BQ-123

Summary

BQ-123 is a cyclic pentapeptide (cyclo[D-Asp-Pro-D-Val-Leu-D-Trp]) originally developed as a selective endothelin-A (ETA) receptor antagonist. It has been extensively used as a pharmacological tool to investigate the role of endothelin in cardiovascular, renal, and pulmonary physiology. It has been administered intravenously in human experimental studies examining conditions such as pulmonary arterial hypertension, heart failure, and hypertension, but it is not approved for clinical use.

Mechanism of Action

Selective competitive antagonist of the endothelin type A (ET-A) receptor, blocking the vasoconstrictive and mitogenic effects of endothelin-1 (ET-1). Inhibits ET-1-mediated vasoconstriction, smooth muscle proliferation, and fibrosis.

Routes of Administration

Goals & Uses

• Hypertension researchCardiovascularModerate
• Pulmonary arterial hypertension (PAH) researchCardiovascularModerate
• Heart failure hemodynamic researchCardiovascularModerate
• Raynaud's phenomenon / peripheral vascular diseaseVascularLow
• Renal vascular physiologyRenalLow

Contraindications

• PregnancyPopulationHighPotential fetal risk or insufficient safety data
• Hypersensitivity to BQ-123 or peptide excipientsAllergic/ImmunologicHigh
• Severe hypotensionCardiovascularHigh

Adverse Effects

• Vasodilation / flushingCardiovascularCommon
• Injection site reactionsLocalUncommon
• HeadacheNeurologicUncommonPain in the head or upper neck
• HypotensionCardiovascularUncommonLow blood pressure

Drug Interactions

• Antihypertensive agentsModerate
• Endothelin-B (ETB) antagonistsModerate
• Phosphodiesterase-5 (PDE5) inhibitorsModerate

Population Constraints

• Pediatric populationsAgeRelative
• Patients with severe hepatic impairmentHepaticRelative
• Pregnant womenReproductiveAbsolute

Regulatory Status

• European UnionUnapprovedNot approved by EMA. Used solely in research settings.
• United StatesUnapprovedResearch tool compound only; not FDA-approved for any indication. Available for laboratory and investigational use.
• United KingdomUnapprovedNot approved by MHRA. Research use only.

Not approved by FDA, EMA, or other major regulatory agencies for any clinical indication. Used exclusively as an investigational/research tool compound in preclinical and early-phase human experimental studies.

Evidence & Sources

No sources recorded yet.