The first 34 amino acids of parathyroid hormone. An FDA-approved daily injection that builds new bone in high-risk osteoporosis.
Also called Forteo, Forsteo, Bonsity, Terrosa, Movymia, PTH 1-34, PTH(1-34), rhPTH(1-34), Parathyroid hormone 1-34, Teriparatide injection, Parathar
When Teriparatide's status or evidence changes, it's in the next morning's email.
Teriparatide is a lab-made copy of the first 34 amino acids of human parathyroid hormone, the part of the hormone that does its work. Given as one small injection a day, it switches on the cells that lay down bone more than the cells that remove it, so the skeleton gains bone. Most osteoporosis pills only slow bone loss. Lilly launched it as Forteo in 2002. FDA approves it for postmenopausal women and for men with osteoporosis at high risk of fracture, and for men and women losing bone from long-term steroid tablets (5 mg of prednisone a day or more).
The fracture data are strong. In the 2001 trial of 1,637 women who already had a spine fracture, 20 mcg a day cut new spine fractures from 14% to 5% over a median of 21 months, and other fragility fractures from 6% to 3%. In the VERO trial of 1,360 women with severe osteoporosis, new spine fractures were 5.4% on teriparatide and 12.0% on the bisphosphonate risedronate after 2 years. In 428 people on long-term steroids, spine bone density rose 7.2% on teriparatide and 3.4% on alendronate.
Rats given teriparatide for most of their lives developed osteosarcoma, a bone cancer, so Forteo carried a boxed warning and a 2-year lifetime limit for 18 years. Two US surveillance studies then found 3 osteosarcoma cases among 379,283 users and none among 153,316, in line with the background rate. In November 2020 FDA removed the boxed warning and changed the limit: use beyond 2 years is now allowed if fracture risk stays high. Copies are now on the market: Bonsity in 2019, AP-rated generics from Apotex and Teva in November 2023, and the EU biosimilars Terrosa and Movymia since January 2017.
What it binds to, and what happens inside the body after that, step by step.
Teriparatide binds the same receptor as natural parathyroid hormone, the PTH type 1 receptor, with the same affinity. Timing decides what it does to bone: a brief daily spike stimulates bone-forming osteoblasts more than bone-removing osteoclasts, so new bone builds up on the inner and outer surfaces of bones. A constant excess of the hormone, as in an overactive parathyroid gland, does the opposite and drains bone.
Human results and animal results are kept apart below. A result in rats tells you a mechanism is plausible. It does not tell you what happens in a person.
Several large RCTs show daily teriparatide prevents new spine fractures, by 65% against placebo and by 56% against risedronate, and builds more spine bone than alendronate in steroid-induced osteoporosis. The rat osteosarcoma signal has not shown up in humans: US surveillance of more than 500,000 users found no rise in osteosarcoma, though the estimates are imprecise because the cancer is rare.
1,637 postmenopausal women with prior spine fractures, median 21 months
New spine fractures fell from 14% on placebo to 5% on 20 mcg (relative risk 0.35); other fragility fractures fell from 6% to 3%.
Read the study1,360 postmenopausal women with severe osteoporosis, 24 months, double-blind
New spine fractures were 5.4% on teriparatide and 12.0% on risedronate (risk ratio 0.44); clinical fractures 4.8% vs 9.8%.
Read the study428 men and women on long-term glucocorticoids, 18 months
Spine bone density rose 7.2% vs 3.4%; new spine fractures 0.6% vs 6.1%.
Read the study437 men with low bone density, median 11 months
Spine bone density rose 5.9% on 20 mcg and 9.0% on 40 mcg; the trial stopped early after the rat osteosarcoma finding.
Read the study153,316 teriparatide users aged 65 and older vs 613,247 matched comparators (observational)
No osteosarcoma cases in the teriparatide group; incidence rate ratio 0.0 (95% CI 0.0 to 3.2).
Read the studyAdult teriparatide users matched to unexposed osteoporosis and general-population cohorts (observational)
3 osteosarcoma cases among teriparatide users, within the expected background range; incidence rate ratio about 1.0.
Read the studyNo preclinical studies are listed as key studies here. The human data above carries the evidence.
When a new Teriparatide study in people is published, the daily email covers it.
These are questions the published research has not answered.
FDA approved Forteo on November 26, 2002 with a boxed warning for osteosarcoma and a 2-year lifetime limit. The November 2020 label removed the boxed warning and now says use beyond 2 years should only be considered if the patient remains at or has returned to high fracture risk. The label still advises avoiding it in people with a higher baseline risk of osteosarcoma: children and young adults with open growth plates, Paget's disease of bone, bone metastases or past skeletal cancer, prior radiation to the skeleton, and inherited conditions that predispose to osteosarcoma. The Forteo label lists 1987 as the first US approval of teriparatide; FDA records also show an older, now discontinued teriparatide product, Parathar (NDA 19-498). Generic teriparatide pens from Apotex and Teva were approved November 16, 2023 (ANDA 211097 and ANDA 208569, both AP-rated). Not named on the WADA Prohibited List.
When the FDA or WADA changes Teriparatide's status, it's in the next morning's email.
How much of Teriparatide is left after a single dose
Simple first-order model from the published half-life. Real clearance varies with dose, route, kidney and liver function and formulation. This is not a dosing schedule.
This table records the doses that trials and approved labels used, with the source for each row. It is a record of research, not a recommendation, and it is open to free members.
Which symptoms are expected and which mean stop and get help: side effects and red flags.
Tap a claim to see what the studies found.
Rats given high doses for most of their lives developed osteosarcoma. In humans, surveillance of more than 500,000 US users found osteosarcoma at the expected background rate, which is why FDA removed the boxed warning in 2020.
That was the rule until November 2020. The current label allows longer use if the patient remains at or returns to high fracture risk, while noting limited data past 2 years.
In VERO, new spine fractures were 5.4% vs 12.0% on risedronate. In steroid users, spine fractures were 0.6% vs 6.1% on alendronate.
The Apotex and Teva generics are AP-rated by FDA, meaning therapeutically equivalent to Forteo. Bonsity is a separate case: it was approved through a 505(b)(2) NDA and has no substitution rating.
Not supplied as a powder. Forteo comes as a ready-to-use solution in a pen: store refrigerated at 2 to 8 C (36 to 46 F) at all times except when injecting, and do not freeze (label).
No mixing needed. Recap the pen to protect it from light and discard it 28 days after first use (label).
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