Synthetic analog of parathyroid hormone–related peptide (PTHrP 1–34). When given as once‑daily subcutaneous pulses, it activates PTH1 receptors on osteoblast lineage cells, favoring bone formation over resorption and increasing bone mineral density.
An anabolic osteoporosis therapy that reduces vertebral and non‑vertebral fractures in very high‑risk patients. Shares class warnings with teriparatide and has a strict lifetime use limit.
Postmenopausal patient with severe osteoporosis or multiple fragility fractures starting a daily SC injection.
Bone density rises quickly (first 6–12 months) compared with antiresorptive drugs.
Therapy duration capped at ≤ 2 years total across all PTH‑analog use, followed by an antiresorptive to maintain gains.
Confirm adequate calcium & vitamin D before starting; check baseline serum calcium (avoid if hypercalcemic).
Avoid in patients at increased osteosarcoma risk: Paget disease, prior skeletal radiation, bone metastases/malignant bone tumors, or unexplained elevated alkaline phosphatase.
Use caution with urolithiasis or hypercalciuria; consider urine calcium in those with stone history.
If symptomatic hypercalcemia occurs, hold drug and reassess vitamin D/calcium supplements and thiazide use.
Plan for sequential therapy: after completing abaloparatide, start a bisphosphonate or denosumab to preserve bone density.
Not used concurrently with other PTH analogs; lifetime class exposure ≤ 2 years.
Sclerostin inhibitor with anabolic/antiresorptive effects; cardiovascular risk warning.
Indication: Osteoporosis at very high fracture risk or after failure/intolerance of antiresorptives (commonly in postmenopausal patients).
Dose: 80 micrograms SC once daily into the periumbilical abdomen; rotate sites.
Duration: Use for no more than 2 years total (class limit); then transition to an antiresorptive agent.
Monitoring: Baseline and symptom‑triggered serum calcium; consider urinary calcium in stone formers; periodic BMD (DEXA). Counsel on orthostasis precautions after injection.
Mnemonic: “A‑BONE‑lo‑paratide” — builds bone when given in pulses.
Continuous PTH signaling breaks bone; intermittent PTH‑receptor stimulation makes bone.
Rotate abdominal injection sites; counsel about brief post‑dose lightheadedness.
Boxed warning (class): possible osteosarcoma risk (seen in rats). Do not use with Paget disease, prior skeletal radiation, bone malignancy/metastases, unexplained ↑ALP, or open epiphyses.
Stop if persistent hypercalcemia or severe orthostatic symptoms occur.
Assess fracture risk and secondary causes; ensure calcium/vitamin D sufficiency and fall‑risk mitigation.
If very high risk (e.g., T‑score ≤ −3.0 or fractures on therapy) → consider abaloparatide/teriparatide.
Screen for contraindications (Paget disease, prior radiation, bone cancer). Obtain baseline calcium.
Start abaloparatide 80 mcg SC daily; educate on timing and orthostasis.
Reassess symptoms and calcium early; continue up to 24 months maximum.
Upon completion → switch to antiresorptive (bisphosphonate or denosumab) to maintain bone mass.
Postmenopausal woman with multiple vertebral compression fractures despite alendronate → started on daily SC abaloparatide; question asks why it works: intermittent PTH‑receptor activation stimulates osteoblasts.
Patient on new osteoporosis injection develops fever‑free dizziness + tachycardia soon after doses and mild hypercalcemia on labs → identify expected adverse effects of a PTH analog.
Osteoporosis with Paget disease history → which drug is contraindicated due to osteosarcoma risk? Abaloparatide (and other PTH analogs).
Case 1
A 67‑year‑old woman with two low‑trauma vertebral fractures despite 2 years of alendronate has a T‑score of −3.1.
Case 2
A 58‑year‑old with severe osteoporosis and a history of Paget disease asks about ‘bone‑building shots.’
Abaloparatide—PTHrP analog that builds bone with intermittent dosing
