# Teriparatide (PTH 1-34) > The active fragment of parathyroid hormone — a recombinant peptide that builds bone, exploiting a paradox: the same hormone resorbs bone when continuous, but builds it when pulsed. - Also known as: PTH(1-34), Forteo, Bonsity, recombinant parathyroid hormone - Class: Healing & Repair, Longevity - FDA approved: Yes - Canonical page: https://www.americanpeptide.com/catalog/teriparatide ## Overview Teriparatide is the first 34 amino acids of parathyroid hormone (PTH), the body’s master regulator of calcium. It is one of the few osteoporosis drugs that is genuinely anabolic — it builds new bone rather than just slowing its loss — and it does so by exploiting a striking biological paradox. The same PTH signal that dissolves bone when it is chronically elevated stimulates bone formation when it is delivered as a brief, once-daily pulse. Teriparatide turns that timing trick into a therapy. Parathyroid hormone is the body’s calcium thermostat, and the N-terminal 1-34 fragment retains its full receptor activity — which is why teriparatide is that fragment rather than the whole 84-residue hormone. Its defining feature is the dose-pattern paradox: a continuously high PTH level (the disease state of hyperparathyroidism) leaches calcium from bone, but a short daily spike tips the balance toward the bone-building osteoblasts. Teriparatide (Forteo, approved 2002) was among the first treatments to add bone rather than merely preserve it, used in severe osteoporosis and high fracture risk. It also carries one of the more instructive drug-safety stories. Teriparatide launched with a black-box warning for osteosarcoma, a bone cancer seen when rats were given very high, lifelong doses — which translated into a strict two-year lifetime limit on use in people. Over nearly two decades of post-marketing data that signal did not materialize in humans, and in 2020 the FDA removed the boxed warning and the lifetime restriction. It is a useful case of a precautionary animal-derived warning being revised as real-world human evidence accumulated. For a reference catalog, teriparatide is a clean example of how *timing*, not just the molecule, determines a hormone’s effect — and of how a peptide fragment can outperform the full hormone for a specific therapeutic goal. ## Mechanism Agonist at the PTH1 receptor on osteoblasts. Intermittent (once-daily) exposure favors osteoblast activity and new bone formation; continuous elevation (as in hyperparathyroidism) instead drives osteoclastic resorption. The therapeutic effect depends entirely on the pulsatile dosing. ## Chemistry | Property | Value | | --- | --- | | Molecular formula | C181H291N55O51S2 | | Molecular weight | 4117.8 Da | | CAS number | 52232-67-4 | ## Sequence ``` SVSEIQLMHNLGKHLNSMERVEWLRKKLQDVHNF ``` ## Research areas Studied in: Osteoporosis, Bone formation, Fracture healing, Calcium regulation. ## Key research - Anabolic osteoporosis therapy — builds new bone, distinct from antiresorptives that only slow loss. - The dose-pattern paradox — intermittent PTH builds bone; continuous PTH resorbs it. - Fracture-risk reduction — the approved use in severe osteoporosis and high fracture risk. - Boxed-warning reversal — the rat osteosarcoma warning and 2-year limit were removed by the FDA in 2020 after human data. - PTH1-receptor signaling — acts on osteoblasts; the 1-34 fragment retains full activity of the 84-residue hormone. ## Storage, handling & synthesis **Storage.** Teriparatide is supplied as a refrigerated (2–8 °C) solution pen; it must not be frozen and is protected from light, with an in-use window defined by the label. **Handling.** A peptide in aqueous solution — kept cold, not frozen or shaken. Pen devices deliver fixed daily doses to maintain the pulsatile exposure the mechanism depends on. **Synthesis.** Teriparatide is recombinant human PTH(1-34), expressed in E. coli and purified to a defined 34-residue peptide. Because it is the minimal active fragment rather than the full 84-residue hormone, it can be manufactured and characterized more like a long synthetic/recombinant peptide than a large folded protein — identity by mass spectrometry and peptide mapping, with potency confirmed functionally. ## FAQs ### What is teriparatide? Teriparatide is PTH(1-34), the active fragment of parathyroid hormone, used as a recombinant injectable (Forteo) for osteoporosis. Unlike most bone drugs, it is anabolic — it builds new bone. ### How can parathyroid hormone both build and break down bone? It is about timing. A brief once-daily pulse of PTH favors bone-building osteoblasts, while a continuously high level (as in hyperparathyroidism) drives bone resorption. Teriparatide uses the pulsatile pattern deliberately. ### Is teriparatide still limited to two years? The original 2-year lifetime limit and osteosarcoma boxed warning — based on high-dose rat studies — were removed by the FDA in 2020 after long-term human data did not show that risk. ### Is this medical advice? No — this is a research and educational reference, not dosing guidance. ## Latest research Recent trials and publications mentioning Teriparatide, pulled automatically from ClinicalTrials.gov and PubMed (unfiltered search results, refreshed daily). ### Recent trials - [Treatment of Osteogenesis Imperfecta With Parathyroid Hormone and Zoledronic Acid](https://clinicaltrials.gov/study/NCT03735537) — COMPLETED · PHASE4 · NCT03735537 - [MicroRNA and Markers and Therapeutic Response to Romosozumab and Abaloparatide in Postmenopausal Osteoporosis](https://clinicaltrials.gov/study/NCT07616401) — RECRUITING · NA · NCT07616401 - [Teriparatide (Forsteo) Treatment in Postmenopausal Women: Mechanism of Action](https://clinicaltrials.gov/study/NCT01293292) — COMPLETED · PHASE4 · NCT01293292 - [The Effect of Monoallelic Variants in the ALPL Gene on the Natural Course of Hypophosphatasia in Russia](https://clinicaltrials.gov/study/NCT07390240) — RECRUITING · NCT07390240 - [Novel Precision Medicine Approach to Treatment of Osteoporosis Based on Bone Turnover](https://clinicaltrials.gov/study/NCT05151484) — ACTIVE_NOT_RECRUITING · PHASE4 · NCT05151484 - [Preoperative Teriparatide Use on Insertional Torque of Pedicle Screws for Lumbar Fusion Surgery](https://clinicaltrials.gov/study/NCT03770338) — ACTIVE_NOT_RECRUITING · NA · NCT03770338 --- Source: AmericanPeptide.com — https://www.americanpeptide.com/catalog/teriparatide Data license: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Attribution: AmericanPeptide.com. Research reference only — computational and educational content, not medical advice.