Peptide Profile
Relaxin
Relaxin-2 · RLN2 · H2 relaxin · human relaxin
Relaxin (relaxin-2; serelaxin; RLX030) is a 53-residue two-chain polypeptide hormone structurally related to insulin, produced primarily by the corpus luteum during pregnancy and by the heart during cardiac stress, that acts…
- Routes
- subcutaneous, intravenous
Educational research information — not medical advice. Review primary sources and consult a qualified professional before any decision.
Educational research tools — not medical advice.
What Relaxin is
About Relaxin
Binds RXFP1 receptor, activating adenylyl cyclase and cAMP/PKA pathway. Upregulates matrix metalloproteinases (MMPs) to degrade excess collagen. Inhibits TGF-β fibrotic signaling. Promotes cervical softening and pelvic ligament compliance.
Relaxin (relaxin-2; serelaxin; RLX030) is a 53-residue two-chain polypeptide hormone structurally related to insulin, produced primarily by the corpus luteum during pregnancy and by the heart during cardiac stress, that acts through RXFP1 receptors to promote vasodilation, reduce systemic vascular resistance, increase renal perfusion, and attenuate fibrotic signaling — properties that made it a compelling candidate for acute decompensated heart failure, where peripheral vasoconstriction and organ hypoperfusion are central pathophysiological features. RXFP1 activation stimulates cAMP/PKA and nitric oxide signaling to acutely reduce systemic and renal vascular resistance, increase cardiac output without directly affecting heart rate, and suppress TGF-beta-mediated fibrotic remodeling; these hemodynamic and organoprotective mechanisms distinguished relaxin mechanistically from existing vasodilators and diuretics. The RELAX-AHF Phase 3 randomized controlled trial, published in The Lancet (2013), demonstrated that serelaxin significantly improved dyspnea and reduced cardiovascular mortality at 180 days versus placebo in acute heart failure patients; however, the subsequent confirmatory RELAX-AHF-2 Phase 3 trial failed to meet its co-primary endpoint of cardiovascular death reduction, and regulatory applications in the US and Europe were not approved. Serelaxin has no FDA approval and no approved indication in any jurisdiction; the clinical development program was discontinued following the RELAX-AHF-2 results; endogenous relaxin and its RXFP1 pathway remain active areas of basic research in fibrosis biology and obstetric physiology, but no injectable formulation is currently available outside of clinical trials.
Relaxin Benefits & Research Areas
What the evidence says about Relaxin
Research Evidence
Score: 0.51
Regulatory Status
- Availability Status
- Research Only
- FDA Status
- Investigational
Regulatory status reflects publicly available information and may change. This is not legal or medical advice.
Research Sources
11 sources cited · 1 strong · 10 moderate
1 RCT · 10 Cohorts
Serelaxin, recombinant human relaxin-2, for treatment of acute heart failure (RELAX-AHF): a randomised, placebo-controlled trial
Lancet · 2013
The RELAX-AHF trial of 1,161 patients demonstrated that serelaxin (recombinant human relaxin-2, 30 μg/kg/day IV) significantly improved the dyspnoea VAS AUC primary endpoint (p=0.007) and reduced 180-day all-cause mortality (HR 0.63, p=0.019) in acute heart failure, establishing the systemic vasodilatory and organ-protective pharmacology of recombinant relaxin-2 in humans and supporting its broader therapeutic relevance as a peptide hormone.
Huoxue Jiegu compound capsule accelerates tibial fracture healing via angiogenesis-driven repair mechanisms.
Front Med (Lausanne) · 2026
# Summary Research found that Huoxue Jiegu Compound Capsule accelerates tibial fracture healing primarily through activation of angiogenesis-related signaling pathways, with key molecular targets including AKT1, STAT3, IL6, and EGFR operating via HIF-1, PI3K-Akt, Relaxin, TNF, and FoxO pathways. This study demonstrated that the compound increases vascular density and upregulates pro-angiogenic genes in fracture regions, supporting a multi-component mechanism that enhances blood vessel formation and oxygen delivery critical to the fracture repair process.
Serelaxin has greater anti-fibrotic potential than perindopril but maintains its anti-fibrotic efficacy in the presence of perindopril in normotensive mouse models of heart disease.
Life Sci · 2026
# Research Summary Research found that serelaxin demonstrated greater anti-fibrotic effects than the ACE inhibitor perindopril in mouse models of heart disease, while maintaining its anti-fibrotic efficacy when combined with perindopril treatment. This study demonstrated that serelaxin could serve as an effective adjunct therapy to standard ACE inhibitor treatment without compromising its therapeutic benefits.
Show 8 more sources ↓
Incidence of sacral somatic dysfunction in vaginal delivery after spontaneous labor.
J Osteopath Med · 2026
# Summary Research found that relaxin, a hormone elevated during pregnancy, causes ligamentous laxity that allows the musculoskeletal system to stretch and accommodate fetal growth, but this relaxation contributes to structural changes including lumbar lordosis, pelvic pain, and joint pain that may persist long after delivery. This study demonstrated the incidence and types of sacral somatic dysfunction in postpartum patients and investigated correlations between various demographic factors and the development of these dysfunctions.
Development of a long-acting relaxin for the treatment of pulmonary hypertension.
Br J Pharmacol · 2026
# Summary Research found that TX000045, a long-acting relaxin therapeutic engineered by fusing human relaxin-2 to an immunoglobulin Fc domain, demonstrated an extended half-life of 2–3 weeks and was well-tolerated in early human studies while reducing pulmonary hypertension markers in animal models. This study demonstrated that TX45's pharmacokinetic and pharmacodynamic properties—including vasodilatory effects on renal plasma flow and reductions in cardiac hypertrophy and pulmonary arterial changes—were consistent with preclinical predictions, supporting its advancement toward clinical evaluation for pulmonary hypertension treatment.
[Advances in targeted pharmacotherapies for pulmonary hypertension associated with left heart disease].
Zhonghua Yi Xue Za Zhi · 2026
# Summary Research found that novel therapeutic agents, including activin signaling inhibitors and long-acting relaxin analogs, demonstrated potential benefits in preliminary studies for treating pulmonary hypertension associated with left heart disease. This study highlighted that these agents with distinct mechanisms may offer new treatment avenues for this prevalent form of pulmonary hypertension, where current PAH-targeted therapies have not shown proven efficacy and safety benefits.
A trajectory analysis of blood pressure development during pregnancy. An inception cohort study.
Pregnancy Hypertens · 2026
Reduced serum cortisol, IGF-1, GLP-1, and T3 levels in medication-free children and adolescents with obsessive-compulsive disorder: a case-control study.
Front Psychiatry · 2026
Study on transdermal delivery system of sulforaphane chitosan nanoparticles based on methacryloylated chitosan microneedles: application in the treatment of irritant contact dermatitis.
Int J Pharm · 2026
Divergent activation of the RXFP1 relaxin receptor by protein and small molecule agonists.
bioRxiv · 2026
Association of Relaxin-1 Levels with Mortality in Sepsis and Septic Shock.
J Clin Med · 2026
Relaxin Side Effects & Safety Considerations
Research-use compound. The considerations below are reported from preclinical / non-clinical sources; evidence strength varies — see the Evidence section.
Reported contraindications & considerations
Consult a qualified healthcare professional before making any health decisions. This information is educational only and does not constitute medical advice.
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VSRelaxin
Frequently Asked Questions — Relaxin
Relaxin (relaxin-2; serelaxin; RLX030) is a 53-residue two-chain polypeptide hormone structurally related to insulin, produced primarily by the corpus luteum during pregnancy and by the heart during cardiac stress, that acts through RXFP1 receptors to promote vasodilation, reduce systemic vascular resistance, increase renal perfusion, and attenuate fibrotic signaling — properties that made it a compelling candidate for acute decompensated heart failure, where peripheral vasoconstriction and organ hypoperfusion are central pathophysiological features. RXFP1 activation stimulates cAMP/PKA and nitric oxide signaling to acutely reduce systemic and renal vascular resistance, increase cardiac output without directly affecting heart rate, and suppress TGF-beta-mediated fibrotic remodeling; these hemodynamic and organoprotective mechanisms distinguished relaxin mechanistically from existing vasodilators and diuretics.
connective tissue remodeling, anti-fibrotic, pelvic floor support, fertility support, cardiac protection.
Research on Relaxin primarily documents effects related to connective tissue remodeling and anti-fibrotic and pelvic floor support and fertility support and cardiac protection. These are areas covered in preclinical and clinical literature — individual response varies and effects depend on context of use.
Reported contraindications and considerations for Relaxin include cardiovascular condition, kidney or liver condition, pregnant or nursing. This is educational information only — consult a qualified healthcare professional before use.
For Relaxin, its FDA status is investigational (not FDA-approved), and it is designated for research use only. Regulatory status reflects publicly available information and may change. This is not legal or medical advice.
The RELAX-AHF trial of 1,161 patients demonstrated that serelaxin (recombinant human relaxin-2, 30 μg/kg/day IV) significantly improved the dyspnoea VAS AUC primary endpoint (p=0.007) and reduced 180-day all-cause mortality (HR 0.63, p=0.019) in acute heart failure, establishing the systemic vasodilatory and organ-protective pharmacology of recombinant relaxin-2 in humans and supporting its broader therapeutic relevance as a peptide hormone.
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Where to buy Relaxin
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