B7-33

Key points

• B7-33 is a single chain peptide based on part of human relaxin, a hormone involved in softening tissue.
• It is studied for anti fibrotic effects, meaning reducing the scarring that can stiffen organs.
• All the evidence is preclinical, from rodent and laboratory studies.
• It is not a licensed medicine in the UK and is sold only for research use.

Quick facts

What it is

Experimental relaxin based peptide

Studied for

Reducing fibrosis and scarring

UK status

Not a licensed medicine; sold for research use

Human evidence

None; animal and laboratory studies only

How it works

B7-33 activates the relaxin receptor in a selective way, favouring the signalling linked to reducing fibrosis and relaxing blood vessels, along with nitric oxide release. In animal models this has been studied in the heart, kidneys and blood vessels. Whether it does anything useful in people is untested.

What the evidence shows

All the data is preclinical: rodent models and laboratory work on fibrosis and the circulation. There are no registered or published human trials, and no established dose or safety picture in people.

What it does not settle

• There are no human trials of benefit or safety.
• Human dosing and pharmacology are unknown.
• Long term safety is unknown.

Side effects

Less common but serious

• Because it relaxes blood vessels in animals, low blood pressure is a theoretical concern in people.
• Because there is no licensed product, the dose, purity and contents of material bought online cannot be verified.

Report any suspected side effect through the MHRA Yellow Card scheme.

UK legal status and access

B7-33 has no UK marketing authorisation, so it is not a licensed medicine and is not offered by registered clinics or pharmacies. It is sold online as a research chemical.

Common questions