Quick summary
Bradykinin is a 9-amino acid endogenous vasodilator and pain-sensitizing mediator generated by the kallikrein-kinin system. Its B2 receptor antagonist Icatibant is FDA-approved for hereditary angioedema, and bradykinin potentiation by ACE inhibitors explains the cough side effect of that drug class.
Overview
Bradykinin is an endogenous nonapeptide generated from kininogens by the enzyme kallikrein. It is a potent vasodilator and pain-sensitizing mediator involved in inflammation, blood pressure regulation, and the pain cascade. Its receptor antagonist Icatibant is FDA-approved for treatment of hereditary angioedema (HAE), validating the clinical significance of this kinin pathway.
Mechanism of action
Bradykinin acts on two G-protein-coupled receptors: B1 (inducible, involved in chronic inflammation) and B2 (constitutively expressed, mediates acute effects). B2 receptor activation stimulates phospholipase C, increases intracellular calcium, triggers nitric oxide synthase, and releases prostaglandins. These combined effects produce vasodilation, increased vascular permeability, smooth muscle contraction, and sensitization of nociceptors underlying pain and inflammation.
Dosing protocols
| Purpose | Route | Dosage | Frequency | Notes |
|---|---|---|---|---|
| cardiovascular/pain research | intravenous | 100–1000 ng/kg/min | continuous infusion per protocol |
Dosing information is for educational purposes only. Consult a qualified healthcare professional before using any peptide.
Research summary
Bradykinin is extensively studied in cardiovascular physiology, pain research, and inflammatory disease. Its role in ACE inhibitor-induced cough (potentiation of bradykinin via reduced degradation) is well established. Icatibant, a B2 receptor antagonist, received FDA approval in 2011 for HAE. Ongoing research examines bradykinin's role in COVID-19 pathophysiology and potential therapeutic targets in the kinin-kallikrein system.[1][2][3][4]
Evidence grading
Each claimed benefit is graded by the strength of available evidence. Grades reflect study quality, not effect size.
Strong = multiple RCTs · Moderate = limited trials or observational · Preliminary = animal or in vitro only · Insufficient = anecdotal or no published data
Side effects
Side effects vary by individual. This is not an exhaustive list. Report unusual symptoms to a healthcare professional.
Common stacks
Peptides commonly paired with Bradykinin for synergistic effects.
Legal status
Bradykinin itself is a research compound. Icatibant (Firazyr), a bradykinin B2 receptor antagonist, is FDA-approved as a prescription drug for hereditary angioedema and requires a prescription.
Sourcing & access
Research compound
Bradykinin is classified as a research compound. Regulatory status varies by jurisdiction. Always verify current legal status and source from vendors providing third-party certificates of analysis (COA).
Frequently asked questions
Bradykinin is an endogenous nonapeptide generated from kininogens by the enzyme kallikrein. It is a potent vasodilator and pain-sensitizing mediator involved in inflammation, blood pressure regulation, and the pain cascade.
Bradykinin acts on two GPCRs: B1 (inducible, involved in chronic inflammation) and B2 (constitutively expressed, mediating acute effects). B2 receptor activation stimulates phospholipase C, increases calcium, triggers nitric oxide synthase, and releases prostaglandins, producing vasodilation, increased vascular permeability, and pain sensitization.
Bradykinin is a research compound with an extremely short half-life of about 17 seconds. Effects include hypotension, flushing, pain at injection site, and bronchoconstriction. Icatibant, a B2 receptor antagonist, is FDA-approved for hereditary angioedema and has an established clinical safety profile.
ACE (angiotensin-converting enzyme) also degrades bradykinin. ACE inhibitors reduce bradykinin breakdown, leading to accumulation that causes the well-known dry cough side effect in approximately 10-20% of patients. This potentiation also contributes to the vasodilatory benefits of ACE inhibitor therapy.
Research references
- Bradykinin and the kallikrein-kinin system in cardiovascular homeostasisPubMed
- Bradykinin B2 receptor antagonist icatibant in hereditary angioedemaPubMed
- Role of bradykinin in ACE inhibitor cardiovascular protection beyond blood pressurePubMed
- Kinin receptors: pharmacology and therapeutic implicationsPubMed