Teriparatide

Overview

Teriparatide (PTH(1-34), rhPTH(1-34); brand names Forteo/Forsteo and the follow-on product Bonsity) is a recombinant human parathyroid hormone fragment corresponding to the first 34 amino acids of native, 84-residue human parathyroid hormone (PTH). Unlike most compounds documented on this site, teriparatide is an approved prescription medicine. It was FDA-approved in November 2002 as the first anabolic (bone-forming) agent for osteoporosis, and EMA-approved in June 2003 (marketed in the EU as Forsteo).

Where most osteoporosis drugs (e.g., bisphosphonates) work by slowing bone breakdown, teriparatide is distinctive in that it stimulates new bone formation. It acts as an agonist at the parathyroid hormone 1 receptor (PTH1R), and when given as an intermittent once-daily injection it preferentially favors bone-building over bone resorption.

Chemistry and structure

Teriparatide is a 34-amino-acid peptide whose sequence is identical to the biologically active N-terminal 1-34 region of human PTH. This N-terminal fragment retains the full receptor-activating biology of the native hormone.

Mechanism of action

• Acts as an agonist at the parathyroid hormone 1 receptor (PTH1R); the 1-34 fragment retains the full receptor-activating biology of native PTH. [Human] — Source: Wikipedia / FDA label
• Intermittent (once-daily) exposure nets stimulation of osteoblasts more than osteoclasts, driving new bone formation and increased bone mineral density — distinct from the catabolic effect of continuously elevated PTH. [Human] — Source: Wikipedia; Neer et al., NEJM 2001
• Reduces the incidence of new vertebral and nonvertebral fragility fractures in postmenopausal osteoporosis. [Human] — Source: Neer RM et al., NEJM 2001;344:1434-1441

Research and evidence

Human evidence. Teriparatide has strong Phase 3 human evidence. The pivotal Fracture Prevention Trial (Neer et al., NEJM 2001) randomized 1,637 postmenopausal women with prior vertebral fractures to teriparatide (20 or 40 µg/day subcutaneously) or placebo for a median of 19 months, and found significant reductions in new vertebral and nonvertebral fragility fractures alongside increased lumbar-spine bone mineral density [Human, RCT]. More than two decades of post-marketing use are documented [Human], and teriparatide has been studied extensively in glucocorticoid-induced and male osteoporosis in randomized trials (e.g., teriparatide vs alendronate in glucocorticoid-induced osteoporosis, NEJM 2007) [Human, RCT].

Status and regulation

• United States (FDA — approved): Approved November 2002 as Forteo (Eli Lilly), the first anabolic bone agent for osteoporosis. A follow-on product, Bonsity, was FDA-approved in October 2019. In November 2020, the FDA removed the prior 2-year lifetime treatment limitation and the boxed warning regarding potential osteosarcoma risk from the label.
• European Union (EMA — approved): Approved June 2003, marketed in the EU as Forsteo. (EMA approval month is per Wikipedia; the primary EMA EPAR for Forsteo was not independently fetched.)
• Indications: postmenopausal women and men with osteoporosis at high fracture risk, and glucocorticoid-induced osteoporosis.
• WADA status: Not established / not found in sources. No source in this research explicitly lists teriparatide on the WADA Prohibited List or assigns it an S-class code; no class is asserted by inference. Verify against the official current WADA Prohibited List (wada-ama.org) if sport-eligibility matters.

Safety

• As an approved prescription medicine, teriparatide is used under clinician supervision with product-specific labeling; it is not intended for self-directed use.
• The prior label carried a boxed warning about a theoretical osteosarcoma risk (based on rat studies); the FDA removed this boxed warning in November 2020 along with the 2-year lifetime treatment limit.
• Detailed adverse-effect, contraindication, and monitoring information: Not established / not found in sources here — consult the current FDA/EMA prescribing information.

Legal status

Teriparatide is an approved medicine in the United States (FDA) and the European Union (EMA). Its regulatory status is that of a prescription-only pharmaceutical for its licensed osteoporosis indications. Approval attaches to the specific licensed products (Forteo/Forsteo, Bonsity), not to research-grade peptide material sold outside the regulated supply chain — such material is not the approved medicine and becomes an unauthorised medicine the moment it is intended for human use. WADA sport-prohibition is a separate axis from legality; no WADA class is asserted here (see Status and regulation). Legal specifics vary by country; this is a regulatory reference, not legal advice — check your jurisdiction. Framing dated 2026-07-08.

How it compares

Teriparatide is one of the few approved peptide medicines documented here. Among the growth/hormonal-axis peptides in our set, the closest comparators by regulatory standing are the growth-hormone-axis agents rather than direct bone analogs:

• Tesamorelin — an FDA-approved GHRH analog, but for a different indication (HIV-associated visceral fat), acting on the GH/IGF-1 axis rather than the PTH1 receptor.
• Sermorelin — a related GHRH-axis peptide, previously approved and now discontinued/compounded.

These act through entirely different receptors and pathways; teriparatide's mechanism (PTH1R agonism driving bone formation) is distinct. Most other peptides in our set are research chemicals without regulatory approval, and should not be assumed to share teriparatide's evidence base or approval standing.

Common misconceptions

• "Teriparatide is just parathyroid hormone, which weakens bones." Continuous PTH elevation is catabolic and can weaken bone, but intermittent once-daily teriparatide nets osteoblast stimulation over osteoclast activity, building new bone. [Human]
• "It still carries a black-box osteosarcoma warning and a 2-year limit." The FDA removed both the boxed warning and the 2-year lifetime treatment limitation from the label in November 2020.
• "Research-grade PTH(1-34) is the same as the approved drug." The approval applies only to the licensed products (Forteo/Forsteo, Bonsity). Research-grade material is not the approved medicine and cannot be assumed equivalent for identity, potency, or purity.
• "Teriparatide is a weight-loss or performance peptide." Its approved indications are osteoporosis (postmenopausal, male, and glucocorticoid-induced) at high fracture risk — not body composition or performance.

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This article is provided for educational purposes only and is not medical advice. Teriparatide (Forteo/Forsteo, Bonsity) is a prescription medicine that should be used only under the supervision of a qualified healthcare professional. Approval applies to the specific licensed products, not to research-grade material. Framing dated 2026-07-08; check your jurisdiction.