Quick summary
Teriparatide (Forteo) is the first FDA-approved anabolic osteoporosis treatment, a recombinant PTH(1-34) that builds new bone by stimulating osteoblasts. It reduced vertebral fractures by 65 percent and non-vertebral fractures by 53 percent in the pivotal trial.
Overview
Teriparatide is a recombinant form of the first 34 amino acids of human parathyroid hormone (PTH 1-34) and the first anabolic osteoporosis treatment approved by the FDA. Sold under the brand name Forteo, it stimulates new bone formation on trabecular and cortical surfaces and is indicated for postmenopausal women, men with osteoporosis, and patients with glucocorticoid-induced osteoporosis at high fracture risk. It became generic (Bonsity) in 2019.
Mechanism of action
Teriparatide binds to the PTH1 receptor (PTH1R) on osteoblasts and osteoblast precursors, activating the Gs-protein/cAMP/PKA and Gq-protein/PLC/PKC pathways. Intermittent once-daily administration creates transient PTH1R stimulation that preferentially activates osteoblasts over osteoclasts, resulting in net bone formation. The drug increases osteoblast number by promoting differentiation from precursors and inhibiting osteoblast apoptosis, increases periosteal bone formation, and enhances cancellous connectivity. Continuous PTH exposure (unlike once-daily pulses) stimulates both formation and resorption; the pulsatile dosing exploits the anabolic window. Bone mineral density increases are seen at spine and hip within 3–6 months of treatment.
Dosing protocols
| Purpose | Route | Dosage | Frequency | Notes |
|---|---|---|---|---|
| Osteoporosis — anabolic bone building | subcutaneous | 20–20 mcg | once daily | Inject into thigh or abdominal wall. Use prefilled delivery device (3 mL pen, 750 mcg total). Administer first dose sitting or lying down. Maximum lifetime cumulative use: 2 years. Follow with antiresorptive therapy to maintain gains. |
Dosing information is for educational purposes only. Consult a qualified healthcare professional before using any peptide.
Research summary
The pivotal Fracture Prevention Trial (n=1,637) demonstrated teriparatide reduced vertebral fractures by 65% and non-vertebral fractures by 53% versus placebo over 21 months. Significant BMD increases occur at the lumbar spine (+9%) and femoral neck (+3%) within 18 months. Studies confirm superiority to antiresorptives for spine BMD gains. The drug is approved for up to 2 years of cumulative lifetime use due to osteosarcoma risk observed in rat carcinogenicity studies (high dose, lifetime exposure); no osteosarcoma cases attributable to teriparatide have been reported in humans after 20+ years of clinical use.[1][2][3][4][5]
Evidence grading
Each claimed benefit is graded by the strength of available evidence. Grades reflect study quality, not effect size.
Strong = multiple RCTs · Moderate = limited trials or observational · Preliminary = animal or in vitro only · Insufficient = anecdotal or no published data
Side effects
Side effects vary by individual. This is not an exhaustive list. Report unusual symptoms to a healthcare professional.
Common stacks
Peptides commonly paired with Teriparatide for synergistic effects.
Legal status
FDA-approved (NDA 021318, 2002) for treatment of osteoporosis in postmenopausal women, men with osteoporosis, and men and women with glucocorticoid-induced osteoporosis at high fracture risk. Prescription-only. Carries a boxed warning for osteosarcoma risk based on rat data. Lifetime use limited to 2 years.
Sourcing & access
Prescription required
Teriparatide is an FDA-approved prescription medication available through licensed healthcare providers, telehealth platforms, and 503A/503B compounding pharmacies.
Frequently asked questions
Teriparatide (Forteo) is a recombinant form of the first 34 amino acids of human parathyroid hormone. It is the first anabolic bone-building drug approved by the FDA for osteoporosis in postmenopausal women, men, and patients with glucocorticoid-induced osteoporosis.
Once-daily intermittent injections create transient PTH1R stimulation that preferentially activates osteoblasts over osteoclasts, resulting in net new bone formation. This is fundamentally different from antiresorptive drugs that only slow bone loss.
Teriparatide has a lifetime cumulative use limit of 2 years. This is due to an osteosarcoma signal observed in rat studies at high lifetime doses, though no osteosarcoma cases attributable to teriparatide have been reported in humans after 20 years of clinical use.
The pivotal Fracture Prevention Trial showed teriparatide reduced vertebral fractures by 65 percent and non-vertebral fractures by 53 percent versus placebo. Lumbar spine BMD increased approximately 9 percent and femoral neck BMD by 3 percent within 18 months.
Bone density gains are progressively lost after discontinuation unless followed by an antiresorptive therapy such as alendronate or denosumab. Transitioning to an antiresorptive agent is considered standard of care to maintain the anabolic gains.
Research references
- Effect of parathyroid hormone (1-34) on fractures and bone mineral density in postmenopausal women with osteoporosisPubMed
- Effects of Teriparatide Compared with Risedronate on the Risk of Fractures in Subgroups of Postmenopausal Women with Severe Osteoporosis: The VERO TrialPubMed
- Teriparatide for acceleration of fracture repair in humans: a prospective, randomized, double-blind study of 102 postmenopausal women with distal radial fracturesPubMed
- Randomized Teriparatide [human parathyroid hormone (PTH) 1-34] Once-Weekly Efficacy Research (TOWER) trial for examining the reduction in new vertebral fractures in subjects with primary osteoporosis and high fracture riskPubMed
- Update on the safety and efficacy of teriparatide in the treatment of osteoporosisPubMed