Ostabolin-C

Parathyroid Hormone Analog (cyclic PTH Fragment)Rx: ResearchCompound: Investigational

Also known as: Ostabolin C, PTH(1-31) cyclic lactam, RS-66271

Educational Only — Not medical advice. Consult a qualified clinician before using any peptide.

Summary

Ostabolin-C (also known as RS-66271) is a cyclic lactam analog of human parathyroid hormone fragment PTH(1-31), developed as a bone anabolic agent for osteoporosis. Its cyclization via a lactam bridge between Lys26 and Asp30 confers conformational stability and selective receptor signaling favoring bone formation over resorption. It was investigated as a potential alternative to teriparatide with improved safety profile, particularly regarding hypercalcemia.

Mechanism of Action

Selective PTH receptor (PTH1R) agonist; cyclic lactam analog of PTH(1-31) that stimulates osteoblast activity and bone formation while minimizing bone resorption signaling, promoting anabolic effects on bone with reduced hypercalcemic liability compared to full-length PTH.

Routes of Administration

Subcutaneous

Goals & Uses

  • Osteoporosis treatmentBone MetabolismModerate
  • Fracture risk reductionBone HealthLow
  • Reduced hypercalcemia risk vs full PTHSafety ProfileModerate
  • Increase bone mineral densityBone HealthModerate

Contraindications

  • HypercalcemiaMetabolic DisorderHigh
  • Severe renal impairmentOrganModerateKidney function concerns
  • Paget's disease of boneBone DisorderModerate
  • Prior radiation therapy to skeletonOncologic HistoryModerate
  • Active malignancy or history of bone metastasesOncologicHigh

Adverse Effects

  • Dizziness/orthostatic hypotensionCardiovascularUncommon
  • HypercalcemiaMetabolicUncommon
  • Injection site reactionsLocalCommon
  • HypercalciuriaMetabolicUncommon
  • NauseaGastrointestinalUncommonFeeling of sickness or urge to vomit

Drug Interactions

  • BisphosphonatesLow
  • DigoxinHigh
  • Calcium supplementsModerate
  • Vitamin D analogsModerate

Population Constraints

  • Pediatric patientsAgeRelative
  • Patients with hyperparathyroidismEndocrineAbsolute
  • Pregnant womenReproductiveRelative
  • Severe renal impairment (CrCl <30 mL/min)Organ ImpairmentRelative

Regulatory Status

  • European UnionInvestigationalNo EMA marketing authorization obtained.
  • United StatesInvestigationalNever received FDA approval; clinical development did not advance to NDA submission.
  • United KingdomInvestigationalNo MHRA approval; remains a research compound.

Has not received regulatory approval in any major jurisdiction. Investigated primarily in preclinical and early clinical studies. Development was largely conducted by Allelix Biopharmaceuticals/NPS Pharmaceuticals in the 1990s–2000s.

Evidence & Sources

No sources recorded yet.

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