Glossary · Treatments

Bisphosphonates

Definition: Bisphosphonates are a class of bone-active medications — alendronate, risedronate, ibandronate, zoledronic acid — that bind bone hydroxyapatite and reduce osteoclast-mediated bone resorption. They are first-line pharmacologic treatment for postmenopausal osteoporosis and reduce fracture risk by 30–50%.

Detailed definition

Bisphosphonates inhibit farnesyl pyrophosphate synthase in osteoclasts, reducing bone resorption and slowing bone turnover. Oral options (alendronate weekly, risedronate weekly or monthly, ibandronate monthly) are first-line for postmenopausal osteoporosis. Intravenous zoledronic acid is administered annually and is useful for patients who cannot tolerate oral bisphosphonates. Major trials (FIT, VERT, HORIZON-PFT) demonstrate 30–50% reductions in vertebral fracture risk and roughly 20–40% reductions in hip and nonvertebral fractures over 3+ years. Bisphosphonates accumulate in bone, providing some residual effect after discontinuation. Adverse effects include esophageal irritation (oral), acute-phase reaction (zoledronic acid), and rare osteonecrosis of the jaw and atypical femoral fractures (more common with long-duration use, prompting "drug holidays" after 5–10 years of use). Bisphosphonates and HRT can be used sequentially (HRT in younger postmenopausal years, bisphosphonates later) or selectively combined.

Why it matters in menopause

For women with established osteoporosis (T-score ≤ -2.5 or fragility fracture), bisphosphonates are typically first-line. For women in early postmenopause primarily on HRT for symptoms, bisphosphonates may be added later if BMD continues to decline. ClearedRx coordinates with bone-health specialists for women with significant osteoporosis.

Sources

External references: Wikipedia.

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