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teriparatide (Forteo)

Indications: - osteoporosis with high risk of fracture - hypogonadism Contraindications: - patients at risk for osteosarcoma - Paget's disease of the bone - skeletal radiation - bone metastases - hypercalcemia Dosage: 1) 20-40 ug SC QD 2) pen injector delivers 20 ug SC QD 3) duration of treatment 18-24 months * osteoclast inhibition with bisphosphonate should be started within 1 month of teriparatide discontinuation to prevent rapid loss of new bone formation [4] Pharmacokinetics: - anabolic on bone high initially, but declines after 1-2 years of treatment [2] Adverse effects: 1) dizziness or tachycardia after injection a) less likely after 1st few doses b) supine position provides relief 2) may increase risk of bone cancer (animal studies) 3) hypercalcemia (6%) [5] Radiology: - DEXA before & during teriparatide not useful for assessing response to therapy or revision of fracture risk [4] Mechanism of action: 1) human parathyroid hormone 2) stimulates osteoblast activity & new bone growth 3) reduces vertebral fractures by 65% & non-vertebral fractures by 53% in women with prior vertebral fractures [6] 4) teriparatide reduces vertebral fracture vs alendronate at incremental cost of $455,000 per fracture prevented [7] 5) number need to treat to prevent one vertebral fracture is 30 [8]

General

parathyroid hormone; parathormone; parathyrin (PTH) endocrine agent

References

  1. Prescriber's Letter 10(1):5 2003
  2. Bauer DC Review: human parathyroid hormone reduces fractures and increases bone mineral density in severe osteoporosis. ACP J Club. 2006 Nov-Dec;145(3):71. PMID: 17080983
  3. Cranney A et al Parathyroid hormone for the treatment of osteoporosis: a systematic review. CMAJ. 2006 Jul 4;175(1):52-9. Review. PMID: 16818910
  4. Medical Knowledge Self Assessment Program (MKSAP) 19 American College of Physicians, Philadelphia 2022
  5. Young K, Fairchild DG, Di Francesco L Experimental Drug Abaloparatide Tied to Reduced Fracture Risk in Osteoporosis. Physician's First Watch, Aug 17, 2016 David G. Fairchild, MD, MPH, Editor-in-Chief Massachusetts Medical Society http://www.jwatch.org
  6. Geriatric Review Syllabus, 10th edition (GRS10) Harper GM, Lyons WL, Potter JF (eds) American Geriatrics Society, 2019
  7. Albert SG, Reddy S CLINICAL EVALUATION OF COST EFFICACY OF DRUGS FOR TREATMENT OF OSTEOPOROSIS: A META-ANALYSIS. Endocr Pract. 2017 Jul;23(7):841-856 PMID: 28448754
  8. Reginster JY, Hattersley G, Williams GC et al Abaloparatide is an Effective Treatment Option for Postmenopausal Osteoporosis: Review of the Number Needed to Treat Compared with Teriparatide. Calcif Tissue Int. 2018 Nov;103(5):540-545. PMID: 29951742 Free PMC article