can estrogen be used to prevent osteoporosis?
Yes - low dose therapy maintains bone mineral density
True/False: Taking vitamin D w/ calcium supplementation will decrease absorption
Vitamin D is required w/ calcium supplementation to enhance absorption
What patient populations would need bisphosphonates as first line therapy for osteoporosis?
No longer used for preventative therapy
First line for postmenopausal women and men older than 70 years
What is considered second line therapy for osteoporosis?
Selective estrogen receptor modulators (SERM)
- Example: Raloxifene (Evista)
