Peptide Schedule
B7-3326 residuesVIKLSGRELVRAQIAISGMSTWSKRSLEach bubble = one amino acid. Size = residue mass. Color = chemical class.B7-33 Dosage Calculator
B7-33 is a synthetic single-chain peptide derived from the B-chain of human relaxin-2 (H2 relaxin).
100mcg · Daily
Summary: Add 2mL BAC water to your 2mg vial. Draw to 10.0 units on a U-100 syringe for a 100mcg dose. This vial will last 20 doses.
Cycle Planner
B7-33 Pharmacokinetics
Pharmacokinetics — Active Dose Over Time
t½ = ~6 minutes in vitro (native peptide; rapid serum degradation)Disclaimer: This curve is a simplified first-order exponential decay model. Actual pharmacokinetics vary based on injection site, individual metabolism, body composition, and other factors. Half-life values are approximate and based on available preclinical and clinical literature. Many research peptides lack formal human pharmacokinetic studies. This is for educational purposes only — not medical advice.
B7-33 Dosing Protocol
| Level | Dose / Injection | Frequency |
|---|---|---|
| Beginner | 100mcg | Daily |
| Moderate | 250mcg | Daily |
| Aggressive | 500mcg | Daily |
Note: B7-33 is a preclinical research peptide with no human dosing data. The extremely short in vitro serum half-life (~6 minutes) is a primary limitation — twice-daily subcutaneous dosing (0.25 mg/kg per dose, 12 hours apart) was used in mouse studies. All dosing figures here are extrapolated from rodent models. A lipidated derivative (AcK(PalmGlu)-PEG12-B7-33) extends in vitro half-life to ~60 minutes but remains investigational. Store reconstituted peptide cold and use promptly. This is a research compound only — not for human therapeutic use.
About B7-33
B7-33 is a synthetic single-chain peptide derived from the B-chain of human relaxin-2 (H2 relaxin). It was first described in 2016 by Hossain et al. at the Florey Institute and Monash University as a simplified alternative to native H2 relaxin, which requires a two-chain, three-disulfide-bond insulin-like structure that is expensive and technically difficult to produce. Despite being a short linear peptide that is largely unstructured in solution, B7-33 adopts the correct conformation upon binding to the relaxin family peptide receptor 1 (RXFP1). It is the first functionally selective agonist of RXFP1 — it preferentially activates the pERK1/2 signaling pathway over the canonical cAMP pathway. This biased signaling profile drives its anti-fibrotic activity while potentially avoiding side effects linked to full receptor activation. In preclinical studies, B7-33 demonstrated anti-fibrotic efficacy matching native H2 relaxin across multiple disease models. In mouse myocardial infarction models (ischemia-reperfusion), B7-33 reduced infarct size from 45.3% to 22.0% (P=0.02) and preserved fractional shortening at 7 days post-MI. In isoprenaline-induced cardiomyopathy, B7-33 reduced left ventricular fibrosis more rapidly than the ACE inhibitor perindopril. It also prevented organ fibrosis in preclinical models of lung disease. B7-33 replicates the vasoprotective effects of serelaxin (recombinant H2 relaxin) in rat mesenteric arteries at equimolar doses and prevented endothelial dysfunction caused by placental trophoblast conditioned media, suggesting potential relevance to preeclampsia. In implant studies, PLGA coatings releasing B7-33 reduced fibrotic capsule thickness by 49.2% over 6 weeks in a subcutaneous mouse model. Critically, B7-33 did not promote prostate tumor growth in vivo — a concern with native relaxin-2, which has been implicated in certain cancer progressions. This selective signaling profile makes B7-33 an attractive research tool for studying relaxin receptor biology without the oncogenic risk associated with full RXFP1 activation.