Osteoporosis and peptides — what the literature actually supports for low bone density and fragility fracture

Why this dossier exists

Osteoporosis is the condition where peptide and protein pharmacology arrives at fracture prevention through a different door than the rest of the drug class — and where three of the most clinically consequential agents in the indication are biologics rather than small molecules. The WHO operational diagnostic threshold is a BMD T-score of −2.5 or lower at the femoral neck, total hip, or lumbar spine on DXA, with case-finding now incorporating fracture-risk algorithms (FRAX, Garvan) that combine BMD with clinical risk factors (Compston, McClung and Leslie, Lancet 2019, 393:364–376). US prevalence sits around 10.2 million adults aged 50 and older, with another 43.4 million carrying low bone mass (Wright NC, Looker AC, Saag KG et al., J Bone Miner Res 2014, 29(11):2520–2526). Lifetime fragility-fracture risk is roughly 40–50% in white women and 13–22% in men aged 50 and older; one-year mortality after hip fracture exceeds 20% in high-income countries. Hip and vertebral fractures carry the highest mortality and disability burden.

Standard of care in 2026 sits on three pillars. The non-pharmacological floor is calcium (~1,200 mg/day), vitamin D sufficiency (25-OH-D above 30 ng/mL in most guidelines), weight-bearing and resistance exercise, fall prevention, and management of secondary contributors (glucocorticoid exposure, hypogonadism, hyperparathyroidism, malabsorption). The antiresorptive class — bisphosphonates (alendronate, risedronate, ibandronate, zoledronic acid) and the RANKL-blocking antibody denosumab — inhibits the osteoclast. The anabolic class — teriparatide, abaloparatide, and romosozumab — increases bone formation. The 2020 AACE/ACE clinical practice guideline (Camacho PM, Petak SM, Binkley N et al., Endocr Pract 2020, 26(Suppl 1):1–46) and the 2020 Endocrine Society guideline update (Shoback D, Rosen CJ, Black DM et al., J Clin Endocrinol Metab 2020, 105(3):587–594) shifted the field's center of gravity by recommending anabolic-first sequencing for very-high-fracture-risk patients — a meaningful change from the bisphosphonate-first algorithm that dominated the prior two decades.

Three of the most effective drugs in modern osteoporosis pharmacology are peptide or protein therapeutics. Teriparatide and abaloparatide are 34-amino-acid peptides (recombinant PTH(1–34) and a synthetic PTHrP analog); romosozumab is a humanized monoclonal antibody (~149 kDa) against sclerostin. Denosumab is a fully human monoclonal antibody (~147 kDa) against RANKL — a protein therapeutic, not a peptide in the conventional sense. The rest — bisphosphonates, raloxifene, estrogen, calcitriol — is small molecule. Salmon calcitonin is the historical peptide entry, largely replaced by modern options. The editorial center is the anabolic peptide class entry; this dossier walks the surrounding context — the pharmacology peptide users encounter when osteoporosis sits in their differential, and the GH-axis and GLP-1 classes that interact with bone biology in ways that matter clinically.