peptideNot FDA-approvedResearch chemicalNever approved by the FDA or EMA; the RELAX-AHF-2 trial did not meet its primary endpoints and clinical development for acute heart failure was discontinuedOnly ever administered as an investigational hospital infusion in trials, never sold as a retail product
SerelaxinBenefits, Dosage & Interactions
Serelaxin is a recombinant form of human relaxin-2, a naturally occurring peptide hormone structurally related to insulin. Research on Serelaxin focuses on tissue recovery. Serelaxin is administered by injection rather than orally. Dose, response, and interaction risk vary by individual, so use should be reviewed with a clinician.
Researched by DoseRoutine R&D TeamReviewed for accuracy by Nicholas Alexander, RSELast updated
Evidence: Strong — 1 human randomized trial published.
Evidence strengthStrong · 4/4
PreclinicalStrong human evidence
1 human randomized trial published.
Plasma half-life
Approximately 10 minutes (recombinant human relaxin-2)
Default unit
mg
What published protocols report
Ranges documented in the literature, shown for reference. DoseRoutine does not recommend an amount — your prescriber or the product label sets the dose.
- Reported amounts
- The pivotal RELAX-AHF-2 trial used a fixed 30 µg/kg/hour continuous infusion[1]
- Route studied
- Intravenous infusion in every published trial[1]
- Frequency
- Continuous infusion for up to 48 hours[1]
- Cycle length
- Single hospitalization episode (up to 48 hours) in the trials[1]
- Half-life
- Approximately 10 minutes (recombinant human relaxin-2)[1]
- Storage
- Refrigerated lyophilized vial, reconstituted immediately before infusion in hospital[1]
Reported for Serelaxin in the cited sources. Published ranges are not dosing advice.
References & evidence
Documents the Serelaxin entry is written from. Each number matches an inline marker above.
- [1]Effects of Serelaxin in Patients with Acute Heart FailureMetra M, Teerlink JR, Cotter G, et al. · The New England Journal of Medicine · 2019 · Peer-reviewed · PMID 31433919
- [2]Effects of serelaxin in patients admitted for acute heart failure: a meta-analysisTeerlink JR, Davison BA, Cotter G, et al. · European Journal of Heart Failure · 2020 · Peer-reviewed · PMID 31886953
How to track Serelaxin doses
Serelaxin is tracked as a protocol rather than a single reminder: a vial with a concentration, a schedule that may be titrated or cycled, and a rotation of injection sites. Here is the record that keeps all three consistent.
- 1
Record the vial and concentration
Log the vial strength and the volume of bacteriostatic water you added so Serelaxin is stored as a concentration rather than a guess. DoseRoutine converts that into mg per syringe unit and counts the doses left in the vial as you log.
- 2
Set the schedule, not just a reminder
Enter the dose in mg and the frequency. Cycled protocols get a start and end date so the history stays accurate when Serelaxin comes out of the routine.
- 3
Rotate and log the injection site
Pick the site at the moment you log the dose. The site map shows what you used last and how recently, which is the part that drifts fastest when two compounds run on different frequencies.
- 4
Log adherence, not intentions
Mark each dose taken, skipped or delayed as it happens. Weeks of honest logs are what make an adherence rate or a trend line meaningful; retrospective guessing is not.
- 5
Review against outcomes
Review Serelaxin alongside your logged metrics and any relevant blood work every few weeks before changing the dose, so the change is a response to data rather than to a good or bad day.
What to log each time
- Dose in mg and the syringe units it worked out to
- Vial: reconstitution date, concentration, doses remaining
- Injection site and time
- Any side effects in the 24 h after the dose
References & Evidence
Sources on this page that document Serelaxin dosing, timing and safety.
- [1]National Center for Biotechnology Information View source
Educational information only — not medical advice. Dose ranges vary by person, indication and prescriber.
What is Serelaxin studied for?
What is Serelaxin?Sources for this section: Jumps to this entry in the sources and references list at the end of the page.
Serelaxin is a recombinant form of human relaxin-2, a naturally occurring peptide hormone structurally related to insulin. In humans, relaxin-2 is primarily known for its roles in the female reproductive system, particularly during pregnancy and childbirth, where it mediates connective tissue remodeling and vasodilation. Serelaxin was developed as an investigational drug for the treatment of acute heart failure (AHF). Its physiological effects include vasodilation, anti-fibrotic activity, and anti-inflammatory properties. These actions are mediated through its interaction with relaxin family peptide receptor 1 (RXFP1), primarily found in the heart, kidneys, and blood vessels. The peptide's half-life in the human body is approximately 8 hours, requiring continuous intravenous administration in clinical studies (DrugBank, PubChem).
What does the research say about Serelaxin?
Tap a section to expand.
Serelaxin exerts its pharmacological effects through the activation of relaxin family peptide receptor 1 (RXFP1). This receptor is a G protein-coupled receptor (GPCR) that, upon activation, can trigger various intracellular signaling pathways. In the cardiovascular system, RXFP1 activation by serelaxin leads to a cascade of events that promote vasodilation. This involves increased production of nitric oxide (NO) and prostacyclin, both potent vasodilators, in endothelial cells. The resultant relaxation of blood vessels, particularly in the systemic and renal circulations, contributes to reduced preload and afterload on the heart, which is beneficial in conditions like acute heart failure. Beyond its direct vasodilatory effects, serelaxin also demonstrates anti-fibrotic and anti-inflammatory properties. These actions may involve modulating collagen synthesis and turnover, as well as inhibiting certain inflammatory pathways, potentially contributing to myocardial protection and remodeling. These mechanisms collectively aim to improve hemodynamic function and organ perfusion in acute cardiovascular stress (DrugBank, PubChem).
Source for this section: Sources for How does Serelaxin work?: Jumps to this entry in the sources and references list at the end of the page.
Clinical research has primarily investigated serelaxin for its potential benefits in acute heart failure (AHF). Studies have explored its ability to:
* **Improve symptoms of dyspnea:** Some early trials indicated that serelaxin might alleviate shortness of breath in patients experiencing acute heart failure, as measured by patient-reported breathing ease (Cochrane, ClinicalTrials.gov reports).
* **Reduce organ congestion:** Its vasodilatory and diuretic effects were hypothesized to lessen congestion in various organs, including the lungs and kidneys, which are commonly affected in AHF (Cochrane).
* **Improve renal function:** By promoting renal vasodilation, serelaxin was thought to improve kidney perfusion and potentially mitigate renal dysfunction often associated with acute heart failure (Cochrane).
* **Decrease cardiovascular mortality:** While initial studies showed promise in some endpoints, larger trials were conducted to assess its impact on major cardiovascular events and mortality, though these did not consistently meet primary endpoints (Cochrane, EMA rejection reports).
It is important to note that while some early-phase studies showed potential, larger and more definitive trials did not consistently demonstrate significant clinical benefits in reducing cardiovascular mortality or rehospitalization rates in acute heart failure. Consequently, serelaxin has not received regulatory approval for this indication (EMA SmPC, FDA review documents).
The evidence supporting the use of serelaxin for acute heart failure comes primarily from several large-scale clinical trials. The RELAX-AHF (Relaxin in Acute Heart Failure) program was a key part of its development.
Early phase 2 trials suggested that serelaxin could improve symptoms like dyspnea and might have beneficial effects on cardiovascular and renal outcomes in patients with acute heart failure. These promising results led to larger phase 3 trials.
The RELAX-AHF-2 study, a pivotal phase 3 trial, aimed to confirm these benefits. This randomized, double-blind, placebo-controlled study enrolled a large number of patients with acute heart failure. The primary endpoints were cardiovascular death or worsening heart failure by day 180, and cardiovascular death by day 180. The findings of RELAX-AHF-2 did not demonstrate a statistically significant reduction in either of these primary endpoints. While serelaxin was generally well-tolerated, the study did not meet its primary efficacy goals (Cochrane Review, ClinicalTrials.gov NCT01870766).
Another review by Cochrane evaluating various therapies for acute heart failure noted that while serelaxin showed some early promise in symptom relief, the larger trials did not provide conclusive evidence for hard clinical outcomes such as mortality or rehospitalization. Regulatory bodies, including the European Medicines Agency (EMA) and the U.S. Food and Drug Administration (FDA), reviewed the extensive clinical data. Due to the lack of consistent and significant benefit on major clinical endpoints, serelaxin did not receive marketing authorization for acute heart failure (EMA SmPC rejection documents, FDA review documents).
Clinical trials of serelaxin for acute heart failure have reported various side effects. These are generally mild to moderate in severity. Common side effects observed included:
* Headache
* Nausea
* Hypotension (low blood pressure), which is consistent with its vasodilatory properties
* Tachycardia (increased heart rate)
* Dizziness
* Flushing
More serious but less common side effects reported during clinical investigations included worsening heart failure or renal dysfunction, although these were not consistently attributed solely to serelaxin. The overall safety profile was considered acceptable, but the lack of significant efficacy limited its development. This is educational information, not medical advice — consult a qualified clinician before starting, stopping or combining any compound.
Individuals with certain pre-existing conditions or those on specific medications may need to exercise caution with serelaxin.
* **Hypotension:** Due to its vasodilatory effects, serelaxin can lower blood pressure. Patients who already have low blood pressure or are on medications that lower blood pressure should be monitored carefully.
* **Renal Impairment:** While studies explored potential renal benefits, careful monitoring of kidney function is advised due to the complex interplay between cardiovascular and renal systems in acute heart failure.
* **Pregnancy and Lactation:** As a recombinant human relaxin, its effects on pregnancy and lactation are not fully established in a therapeutic context for acute heart failure. Given relaxin's natural role in pregnancy, caution would be warranted.
Clinical trials have generally indicated that serelaxin was well-tolerated for short-term use in acute settings. However, as it did not receive regulatory approval, broader long-term safety data in diverse populations are not available. This is educational information, not medical advice — consult a qualified clinician before starting, stopping or combining any compound.
Specific contraindications for serelaxin have not been established through regulatory approval processes, as the drug did not obtain marketing authorization. However, based on its pharmacological profile and observed side effects in clinical trials, potential relative contraindications or situations where caution would be strongly advised include:
* **Severe Hypotension:** Patients experiencing severe or uncontrolled low blood pressure, as serelaxin's vasodilatory effects could exacerbate this condition.
* **Cardiogenic Shock:** In conditions of profound circulatory collapse, the acute administration of a vasodilator might be detrimental.
* **Known Hypersensitivity:** Any individual with a known allergy or severe reaction to relaxin or any components of the serelaxin formulation.
Without regulatory approval, a comprehensive list of contraindications, warnings, and precautions is not fully delineated as it would be for an approved medication. This is educational information, not medical advice — consult a qualified clinician before starting, stopping or combining any compound.
Given that serelaxin did not receive regulatory approval and is not commercially available, definitive drug-drug interaction studies with a broad range of medications are not extensively documented in public regulatory databases. However, based on its known vasodilatory mechanism, potential interactions could include:
* **Other Vasodilators:** Concomitant use with other medications that lower blood pressure (e.g., nitrates, ACE inhibitors, ARBs, phosphodiesterase-5 inhibitors) could lead to an additive hypotensive effect, potentially resulting in symptomatic low blood pressure.
* **Diuretics:** While serelaxin was studied alongside diuretics in acute heart failure, close monitoring would be necessary to avoid excessive fluid loss or electrolyte imbalances, given its potential to influence renal function.
As with any investigational agent, clinical judgment and careful monitoring for adverse effects and interactions would be paramount if serelaxin were to be used in a research setting. This is educational information, not medical advice — consult a qualified clinician before starting, stopping or combining any compound.
Serelaxin was administered intravenously in clinical trials, typically as a continuous infusion. The duration of infusion varied depending on the study protocol, often lasting for 24 to 48 hours for patients hospitalized with acute heart failure. Its half-life of approximately 8 hours necessitates continuous administration to maintain therapeutic levels. The timing of administration was generally initiated upon presentation of acute heart failure symptoms, as early intervention was hypothesized to be most beneficial. The formulation was designed for hospital-based use, given the need for intravenous access and continuous monitoring. Specific timing relative to meals (food rule: either) was not a critical factor, given its intravenous route of administration and the acute clinical setting (DrugBank, ClinicalTrials.gov reports).
Source for this section: Sources for When should you take Serelaxin?: Jumps to this entry in the sources and references list at the end of the page.
What interacts with Serelaxin?
| Interacts with | Severity | Type | What happens | What to do |
|---|---|---|---|---|
| Any peptide + hormone | Note | Category ruleConfidence: theoretical | Injectable peptides plus hormones can have overlapping or compounding effects that aren't always well characterized.Source pending | Track bloodwork with a provider; don't assume combinations are neutral. |
Frequently asked questions about Serelaxin
Serelaxin is a research peptide. The references summarized come from NIH and PubMed records, FDA labeling where it exists, and Mayo Clinic patient material.
Serelaxin is commonly discussed in the context of supporting recovery. Individual response varies, and use should be reviewed with a licensed clinician who can weigh the benefits and risks for your situation.
For Serelaxin, it is typically administered by injection and it is typically taken null. Always follow the specific dose your clinician or the product label prescribes.
Serelaxin carries potential side effects and drug interactions, documented in NIH, Mayo Clinic, and FDA label sources. Stop use and contact a clinician if you experience unexpected symptoms.
As a peptide, Serelaxin can overlap with other supplements, prescription medicines, hormones and peptides. Risk depends on dose, timing and what else is taken the same day, so each pairing has to be checked rather than assumed safe. The free checker at https://doseroutine.com/interaction-checker covers Serelaxin with no sign-up.
Whether Serelaxin fits alongside testosterone replacement therapy depends on the protocol — dose, ester and ancillaries such as HCG or anastrozole — and on current bloodwork. No general contraindication applies across every TRT protocol, so confirm the combination with the prescribing clinician. See the free TRT interaction reference: https://doseroutine.com/trt-supplement-interactions
"Peptides" is not one category — healing peptides, GLP-1 agonists, growth-hormone secretagogues and melanocortins each behave differently next to Serelaxin. Check the combination peptide by peptide rather than as one group, and review it with a clinician familiar with peptide protocols.
Published frequency for Serelaxin varies by protocol and formulation, so the label or prescription is what sets it. Frequency is a clinical decision, not a fixed rule — confirm it with the prescriber or product label. Comparison of apps that keep a schedule like this: https://doseroutine.com/best-dose-tracking-apps
The effect of a missed dose of Serelaxin depends on the protocol and formulation you are on. For injectable protocols, shifting the next injection is usually preferred over doubling it. Follow the missed-dose instructions on your label or from your clinician, and log the miss so the pattern is visible later rather than forgotten.
For an injectable like Serelaxin the record needs more than a checkbox: vial concentration, the measured volume, and which site the last injection went into. A written log or spreadsheet works for planning but does not remind you or flag conflicts — see the honest comparison at https://doseroutine.com/vs/spreadsheet and the wider roundup at https://doseroutine.com/best-dose-tracking-apps — DoseRoutine tracks the schedule, the remaining supply and interactions with the rest of your routine in one place.
Which studies looked at Serelaxin?
Peer-reviewed research indexed in PubMed. Each entry links to the original record.
- 1.Effects of Serelaxin in Patients with Acute Heart Failure(opens PubMed in a new tab)N Engl J Med · 2019 · PMID 31433919 · https://pubmed.ncbi.nlm.nih.gov/31433919/
- 2.Serelaxin and acute heart failure(opens PubMed in a new tab)Heart · 2016 · PMID 26603680 · https://pubmed.ncbi.nlm.nih.gov/26603680/
- 3.Serelaxin in acute heart failure: Most recent update on clinical and preclinical evidence(opens PubMed in a new tab)Cardiovasc Ther · 2017 · PMID 27727514 · https://pubmed.ncbi.nlm.nih.gov/27727514/
- 4.Effects of serelaxin in patients admitted for acute heart failure: a meta-analysis(opens PubMed in a new tab)Eur J Heart Fail · 2020 · PMID 31886953 · https://pubmed.ncbi.nlm.nih.gov/31886953/
Sources cited on this page
Specific documents referenced by the numbered markers above. Each number matches the marker in the text.
- PubChem CID 71300755(opens in a new tab)National Center for Biotechnology Information · pubchem.ncbi.nlm.nih.gov/compound/71300755
Verify at
Publisher search links for Serelaxin. These are places to check the information — they are not citations, so they are not numbered.
- Cochrane Library(publisher search, opens in a new tab)Cochrane · publisher search
- ClinicalTrials.gov(publisher search, opens in a new tab)U.S. National Library of Medicine · publisher search
- DrugBank(publisher search, opens in a new tab)DrugBank Online · publisher search
- European Medicines Agency(publisher search, opens in a new tab)European Medicines Agency · publisher search
- FDA-approved labeling (DailyMed)(publisher search, opens in a new tab)U.S. Food and Drug Administration · publisher search
- PubMed literature search(publisher search, opens in a new tab)National Library of Medicine · publisher search
- Wikipedia entry(publisher search, opens in a new tab)Wikipedia · publisher search
DoseRoutine compiles summaries from publicly available scientific and regulatory references. Always verify important decisions with a licensed clinician. How we source and review this information.
What is the short answer on Serelaxin?
Plain-text summary, safe to quote verbatim:
Serelaxin is a recombinant form of human relaxin-2, a naturally occurring peptide hormone structurally related to insulin. Research on Serelaxin focuses on tissue recovery. Serelaxin is administered by injection rather than orally. Dose, response, and interaction risk vary by individual, so use should be reviewed with a clinician.
Source: DoseRoutine — https://doseroutine.com/library/serelaxin
Cite this page
Using this in an article, AI answer, or research note? Please attribute:
DoseRoutine. (2026). Serelaxin — Overview, Benefits & Side Effects. Retrieved from https://doseroutine.com/library/serelaxin
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Other compounds studied for the same benefits as Serelaxin.
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