Relaxin-2
Also known as: Serelaxin, RLX-2, Human Relaxin-2
Relaxin-2 is a peptide hormone that acts as a potent vasodilator and anti-fibrotic agent, primarily studied for heart failure and cardiovascular applications. This hormone binds to relaxin family peptide receptors (RXFP1 and RXFP3) to activate multiple signaling pathways that reduce vascular resistance and inhibit collagen deposition.
Relaxin-2 is a 6034.8 Da research peptide. Relaxin-2 is a peptide hormone that acts as a potent vasodilator and anti-fibrotic agent, primarily studied for heart failure and cardiovascular applications. This hormone binds to relaxin family peptide receptors (RXFP1 and RXFP3) to activate multiple signaling pathways that reduce vascular resistance and inhibit collagen deposition.
Also called: Serelaxin, RLX-2, Human Relaxin-2
6034.8
Molecular Weight
Daltons
2
Strong Evidence
benefits
4
Studies Cited
peer-reviewed
10-30
Typical Dose
μg/kg/h
Overview
Relaxin-2 belongs to the insulin-like growth factor superfamily and represents one of the most extensively studied cardiovascular peptides in clinical development. Originally identified for its role in pregnancy and childbirth, relaxin-2 demonstrates remarkable therapeutic potential through its ability to activate endothelial nitric oxide synthase, stimulate VEGF production, and suppress transforming growth factor-beta signaling. The peptide's dual mechanism of acute hemodynamic effects and long-term anti-fibrotic properties makes it particularly valuable for research into heart failure, pulmonary hypertension, and organ fibrosis. Relaxin-2's effects extend beyond the cardiovascular system, influencing renal function, wound healing, and inflammatory responses through complex interactions with extracellular matrix proteins and growth factor cascades.
Key Takeaways: Relaxin-2
- Strongest evidence supports Relaxin-2 for acute heart failure management and anti-fibrotic effects
- Research doses typically range from 10 to 30 μg/kg/h via iv infusion
- 2 benefits with strong evidence, 2 moderate, 2 preliminary
- Half-life: 10-16 minutes (IV)
- 4 cited research studies in this guide
Mechanism of Action
Relaxin-2 binds to relaxin family peptide receptor 1 (RXFP1) on target cells, activating adenylyl cyclase and increasing cAMP levels. This triggers protein kinase A phosphorylation cascades that activate endothelial nitric oxide synthase (eNOS), leading to increased nitric oxide production and subsequent vasodilation. The peptide also stimulates VEGF and basic FGF expression while inhibiting endothelin-1 synthesis. Long-term effects include suppression of TGF-β1 signaling, reduced collagen synthesis by fibroblasts, and enhanced matrix metalloproteinase activity that breaks down existing fibrotic tissue.
Research Benefits
Relaxin-2 at a Glance
Relaxin-2 binds to relaxin family peptide receptor 1 (RXFP1) on target cells, activating adenylyl cyclase and increasing cAMP levels.
Acute Heart Failure Management
Strong EvidenceRelaxin-2 reduces pulmonary capillary wedge pressure and systemic vascular resistance while maintaining cardiac output, providing rapid symptom relief in acute heart failure without increasing heart rate or myocardial oxygen demand.
Anti-Fibrotic Effects
Strong EvidenceThe peptide inhibits collagen synthesis and promotes collagen degradation through MMP activation, preventing and reversing fibrosis in cardiac, pulmonary, renal, and hepatic tissues.
Renal Protection
Moderate EvidenceRelaxin-2 increases renal blood flow and glomerular filtration rate while reducing renal vascular resistance, protecting against acute kidney injury and chronic kidney disease progression.
Pulmonary Hypertension Treatment
Moderate EvidenceThe peptide reduces pulmonary arterial pressure and pulmonary vascular resistance through direct vasodilation and anti-remodeling effects on pulmonary vessels.
Wound Healing Enhancement
PreliminaryRelaxin-2 accelerates wound closure by promoting angiogenesis, reducing scar formation, and enhancing collagen remodeling during the healing process.
Vascular Compliance Improvement
PreliminaryThe peptide increases arterial compliance and reduces arterial stiffness by modulating smooth muscle cell function and extracellular matrix composition in vessel walls.
Research Dosing Protocols
Research Purposes Only: All content is for informational and research purposes only. This site does not provide medical advice, diagnosis, or treatment. Consult a qualified healthcare professional before using any peptide or supplement.
| Research Protocol | Dose Range | Route |
|---|---|---|
| Acute heart failure | 10–30 μg/kg/h | IV infusion |
| Anti-fibrotic studies | 0.5–2 mg/kg/day | SC injection |
| Cardiovascular research | 5–20 μg/kg/h | IV infusion |
| Wound healing studies | 10–50 μg | topical application |
Frequency
Continuous infusion for acute studies, daily injections for chronic protocols
Timing
Infusions typically 48-168 hours for acute studies, daily dosing for 4-12 weeks in chronic studies
Cycle Length
2-7 days for acute protocols, 4-12 weeks for anti-fibrotic studies
Research Notes
- 1Requires continuous cardiac monitoring during infusion
- 2Dose titration based on hemodynamic response
- 3Refrigerated storage required for reconstituted solution
- 4Infusion rate adjustments needed for hypotensive responses
Reconstitution Guide
Standard Reconstitution
Vial Size
1 mg
Bacteriostatic Water
1 mL
Concentration
10 mcg
per 0.1 mL (10 units)
Step-by-Step Guide
Gather Materials
Relaxin-2 vial, bacteriostatic water, alcohol swabs, insulin syringes.
Equilibrate Temperature
Remove the vial from storage and allow it to reach room temperature (5-10 minutes).
Sanitize
Swab the rubber stopper of both the peptide vial and bacteriostatic water vial with alcohol.
Draw Water
Draw 1 mL of bacteriostatic water into a syringe.
Add Water to Vial
Insert the needle into the peptide vial and direct the water stream against the glass wall — not directly onto the powder.
Mix Gently
Swirl the vial gently until the powder is fully dissolved. Never shake. The solution should be clear and colorless.
Store Properly
Refrigerate at 2-8°C. 24-48 hours reconstituted.
Storage Temperature
2-8°C
Shelf Life
24-48 hours reconstituted
Important Notes
- •Use sterile water for injection or normal saline
- •Gentle swirling to dissolve, avoid vigorous shaking
- •Solution should be clear and colorless
- •Single-use vials, discard after reconstitution period
- •Protect from light during storage
Relaxin-2 Dosing Calculator
Calculate daily intake, cycle totals, and vials needed with pre-filled protocols →
Relaxin-2 Reconstitution Calculator
Calculate concentration, syringe units, and doses per vial with auto-filled values →
Safety & Side Effects
Reported Side Effects
- !Hypotension and orthostatic changes
- !Headache and dizziness
- !Nausea and vomiting
- !Injection site reactions (subcutaneous administration)
- !Flushing and peripheral edema
- !Fatigue and weakness
- !Potential arrhythmias with rapid infusion
- !Rebound hypertension after discontinuation
Potential Interactions
- ⚡ACE inhibitors and ARBs may enhance hypotensive effects
- ⚡Diuretics can potentiate volume depletion and hypotension
- ⚡Beta-blockers may mask compensatory tachycardia
- ⚡Vasodilators increase risk of severe hypotension
- ⚡NSAIDs may reduce renal protective effects
Important: Side effects and interactions listed here are compiled from published research and community reports. This is not a complete list. No formal drug interaction studies have been conducted for most research peptides. Always consult a qualified healthcare provider.
Research Studies
The following studies are referenced in this profile. PubMed IDs are provided where available for independent verification.
Serelaxin, recombinant human relaxin-2, for treatment of acute heart failure (RELAX-AHF): a randomised, placebo-controlled trial
Phase 3 trial of 1,161 patients with acute heart failure showed serelaxin reduced cardiovascular mortality and improved dyspnea when added to standard care.
Anti-fibrotic actions of relaxin
Comprehensive review demonstrating relaxin's anti-fibrotic mechanisms across multiple organ systems through inhibition of collagen synthesis and enhanced matrix degradation.
Relaxin reverses cardiac and renal fibrosis in spontaneously hypertensive rats
Animal study showing relaxin treatment reversed established cardiac and renal fibrosis in hypertensive rats through reduced collagen deposition and enhanced matrix turnover.
Effects of serelaxin in acute heart failure patients with renal impairment
Post-hoc analysis of RELAX-AHF trial demonstrated serelaxin's renal protective effects, particularly in patients with baseline renal dysfunction.
Note: This is not an exhaustive list of all published research. Studies are selected for relevance and quality. Click PubMed IDs to verify sources independently. Inclusion does not imply endorsement of the peptide for any clinical use.
Frequently Asked Questions
Relaxin-2 has a very short half-life of 10-16 minutes when given intravenously, requiring continuous infusion for sustained effects. The peptide is rapidly cleared by the kidneys and metabolized by proteases.
While relaxin-2 shows promise for acute heart failure, its extremely short half-life makes it impractical for chronic outpatient use. Research focuses on acute inpatient treatment and developing longer-acting analogs.
Unlike traditional vasodilators, relaxin-2 provides both immediate hemodynamic benefits and long-term anti-fibrotic effects. It reduces afterload without significantly increasing heart rate or myocardial oxygen consumption.
Relaxin-2 may actually provide renal protection by increasing renal blood flow and reducing fibrosis. However, dose adjustments may be needed in severe renal impairment due to altered clearance.
Relaxin-2 is typically given as a continuous intravenous infusion at 10-30 μg/kg/hour for acute studies, or as daily subcutaneous injections for chronic anti-fibrotic research protocols.
The most frequent side effects are hypotension, headache, and nausea. These effects are generally dose-dependent and reversible upon discontinuation or dose reduction.
Yes, relaxin-2 has been studied as an add-on therapy to standard heart failure treatments. However, careful monitoring is required due to potential additive hypotensive effects with ACE inhibitors and other vasodilators.
Once reconstituted, relaxin-2 should be stored at 2-8°C and used within 24-48 hours. The solution should be protected from light and never frozen after reconstitution.
Research & Educational Use Only
All content is for informational and research purposes only. This site does not provide medical advice, diagnosis, or treatment. Consult a qualified healthcare professional before using any peptide or supplement.
The information presented here is compiled from published research studies and is intended for informational purposes only. Individual results may vary. Always consult with a licensed healthcare provider.