Parathyroid Hormone 1-34 (Teriparatide)

Overview

Teriparatide (Forteo) is a synthetic 34-amino acid N-terminal fragment of human parathyroid hormone (PTH) representing the biologically active portion of the full 84-amino acid hormone. Unlike full-length PTH or bisphosphonates that reduce bone resorption, teriparatide is an anabolic bone agent that actually stimulates new bone formation when administered as once-daily injections (as opposed to continuous infusion, which causes resorption). FDA-approved in 2002 for osteoporosis in postmenopausal women, men, and glucocorticoid-induced osteoporosis at high fracture risk, teriparatide typically increases lumbar spine BMD by 9–13% and reduces vertebral fracture risk by 65%.

Mechanism of Action

Teriparatide binds PTH receptor 1 (PTH1R), a class B GPCR expressed on osteoblasts, osteoclasts, and renal tubular cells. Intermittent (pulsatile) PTH1R activation on osteoblasts paradoxically stimulates bone formation by: (1) reducing osteoblast apoptosis via anti-apoptotic signaling; (2) activating quiescent lining cells to become active osteoblasts; (3) stimulating osteoblast precursor differentiation; (4) inhibiting the expression of sclerostin and DKK1 (Wnt signaling inhibitors), thereby activating Wnt-mediated osteogenesis. Net effect: anabolic bone formation exceeds bone resorption in the intermittent dosing regimen.

Potential Benefits

• Anabolic bone formation (unique mechanism vs. antiresorptive drugs)
• 65% reduction in vertebral fracture risk
• 35–53% reduction in nonvertebral fracture risk
• FDA-approved for multiple osteoporosis indications
• Effective in glucocorticoid-induced osteoporosis
• Can re-anabolize bone even after prolonged antiresorptive treatment

Research Dosage Notes

The following reflects doses used in published research studies. This is not medical advice.

20 mcg SC once daily for maximum 2 years lifetime cumulative use.

Amino Acid Sequence

Side Effects & Safety

• Nausea, dizziness, leg cramps
• Transient hypercalcemia
• Orthostatic hypotension
• Black box warning: osteosarcoma risk (based on rat data; not confirmed in humans)
• Contraindicated in patients at high osteosarcoma risk (Paget's disease, prior radiation)

Synergistic Compounds

The following compounds have been studied alongside Parathyroid Hormone 1-34 (Teriparatide) for potential complementary or synergistic effects:

Related Peptides

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References & Further Reading

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