Abaloparatide
Also known as: Tymlos, Eladynos, BA058, BIM-44058, PTHrP(1-34) analog
PTHrP Analog | Anabolic Bone-Building Agent
Overview
Abaloparatide is an FDA-approved anabolic bone-building agent and synthetic analog of parathyroid hormone-related protein (PTHrP). It selectively activates the PTH1 receptor to stimulate new bone formation while minimizing bone resorption. In the phase III ACTIVE trial, abaloparatide showed superior BMD increases at the hip compared to teriparatide, with substantial fracture risk reduction. It was approved in the US in 2017 and EU in 2022 for postmenopausal women and men with osteoporosis at high fracture risk.
Key benefits
- FDA-approved for osteoporosis treatment
- Actively builds new bone (anabolic mechanism)
- Superior hip BMD gains vs teriparatide in trials
- Reduces vertebral fracture risk significantly
- Reduces nonvertebral fracture risk
- Lower hypercalcemia risk than teriparatide
- Works through selective PTH1R activation
- Benefits seen within 6 months
Mechanism of action
Abaloparatide works through selective activation of the parathyroid hormone 1 receptor (PTH1R), a G protein-coupled receptor expressed on osteoblasts and osteocytes. It preferentially binds to the RG (relaxed, G-protein-coupled) conformational state of PTH1R, which elicits a transient downstream cyclic AMP signaling response favoring anabolic bone formation over resorption. This selective binding pattern produces more bone-building activity with less hypercalcemic effect compared to native PTH. The result is increased cortical and trabecular bone volume, density, and improved microarchitecture.
Molecular data
- Type
- Synthetic PTHrP analog
- Half-life
- ~1.7 hours
Sequence
C174H299N56O49 - 41% homology to PTH(1-34), 76% homology to PTHrP(1-34)
Indications
What the research community uses this compound for, with self-reported effectiveness.
Osteoporosis (FDA-Approved)
Postmenopausal Osteoporosis
Most effectiveFDA-approved for postmenopausal women with osteoporosis at high risk for fracture or who have failed other therapies.
Male Osteoporosis
Most effectiveFDA-approved for men with osteoporosis at high risk for fracture or intolerant to other treatments.
Bone Health Research
Fracture Prevention
Most effectivePhase III trials demonstrated substantial reduction in vertebral and nonvertebral fractures.
Sequential Therapy
EffectiveACTIVExtend trial showed benefits of abaloparatide followed by alendronate for maintained bone protection.
Dosing protocols
Common protocols by delivery method. Adjust the curve below to model accumulation in your own cycle.
Injectable
Abaloparatide is administered as a once-daily subcutaneous injection in the periumbilical (around the navel) region of the abdomen. It comes in pre-filled pen devices (Tymlos). Cumulative lifetime use is limited to 2 years due to theoretical osteosarcoma risk observed in rodent studies. A transdermal patch formulation is also in development.
| Protocol | Dose | Frequency | Route / duration |
|---|---|---|---|
| Osteoporosis treatment | 80 mcg | Once daily | SubQ (periumbilical abdomen) |
Preparation
You will need
- Pre-filled pen device (Tymlos)
- Pen needles
- Alcohol swabs
Steps
- Store pen refrigerated at 2-8°C (do not freeze)
- Allow to reach room temperature before injection
- Attach new needle for each injection
- Inject subcutaneously in periumbilical region
- Rotate injection sites
- Discard pen after 30 days even if medication remains
Work out the water volume and syringe units in the reconstitution calculator →
Interactions
Pairwise interactions with other compounds you might be cycling — the same data behind the cycle builder's safety check.
Teriparatide
AvoidDo not use concurrently; both are PTH receptor agonists. Choose one or use sequentially.
Bisphosphonates (Alendronate)
SynergisticACTIVExtend trial showed sequential abaloparatide then alendronate maintained and extended bone benefits.
Calcium/Vitamin D
SynergisticAdequate calcium (500-1000mg) and vitamin D (400-800 IU) supplementation recommended during therapy.
BPC-157
CompatibleDifferent mechanisms; no known interactions.
TB-500
CompatibleDifferent mechanisms; no known interactions.
Timeline
Typical week-by-week effects reported in clinical and observational data.
- Month 1-3
Bone formation markers increase; initial BMD changes begin
- Month 3-6
Significant BMD increases at spine, hip, and femur
- Month 6-12
Continued bone density improvements; fracture risk reduction
- Month 12-18
Maximum benefits in ACTIVE trial; substantial fracture reduction
- Month 18-24
Transition to maintenance therapy (e.g., bisphosphonates) recommended
Safety
Reported adverse effects, contraindications, and what to monitor on cycle.
Common side effects
- Hypercalciuria (high calcium in urine)
- Dizziness
- Nausea
- Headache
- Palpitations
- Fatigue
- Upper abdominal pain
- Vertigo
- Injection site reactions
Rare side effects
- Hypercalcemia
- Orthostatic hypotension
- Osteosarcoma (theoretical - seen in rodent studies at high doses)
Stop signs — stop and seek advice
- Signs of hypercalcemia (confusion, fatigue, excessive thirst)
- Persistent bone pain
- Severe dizziness or fainting
- Allergic reactions
Contraindications
- Paget's disease of bone
- Prior external beam or implant radiation therapy to skeleton
- Bone metastases or history of skeletal malignancies
- Metabolic bone diseases other than osteoporosis
- Pre-existing hypercalcemia
- Pregnancy or nursing
- Cumulative use exceeding 2 years lifetime
Monitoring
- Serum calcium levels
- Urine calcium (hypercalciuria common)
- Bone mineral density testing
- Treatment limited to 2 years maximum lifetime
- Follow with antiresorptive therapy to maintain gains
Quality checks
What a legitimate product looks like, what should give pause, and what should make you stop.
Good signs
- Clear, colorless solution
- Pharmaceutical grade (Tymlos/Eladynos)
- Proper cold chain maintained
- Intact pen device
- Within expiration date
Warning signs
- Research-grade products lack FDA oversight
- Temperature excursions may affect potency
Stop signs — don't use
- Cloudy or discolored solution
- Particulates visible
- Exposed to freezing or high temperatures
- Damaged pen device
References
Primary literature and clinical-trial data informing this entry.
Effect of Abaloparatide vs Placebo on New Vertebral Fractures in Postmenopausal Women With Osteoporosis (ACTIVE Trial)
Miller PD, Hattersley G, Riis BJ, et al. · JAMA · 2016
Abaloparatide showed substantial reduction in vertebral fractures and greater BMD increases at spine, hip, and femur compared to placebo and teriparatide.
ACTIVExtend Trial: Abaloparatide Followed by Alendronate
Cosman F, Miller PD, Williams GC, et al. · Mayo Clinic Proceedings · 2017
18 months abaloparatide followed by alendronate significantly reduced vertebral and nonvertebral fractures.
Phase 2 Dose-finding Study of BA058 in Postmenopausal Women
Leder BZ, O'Dea LS, Zanchetta JR, et al. · Journal of Clinical Endocrinology and Metabolism · 2015
Significant BMD increases at 40 and 80 mcg doses; abaloparatide showed superior anabolic effects on hips vs teriparatide.
Profile of Abaloparatide and Its Potential in Postmenopausal Osteoporosis
Tella SH, Kommalapati A, Correa R · Cureus · 2017
Abaloparatide preferentially binds RG conformational state of PTH1R, producing more anabolic bone effects.
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