Angiotensinamide

Summary

Angiotensinamide is a synthetic peptide analogue of angiotensin II, studied primarily in laboratory settings. It acts as an agonist at angiotensin receptors, producing vasoconstriction, blood‑pressure elevation, and a strong thirst‑stimulating (dipsogenic) response in animal models. Research has examined its pharmacology, structure‑activity relationships, and, more recently, its potential as a scaffold for SARS‑CoV‑2 main protease inhibition.

Mechanism of Action

Angiotensinamide mimics the C‑terminal sequence of angiotensin II and binds to angiotensin II receptors (principally AT1) on vascular smooth muscle and central thirst‑regulating centers. Receptor activation triggers G‑protein‑mediated signaling that raises intracellular calcium, leading to vasoconstriction and increased arterial pressure, while also stimulating thirst pathways. Modifications of the guanidino and phenolic groups alter its affinity and potency, as shown in structure‑activity studies.

What the Research Shows

Early work (1960‑1972) demonstrated that angiotensinamide raises blood pressure in rats and contracts isolated uterine and ileal tissues; structural changes reduced potency variably across tissues. In rats, the peptide produced a pressor response that could be antagonized by related analogues at nanomolar concentrations. A 1980 pigeon study showed that intravenous angiotensinamide induces a robust drinking response, comparable to hypertonic saline. Crystallisation of the peptide was reported in 1971. A 2022 computational analysis identified angiotensinamide among several compounds predicted to bind the SARS‑CoV‑2 main protease, suggesting possible antiviral scaffold properties, though no experimental validation was provided.

Reported Benefits

Animal experiments confirm that angiotensinamide is a potent vasoconstrictor and dipsogen, useful for probing the renin‑angiotensin system. Structure‑activity investigations have clarified which molecular features are critical for activity, informing peptide design. In silico screening highlights a potential new application as a scaffold for SARS‑CoV‑2 protease inhibitors, offering a starting point for drug‑discovery efforts.

Limitations of the Evidence

All functional data are limited to rodents, birds, or computer models; no human pharmacology or safety data exist. The antiviral predictions are purely computational and have not been tested in vitro or in vivo. Antagonism studies were performed at very low concentrations and may not translate to therapeutic contexts. Overall, evidence is preclinical and does not support clinical use.

Safety Considerations

Published studies report dose‑dependent pressor effects in rats and a strong thirst response in pigeons, indicating potential for hypertension and fluid imbalance. No adverse events or toxicity assessments were described in the abstracts. Without human data, safety cannot be established, and caution is warranted if the peptide were to be used experimentally.

How It Is Administered

Experimental investigations have administered angiotensinamide by intravenous or subcutaneous injection, typically as a sterile peptide solution. Formulations described are limited to laboratory preparations; no commercial dosage forms are reported.

Routes of Administration

Goals & Uses

• Pharmacological research toolResearchHigh
• Diagnostic assessment of renin‑angiotensin systemDiagnosticLow
• Acute elevation of blood pressureCardiovascularModerate
• Vasopressor support in distributive shockHemodynamic SupportModerate
• Treatment of refractory hypotensionHemodynamic SupportModerate

Contraindications

• HypervolemiaFluid BalanceModerate
• HypertensionCardiovascularHigh
• PregnancyPopulationModeratePotential fetal risk or insufficient safety data
• Known hypersensitivity to angiotensin analogsAllergy/ImmunologyHigh
• Severe hypertensionCardiovascularHigh

Adverse Effects

• Oliguria / renal impairmentRenalUncommon
• Hypertension / hypertensive crisisCardiovascularCommon
• HypertensionCardiovascularCommonHigh blood pressure
• HeadacheNeurologicUncommonPain in the head or upper neck
• TachycardiaCardiovascularCommonAbnormally fast heart rate
• Hyperkalemia or hypokalemiaMetabolicUncommon
• BradycardiaCardiovascularCommon

Drug Interactions

• AT1 receptor blockers (ARBs)High
• Angiotensin Receptor Blockers (ARBs)High
• Other vasopressors (e.g., norepinephrine, vasopressin)Moderate
• ACE inhibitorsModerate

Population Constraints

• PregnancyReproductive SafetyAbsolute
• Renal impairmentOrgan ImpairmentRelative
• Pediatric patientsAgeRelative
• ElderlyAgeRelative
• Elderly patientsAgeRelative

Regulatory Status

• European UnionUnapprovedClassified as a research chemical; no marketing authorization.
• United StatesUnapprovedAvailable only for research use; not FDA‑approved for therapeutic indication.
• United KingdomUnapprovedNot licensed for clinical use.

Angiotensinamide was previously approved and marketed in some jurisdictions (notably Europe and parts of the Americas) under the brand name Hypertensin for vasopressor use. It is no longer widely commercially available and is considered largely withdrawn or discontinued in most markets. Synthetic angiotensin II has been re-investigated and re-approved in the US (as giapreza) but angiotensinamide specifically is not the same formulation.

Evidence & Sources

• [Testing of angiotensinamide]
  Journal ArticleLowPfeifer S, Wolf I1972-01-01T00:00:00.000000Z
• [Specific antagonism between angiotensin II and several of its analogs]
  Journal ArticleLowMyshliakova NV, et al.1976-01-01T00:00:00.000000Z
• Quantitative structure-activity relationships, molecular docking and molecular dynamics simulations reveal drug repurposing candidates as potent SARS-CoV-2 main protease inhibitors
  Journal ArticleLowde Souza AS, de Souza RF, Guzzo CR2022-01-01T00:00:00.000000Z
• Crystallisation of angiotensinamide II
  Journal ArticleLowFermandjian S, et al.1971-01-01T00:00:00.000000Z
• Regulatory drinking in the pigeon Columba livia
  Journal ArticleLowKaufman S, Peters G1980-01-01T00:00:00.000000Z
• Some pharmacological actions of synthetic analogues of angiotensinamide
  Journal ArticleLowPAIVA TB, PAIVA AC1960-01-01T00:00:00.000000Z

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