B7-33
Preclinical ResearchB7-33 (relaxin-2 analog)
A single-chain peptide derived from relaxin-2, studied preclinically for anti-fibrotic effects in cardiac, renal, and lung tissue.
Dose
0.1 mg/kg
Route
Subcutaneous injection
Cycle
Typically 7-14 days in animal models, or until research endpoint
Storage
2°C to 8°C (refrigerator) away from light
What is B7-33?
B7-33 is a synthetic, single-chain peptide derived from the B-chain of human relaxin-2, a hormone known for its anti-fibrotic and vasodilatory properties. It was developed to selectively activate the relaxin family peptide receptor 1 (RXFP1) without activating RXFP2, the receptor for INSL3. Preclinical research has primarily focused on its potential anti-fibrotic effects across various organ systems, including the heart, kidneys, and lungs. Studies in animal models of fibrosis have shown B7-33's ability to reduce collagen deposition, inhibit myofibroblast differentiation, and exert anti-inflammatory actions. Its mechanism is thought to involve the activation of RXFP1, leading to downstream signaling pathways such as nitric oxide production and cAMP elevation, which contribute to its beneficial effects.
Key Benefits
- Anti-fibrotic activity (preclinical)
- Relaxin receptor signaling
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Molecular Information
Molecular weight
4261.7 g/mol
Type
Synthetic Relaxin-2 derivative
Amino acid sequence
Ac-R-S-L-K-D-L-C-C-Q-V-G-C-R-L-I-G-K-Y-C-A-N-R-S-F-T-A-K-C-G-R-V-G-A-K-C-D-OH
B7-33 is a single-chain peptide designed to mimic the relaxin-2 B-chain, with an N-terminal acetylation and C-terminal amidation for enhanced stability and receptor affinity.
Pharmacokinetics
Time to peak
1-2 hours (subcutaneous, animal models)
Half-life
2.5 h
Time to clear
Elimination half-life around 1.5-3 hours in animal models, but extended receptor binding may prolong biological effect.
Based on preclinical pharmacokinetic studies in rats and mice.
Research Indications
Cardiac Fibrosis
Preclinical studies in animal models of heart failure (e.g., myocardial infarction, pressure overload) have demonstrated B7-33's ability to reduce myocardial fibrosis, improve cardiac remodeling, and enhance heart function. Evidence: Animal studies.
Pulmonary Hypertension
Research indicates potential for B7-33 to attenuate vascular remodeling and fibrosis in models of pulmonary hypertension, suggesting a role in improving cardiopulmonary hemodynamics. Evidence: Animal studies.
Research Protocols
| Goal | Dose | Frequency | Route |
|---|---|---|---|
| Investigate cardiac anti-fibrotic effects | 0.1 mg/kg | Once daily | Subcutaneous |
| Evaluate renal anti-fibrotic activity | 0.1 mg/kg | Once daily | Subcutaneous |
| Assess pulmonary anti-fibrotic potential | 0.1 mg/kg | Once daily | Subcutaneous |
| Dose-response study in animal models | 0.01 mg/kg, 0.03 mg/kg, 0.1 mg/kg | Once daily | Subcutaneous |
| Pharmacokinetic profiling in animal models | 0.1 mg/kg | Single dose | Subcutaneous |
Timing often depends on the specific animal model of disease and research endpoint. Daily administration is common to maintain consistent levels in chronic disease models.
Peptide Interactions
- Monitor Combination
Angiotensin-Converting Enzyme (ACE) Inhibitors
While not directly studied for B7-33, relaxin-2, its parent molecule, can interact with the renin-angiotensin-aldosterone system. Monitoring for synergistic blood pressure lowering or renal effects may be warranted in preclinical co-administration studies.
- Monitor Combination
Beta-blockers
Similar to ACE inhibitors, broad cardiovascular agents like beta-blockers could theoretically interact with B7-33's cardiovascular effects. Careful observation in co-administration studies is advisable.
- Compatible
Anti-inflammatory drugs
B7-33 exhibits anti-inflammatory properties. Concurrent use of other anti-inflammatory agents may be compatible or even synergistic in reducing inflammation in fibrotic conditions, without direct contraindications identified in preclinical data.
- Monitor Combination
Diuretics
Relaxin family peptides can influence fluid balance. If B7-33 were combined with diuretics in models of fluid overload, close monitoring of electrolyte and fluid status would be important. No direct interaction data for B7-33.
How to Reconstitute
- 1Gather supplies: B7-33 lyophilized powder vial, sterile bacteriostatic water for injection (BW), sterile syringes, sterile needles, alcohol swabs.
- 2Remove the plastic cap from the B7-33 vial and wipe the rubber stopper with an alcohol swab. Allow to air dry.
- 3Draw the desired volume of BW into a sterile syringe. Common reconstitution ratios are 1-2 mL of BW per 2 mg, 5 mg, or 10 mg vial, to achieve a manageable concentration (e.g., 1-5 mg/mL).
- 4Slowly inject the BW into the B7-33 vial, directing the stream down the side of the vial to minimize foaming.
- 5Do not shake the vial. Gently swirl the vial to dissolve the powder. If necessary, allow the vial to sit in the refrigerator for 15-30 minutes to ensure complete dissolution.
- 6Visually inspect the solution for any undissolved particles or discoloration. The reconstituted solution should be clear and colorless.
Proper sterile technique is critical during reconstitution. Bacteriostatic water is preferred to maintain sterility for multi-dose vials over the storage period.
What to Expect
- In preclinical models, B7-33 administration has been observed to reduce markers of fibrosis in various tissues.
- Decreased collagen deposition and improved tissue architecture may be observed in target organs.
- Modulation of inflammatory pathways and reduction of pro-inflammatory cytokines.
- Improved organ function parameters in disease models (e.g., cardiac function, renal filtration) as fibrosis is mitigated.
- Potential for transient local irritation or redness at the subcutaneous injection site, as with any injection.
- Pharmacokinetic studies in animals show relatively rapid absorption and elimination following subcutaneous administration.
Side Effects & Safety
- B7-33 is a research chemical and is not approved for human therapeutic use. It is for research purposes only.
- Handle with appropriate laboratory safety practices, including gloves and eye protection.
- Subcutaneous injections should be performed using sterile technique to prevent infection.
- Proper disposal of sharps (needles, syringes) is essential.
- Any unusual reactions or discomfort in research subjects should be documented and investigated.
- The full long-term safety profile in living systems, beyond controlled preclinical studies, is not established.
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