Adrenomedullin

What is Adrenomedullin?

Adrenomedullin (AM) is an endogenous 52-amino-acid peptide hormone first isolated and sequenced in 1993 by Kazuo Kitamura, Kenji Kangawa, Hisayuki Matsuo, and Tanenao Eto at Miyazaki Medical College, who purified it from extracts of human pheochromocytoma (an adrenal medullary tumor — hence the name) by tracking its potent platelet cAMP-elevating and vasodilator activity. It belongs to the calcitonin/CGRP peptide superfamily, which also includes calcitonin gene-related peptide (CGRP), amylin, and intermedin/adrenomedullin-2, and shares the family's characteristic intramolecular disulfide-bridged ring and amidated C-terminus. AM is produced by a wide range of tissues — vascular endothelium, vascular smooth muscle, cardiomyocytes, renal tubules, and adrenal medulla being the most prominent — making it more accurately described as a ubiquitous paracrine and autocrine vasoactive mediator than a classic adrenal hormone, despite its name. AM signals through the calcitonin-receptor-like receptor (CLR), a class B G-protein-coupled receptor whose pharmacology depends entirely on which receptor activity-modifying protein (RAMP) it is co-expressed with. The 1998 McLatchie et al. paper in Nature defined the framework: CLR plus RAMP1 yields the CGRP receptor, CLR plus RAMP2 yields the AM1 receptor (the dominant AM receptor in vascular endothelium), and CLR plus RAMP3 yields the AM2 receptor. AM produces potent and long-lasting vasodilation, defends endothelial barrier integrity against inflammatory insult, increases cardiac output, promotes natriuresis and diuresis, and modulates aldosterone and ACTH secretion. AM is not a consumer peptide and not an approved therapeutic — its clinical footprint comes through two distinct translational lines: mid-regional proadrenomedullin (MR-proADM), a stable cleavage product of the AM precursor, used as a prognostic biomarker in sepsis, pneumonia, heart failure, and general cardiovascular risk; and enibarcimab (formerly adrecizumab, AdrenoMed AG), a non-neutralizing humanized monoclonal antibody that binds circulating AM and is hypothesized to redistribute it from the interstitial to the intravascular compartment, restoring endothelial barrier function in septic shock — tested in the AdrenOSS-2 phase 2a trial reported by Laterre and colleagues in 2021.

What Adrenomedullin Is Investigated For

Adrenomedullin is a biology and biomarker story, not a peptide consumers take. Its scientific footprint sits at the intersection of three clinical worlds. In sepsis and septic shock, MR-proADM (mid-regional proadrenomedullin) — a stable surrogate for active AM that is much easier to measure in plasma — has accumulated extensive evidence as a prognostic biomarker for mortality, organ dysfunction, and ICU course, with a 2024 systematic review and meta-analysis (Valeriani et al.) consolidating the case. In cardiovascular medicine, MR-proADM predicts mortality and adverse events in heart failure, post-myocardial-infarction populations, community-acquired pneumonia (the foundational Christ-Crain 2006 paper), and the general adult population (Neumann et al. 2013 Atherosclerosis), with the broader interpretation that AM rises in proportion to endothelial stress and circulatory compromise. The drug-development line is more recent and more uncertain: AdrenoMed AG developed adrecizumab (now renamed enibarcimab), a non-neutralizing humanized monoclonal antibody that binds the N-terminal of AM and is hypothesized to redistribute it from the interstitial space — where it contributes to vascular leak — back into the circulation, where it stabilizes the endothelial barrier. The AdrenOSS-2 phase 2a biomarker-guided trial (Laterre 2021) enrolled septic shock patients with high baseline bio-ADM and reported safety and tolerability with signals of benefit on organ dysfunction and 28-day mortality, supporting advancement to phase 3. The honest framing is that AM is one of the best-validated biomarkers in critical care, a credible drug target that has not yet crossed the regulatory finish line, and a peptide whose endogenous biology argues against any consumer self-administration use case.

History & Discovery

Adrenomedullin was isolated and sequenced in 1993 by Kazuo Kitamura, Kenji Kangawa, Hisayuki Matsuo, and Tanenao Eto at Miyazaki Medical College in Japan, working in the same broad scientific lineage that had earlier produced atrial natriuretic peptide and ghrelin. The team purified extracts of human pheochromocytoma — an adrenal medullary tumor — by tracking a potent platelet cAMP-elevating and vasodilator activity, and identified a 52-amino-acid peptide that they named adrenomedullin for its tissue source. The 1993 Biochemical and Biophysical Research Communications paper founded the field. The peptide's structural family membership — the calcitonin/CGRP superfamily, with characteristic intramolecular disulfide ring and amidated C-terminus — was apparent from the sequence and was confirmed by subsequent receptor studies. The receptor pharmacology was unsettled for the first half-decade after discovery. AM was recognized as binding the calcitonin-receptor-like receptor (CLR), but CLR did not behave as a functional receptor when expressed alone — it required something else. The puzzle was solved by Steven Foord's group at SmithKline Beecham. McLatchie, Fraser, Main, Wise, Brown, Thompson, Solari, Lee, and Foord published the landmark Nature paper in 1998 defining the receptor activity-modifying protein (RAMP) framework: three small single-transmembrane proteins (RAMP1, RAMP2, RAMP3) that chaperone CLR to the cell surface and dictate its ligand selectivity. CLR plus RAMP1 yields the CGRP receptor; CLR plus RAMP2 yields the AM1 receptor; CLR plus RAMP3 yields the AM2 receptor. The RAMP discovery reorganized the entire calcitonin/CGRP family receptor pharmacology and remains the foundational reference for AM receptor biology. The physiological story unfolded across the late 1990s and 2000s. Hinson, Kapas, and Smith summarized the foundational biology in their definitive 2000 Endocrine Reviews paper, by which time AM had been characterized as a ubiquitous paracrine vasoactive peptide produced by endothelium, vascular smooth muscle, cardiomyocytes, kidney, and adrenal medulla — far broader than the name suggests. Caron and Smithies at the University of North Carolina anchored the developmental physiology with their 2001 PNAS paper showing that homozygous AM knockout mice die in utero with extreme hydrops fetalis and major cardiovascular abnormalities, demonstrating that AM is essential for vascular development and barrier integrity. The biomarker chapter began with the development of the MR-proADM (mid-regional proadrenomedullin) sandwich immunoassay by Thermo Scientific BRAHMS, which gave clinicians a stable, reliable surrogate for active AM that was much easier to measure than the rapidly cleared mature peptide. Mirjam Christ-Crain and colleagues in Basel published the foundational 2006 Critical Care paper showing that MR-proADM predicts severity and outcome in community-acquired pneumonia, and the indication subsequently expanded to sepsis (with the 2024 Valeriani systematic review and meta-analysis consolidating the case), heart failure, post-MI, and general-population cardiovascular risk (Neumann 2013 Atherosclerosis; Brouwers 2012 Heart). The drug-development chapter began with AdrenoMed AG, a German biotech founded around the AM-targeting hypothesis. The company developed adrecizumab (HAM8101), a non-neutralizing humanized monoclonal antibody that binds the N-terminal of AM, with the proposed mechanism of redistributing AM from the interstitial to the intravascular compartment to restore endothelial barrier function in septic shock. Preclinical work in murine sepsis models and porcine two-hit models (Geven 2019; Thiele 2020) supported translation. The AdrenOSS-2 phase 2a biomarker-guided trial (Laterre et al., Intensive Care Medicine 2021) enrolled septic shock patients with elevated baseline bio-ADM and reported safety and tolerability with signals of benefit on organ dysfunction and 28-day mortality, supporting advancement to confirmatory phase 3. The molecule was subsequently renamed enibarcimab. As of 2026, enibarcimab remains investigational and no AM-targeted product is approved for any indication. A parallel line of human disease biology was opened by Xie, Chan, and Druey at NIH/NIAID in 2018, who showed that AM surges accompany acute episodes of systemic capillary leak syndrome (Clarkson disease) — a rare and dramatic disorder of recurrent capillary hyperpermeability — directly implicating the AM system in human capillary leak biology and providing additional rationale for AM-targeted therapeutic development.

How It Works

Adrenomedullin is a small protein your body makes that loosens blood vessels and tightens the seal between the cells lining them. It does two things at once: it relaxes the vessel wall (lowering blood pressure and improving blood flow), and it stabilizes the vessel's inner lining so that fluid does not leak out into surrounding tissues. In sepsis and severe inflammation, the body produces a huge amount of adrenomedullin to try to defend the blood vessels — and the level of adrenomedullin in the blood is a strong signal of how sick a patient is. Doctors do not give patients adrenomedullin as a drug. Instead, they measure a stable piece of it (called MR-proADM) to predict outcomes, and a German biotech company has developed an antibody (enibarcimab, formerly adrecizumab) that binds adrenomedullin in a way that may help it work better, currently being tested in septic shock trials.

Adrenomedullin (AM) is a 52-amino-acid peptide produced by proteolytic processing of a 185-amino-acid precursor (preproadrenomedullin), which also yields proadrenomedullin N-terminal 20 peptide (PAMP, a separate vasoactive product) and the inactive but stable mid-regional fragment MR-proADM that is used clinically as an AM surrogate. Mature AM features the calcitonin/CGRP family signature: an intramolecular disulfide bridge between cysteines 16 and 21 forming a six-membered ring, and an amidated C-terminal tyrosine essential for receptor activation. AM signals through the calcitonin-receptor-like receptor (CLR), a class B (secretin-family) G-protein-coupled receptor whose ligand selectivity is determined by its obligatory heterodimerization with one of three single-transmembrane accessory proteins called receptor activity-modifying proteins (RAMP1, RAMP2, RAMP3). The 1998 McLatchie et al. Nature paper defined this framework: CLR + RAMP1 yields the CGRP receptor; CLR + RAMP2 yields the AM1 receptor (the dominant AM receptor in vascular endothelium); CLR + RAMP3 yields the AM2 receptor. Both AM1 and AM2 couple primarily through Gs to activate adenylate cyclase and elevate intracellular cAMP, which is the proximate signal driving most AM effects on vascular tone and barrier function. RAMP3 also couples AM signaling to additional pathways with distinct trafficking and desensitization profiles. Vascular biology is the dominant story. In endothelial cells, AM acting through the AM1 receptor activates protein kinase A and Epac (exchange protein activated by cAMP), stabilizing cortical actin, strengthening VE-cadherin-based adherens junctions, and reducing paracellular permeability. This barrier-stabilizing action is the mechanistic basis for the proposed therapeutic value of AM modulation in septic shock and capillary leak syndromes. In vascular smooth muscle, AM elevates cAMP to relax contractile machinery, producing vasodilation that is more sustained than that of CGRP and contributes to the marked hypotension seen during AM infusion. AM also stimulates endothelial nitric oxide synthase, adding an NO-mediated component to vasodilation and barrier protection. The sepsis biology is bidirectional. AM concentrations rise dramatically during sepsis — by an order of magnitude or more — as a defensive response to endothelial injury, but the same AM that stabilizes the barrier from the luminal (blood-vessel-lumen) side appears to leak into the interstitial compartment where it contributes to ongoing vasodilation and vascular leak by acting on smooth muscle from the abluminal (tissue) side. This dual-sided pharmacology underlies the rationale for adrecizumab/enibarcimab: a non-neutralizing antibody that binds the N-terminal of AM without blocking the C-terminal receptor-binding domain may redistribute AM from interstitium to circulation, restoring barrier function while preserving AM's beneficial signaling. Genetic loss-of-function studies anchor the physiology. Caron and Smithies showed in 2001 that homozygous AM-knockout mice die in utero with extreme hydrops fetalis (massive interstitial fluid accumulation) and major cardiovascular abnormalities — a phenotype consistent with AM's essential role in vascular barrier integrity from earliest development. Heterozygous mice survive but have measurable impairments in vascular barrier function under stress. Beyond the cardiovascular core, AM has documented roles in renal physiology (natriuresis, diuresis, modulation of glomerular hemodynamics), endocrine signaling (modulation of aldosterone and ACTH secretion), reproduction (placental development and maternal vascular adaptation), and inflammation (suppression of pro-inflammatory cytokine production by macrophages). The 2018 Xie et al. paper showed that AM surges accompany acute episodes of systemic capillary leak syndrome (Clarkson disease), a rare disorder of recurrent capillary hyperpermeability — implicating the AM system directly in human capillary leak biology.

Evidence Snapshot

Research Gaps & Open Questions

What the current literature has not yet settled about Adrenomedullin:

• 01Whether enibarcimab (adrecizumab) will deliver mortality benefit in confirmatory phase 3 septic shock trials — the AdrenOSS-2 phase 2a signals are encouraging but not definitive, and sepsis is a graveyard of phase 2 successes that have not survived phase 3.
• 02The optimal patient-selection biomarker threshold for AM-targeted therapy in sepsis — bio-ADM enrichment was used in AdrenOSS-2, but the right cut-off and the right combination with other severity markers (lactate, SOFA, procalcitonin) remain to be defined.
• 03Whether AM-targeted strategies will find indications beyond septic shock — acute heart failure decongestion, vasoplegic shock after cardiac surgery, capillary leak syndromes, and ARDS have all been raised as possibilities but lack definitive trial evidence.
• 04The therapeutic potential of AM agonism (rather than antibody-mediated redistribution) — direct AM infusion or stable AM analogs have been explored in early-phase work but have not advanced, and the right balance between barrier-protective and hypotensive effects of exogenous AM remains unresolved.
• 05The mechanistic basis of the proposed adrecizumab/enibarcimab mode of action — whether the antibody truly redistributes AM from interstitial to intravascular compartments, or whether the apparent beneficial effects derive from a different mechanism (extended half-life, altered receptor signaling kinetics), is not fully established.
• 06Whether MR-proADM should be incorporated into routine ICU and emergency-department triage workflows — the prognostic data are strong, but the operational and cost-effectiveness case for routine use versus existing severity scoring has not been definitively made.
• 07The contribution of AM dysregulation to non-sepsis capillary leak syndromes — Clarkson disease, post-cardiac-surgery capillary leak, severe COVID-19, and engraftment syndrome have all been linked observationally to AM dysregulation, but causal therapeutic targeting has not been demonstrated.

Forms & Administration

Adrenomedullin is not formulated or approved as a consumer or prescription therapeutic in any jurisdiction. Research applications use synthetic human AM(1-52) for in vitro receptor binding, signaling assays, ex vivo vascular preparations, and small numbers of human investigational infusion studies under research protocols. MR-proADM is measured by sandwich immunoassay (the Thermo Scientific BRAHMS MR-proADM KRYPTOR assay is the most widely cited platform) on standard plasma samples. Adrecizumab/enibarcimab is an intravenous humanized monoclonal antibody administered in clinical trial settings only; no commercial product exists. There is no compounded-pharmacy or peptide-marketplace presence for adrenomedullin worth discussing, and any product marketed as 'adrenomedullin' to consumers should be regarded with deep skepticism.

Common Questions

Who Adrenomedullin Is NOT For

Drug & Supplement Interactions

There is no validated human drug-interaction profile for exogenous adrenomedullin because no AM agonist product has been clinically developed. For enibarcimab (adrecizumab), interaction data are limited to the early-phase trial program and no clinically significant pharmacokinetic interactions have been reported. Theoretical interactions follow from AM's known pharmacology. AM is a potent vasodilator acting through cAMP elevation, with potential for additive hypotension when combined with antihypertensive agents (ACE inhibitors, angiotensin receptor blockers, calcium channel blockers, beta-blockers, alpha-blockers, nitrates), phosphodiesterase-5 inhibitors (sildenafil, tadalafil, avanafil), and other vasodilators. AM's calcitonin/CGRP-family receptor architecture creates theoretical cross-talk with CGRP-pathway migraine therapeutics — anti-CGRP monoclonal antibodies (erenumab, fremanezumab, galcanezumab, eptinezumab) and oral CGRP-receptor antagonists (rimegepant, ubrogepant, atogepant, zavegepant) — although no clinically significant interactions have been documented. AM stimulates renin and modulates aldosterone secretion, with theoretical interaction with renin-angiotensin-aldosterone-system blockade, and AM has documented natriuretic and diuretic effects with theoretical additivity with loop and thiazide diuretics. None of these interactions has been characterized in controlled human studies; they are mechanistic possibilities that argue for cautious clinical development rather than documented clinical events.

Safety Profile

Legal Status

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Myths & Misconceptions