Teriparatide

Mechanism

Teriparatide is the N-terminal 1-34 fragment of human parathyroid hormone, comprising the biologically active region that binds to and activates the PTH1 receptor (PTH1R), a G protein-coupled receptor expressed on osteoblasts and renal tubular cells. The pharmacological effect depends on the dosing pattern: continuous endogenous PTH elevations (as in hyperparathyroidism) cause net bone resorption, whereas intermittent daily administration of teriparatide produces net bone formation. The mechanism involves: (1) direct stimulation of osteoblast differentiation and activity, increasing bone matrix deposition; (2) activation of canonical Wnt signalling pathway via suppression of sclerostin (SOST); (3) stimulation of osteocyte-mediated signalling; and (4) indirect enhancement of bone remodelling through increased RANKL expression that initially activates osteoclasts, but the net effect of intermittent dosing favours formation over resorption. At skeletal sites, teriparatide increases cortical porosity but improves trabecular connectivity and overall bone strength — a pattern distinct from antiresorptive agents.

Evidence base

Key Published Trials

1. Fracture Prevention Trial (Neer RM, et al. New England Journal of Medicine. 2001;344(19):1434-1441): RCT of 1,637 postmenopausal women. 65% reduction in vertebral fractures, 53% reduction in non-vertebral fractures vs. placebo. NCT00281491.

2. Glucocorticoid osteoporosis (Saag KG, et al. Arthritis & Rheumatism. 2007;56(11):3641-3651): RCT showing teriparatide superior to alendronate for BMD and vertebral fracture reduction in glucocorticoid-treated patients.

3. Fracture healing meta-analysis (Gao J, et al. Osteoporosis International. 2022): Pooled analysis of RCTs showing improved radiological healing in pelvic and atypical femoral fractures.

4. ACTIVE trial (Tsai JN, et al. Lancet Diabetes & Endocrinology. 2020): Demonstrated superiority of teriparatide followed by denosumab vs. combination or denosumab alone for BMD.

Regulatory Status

• FDA approval: November 2002
• EMA approval: 2003
• NICE TA161: Recommended for severe postmenopausal osteoporosis under specific criteria
• Black box warning (rat osteosarcoma): Cumulative lifetime limit of 24 months treatment

Protocols

Teriparatide is supplied as a pre-filled pen (Forteo/Forsteo, Eli Lilly):

• Standard dose: 20 µg (one pen injection) subcutaneously once daily
• Injection site: Abdomen or thigh, rotating sites
• Duration: Up to 24 months maximum (lifetime cumulative limit due to preclinical osteosarcoma signal)
• Sequential therapy: After discontinuation, antiresorptive therapy (bisphosphonate or denosumab) is recommended to preserve bone gains

These details are for research documentation. Teriparatide is a prescription-only medicine and is not available for self-directed research use.

UK legal status

Teriparatide is a prescription-only medicine (POM) in the UK under the Human Medicines Regulations 2012. It is not a controlled substance under the Misuse of Drugs Act. It is not legally available as a research chemical.

Key points:

• MHRA status: Licensed medicinal product (Forsteo, Eli Lilly)
• Prescription requirement: Requires a valid prescription, typically from a specialist in rheumatology, endocrinology, or primary care osteoporosis service
• NHS availability: NICE TA161 recommends teriparatide for postmenopausal women with severe osteoporosis who are intolerant of or unresponsive to bisphosphonates; NHS prescribing criteria are restrictive due to cost
• Importation: Personal importation without a prescription is not legal

This compound is included in the Peptide Data knowledge base for educational completeness, given its significance as an anabolic bone peptide. It is not available through any UK research peptide vendor.

Vendor notes

Teriparatide is not available through any UK research peptide vendor. It is a licensed prescription medicine dispensed exclusively through pharmacies with a valid prescription. No vendor profile on Peptide Data lists teriparatide, and none should.