Abaloparatide

Tymlos (US), Eladynos (EU/UK), BA058, PTHrP (1-34) analogue

Metabolic & weight

Awaiting medical reviewEN ES DE FR PT ZH+ Follow for updates

Note on this profile. Abaloparatide is an approved prescription medicine for osteoporosis, not a research-only compound. This page explains the published science. It is not sold in the research-peptide market in any meaningful way, and no community use is documented.

Summary

Class: Synthetic 34-amino-acid peptide; analogue of parathyroid hormone-related protein (PTHrP) 1-34 with ~40% of residues changed versus native PTHrP
Mechanism: Activates the same PTH1 receptor as teriparatide but binds preferentially to a short-lived receptor conformation, producing a briefer signal that favours bone formation with less bone resorption and less calcium release
Routes studied: Subcutaneous once daily (approved); transdermal microneedle patch (phase 3, did not meet non-inferiority)
Half-life: ~1 hour; serum calcium peaks at ~4 h and normalises within 16 h
Storage: Approved pen: refrigerate before first use; after first use store at room temperature (20–25 °C) for up to 30 days; do not freeze
Regulatory status: Approved medicine (US 2017, men 2022; EU Dec 2022; UK 2023 †); not approved in Australia or South Africa †

Doses are as reported in studies or by the community — never recommendations.

1What it is

Parathyroid hormone-related protein (PTHrP) is a natural cousin of PTH. It was discovered in the 1980s as the cause of high calcium in some cancers, but its normal roles are local: it directs cartilage development, tooth eruption, breast development and calcium transfer to milk. The first 34 amino acids activate the PTH1 receptor, the same receptor PTH uses. Abaloparatide is a heavily modified copy of PTHrP(1-34), engineered by Ipsen and developed by Radius Health, designed to keep the bone-building signal while reducing the calcium-raising and bone-resorbing effects of PTH itself.

It is the second anabolic osteoporosis peptide to reach approval (after teriparatide, profile 121) and the only one developed specifically for a once-daily injection with less hypercalcaemia. Community/self-directed use: essentially none documented.

2How it's thought to work

The PTH1 receptor exists in two conformations: a longer-lived one that keeps signalling after the hormone leaves (and drives sustained resorption), and a short-lived one that signals briefly. Abaloparatide binds the short-lived conformation much more selectively than teriparatide does (Hattersley 2016, Endocrinology). The result in trials is a similar or larger rise in bone formation markers, a smaller rise in resorption markers, and roughly half the rate of transient hypercalcaemia. Beyond that it behaves like teriparatide: osteoblast activation, improved trabecular microarchitecture, and gains that need an anti-resorptive afterwards to hold.

An analogue of PTH-related protein at the same receptor, selective for a receptor conformation that is thought to shift the balance further towards building and away from resorption.Schematic — not to scale

3What the research shows

Fracture reduction in postmenopausal osteoporosis

ACTIVE (n=2,463 postmenopausal women; 18 months) compared abaloparatide 80 µg, open-label teriparatide 20 µg and placebo. New vertebral fractures occurred in 0.58% on abaloparatide vs 4.22% on placebo (86% relative reduction) and 0.84% on teriparatide; non-vertebral fractures fell 43% vs placebo. Hip BMD gains were larger than with teriparatide; hypercalcaemia was less frequent (3.4% vs 6.4%) (Miller 2016, JAMA). [1]

Maintenance of effect after switching to alendronate

ACTIVExtend followed women onto 24 months of alendronate after abaloparatide or placebo: cumulative vertebral fracture reduction was maintained (84%), with continued BMD gains (Bone 2018, J Clin Endocrinol Metab). [2]

Graded A (BMD endpoint)

Men with osteoporosis

ATOM (n=228 men, 12 months) showed lumbar spine BMD +8.5% vs +1.2% on placebo, with hip gains too; it was not powered for fractures (Czerwinski 2022, J Bone Miner Res). This led to US approval for men in December 2022. [3]

Graded A (negative)

Transdermal patch

The wearABLe phase 3 trial of a microneedle patch did not meet non-inferiority to the injection on spine BMD; the patch was not pursued.

Fracture healing, periodontal and other uses

Rodent fracture and implant-osseointegration studies are positive; no human trials for these uses.

4Reported side effects and interactions

Literature-reported

Literature. the most common are hypercalciuria (raised urine calcium, ~11% vs 9% placebo), dizziness (10%), nausea (8%), headache, palpitations, injection-site redness and orthostatic hypotension — a transient drop in blood pressure within about 4 hours of injecting, especially the first doses, which is why patients are told to inject where they can sit or lie down. Transient hypercalcaemia is roughly half as frequent as with teriparatide. Palpitations and a small rise in heart rate are more noticeable than with teriparatide. Anti-drug antibodies occur in about half of patients but do not appear to affect efficacy.

Contraindications (label). as for teriparatide — Paget's disease or unexplained raised alkaline phosphatase, open growth plates, prior skeletal radiation, bone metastases or skeletal malignancy, pre-existing hypercalcaemia, hyperparathyroidism and other metabolic bone diseases.

Community-reported

none documented.

Osteosarcoma. as with teriparatide, high-dose lifelong rodent studies produced osteosarcoma. The US boxed warning was removed in December 2021 on the strength of the teriparatide surveillance data and abaloparatide's own carcinogenicity data; the US label retains a cumulative 2-year lifetime limit †. No human case has been attributed to it.

Theoretical. cardiac effects of the heart-rate rise in people with arrhythmia history; the EU initially declined approval in 2018 partly over cardiovascular safety questions before approving in 2022 on fuller data.

Interactions. none formally identified; the same caution with digoxin and hypercalcaemia applies as for teriparatide.

Markers researchers commonly monitor

Per the label and ACTIVE protocol:

Marker	Why it's watched
Serum calcium (pre-dose and ~4 h post-dose early in treatment)	less hypercalcaemia than teriparatide but still the main safety marker.
24-hour urinary calcium	hypercalciuria is the most common lab abnormality; relevant for stone formers.
Serum uric acid	rises in some patients, as with teriparatide.
Alkaline phosphatase, 25-hydroxy vitamin D, baseline PTH	screen for contraindications and correct vitamin D first.
P1NP	formation marker; rises early and tracks response.
Resting heart rate and sitting/standing blood pressure	palpitations and orthostatic hypotension are label effects.
DEXA (spine and hip)	baseline and 12–18 months.

Free for everyone. Safety information is never behind a paywall.

5Reconstitution and handling

Supplied only as a pre-filled 30-dose pen (3,120 µg in 1.56 mL) that needs no . Unlike the teriparatide pen it can be kept at room temperature once in use. There is no version in circulation and the calculator is not needed for this compound.

6Commonly studied alongside

Teriparatide (profile 121, the direct comparator in ACTIVE), alendronate and other bisphosphonates (ACTIVExtend sequence), denosumab (sequence studies). Calcium and vitamin D are co-prescribed on the label.

Informational cross-links. Not stack recommendations.

7Regulatory status by region

Region	Status (checked —)
United States	FDA-approved (Tymlos, April 2017) for postmenopausal women at high fracture risk; men added Dec 2022. Boxed warning removed Dec 2021
European Union	EMA refused in 2018; approved as Eladynos in Dec 2022 for postmenopausal women at high fracture risk, marketed by Theramex
United Kingdom	MHRA-licensed (Eladynos) †
Australia	Not TGA-registered as of review date †
South Africa	Not SAHPRA-registered †
Sport	Not specifically named by WADA; same uncertainty as teriparatide under S2 †

8Open questions

Head-to-head fracture superiority over teriparatide has not been formally tested (ACTIVE's teriparatide arm was open-label and the trial was not powered for that comparison).
Durability of fracture protection beyond the ACTIVExtend period and in men.
Whether the cardiovascular signals (heart rate, palpitations) matter over years in older patients.

9References

1Miller PD et al. (2016). Effect of abaloparatide vs placebo on new vertebral fractures in postmenopausal women with osteoporosis: a randomized clinical trial (ACTIVE). JAMA. PubMed · DOI
2Bone HG et al. (2018). ACTIVExtend: 24 months of alendronate after 18 months of abaloparatide or placebo for postmenopausal osteoporosis. J Clin Endocrinol Metab. PubMed · DOI
3Czerwinski E et al. (2022). The efficacy and safety of abaloparatide-SC in men with osteoporosis: a randomized clinical trial (ATOM). J Bone Miner Res. PubMed · DOI
4Hattersley G et al. (2016). Binding selectivity of abaloparatide for PTH-type-1-receptor conformations and effects on downstream signaling. Endocrinology. PubMed · DOI
5Leder BZ et al. (2015). Effects of abaloparatide, a human parathyroid hormone-related peptide analog, on bone mineral density in postmenopausal women with osteoporosis (phase 2). J Clin Endocrinol Metab. PubMed · DOI
6Radius Health. Tymlos (abaloparatide) prescribing information, revised Dec 2022. PubMed
7European Medicines Agency. Eladynos: EPAR summary (2022). PubMed

References are being resolved to PubMed/DOI identifiers; links search PubMed for the citation until then.

† Being confirmed by our reviewers against current sources.

10Community

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Self-reported side effects Phase 2

Not enough data yet. 0 of the 50 members needed have logged this compound for 4+ weeks. We don't show anything below 50, so no one can be identified.

11Page history

30 Oct 2026Profile published — awaiting medical review

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