How Long Does KLOW Last? Storage Before and After Mixing

Lyophilised KLOW keeps sealed and dry for the weeks a vial is in use at 2 to 8 °C and for months at −20 °C; once mixed with bacteriostatic water it lasts 8 to 12 weeks at 2 to 8 °C under Vistara Labs’ handling guidance, kept dark, with quality slowly fading from around week 6 to 8. No published stability study covers the four peptides together, so that window is the general guidance each component already takes. The blend is handled to suit its most demanding peptides: GHK-Cu for light and colour, KPV for heat.

Findings

• A KLOW vial holds 50 mg GHK-Cu and 10 mg each of BPC-157, TB-500 and KPV, 80 mg in total (Vistara Labs product listing).
• In a preformulation study, GHK-Cu was stable in water and pH 4.5 to 7.4 buffers for at least two weeks at 60 °C, but broke down under alkaline and oxidative stress (Badenhorst et al., Pharm Dev Technol, 2016).
• A 2026 review notes that the copper complex can come apart without any loss of peptide, and that both the peptide and its copper centre may be light-sensitive (Mateescu et al., Pharmaceutics, 2026).
• BPC-157 has no methionine, cysteine, tryptophan, asparagine or glutamine; its main chemical weak point is slow hydrolysis at the Asp10 to Asp11 bond (Mateescu et al., Pharmaceutics, 2026).
• KPV starts lysine then proline, a shape that can split off a diketopiperazine ring: a lysine-first model peptide had a half-life of 53 minutes at 75 °C (Zhang et al., J Am Soc Mass Spectrom, 2022).

How long does KLOW powder last?

No supplier publishes a stability data sheet for the blend, so the powder windows follow the component pages. Sealed and dry, the KLOW Blend 80 mg vial keeps at 2 to 8 °C for the weeks it is in use and at −20 °C for months, in its box. The cake is blue because the copper in GHK-Cu is already bound; the colour is not a dye. A cold vial is brought to room temperature before the stopper is pierced, so condensation does not form on the powder.

How long does KLOW last after mixing?

At 2 to 8 °C, dark and accessed only through a swabbed stopper, mixed KLOW lasts 8 to 12 weeks, with quality fading from around week 6 to 8. GHK-Cu, GLOW and KLOW share one row in how long peptides last after mixing, with “kept dark” added. The KLOW reconstitution page has the calculator for the 80 mg vial. Once mixed, the four peptides share one solution and one clock, so the vial is treated as lasting only as long as its most demanding component.

What the components say about stability

Each component has its own storage page: how long GHK-Cu lasts, BPC-157, TB-500 and KPV. None has a published solution shelf life shorter than the general window, and all four give the same 8 to 12 weeks. What differs is the weak point.

GHK-Cu makes up 50 of the 80 mg, and it has two ways to lose quality: the peptide chain can break, or the copper can leave or change partners while the chain stays intact. The 2026 review lists histidine, amino acids, phosphate, citrate and proteins among things that can redistribute copper, and flags the copper centre as possibly light-sensitive, which is why a KLOW vial lives in its box. BPC-157 is unusually forgiving, since it lacks the residues that oxidise or deamidate. TB-500 is the acetylated fragment Ac-LKKTETQ (Esposito et al., Drug Test Anal, 2012), which has no methionine or cysteine. KPV’s lysine-proline start reacts to heat: in the 2022 model work the same reaction ran about three times faster at 75 °C than at 65 °C. Those were harsh lab conditions, not a shelf life. Whether the four peptides affect each other in solution has not been studied, so colour is the practical check.

How long does KLOW last at room temperature?

There is no published figure for KLOW in solution at room temperature. GHK-Cu held up for two weeks at 60 °C in one study, but that was a stress test of one component, not a figure for the blend, and KPV’s ring-forming reaction speeds up sharply with heat. A mixed vial is taken out of the fridge only for handling.

Can KLOW be frozen?

The sealed powder can: −20 °C is the standard for holding it for months. A working vial should not be frozen and thawed, since freeze-thaw cycles aggregate peptides in solution. Laboratories that need long holding freeze single-use aliquots once instead.

How can you tell mixed KLOW has degraded?

• Clear blue is normal. The colour comes from the copper complex, whose absorption band at 580 to 600 nm shifts when the copper’s surroundings change.
• Fading, yellowing or darkening means the copper environment has changed.
• Cloudy blue that does not clear within 10 to 15 minutes of mixing, or that appears later.
• Particles, strands or gel.

Breakdown of BPC-157, TB-500 or KPV gives colourless fragments, so a vial that still looks right is not proof of full strength. The mixing date matters as much as the look.

How long does KLOW nasal spray last?

The KLOW Nasal Spray arrives ready-mixed: the same 80 mg in 10 mL of sterile saline, in a sealed metered pump. Once opened it is kept at 2 to 8 °C, upright, capped and in the dark, and never frozen. It lasts as long as its label allows; the vial window above does not carry over, because a spray in saline is a different preparation. Date the bottle when first opened, and discard it sooner if the clear blue changes, clouds or shows particles. Full rules: how to store a peptide nasal spray.

Travelling with KLOW

Sealed powder vials are the form to travel with, boxed and out of heat. A mixed vial or opened spray travels upright and dark in an insulated case with a cold pack that does not touch the glass. The choice between the two copper blends is set out in KLOW vs GLOW.

KLOW storage at a glance

State	Where	How long
Powder, sealed	−20 °C, dry	Months (store guidance)
Powder, sealed	2 to 8 °C, dark	The weeks the vial is in use (store guidance)
Mixed with bacteriostatic water	2 to 8 °C, dark	8 to 12 weeks, fading from week 6 to 8 (store guidance)
Mixed, room temperature	Handling only	No published figure

Certificates of analysis are on the lab reports page, and every order ships from within Canada by Canada Post Xpresspost.

Frequently asked questions

How long does KLOW last in the fridge after mixing?

Under Vistara Labs’ handling guidance, 8 to 12 weeks at 2 to 8 °C in the dark, with quality fading from around week 6 to 8.

How long does KLOW last at room temperature?

No published figure exists for KLOW in solution at room temperature. A mixed vial is kept in the fridge and taken out only for handling.

Can you freeze KLOW?

Yes as sealed powder, which keeps for months at −20 °C. A mixed vial that will be opened again should not be frozen, because freeze-thaw cycles aggregate peptides in solution.

Does KLOW go bad?

Yes. In solution GHK-Cu can lose or exchange its copper, faster with light, and the other three peptides slowly break into colourless fragments. A change from clear blue, cloudiness or particles mean it has degraded.

Does KLOW last as long as its four peptides on their own?

Yes: GHK-Cu, BPC-157, TB-500 and KPV each take the same 8 to 12 week window once mixed. In the blend they share one solution, so the vial is handled to suit the most demanding of them, GHK-Cu for light and KPV for heat.

Related reading. What is KLOW?, KLOW vs GLOW, how long GHK-Cu lasts and how long KPV lasts.

Handling windows: Vistara Labs, October 2026. Sources: Badenhorst T, Svirskis D, Wu Z. Physicochemical characterization of native glycyl-L-histidyl-L-lysine tripeptide for wound healing and anti-aging: a preformulation study for dermal delivery. Pharm Dev Technol. 2016. PMID 25384620. Mateescu DM et al. GHK-Cu as a bioactive metallopeptide and drug-delivery cargo: coordination chemistry, formulation science, therapeutic evidence, and a translational roadmap. Pharmaceutics. 2026. PMID 42797253. Mateescu DM et al. BPC-157 as an investigational peptide therapeutic: biopharmaceutical challenges, formulation strategies, and translational development barriers. Pharmaceutics. 2026. PMID 42198317. Esposito S et al. Synthesis and characterization of the N-terminal acetylated 17-23 fragment of thymosin beta 4 identified in TB-500, a product suspected to possess doping potential. Drug Test Anal. 2012. PMID 22962027. Zhang ZC, Hales DA, Clemmer DE. Influence of N terminus amino acid on peptide cleavage in solution through diketopiperazine formation. J Am Soc Mass Spectrom. 2022. PMID 35576623.

More on this: How Long Do Peptides Last After Mixing?