Is abaloparatide FDA-approved, and what does the research show?

What is abaloparatide?

Abaloparatide is a laboratory-made peptide, a chain of 34 amino acids, the building blocks of proteins ¹. It is modeled on parathyroid hormone-related protein, written PTHrP ¹. PTHrP is a protein the body makes, and it acts on the same receptor as parathyroid hormone ². The label calls abaloparatide an analog of the first 34 amino acids of human PTHrP ¹. It shares 76 percent of that sequence, and 41 percent of the matching stretch of parathyroid hormone ¹.

A review of its design says the first 21 amino acids, the part that switches the receptor on, are PTHrP's own ². The rest were altered to make the peptide last longer in the body ².

Osteoporosis is the disease it treats. Bone loses mineral and its inner structure changes, so bones become weak and brittle and break more easily ⁶, ⁷. Radius Health sells abaloparatide in the United States as Tymlos, injected under the skin ³, ¹. Teriparatide is a different molecule, a copy of the first 34 amino acids of parathyroid hormone itself, and has its own page ², ¹.

Is abaloparatide FDA-approved?

Yes. Abaloparatide is approved by FDA as the prescription medicine Tymlos, a bone drug for osteoporosis at high risk of fracture ¹, ³. FDA's Drugs@FDA record shows Radius Health's new drug application, NDA 208743, approved on April 28, 2017, with marketing status "Prescription" ³. The approval letter of that day covered one use, "the treatment of postmenopausal women with osteoporosis at high risk for fracture" ⁴. The use in men came with a supplement approved December 19, 2022 ³.

The current label, revised August 2026 and held in FDA's files, lists two indications ¹. The first is "the treatment of postmenopausal women with osteoporosis at high risk for fracture (defined as a history of osteoporotic fracture or multiple risk factors for fracture), or patients who have failed or are intolerant to other available osteoporosis therapy" ¹. The second is "to increase bone density in men with osteoporosis at high risk for fracture (defined as a history of osteoporotic fracture or multiple risk factors for fracture), or patients who have failed or are intolerant to other available osteoporosis therapy" ¹.

The label adds that in postmenopausal women with osteoporosis the drug "reduces the risk of vertebral fractures and nonvertebral fractures" ¹. A vertebral fracture is a break in one of the bones of the spine ⁸. A nonvertebral fracture is a break elsewhere, such as the hip, wrist or upper arm ⁸. Abaloparatide's label lists only osteoporosis uses ¹.

The label says the drug "is not indicated for use in females of reproductive potential" ¹. The Medication Guide calls Tymlos "a prescription medicine," and the route to it is a licensed clinician's prescription ¹.

See the FDA status of every peptide, updated weekly.

How does abaloparatide work?

Abaloparatide "acts as an agonist at the PTH1 receptor (PTH1R)," meaning it switches on the receptor the body's parathyroid hormone uses ¹, ². That "results in activation of the cAMP signaling pathway in target cells," cAMP being a messenger molecule inside the cell ¹. And "once-daily administration of abaloparatide stimulates new bone formation on trabecular and cortical bone surfaces by stimulation of osteoblastic activity" ¹.

Osteoblasts are the cells that build bone, and osteoclasts are the cells that remove it ⁹. Bone is renewed throughout life by removal of old bone followed by deposition of new bone ⁹. Trabecular bone is the spongy inner bone, and cortical bone is the dense outer layer ⁹.

In the trial that led to approval, a blood marker of bone formation rose 93 percent above baseline in the first month ¹. It was still 45 percent above baseline at 18 months ¹. A marker of bone removal peaked at 26 percent above baseline at month 3 and had returned to baseline by month 18 ¹. The drug is quick to come and go ¹. It peaks in the blood about half an hour after injection and has a half-life of about an hour ¹.

Why it differs from teriparatide is proposed, not settled. A 2019 review hypothesized that abaloparatide binds a shorter-lived state of the receptor, so its signal is briefer ². That would mean less bone removal and a smaller rise in blood calcium than teriparatide causes ². The trial's authors wrote that the smaller rise in the removal marker "support[s] the hypothesis that abaloparatide might have an enhanced net anabolic effect compared with teriparatide" ⁵. They added that further research is needed ⁵.

In rats and monkeys the label reports gains in bone mass and bone strength ¹. This account is the label's, for an approved drug, drawn from human trials and animal studies ¹.

What does the research show?

The evidence is at the top tier: FDA approval on randomized, placebo-controlled trials in people with osteoporosis ⁵, ¹. The pivotal trial, ACTIVE, was published in August 2016 ⁵. It ran at 28 sites in 10 countries from March 2011 to October 2014 ⁵. Radius Health funded it, and its employees were among the authors ⁵, ¹⁰. It enrolled 2,463 postmenopausal women aged 49 to 86, mean age 69 ⁵.

Entry had two routes ⁵. A woman could enter with a T-score of −2.5 or lower at the lumbar spine or the femoral neck, the top of the thigh bone ⁵. She also needed spine fractures seen on X-ray or a low-trauma fracture elsewhere in the past five years ⁵. A woman over 65 could enter with a score of −3.0 or lower and no fracture, or −2.0 or lower with one ⁵.

Bone mineral density is the mineral content of bone, measured by X-ray scan ⁷. A T-score compares it with a healthy young adult's, and −2.5 or lower is the threshold for osteoporosis ⁷.

The women were assigned to daily injections of placebo (821), abaloparatide (824) or open-label teriparatide (818) for 18 months ⁵. Open-label means the women and their doctors knew who received teriparatide ⁵. Of them, 1,901 completed the study ⁵.

The primary outcome was a new vertebral fracture seen on spine X-rays, whether or not the woman felt it ⁵. Studied in people against placebo: new vertebral fractures were counted in the women with spine X-rays at both ends, 690 abaloparatide-treated and 711 on placebo ⁵, ¹. They occurred in 0.58 percent of the 690, 4 women, against 4.22 percent of the 711, 30 women ⁵. The relative risk, the rate on the drug divided by the rate on placebo, was 0.14 ⁵. Its 95 percent confidence interval, the range within which the true value most likely lies, was 0.05 to 0.39 ⁵.

The absolute risk difference was 3.64 percentage points ⁵. In the teriparatide arm the rate was 0.84 percent, 6 women ⁵.

Nonvertebral fractures over 19 months were estimated at 2.7 percent with abaloparatide against 4.7 percent on placebo ⁵. The hazard ratio, the rate of fractures over time on the drug relative to placebo, was 0.57, with a confidence interval of 0.32 to 1.00 ⁵. The p-value, the chance of a difference that size arising by luck, was .049 ⁵. Only two hip fractures occurred in the whole trial, both on placebo ⁵.

Bone density at 18 months rose 9.2 percent at the lumbar spine on abaloparatide against 0.5 percent on placebo ¹. At the total hip it rose 3.4 percent against a fall of 0.1, and at the femoral neck 2.9 against a fall of 0.4 ¹. The label puts the relative risk reduction in new vertebral fractures at 86 percent, confidence interval 61 to 95 ¹.

Two exploratory outcomes also favored abaloparatide over placebo ⁵. Clinical fractures, those that sent a woman for care, were 4.0 percent against 8.3 percent, hazard ratio 0.57 ⁵, ⁸. Major osteoporotic fractures, of the wrist, upper arm, hip or spine, were 1.5 percent against 6.2 percent, hazard ratio 0.30 ⁵, ⁸.

The teriparatide arm's rates of nonvertebral, clinical and major osteoporotic fractures "were not significantly different from placebo" ⁵. The paper's fracture comparison of abaloparatide against teriparatide was exploratory ⁵. The prespecified safety comparison between the two drugs was hypercalcemia, high blood calcium ⁵. It occurred in 3.4 percent on abaloparatide against 6.4 percent on teriparatide ⁵.

The authors listed the limits of their trial ⁵. Sixty-three percent of the women had a prior fracture, so the effect in women at lower risk is unknown ⁵. Fracture events were few, and the placebo rate was lower than the design assumed ⁵. The data "indicate a reduction of risk until 18 months of treatment; it is not clear how long the benefit associated with abaloparatide may endure" ⁵.

A later analysis was funded by Radius Health, and four of its six authors were company employees ¹¹. It calculated the number of women who would need 18 months of treatment to prevent one fracture ¹¹. For abaloparatide it was 28 for a vertebral fracture, 55 for a nonvertebral fracture, 37 for a clinical fracture and 34 for a major osteoporotic fracture ¹¹. For teriparatide in the same trial the figures were 30, 92, 59 and 75 ¹¹.

Studied in people after the trial: ACTIVExtend followed the women from the abaloparatide and placebo arms, not the teriparatide arm ¹², ¹³. They received alendronate, an oral bone drug of a different class that slows bone removal, for up to 24 months ¹², ¹, ⁸. It enrolled 1,139 women, 92 percent of those eligible: 558 from the abaloparatide arm and 581 from the placebo arm ⁸, ¹. At 25 months from the start of ACTIVE, new vertebral fractures were 0.55 percent in the abaloparatide-then-alendronate group against 4.4 percent in the placebo-then-alendronate group ¹². The relative risk was 0.13, with a confidence interval of 0.04 to 0.41 ¹².

Nonvertebral fractures at 25 months were 2.7 percent against 5.6 percent, hazard ratio 0.48 ¹². Spine density had risen 12.8 percent from the original baseline against 3.5 percent ¹², ¹. Over the full 43 months, 0.9 percent of evaluable women in the abaloparatide-then-alendronate group had a new vertebral fracture against 5.6 percent ⁸. That is an 84 percent relative reduction ⁸. Both groups took alendronate, so these are comparisons of two sequences, not of abaloparatide against no treatment ⁸.

One analysis covered all women randomized to abaloparatide or placebo in ACTIVE, including those who did not enter the extension ⁸. Over 43 months, none on abaloparatide had a hip fracture against five on placebo ⁸.

Studied in men: the ATOM trial randomized 228 men aged 42 to 85 with osteoporosis, 149 to abaloparatide and 79 to placebo, for 12 months ¹⁴, ¹. The primary endpoint was lumbar spine bone density, not fractures ¹⁴. Spine density rose 8.48 percent on abaloparatide against 1.17 percent on placebo ¹⁴. Total hip density rose 2.14 percent against 0.01, and femoral neck density 2.98 against 0.15 ¹⁴.

The label reports the same figures rounded, with confidence intervals ¹. The men's trial measured density, not fractures, and the label's wording for men is "to increase bone density" ¹, ¹⁴.

What has not been studied is set out in the label ¹. It says "the safety and efficacy of TYMLOS have not been evaluated beyond 2 years of treatment" ¹. Safety and effectiveness have not been established in children, and there are no human data in pregnancy ¹. The label says "no specific drug-drug interaction studies have been performed," and patients on dialysis were not included in the kidney study ¹. A skin patch form has been tested in trials, but the approved product is the injection ⁶, ¹.

What are the side effects?

The placebo-controlled trial in women enrolled 824 on abaloparatide and 821 on placebo for 18 months ¹. Deaths from any cause were 0.4 percent on abaloparatide and 0.6 percent on placebo ¹. Serious adverse events were 10 percent against 11 percent ¹. More women stopped the drug for adverse events, 10 percent against 6 percent, most often for nausea, dizziness, headache and palpitations ¹.

The label's most common adverse reactions in women, at 2 percent or more, are hypercalciuria, dizziness, nausea, headache, palpitations, fatigue, upper abdominal pain and vertigo ¹. Hypercalciuria, too much calcium in the urine, was reported by 11 percent against 9 percent on placebo ¹. Dizziness was reported by 10 percent against 6, nausea by 8 against 3, headache by 8 against 6, and palpitations by 5 percent against 0.4 ¹. In the first month, when injection sites were checked daily, redness occurred in 58 percent against 28 percent ¹. Swelling occurred in 11 percent against 3, and pain in 10 against 7 ¹.

Abaloparatide raises blood calcium after a dose, and the level is back to baseline before the next one ¹. Hypercalcemia at 4 hours after injection occurred in 3 percent of women on abaloparatide and 0.1 percent on placebo ¹. It occurred in 4 percent of those with mild or moderate kidney impairment ¹. Two women stopped the drug for it ¹. A urine calcium-to-creatinine ratio above 400 mg/g occurred in 20 percent against 15 percent, and kidney stones in 2.1 percent against 1.7 percent ¹.

Among women with normal uric acid at the start, 25 percent against 6 percent had at least one reading above normal, without more gout or joint pain ¹. A drop in blood pressure on standing at 1 hour after the first injection occurred in 4 percent against 3 percent ¹. Heart rate rose within 15 minutes of an injection and settled in about six hours ¹. Tachycardia, a fast heart rate, was reported by 2 percent against 1 percent ¹.

In the men's trial, 149 on abaloparatide and 79 on placebo for 12 months, no patient had an adverse reaction with a fatal outcome ¹. Serious adverse reactions were 5.4 percent against 5.1 percent ¹. Injection-site redness was reported by 13 percent against 5, dizziness by 9 against 1, joint pain by 7 against 1, and injection-site swelling by 7 percent against none ¹.

Among women treated for 18 months, 41 percent developed antibodies to abaloparatide, and 26 percent developed neutralizing antibodies, those that block the drug ¹. The label says the antibodies did not appear to have a clinically significant effect on bone density, fracture reduction or adverse events ¹.

Osteosarcoma, a malignant bone tumor, has its own warning in the label and appears in the Medication Guide's "most important information," after allergic reactions ¹. The label says abaloparatide "caused a dose-dependent increase in the incidence of osteosarcoma in male and female rats after subcutaneous administration at exposures 4 to 28 times the human exposure" ¹. In the two-year rat study the tumor occurred in 0 to 2 percent of untreated rats ¹. It occurred in 87 percent of high-dose males and 62 percent of high-dose females ¹. The label states: "It is unknown whether TYMLOS will cause osteosarcoma in humans" ¹.

The label adds that "osteosarcoma has been reported in patients treated with a PTH-analog in the post marketing setting; however, an increased risk of osteosarcoma has not been observed in observational studies in humans" ¹. It also notes "limited data assessing the risk of osteosarcoma beyond 2 years" ¹. That warning once stood in a box. The April 2017 label opened with "WARNING: RISK OF OSTEOSARCOMA" ¹⁵. The box also said that "cumulative use of TYMLOS and parathyroid hormone analogs (e.g., teriparatide) for more than 2 years during a patient's lifetime is not recommended" ¹⁵.

FDA approved a supplement on December 22, 2021 ³. The label revised that month records "Osteosarcoma Boxed Warning, Removed 12/2021" ¹⁶. The warning now stands among the label's warnings and precautions, which say to avoid Tymlos in five groups of patients, those "at increased baseline risk of osteosarcoma" ¹. They are open epiphyses, meaning still-growing bones in children and young adults, and metabolic bone diseases other than osteoporosis, including Paget's disease ¹.

They also include bone metastases or a history of skeletal malignancies, prior radiation therapy involving the skeleton, and hereditary disorders predisposing to osteosarcoma ¹. The label still says that "use of the drug for more than 2 years during a patient's lifetime is not recommended" ¹.

The label contraindicates Tymlos "in patients with a history of severe hypersensitivity to abaloparatide or any of the inactive ingredients" ¹. It notes that such "reactions have included anaphylaxis, angioedema, dyspnea, and urticaria" ¹. The hypersensitivity warning was revised in August 2026 ¹. FDA had notified the company of "new safety information that we have determined should be included in the labeling for parathyroid hormone products," concerning "the risk of drug hypersensitivity reactions" ¹⁷.

The other warnings begin with a drop in blood pressure on standing, "typically within 4 hours of injection" ¹. Next is hypercalcemia, with the drug "not recommended in patients with pre-existing hypercalcemia or in patients who have an underlying hypercalcemic disorder, such as primary hyperparathyroidism" ¹. Last is hypercalciuria and urolithiasis, kidney stones, where "it is unknown whether TYMLOS may exacerbate urolithiasis in patients with active or a history of urolithiasis" ¹.

In severe kidney impairment, exposure to the drug roughly doubled, and the label says to monitor for adverse reactions ¹. Post-marketing reports add abdominal pain and bloating, constipation, diarrhea and vomiting, weakness and lethargy, and insomnia ¹. They also add allergic reactions with shortness of breath, rash and itching, and raised blood pressure ¹. Pain in bone, joints, back and limbs and muscle spasms of the leg and back are listed as well ¹. Bruising and bleeding at the injection site are reported too ¹.

In sport

Abaloparatide is not named on WADA's 2026 Prohibited List, and neither is parathyroid hormone or parathyroid hormone-related protein ¹⁸. WADA, the World Anti-Doping Agency, lists peptide hormones in section S2.2 ¹⁸. That section names testosterone-stimulating peptides, corticotropins and their releasing factors, growth hormone with its analogs and fragments, and growth hormone releasing factors ¹⁸. Abaloparatide belongs to none of those groups ¹⁸.

What JumpstartMD offers

JumpstartMD does not prescribe abaloparatide. Our peptide library covers it so you have the facts on its FDA status and the evidence, current as of November 10, 2026.

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