Teriparatide
Forteo · Recombinant PTH 1-34 · PTH 1-34
Teriparatide is recombinant human parathyroid hormone fragment 1-34 (PTH 1-34), the biologically active N-terminal portion of full-length parathyroid hormone (PTH 1-84). It is FDA-approved as Forteo (Eli Lilly) for postmenopausal osteoporosis with high fracture risk, primary or hypogonadal osteoporosis in men, and glucocorticoid-induced osteoporosis. Approved 2002.
Inject same time daily into thigh or abdominal wall. FORTEO multidose pen is the standard delivery device (28-day pen good after first use). Reconstituted research-grade vials should be refrigerated. Daily timing matters less than consistency - pick a time you will not skip.
Start here. Every protocol below is ordered lowest-first. Begin at the smallest effective dose, hold about a week to assess tolerance, and step up only if needed.
How it works
Teriparatide binds the PTH/PTHrP type 1 receptor (PTH1R) on osteoblasts and osteoblast precursors. Daily subcutaneous administration creates short, transient PTH spikes that preferentially activate osteoblast bone formation over osteoclast bone resorption.
Anabolic Window
Brief PTH elevation (~4-6 hours per dose) activates osteoblasts via PKA/cAMP, IGF-1 local production, Wnt/β-catenin signaling, and decreased sclerostin expression. The pulse profile favors bone formation over the catabolic effect seen with chronic PTH excess.
Bone Remodeling Reset
Increases bone remodeling rate but with positive remodeling balance - more bone formed per cycle than resorbed. This produces gains in trabecular bone (lumbar spine BMD +9-13% over 18-24 months in pivotal trials) and improved cortical thickness.
Bone Quality
Beyond raw BMD, improves bone microarchitecture (trabecular connectivity, cortical thickness) and material properties - producing fracture risk reductions exceeding what BMD changes alone would predict.
Calcium Homeostasis
Acutely raises serum calcium via increased renal reabsorption and intestinal calcium absorption (via 1,25-dihydroxyvitamin D upregulation). Adequate calcium and vitamin D intake required for the anabolic response.
Black Box Warning History
Original FDA approval included a boxed warning for osteosarcoma based on 2-year rat carcinogenicity studies. The rat findings did not translate to human surveillance data, and the boxed warning was removed in 2020 after 18 years of post-marketing data.
What to expect
Weeks 1-4: bone turnover markers rise (P1NP, osteocalcin) but no symptomatic effect. Monitor calcium periodically.
Months 3-6: peak bone formation activity; first measurable BMD gains at lumbar spine. Subjective effects rare - bone gain is silent.
Months 12-24: peak BMD response (lumbar spine +9-13% in pivotal trial). Fracture risk reduction documented at this timeframe. Lifetime cumulative cap: 24 months per FDA.
Evidence
Claims we could not support
No abstract we checked supports these for this molecule at this route. That is not the same as saying they are false — it marks where the evidence is missing.
Exact-molecule abstract evidence. ESearch was run and 6 source-candidate PMIDs were EFetch-checked; no usable exact-molecule abstract sentence was found.
Dose/route: 20mcg; Subcutaneous (SubQ) injection; 1x daily. No selected live abstract sentence verified this complete regimen.
Mechanism as written in source JSON. No selected live abstract sentence verified the complete mechanism at the card formulation/route and relevant population/model.
Primary safety claim as written in source JSON. No selected live abstract sentence verified the complete safety claim for this exact formulation and route.
Side effects & safety
Commonly reported
- Injection site reaction (mild erythema, tenderness)
- Transient hypercalcemia
- Mild orthostatic hypotension or dizziness on initial doses
- Nausea (typically mild, transient)
- Headache
- Leg cramps
Less common & notes
- Hyperuricemia and rare gout flare.
- Allergic reactions to teriparatide or formulation excipients are uncommon.
- Original FDA boxed warning for osteosarcoma was based on rat carcinogenicity findings at supratherapeutic exposures; 18+ years of post-marketing surveillance found no increase in human osteosarcoma incidence, and the boxed warning was removed in 2020.
- The 24-month lifetime cumulative cap is retained as conservative practice.
- In severe renal impairment, PK and clinical safety are not well characterized.
Pharmacokinetics
Plasma
SubQ
Functional bone-anabolic window
subQ ~95%
Daily dosing produces transient anabolic pulse; cumulative effect over 18-24 months drives BMD gains
Hepatic and extrahepatic peptidase cleavage; renal excretion of metabolites
Storage. FORTEO pen: refrigerate (2-8°C / 36-46°F) at all times - do NOT freeze. Pen good 28 days after first use. Discard 28 days after first use even if drug remains. Research vials: lyophilized vial refrigerate or freeze (-20°C) for long-term storage. After reconstitution with bacteriostatic water, refrigerate 2-8°C and use within 14-28 days. Protect from light. Discard if cloudy or discolored.
Regulatory status
FDA-approved as Forteo (Eli Lilly, December 2002) for: postmenopausal osteoporosis with high fracture risk, primary or hypogonadal osteoporosis in men, and glucocorticoid-induced osteoporosis. Boxed warning for osteosarcoma was REMOVED in 2020 after extensive post-marketing surveillance. Maximum lifetime cumulative exposure: 24 months per FDA label. Generic teriparatide approved in 2019 (Bonsity, Pfenex). Outside FDA-approved indications, teriparatide is sometimes used off-label for fracture healing and select non-osteoporotic indications - these uses are off-label and not FDA-endorsed.
Put it to work
Calculate, log & track
Open Teriparatide straight into OnePin with your vial and dose pre-filled, then let it handle the syringe math and remind you before the vial runs out.
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The guide & community
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