Pharmacological Treatment of Osteoporosis & Other Bone Disorders

Comprehensive vocabulary terms and definitions covering the pathology, diagnosis, and pharmacological treatments of osteoporosis and other bone disorders as discussed in the lecture.

Osteoporosis

A bone disease characterized by bones becoming porous, weak, and brittle due to low bone strength.

Osteoclasts

Cells responsible for bone resorption by breaking down old bone.

Osteoblasts

Cells responsible for bone formation by building new bone.

Spongy bone

Also known as trabecular bone, it provides flexibility and is located inside the hard cortical bone.

Compact bone

Also known as cortical bone, it provides strength to the bone structure.

T-Score

A bone density measurement that compares results to a healthy young adult aged $20$ to $35$.

Z-Score

A bone density measurement that compares results to a person of the same gender and age as the patient.

Primary Osteoporosis Type I

Postmenopausal osteoporosis that typically develops between $50$ and $70$ years of age, primarily affecting trabecular bone.

Primary Osteoporosis Type II

Senile osteoporosis typically occurring after $70$ years of age, affecting both trabecular and hard cortical bone.

Early-Onset Osteoporosis (EOOP)

Osteoporosis occurring in children and young adults, defined by specific fracture thresholds or vertebral compression.

Bisphosphonates

The first-line pharmacological treatment for osteoporosis that attaches to bone and induces osteoclast apoptosis.

NBPs

Nitrogen-containing bisphosphonates (e.g., alendronate) that interfere with the prenylation of cell surface proteins on the osteoclast membrane.

NNBPs

Non-nitrogen-containing bisphosphonates (e.g., etidronate) that are incorporated into $ATP$ analogues to promote osteoclast apoptosis.

Drug Holiday

A period of time, usually after $5$ to $10$ years of oral treatment, where bisphosphonates are temporarily discontinued.

Osteonecrosis of the jaw (ONJ)

A serious and rare side effect associated with intravenous ($IV$) bisphosphonates, particularly zoledronate.

Atypical thigh fracture (AFF)

A serious and rare skeletal side effect associated with long-term bisphosphonate or anti-resorptive use.

SERMs

Selective Estrogen Receptor Modulators; non-steroidal drugs that bind to estrogen receptors to exert tissue-selective estrogenic or antiestrogenic activity.

Cathepsin K (CatK)

A potent lysosomal cysteine protease released by osteoclasts that mediates bone resorption by cleaving collagen.

Strontium Ranelate

A dual-action agent that uses calcium-sensing receptors ($CaSRs$) to increase bone formation and decrease bone resorption.

PTH (Parathyroid Hormone)

An $84$-amino acid peptide hormone used in analogue form (e.g., Teriparatide) to exert anabolic effects on bone.

Denosumab

A fully human monoclonal antibody that competitively binds to $RANKL$, inhibiting the $RANK/RANKL$ signaling pathway.

Romosuzumab

A monoclonal antibody that inhibits Sclerostin, leading to increased bone formation and decreased bone resorption.

Burosumab

A monoclonal antibody against fibroblast growth factor $23$ ($FGF23$) used to treat hereditary hypophosphatemia rickets.

PHEX Gene

A gene residing on the $X$ chromosome involved in phosphate sensing; mutations cause the upregulation of $FGF23$.

Setrusumab

An anti-Sclerostin monoclonal antibody administered via intravenous ($IV$) infusion, currently studied for Osteogenesis Imperfecta ($OI$).