Teriparatide

Teriparatide (also known as Forteo, Forsteo, PTH 1-34, rhPTH(1-34)) is a anti-aging research peptide. The first drug that builds bone rather than merely slowing its loss — and it works only because it is given as a daily pulse. Continuous exposure to the same peptide destroys bone instead.

Teriparatide is the recombinant N-terminal 34-amino-acid fragment of human parathyroid hormone, containing the full receptor-activating region of the 84-residue hormone. It is the clearest example in peptide pharmacology of a molecule whose effect depends entirely on the temporal pattern of exposure: continuous PTH elevation, as in hyperparathyroidism, causes net bone resorption, whereas an intermittent daily pulse preferentially stimulates osteoblast activity and produces net bone formation. Approved in 2002, teriparatide was the first anabolic osteoporosis therapy, contrasting with bisphosphonates and denosumab, which are anti-resorptive. It increases lumbar spine bone mineral density substantially and reduces vertebral fracture risk by roughly 65% and non-vertebral fractures by about 53% in the pivotal Fracture Prevention Trial. The original boxed warning for osteosarcoma, based on lifetime high-dose exposure in rats, was removed after long-term surveillance in humans failed to substantiate the signal — the cumulative-lifetime dosing restriction was correspondingly relaxed. Its principal practical limitations are daily injection, cost, and the fact that gains are lost within a year or two of stopping unless followed by an anti-resorptive agent.

1 Mechanism of action

Binds the PTH1 receptor on osteoblasts and osteocytes. Intermittent (daily pulse) exposure preferentially increases osteoblast number and lifespan by reducing apoptosis and activating quiescent bone-lining cells, favouring formation over resorption. Also increases intestinal calcium absorption indirectly via 1,25-dihydroxyvitamin D and increases renal calcium reabsorption. Continuous exposure reverses the balance toward resorption.

Primary targets: PTH1R (PTH/PTHrP receptor)

2 Reported effects

Effects below are those reported in the published literature cited on this page. They are not claims of clinical benefit and not medical advice.

2.1 Reported benefits

• 65% reduction in new vertebral fractures and 53% in non-vertebral fractures
• Lumbar spine BMD increases of 9–13% — genuine bone formation, not just reduced loss
• The first anabolic (bone-building) osteoporosis therapy approved
• Effective in glucocorticoid-induced osteoporosis where anti-resorptives underperform
• Accelerates fracture healing in some studies (off-label)
• Extensive long-term post-marketing safety data

2.2 Side effects

• Transient hypercalcaemia after injection
• Orthostatic hypotension, particularly with the first doses
• Nausea, headache and dizziness
• Leg cramps
• Injection site reactions
• Hyperuricaemia
• Increased urinary calcium excretion

3 Chemical and physical properties

3.1 Amino acid sequence

4 Research dosages

20 μg subcutaneously once daily — the approved dose; historically limited to 24 months cumulative, a restriction since relaxed.

5 Research studies (7)

1. Effect of Parathyroid Hormone (1-34) on Fractures and Bone Mineral Density in Postmenopausal Women with Osteoporosis
   New England Journal of Medicine (2001) · RCT · N=1,637
   The pivotal Fracture Prevention Trial of teriparatide in postmenopausal osteoporosis, median 21 months of treatment.
   Key finding: Reduced new vertebral fractures by 65% and non-vertebral fragility fractures by 53%, with lumbar spine BMD increases of 9–13%.
2. Recent Advances in Osteoporosis Therapeutics.
   Annual review of medicine (2026) · Review
   Postmenopausal osteoporosis is a chronic progressive disease related to estrogen deficiency at menopause, aging, and superimposed genetic and environmental factors.
3. Clinical effects of teriparatide, abaloparatide, and romosozumab in postmenopausal osteoporosis.
   Journal of bone and mineral metabolism (2025) · Review
   In the management of osteoporosis, anti-resorptive agents serve as a primary therapeutic approach.
4. Effectiveness and Safety of Treatments to Prevent Fractures in People With Low Bone Mass or Primary Osteoporosis: A Living Systematic Review and Network Meta-analysis for the American College of Physicians.
   Annals of internal medicine (2023) · Systematic Review
   Bisphosphonates, denosumab, abaloparatide, teriparatide, and romosozumab, followed by alendronate, reduce clinical fractures in postmenopausal females with osteoporosis.
5. Effects of teriparatide and risedronate on new fractures in post-menopausal women with severe osteoporosis (VERO): a multicentre, double-blind, double-dummy, randomised controlled trial.
   Lancet (London, England) (2018) · RCT
   No clinical trials have compared osteoporosis drugs with incident fractures as the primary outcome.
6. Denosumab and teriparatide transitions in postmenopausal osteoporosis (the DATA-Switch study): extension of a randomised controlled trial.
   Lancet (London, England) (2015) · RCT
   Unlike most chronic diseases, osteoporosis treatments are generally limited to a single drug at a fixed dose and frequency.
7. Two years of Denosumab and teriparatide administration in postmenopausal women with osteoporosis (The DATA Extension Study): a randomized controlled trial.
   The Journal of clinical endocrinology and metabolism (2014) · RCT
   Two years of concomitant teriparatide and denosumab therapy increases BMD more than therapy with either medication alone and more than has been reported with any current therapy.

6 Safety and risk profile

6.1 Regulatory status

Teriparatide is currently classified as FDA approved. Approval applies to specific clinical indications and dosing; research-grade material is not the approved product.

Safety score: 80/100 — low concern. Derived from clinical data volume, known risks and regulatory status.

6.2 Contraindications

Conditions and populations in which use is contraindicated:

• Pre-existing hypercalcaemia or primary hyperparathyroidism
• Paget disease of bone or unexplained elevated alkaline phosphatase
• Prior external beam or implant radiation therapy to the skeleton
• Bone metastases or skeletal malignancy
• Open epiphyses (paediatric use)
• Severe renal impairment
• Pregnancy or lactation

6.3 Drug interactions

6.4 Long-term risks

• Loss of accrued bone density within 1–2 years of discontinuation without follow-on therapy
• Sustained hypercalciuria and theoretical nephrolithiasis risk
• Osteosarcoma risk not substantiated in humans but remains a labelled consideration in high-risk groups

6.5 Research best practices

• Store refrigerated at 2–8 °C at all times — teriparatide is heat-labile
• Administer at the same time daily; the pulse pattern is the mechanism
• Inject with the patient able to sit or lie down for the first doses (orthostatic hypotension)
• Monitor serum and urinary calcium; ensure adequate but not excessive calcium and vitamin D
• Plan follow-on anti-resorptive therapy to preserve gains

7 Frequently asked questions

Why does daily dosing build bone when continuous PTH destroys it?

A brief pulse activates osteoblasts and extends their lifespan before the resorptive response fully engages. Sustained elevation gives osteoclast-driven resorption time to dominate, which is what happens in hyperparathyroidism. Same receptor, opposite net outcome, determined purely by exposure pattern.

Was the osteosarcoma warning real?

It came from rats given near-lifetime high-dose exposure, a model poorly suited to predicting human risk for this pathway. After years of post-marketing surveillance failed to show an excess of osteosarcoma in treated patients, the boxed warning was removed and the cumulative lifetime dosing restriction relaxed.

What happens after stopping?

Bone density gains decline over the following one to two years unless an anti-resorptive agent (bisphosphonate or denosumab) follows. Sequential therapy — anabolic first, then anti-resorptive — is the standard approach to preserving the gain.

8 References

1. Recent Advances in Osteoporosis Therapeutics. PubMed (2026). Sølling AS, et al.. View source
2. Clinical effects of teriparatide, abaloparatide, and romosozumab in postmenopausal osteoporosis. PubMed (2025). Ebina K, et al.. View source
3. Effectiveness and Safety of Treatments to Prevent Fractures in People With Low Bone Mass or Primary Osteoporosis: A Living Systematic Review and Network Meta-analysis for the American College of Physicians. PubMed (2023). Ayers C, et al.. View source
4. Effects of teriparatide and risedronate on new fractures in post-menopausal women with severe osteoporosis (VERO): a multicentre, double-blind, double-dummy, randomised controlled trial. PubMed (2018). Kendler DL, et al.. View source

9 See also

• Peptide encyclopedia index
• Peptide reconstitution calculator
• Glossary of peptide research terms