Angiotensin II

What is Angiotensin II?

Angiotensin II is an 8-amino-acid endogenous peptide (Asp-Arg-Val-Tyr-Ile-His-Pro-Phe) generated in plasma and tissues as the terminal effector of the renin-angiotensin-aldosterone system (RAAS). It begins as angiotensinogen, a liver-secreted alpha-2 globulin, which renin (released from juxtaglomerular cells of the kidney in response to low renal perfusion pressure, low tubular sodium, or sympathetic stimulation) cleaves to release the 10-residue angiotensin I. Angiotensin-converting enzyme (ACE) — the same enzyme that degrades bradykinin — then removes a C-terminal dipeptide to produce the 8-residue angiotensin II, the active hormone. Acting at two G-protein-coupled receptors, AT1 and AT2, angiotensin II is the body's most potent endogenous vasoconstrictor: it raises systemic vascular resistance, stimulates adrenal cortical release of aldosterone (driving renal sodium and water retention), constricts the efferent renal arteriole to preserve glomerular filtration in low-flow states, triggers thirst and vasopressin release via central actions, and promotes cardiovascular remodeling over time. In December 2017 the FDA approved synthetic angiotensin II (Giapreza, originally LJPC-501, developed by La Jolla Pharmaceutical and now marketed by Innoviva/La Jolla) as a continuous IV infusion to raise blood pressure in adults with septic or other distributive shock — the clinical peptide drug derived directly from the native sequence. The peptide is also uniquely important as the target of the world's most heavily prescribed drug classes: ACE inhibitors (lisinopril, enalapril, ramipril) that block its generation, and angiotensin receptor blockers (ARBs, e.g., losartan, valsartan) that block its action at AT1.

What Angiotensin II Is Investigated For

Angiotensin II is unusual on this site because it is simultaneously three different things: a foundational endogenous hormone, an approved peptide drug, and the receptor target of the most heavily prescribed medication classes in the world. As a drug, synthetic angiotensin II (Giapreza) is an ICU-only continuous IV infusion approved in December 2017 on the basis of the ATHOS-3 trial (Khanna et al., NEJM 2017), which randomized 321 adults with catecholamine-resistant vasodilatory shock to angiotensin II or placebo added to standard-of-care vasopressors. The primary endpoint — a sustained mean arterial pressure response of 75 mm Hg or a ≥10 mm Hg rise by 3 hours — was met in 69.9% of the angiotensin II arm vs. 23.4% of placebo (p<0.001), with meaningful reduction in background catecholamine requirements. Twenty-eight-day mortality was numerically lower (46% vs. 54%) but did not reach statistical significance. Post-hoc analyses of the subgroup with severe AKI requiring renal replacement therapy (Tumlin et al., Critical Care Medicine 2018) showed improved survival and higher rates of RRT discontinuation with angiotensin II, a signal that has shaped how the drug is positioned in practice even though it was not prespecified. As a system target, the RAAS is arguably the most important pharmacologic pathway in cardiovascular medicine: ACE inhibitors reduce mortality in heart failure with reduced ejection fraction, slow progression of diabetic and non-diabetic CKD, and reduce cardiovascular events post-MI; ARBs do the same and also trigger AT2-receptor signaling that may add counter-regulatory vasodilatory benefit. Tens of millions of people take a drug aimed at angiotensin II every day. The honest caveat is that native angiotensin II is not a wellness peptide — it is not self-administered, has a plasma half-life under a minute, and its therapeutic use is confined to monitored ICU vasodilatory shock. The ATHOS-3 trial was not powered for mortality, and signals in subgroups (AKI, RRT, high-renin phenotypes) have shaped practice ahead of large confirmatory trials.

History & Discovery

The angiotensin II story spans 120 years and three continents, and it is one of the longer arcs in modern endocrine pharmacology. The starting point is Helsinki in 1898, when Robert Tigerstedt, a Finnish physiologist at the Karolinska Institute in Stockholm, and his assistant Per Gustav Bergman reported that injection of saline or glycerin extracts of rabbit kidney into a recipient animal produced a consistent, reproducible rise in blood pressure. They named the pressor principle 'renin' — from 'ren,' Latin for kidney. The work was published in the Scandinavian Archives of Physiology. Tigerstedt and Bergman's finding was accurate and carefully controlled, but it lay essentially dormant for more than thirty years, in part because it did not fit the prevailing understanding of hypertension. The revival came in 1934 when Harry Goldblatt, a pathologist at Western Reserve University in Cleveland, developed the first reproducible experimental model of renovascular hypertension — the 'Goldblatt kidney,' produced by partial clamping of a renal artery. Goldblatt's dogs became hypertensive, demonstrating that reduced renal perfusion could drive sustained blood pressure elevation and linking the kidney to hypertension in a way Tigerstedt's isolated extracts had hinted at but not proven. In 1939-1940, two groups independently identified the pressor substance released by ischemic kidneys. In Buenos Aires, Eduardo Braun-Menendez and colleagues Juan C. Fasciolo, Luis F. Leloir, and Juan M. Munoz, working at the University of Buenos Aires and the Institute of Experimental Physiology and Medicine, isolated a pressor peptide from renal venous blood of ischemic kidneys and named it 'hipertensina' (anglicized as 'hypertensin'). At almost the same moment, Irvine H. Page and Oscar M. Helmer at the Eli Lilly Laboratories (and subsequently at the Cleveland Clinic) isolated what they concluded was the same substance and named it 'angiotonin.' The two names were synonyms for the same hormone, the product of an enzymatic reaction between renin and a plasma substrate. In 1958, at the University of Michigan's Ann Arbor conference on the basic mechanisms of arterial hypertension (organized in part by David F. Bohr), Braun-Menendez and Page met and agreed — in a remarkable piece of scientific diplomacy — to abandon both of their preferred names in favor of a hybrid: 'angiotensin,' taking the 'angio-' prefix from angiotonin and the '-tensin' suffix from hypertensin. The substrate became 'angiotensinogen' by the same construction. The biochemistry matured through the 1950s and 1960s in the hands of Leonard Skeggs, Joseph Kahn, and Norman Shumway at Western Reserve University. Their 1956 Journal of Experimental Medicine papers — 'The existence of two forms of hypertensin,' 'The purification of hypertensin II,' 'The preparation and function of the hypertensin-converting enzyme,' and 'The amino acid composition of hypertensin II' — established the two-step cascade: renin cleaves angiotensinogen to release the 10-residue angiotensin I (inactive), and a converting enzyme (later named angiotensin-converting enzyme, ACE) then removes a C-terminal dipeptide to produce the 8-residue angiotensin II (active). Full amino acid sequencing followed, confirming the octapeptide Asp-Arg-Val-Tyr-Ile-His-Pro-Phe. The therapeutic revolution followed in the 1970s. Sergio Ferreira, a Brazilian pharmacologist, had identified bradykinin-potentiating factors in the venom of the Brazilian pit viper Bothrops jararaca — the same snake whose venom gave rise to bradykinin itself. John Vane's lab at the Royal College of Surgeons of England demonstrated that the snake venom peptides inhibited ACE. Miguel Ondetti, David Cushman, and colleagues at the E.R. Squibb Institute then rationally designed a small-molecule ACE inhibitor, captopril (first synthesized 1975, approved 1980), followed by the structurally related enalapril, lisinopril, ramipril, and others. The angiotensin receptor blockers (ARBs) — losartan first, approved 1995, then valsartan, irbesartan, and others — extended the pharmacologic attack to the receptor level. Today, ACE inhibitors and ARBs together are the most heavily prescribed cardiovascular drug class in the world, with mortality benefit in heart failure, post-MI, and CKD established by dozens of large RCTs. The native peptide itself had been used episodically in experimental hypotension and shock for decades — synthetic angiotensin II was available as a research reagent and, before standardized trials, was administered to raise blood pressure in selected clinical cases. But it was not an approved or standardized drug. La Jolla Pharmaceutical Company, based in California, developed a standardized synthetic angiotensin II acetate preparation as LJPC-501 and ran the Phase 3 ATHOS-3 trial (Angiotensin II for the Treatment of High-Output Shock; Khanna et al., NEJM 2017). The FDA approved the product as Giapreza on December 21, 2017 — the first new class of pressor drug in decades, and one of the only examples of a native human peptide sequence approved for intravenous use in critical care. The post-hoc AKI and RRT signals from Tumlin et al. (Critical Care Medicine 2018) have shaped how clinicians position the drug, although no dedicated confirmatory mortality trial has been completed. La Jolla was acquired by Innoviva in 2022, which now markets Giapreza.

How It Works

Angiotensin II is the body's main 'tighten the vessels and hold onto water' signal. Your kidneys release renin when blood pressure or blood volume drops; renin kicks off a two-step cascade that produces angiotensin II, which then clamps down on blood vessels, tells the adrenal glands to release aldosterone (which makes the kidneys hold onto salt and water), and sends a thirst signal to the brain. Blood pressure pills like lisinopril work by stopping the enzyme that makes angiotensin II, and drugs like losartan work by blocking angiotensin II at its receptor. A synthetic version (Giapreza) is infused in the ICU for shock patients whose blood pressure won't respond to standard drugs.

Angiotensin II sits at the apex of the renin-angiotensin-aldosterone system cascade. The sequence: liver hepatocytes continuously secrete angiotensinogen (a 452-amino-acid alpha-2 globulin) into circulation. Juxtaglomerular cells of the renal afferent arteriole release renin in response to three stimuli — reduced renal perfusion pressure detected at the afferent arteriole, reduced distal tubular sodium delivery detected by the macula densa, and beta-1-adrenergic sympathetic stimulation. Renin cleaves angiotensinogen to release the 10-residue angiotensin I (Asp-Arg-Val-Tyr-Ile-His-Pro-Phe-His-Leu). Angiotensin-converting enzyme (ACE, a zinc metallopeptidase expressed at high density on pulmonary vascular endothelium and on endothelial cells throughout the body) then cleaves the C-terminal His-Leu dipeptide to produce the 8-residue angiotensin II. ACE is the same enzyme that degrades bradykinin — which is why ACE inhibition produces both reduced angiotensin II and elevated bradykinin tone, the latter accounting for the characteristic dry cough (10-20% incidence) and rare angioedema associated with drugs like lisinopril and enalapril. Tissue chymase and other peptidases can also convert angiotensin I to angiotensin II independent of ACE, and this 'ACE-escape' pathway explains why ACE inhibition does not eliminate angiotensin II entirely. Angiotensin II acts at two principal G-protein-coupled receptors. The AT1 receptor, Gq-coupled and predominantly expressed on vascular smooth muscle, adrenal cortex, renal proximal tubule, brain cardiovascular centers, and cardiomyocytes, mediates essentially all of the classical effects of angiotensin II: arteriolar vasoconstriction (the dominant pressor mechanism), aldosterone release from zona glomerulosa cells of the adrenal cortex (which then drives renal sodium reabsorption and potassium excretion in the distal nephron), efferent renal arteriolar constriction preferentially over afferent (preserving glomerular filtration in low-flow states but also producing the characteristic rise in serum creatinine when ACE inhibitors or ARBs are started), proximal tubular sodium reabsorption, central-nervous-system drives for thirst and for vasopressin release, sympathetic facilitation, myocardial hypertrophy, and fibroblast proliferation with collagen deposition. The downstream signaling cascade from AT1 includes phospholipase C activation, IP3/DAG generation, calcium mobilization, protein kinase C activation, reactive oxygen species production via NADPH oxidase, MAP kinase activation (ERK1/2, JNK, p38), and transactivation of receptor tyrosine kinases such as EGFR. The AT2 receptor, counter-intuitively, appears to oppose many AT1 effects — it couples (via G proteins and direct signaling) to nitric oxide synthase activation, bradykinin release, and cGMP generation, producing vasodilation, antiproliferation, and anti-fibrotic effects in multiple tissues. AT2 is highly expressed fetally, is downregulated postnatally, and becomes re-expressed in pathological states. The counter-regulatory arm also includes angiotensin-(1-7), a 7-amino-acid peptide generated from angiotensin II by ACE2 (the same ACE2 that serves as the SARS-CoV-2 entry receptor), acting at the Mas receptor to produce vasodilation, anti-fibrotic, and anti-inflammatory effects opposite to angiotensin II's AT1 actions. Plasma half-life of circulating angiotensin II is roughly 15-30 seconds — the peptide is cleared rapidly by multiple angiotensinases. This very short half-life is why therapeutic angiotensin II (Giapreza) must be given as a continuous IV infusion rather than intermittent dosing, and why ACE-inhibitor and ARB therapy produces sustained RAAS modulation despite angiotensin II itself being a transient signal. In septic and other vasodilatory shock, the pathophysiologic rationale for exogenous angiotensin II is a combination of three strands. First, profound peripheral vasodilation (driven by inducible NO synthase, activated vascular potassium channels, and loss of vasomotor tone) produces hypotension that responds inadequately to catecholamines as catecholamine receptors desensitize at high background doses. Second, renin is often elevated but angiotensin II production can be relatively inadequate — analogous to the relative vasopressin deficiency recognized in septic shock. Third, augmenting angiotensin II provides vasoconstriction via a pathway (AT1-Gq) that is not subject to adrenergic desensitization, permitting catecholamine dose reduction while maintaining or improving MAP.

Evidence Snapshot

Research Gaps & Open Questions

What the current literature has not yet settled about Angiotensin II:

• 01Mortality benefit in the overall vasodilatory-shock population — ATHOS-3 was not powered for mortality, the primary endpoint was MAP response, and a dedicated confirmatory mortality trial has not been completed. Post-hoc AKI and RRT signals are hypothesis-generating rather than definitive.
• 02Optimal timing of initiation — whether to start angiotensin II early (at lower norepinephrine doses) or reserve for refractory shock is not settled by current evidence, although exploratory ATHOS-3 post-hoc analysis suggests early initiation may be preferable.
• 03Identification of responder phenotypes — renin-guided dosing has been proposed as a biomarker approach (higher baseline renin predicting larger angiotensin II benefit, reflecting a true RAAS-deficiency phenotype), but this approach is not standardized or widely implemented.
• 04AT2 receptor-selective agonists — the counter-regulatory, vasodilatory, and anti-fibrotic effects of AT2 signaling offer an orthogonal therapeutic angle that has produced compounds like compound 21 in preclinical testing but no approved drug to date.
• 05Angiotensin-(1-7)/Mas axis therapeutics — the protective arm of the RAAS is of substantial translational interest for cardiovascular and pulmonary conditions but has not yet produced an approved agent; interest was heightened during the COVID-19 pandemic given the ACE2-SARS-CoV-2 interaction.
• 06Long-term outcomes in shock survivors exposed to exogenous angiotensin II — whether transient exposure during an ICU stay has detectable durable effects on vascular, renal, or cardiovascular phenotype is essentially uncharacterized given that the drug has only been approved since 2017.
• 07Pediatric vasodilatory shock — ATHOS-3 enrolled adults only, and angiotensin II dosing, safety, and efficacy in pediatric shock have not been established in randomized trials.
• 08Use in cardiogenic and post-cardiopulmonary-bypass shock — growing observational and small-RCT data, but the drug is not currently approved for these indications, and whether it adds benefit in cardiogenic as opposed to vasodilatory physiology remains open.

Forms & Administration

Clinical angiotensin II is marketed as Giapreza (synthetic human angiotensin II acetate), supplied as a sterile concentrate for IV infusion (2.5 mg/mL, packaged as 1 mL or 2 mL single-dose vials) that must be diluted in 0.9% sodium chloride before administration. The recommended starting dose is 20 ng/kg/min by continuous IV infusion, preferably through a central venous line, with titration in increments of up to 15 ng/kg/min every 5 minutes as needed to achieve a target mean arterial pressure (typically 65-75 mm Hg). The label specifies a cap of 80 ng/kg/min in the first 3 hours and a maintenance-dose cap of 40 ng/kg/min thereafter. Doses as low as 1.25 ng/kg/min may be used when weaning. Angiotensin II is not meaningfully absorbed orally, has a plasma half-life under a minute, and is not administered by any other route in routine care. It is a hospital- and ICU-restricted medication requiring continuous invasive blood pressure monitoring, and concurrent pharmacologic VTE prophylaxis is part of the labeled expectation. There is no legitimate outpatient, compounded-pharmacy, wellness, or self-administered context for angiotensin II; the peptide is not approved and has no rational clinical indication outside the monitored-ICU setting.

Dosing & Protocols

The ranges below reflect protocols commonly discussed in the literature and by clinicians — not a prescription. Actual dosing for any individual should be determined by a qualified healthcare provider who knows the patient.

Angiotensin II (Giapreza) is a hospital- and ICU-restricted drug with FDA approval only for adult septic or other distributive shock. It has no outpatient, self-administered, or wellness indication. Compounded or research-grade angiotensin II sold outside the regulated pharmaceutical supply chain is not equivalent to Giapreza and should not be used in any clinical context.

Timeline of Effects

Common Questions

Who Angiotensin II Is NOT For

Drug & Supplement Interactions

Angiotensin II's clinically relevant drug interactions fall into three categories: RAAS-axis drugs that modify its expected pressor response, other vasoactive agents that produce additive or synergistic hemodynamic effects, and thrombosis-modifying therapies that interact with the drug's thromboembolic signal. ACE inhibitors (lisinopril, enalapril, ramipril, and class-mates): patients on ACE inhibitors present an amplified pressor response to exogenous angiotensin II because the downstream receptor pool is not downregulated and endogenous angiotensin II production is suppressed, so the receptor binding site is available. Clinical implication: start at the low end of the dose range and titrate carefully in patients with recent ACE inhibitor exposure. Angiotensin receptor blockers (losartan, valsartan, olmesartan, candesartan, telmisartan, irbesartan, azilsartan): these drugs competitively block AT1 and will blunt the pressor response to exogenous angiotensin II. Clinical implication: a larger dose may be required, and response is less predictable — anticipate either attenuated effect or, if drug offset is ongoing during the shock episode, variable pressor response. Direct renin inhibitors (aliskiren): effect on exogenous angiotensin II pressor response is less well characterized; endogenous angiotensin II production is suppressed but receptor binding is not blocked, so behavior likely resembles the ACE inhibitor pattern. Other catecholamine and non-catecholamine pressors (norepinephrine, epinephrine, phenylephrine, vasopressin): by design, angiotensin II is typically used in combination with norepinephrine and vasopressin in catecholamine-refractory shock. The effects are synergistic rather than antagonistic — the clinical task is titrating the combination to achieve target MAP without cumulative ischemic burden. No pharmacologic antagonism to flag, but cumulative vasoconstrictor exposure and concurrent thromboprophylaxis should be monitored. Corticosteroids (particularly hydrocortisone in septic shock): concurrent steroid administration (now standard in vasopressor-refractory septic shock per Surviving Sepsis guidance) can potentiate the pressor effect of angiotensin II and other vasoactive agents via upregulation of vascular adrenergic receptor expression. This is generally a useful rather than adverse interaction in practice. Anticoagulants and antithrombotic therapies: the ATHOS-3 thromboembolic signal (13% vs. 5%) argues for concurrent pharmacologic VTE prophylaxis in all patients receiving angiotensin II in the absence of contraindication, and the drug's label explicitly specifies this expectation. Interactions in the usual pharmacokinetic sense do not apply, but the combined need for anticoagulation and vasoactive therapy must be planned. Estrogen-containing therapy and high-dose progesterone: these may upregulate angiotensinogen production, affecting baseline RAAS activity but with unclear implications for short-term exogenous angiotensin II dosing. Because angiotensin II is cleared by plasma angiotensinases and not by cytochrome P450 pathways, no significant CYP-mediated interactions are expected. Outside the ICU context, the far more important practical drug-interaction story for angiotensin II involves the ACE inhibitors and ARBs that target the system: their interactions with potassium-sparing diuretics (hyperkalemia), NSAIDs (reduced antihypertensive effect and acute kidney injury risk), lithium (increased lithium levels), and each other (dual RAAS blockade is avoided because of increased adverse renal and hyperkalemic events). That is a separate topic from Giapreza itself and is covered in the lisinopril/losartan literature.

Safety Profile

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Myths & Misconceptions