The 28-day rule: where it comes from
Bacteriostatic water (BAC water) contains 0.9% benzyl alcohol. Benzyl alcohol disrupts microbial cell membranes, inhibiting bacterial and fungal growth in the reconstituted vial. It does not stabilize the peptide itself - it protects the water from contamination, which would otherwise degrade the peptide indirectly through enzymatic and oxidative byproducts.
The 28-day window is the validated outer limit for BAC water multi-dose use under refrigeration at 2–8°C. Beyond 28 days, the benzyl alcohol concentration may fall below bacteriostatic threshold due to volatilization, and peptide degradation accelerates from cumulative oxidation and temperature micro-excursions.
28 days is a hard limit, not a conservative estimate. Using a vial at day 30 is not "close enough" - it is outside the validated window.
The four Vial Guard categories
Why some peptides must freeze
Klotho is the clearest example. It is an exceptionally fragile protein fragment - each freeze-thaw cycle causes partial denaturation, reducing receptor-binding activity. At refrigerator temperatures (4°C), enzymatic degradation proceeds slowly but measurably. The standard protocol: aliquot into single-use volumes immediately after reconstitution, store at -80°C if possible, -20°C minimum. Use each aliquot once.
IGF-1 LR3 presents a different problem: it requires acetic acid as the diluent, not BAC water. The IGF binding protein bypass that gives LR3 its enhanced activity depends on the low-pH environment. BAC water raises pH and destabilizes the molecule. After acetic acid reconstitution, aliquot and freeze - acetic acid does not carry benzyl alcohol bacteriostatic protection.
BAC water vs sterile water: the real difference
| Property | Bacteriostatic Water | Sterile Water for Injection |
|---|---|---|
| Preservative | 0.9% benzyl alcohol | None |
| Multi-dose use | Yes - 28 days | No - single use |
| Post-open window | 28 days at 2–8°C | Within 1 hour of opening |
| Suitable for Synapsin | No | Use sterile saline instead |
| Suitable for Semax/Selank intranasal | Not preferred | Sterile saline preferred |
| Cost | ~$8–12 / 30mL vial | ~$5–8 / vial |
Synapsin is the notable exception: its GHK-Cu and Dihexa components are degraded by benzyl alcohol. Always reconstitute with preservative-free sterile saline, not BAC water. ASCEND displays this note automatically when Synapsin is selected.
Compound stability reference
| Compound | Diluent | Window | Storage | Calc page |
|---|---|---|---|---|
| Semaglutide | BAC water | 28 days | 2–8°C | → |
| Tirzepatide | BAC water | 28 days | 2–8°C | → |
| Retatrutide | BAC water | 28 days | 2–8°C | → |
| CagriSema | BAC water (each component) | 28 days | 2–8°C | → |
| Cagrilintide | BAC water | 28 days | 2–8°C | → |
| BPC-157 | BAC water | 28 days | 2–8°C | → |
| TB-500 | BAC water | 28 days | 2–8°C | → |
| GHK-Cu | BAC water | 28 days | 2–8°C | → |
| Tesamorelin | BAC water | 3 hours | Inject immediately | → |
| IGF-1 LR3 | 0.6% acetic acid | Freeze aliquots | -20°C | → |
| IGF-1 DES | 0.6% acetic acid | Freeze aliquots | -20°C | → |
| Klotho | BAC water (ice cold) | Freeze aliquots | -80°C preferred | → |
| NAD+ | BAC water | Use same day | Highly unstable post-recon | → |
| Synapsin | Sterile saline (NOT BAC) | 28 days | 2–8°C | → |
| MK-677 | None - oral | No recon needed | Room temp, dry | → |
| Epithalon | BAC water | 28 days | 2–8°C | → |
| PT-141 | BAC water | 28 days | 2–8°C | → |
How ASCEND's Vial Guard works
Every calculation in ASCEND appends a Vial Guard line to the copied protocol. The line is generated from three rules applied in order:
- If water volume is zero or the compound is oral - output: "Oral / no reconstitution"
- If the compound note contains "3 hr" (Tesamorelin) - output: "Use within 3 hours of reconstitution"
- All other reconstituted peptides - output: "Valid for 28 days refrigerated (BAC water)"
This line appears automatically in the copy-to-clipboard output, the Reddit markdown table, and the printed PDF protocol - so it travels with the calculation wherever you take it.
The design goal: a researcher sharing a protocol should never have to manually append storage instructions. Vial Guard makes it impossible to forget.
Practical storage checklist
- ✓ Label every vial with reconstitution date using a marker or label maker
- ✓ Store at 2–8°C - not in the door (temperature fluctuates), in the main body of the fridge
- ✓ Protect from light - wrap in foil or store in the original opaque container
- ✓ Never freeze BAC water vials - ice crystal formation degrades peptide structure (exception: Klotho and IGF-1 LR3 require freezing — see rows below)
- ✓ Discard any vial showing cloudiness, color change, or particulates
- ✓ For freeze-required compounds: aliquot before freezing, use each aliquot once
- ✓ When in doubt, check the Vial Guard line ASCEND prints with every protocol
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