Reconstitution of lyophilized peptides

TL;DR — quick answer

A lyophilizate is the dried form of a peptide from which water has been removed by sublimation under reduced pressure (freeze-drying). Before research use, it must be reconstituted — returned to solution by adding a sterile solvent, most often bacteriostatic water for injection (BAC water).

A brief procedure for most research peptides:

1. Allow vials to equilibrate to room temperature (15–30 min after removal from the refrigerator)
2. Disinfect the stoppers of both the peptide vial and the solvent vial with 70 % isopropanol
3. Draw up the solvent (typically 1–3 mL of bacteriostatic water) with a sterile syringe
4. Slowly apply the solvent to the wall of the peptide vial (not directly onto the lyophilizate)
5. Gently swirl the vial (never shake) until fully dissolved
6. Store in the refrigerator at 2–8 °C in a well-sealed vial

Important: This procedure is intended exclusively for research and laboratory purposes — peptides are not approved for human consumption unless explicitly stated otherwise (and even then, only on medical prescription).

1. What a lyophilizate is and why peptides are supplied in this form

Definition of lyophilization

Lyophilization (synonyms: freeze-drying, cryodesiccation) is a method of dehydrating thermally sensitive substances through three phases:

1. Freezing — the peptide in solution is frozen to −40 to −80 °C
2. Primary drying (sublimation) — under reduced pressure (~0.1–1 mbar) ice passes directly to the gas phase, without flowing through liquid water
3. Secondary drying (desorption) — removal of residual bound water (typically <2 % w/w)

The result is a white or nearly white porous “matrix” in the ampoule / vial, containing the dry peptide in amorphous or crystalline form.

Why peptides are lyophilized

Peptides in aqueous solution undergo several degradation processes:

• Hydrolysis of peptide bonds (especially Asp-Pro, Asp-Gly, and acidic pH)
• Oxidation (especially Met, Cys, Trp, His residues)
• Deamidation (Asn → Asp / iso-Asp)
• Racemization (L → D)
• Microbial contamination

In lyophilized form, these processes are drastically slowed. Shelf life of a dry peptide at 2–8 °C is typically 24–36 months, whereas in solution only 14–28 days (even under optimal storage).

A lyophilizate also has lower weight, better transport stability, and less demanding cold chain requirements.

What a quality lyophilizate looks like

On visual inspection, a quality lyophilizate has:

• White to nearly white color — no yellow, pink, or brown tint
• Solid, porous “pellet” or “cake” adhering to the bottom / wall of the vial
• No cracks in the vial, intact rubber stopper
• Vacuum in the vial — when pierced with a needle, it “draws in” air
• Uniform structure — no dark spots, local deformations

Signs of trouble:

• Brown / yellow discoloration → degradation, oxidation
• Liquid residues → incomplete lyophilization
• No vacuum → potential seal compromise
• Cracks in the lyophilizate itself are normal — not a sign of trouble

2. Why a lyophilizate cannot be used directly

A dry peptide is not pharmacologically active in that form — for receptor binding it must be dissolved in solution with a defined concentration. In addition:

• Dosing the dry form is technically impossible at microgram quantities (typical peptide: 5 mg in the whole vial, dose = several tens to hundreds µg)
• Sterility — handling the dry peptide in lab conditions would lead to microbial contamination
• Reproducibility — a precise concentration in solution allows calculation of the dose on an insulin syringe

Therefore, reconstitution is the first and key step in all research protocols with peptides.

3. What you need — a complete materials list

Lyophilized peptide

• Sterile vial with lyophilizate (typically 2 mg, 5 mg, or 10 mg)
• Certificate of Analysis (CoA) with verified purity ≥99 % and MS identity
• Batch number matching on both the vial and the CoA

Sterile solvent

Choice of solvent depends on the specific peptide, the planned concentration, and the storage duration after reconstitution. Details in the next section.

Equipment

• Insulin syringes with integrated needle (typically 1 mL, U-100 — 100 units = 1 mL)
• Alcohol pads (70 % isopropanol)
• Sterile nitrile gloves
• Bench or surface cleaned with alcohol (ideally in a laminar flow hood for higher standards)
• Labels / marker to indicate batch and reconstitution date
• Plastic or paper underlay to catch needles and injection waste

Optional but recommended

• Storage box in the refrigerator — dedicated to research peptides
• Tweezers for handling pads
• Sharps container for needle disposal

4. Bacteriostatic water vs sterile water — the key difference

Bacteriostatic water (BAC water)

Sterile water with 0.9 % benzyl alcohol added as an antimicrobial preservative. Benzyl alcohol inhibits the growth of bacteria, yeasts, and fungi in the vial after the first puncture.

Advantages:

• Extended stability after reconstitution (28+ days)
• Possibility of multiple withdrawals from one vial
• Standard for most research peptides

Disadvantages:

• Benzyl alcohol may denature some sensitive peptides (rare, but relevant for proteins >50 aa)
• Contraindicated in neonates in clinical practice (irrelevant for research)
• Higher price

Sterile water for injection (WFI)

Pure sterile water without preservative. Produced by distillation or reverse osmosis + filtration through 0.22 µm.

Advantages:

• No additives → compatible with all peptides
• Lower price
• Standard in clinical manufacturing

Disadvantages:

• After the first puncture, rapid microbial contamination → usability 7–14 days in the refrigerator
• The vial should ideally be single-dose

0.9 % sodium chloride (saline)

Sterile isotonic NaCl solution. Used for peptides that have better solubility in an ionic environment or require isotonicity.

Practical recommendation

For most common research peptides (BPC-157, TB-500, Ipamorelin, CJC-1295 with DAC, GHK-Cu, Selank, Semax), BAC water is the optimal choice — extended shelf life, compatibility with typical multi-dose experiments.

5. Preparing the workspace — sterility

Although research applications are not at GMP quality, sterile practice minimizes contamination and protects peptide integrity.

Before reconstitution

1. Wash your hands with soap and warm water for 20 seconds
2. Disinfect your hands with alcohol gel (70 %)
3. Clean the work surface with alcohol spray (70 % isopropanol or ethanol), let it evaporate for 30 s
4. Lay out all materials clearly: peptide vial, solvent vial, syringe, alcohol pads, labels, needle container
5. Put on sterile gloves (nitrile, powder-free)

During reconstitution

• Do not touch the needle or the inner parts of the syringe with your hands
• Do not speak directly over the work area (saliva droplets)
• Work quickly but without rush — minimize the time vials are open
• Disinfect the stopper with an alcohol pad after every puncture

After reconstitution

• Dispose of the needle in a sharps container (never in regular waste)
• Label the peptide vial with the reconstitution date and concentration
• Place immediately in the refrigerator (2–8 °C)

6. Step by step — complete reconstitution procedure

For a clear example we will use the typical scenario: 5 mg of BPC-157 lyophilizate + 2 mL of BAC water.

Step 1 — Prepare materials

• Take the lyophilized peptide (5 mg vial) out of the refrigerator
• Take the BAC water vial (typically 10 mL multi-dose)
• Let them equilibrate to room temperature for 15–30 minutes
  • Why? Cold peptide + cold water → higher chance of precipitation and formation of invisible aggregates. Room temperature facilitates dissolution.
• Prepare a 1 mL insulin syringe (U-100)
• Prepare 2 alcohol pads

Step 2 — Disinfection

• Remove the protective plastic cap from the peptide vial (the rubber stopper stays)
• Thoroughly disinfect the rubber stopper with an alcohol pad — circular motion for 5–10 seconds
• Do the same for the BAC water vial
• Let the alcohol evaporate for 15–30 seconds
  • Why? Wet alcohol on the stopper would be pushed inside the vial by the needle and could contaminate the peptide.

Step 3 — Drawing up the solvent

• Open the sterile syringe wrapping
• Insert the syringe perpendicularly into the BAC water vial through the rubber stopper
• Invert the vial with the syringe upside down
• Slowly draw up exactly 2 mL (200 units on a U-100 syringe = 2.0 mL)
• Check for air bubbles — if present, gently tap the syringe with a finger and push them back into the vial
• Withdraw the syringe from the BAC water vial

Step 4 — Applying the solvent to the peptide vial

This is the most critical step.

• Insert the needle at an angle of ~45° through the rubber stopper of the peptide vial
• Aim the tip of the needle at the inner wall of the vial — not directly at the lyophilizate
• Apply the BAC water very slowly (rate ~1 mL / 10–15 seconds) — the water should flow down the wall of the vial onto the lyophilizate
  • Why? Spraying water directly onto the lyophilizate disperses the peptide and creates foam / aggregates. Slow flow down the wall preserves the structure of the lyophilizate and supports uniform dissolution.
• Gradually withdraw the needle
• Dispose of the syringe in the sharps container

Step 5 — Dissolution

• Gently swirl the vial in circular motions on the table or between your fingers
• Never shake the vial
  • Why? Shaking creates foam and shear forces that can denature the peptide and form aggregates. Some peptides (especially longer and more sensitive ones) are particularly susceptible.
• Continue gentle swirling for 30–60 seconds or until the lyophilizate fully dissolves
• Check visually — the solution should be completely clear, with no visible particles, no foam

Step 6 — Visual inspection of the solution

Step 7 — Labeling and storage

• Label the vial with a label or marker:
  • Peptide name (e.g., “BPC-157”)
  • Concentration (e.g., “2.5 mg/mL”)
  • Reconstitution date
  • Batch number
  • Operator’s initials (for traceability)
• Store in the refrigerator (2–8 °C)
• Do not freeze the reconstituted peptide (most peptides cannot withstand freeze-thaw cycles in solution)

7. Concentration and dose calculation

Basic concentration formula

Concentration (mg/mL) = Mass of peptide (mg) ÷ Volume of solvent (mL)

Example:

• 5 mg BPC-157 + 2 mL BAC water = 2.5 mg/mL = 2,500 µg/mL

Conversion to an insulin syringe (U-100)

An insulin U-100 syringe has a scale in “units” where:

• 100 units = 1 mL
• 1 unit = 0.01 mL

For research dosing:

Units on the syringe = (Dose in µg) ÷ Concentration (µg/mL) × 100

Example:

• Target dose: 250 µg BPC-157
• Concentration: 2,500 µg/mL
• Calculation: (250 ÷ 2,500) × 100 = 10 units on a U-100 syringe

Practical reference tables

5 mg peptide + 2 mL BAC water (concentration 2,500 µg/mL):

5 mg peptide + 1 mL BAC water (concentration 5,000 µg/mL):

Detailed calculator and more scenarios: Dose calculation on an insulin syringe

Choice of solvent volume — how much water to add?

Most common solvent volumes:

Rule: Choose a volume such that the typical dose falls between 5–25 units on a U-100 syringe. Doses below 5 units are imprecise (drawing error); doses above 50 units mean an unnecessarily dilute solution.

8. Storage of the reconstituted peptide

Optimal conditions

Shelf life after reconstitution — by peptide and solvent

Note: These values come from available research literature and internal stability studies. Specific data may differ depending on the supplier and quality of the lyophilizate.

Signs of a degraded solution

• Cloudiness or opalescence appearing after days of storage
• Yellow / brown discoloration
• Visible particles / fibers
• Musty / unpleasant smell on opening (rare with a sterilely prepared solution)
• Loss of efficacy in an experimental context

At any sign of degradation, discard the solution immediately and start with a new reconstitution.

9. Common reconstitution mistakes

Mistake 1 — Shaking the vial

The most common mistake. Shaking creates foam and shear forces that denature the peptide. Always only gently swirl the vial.

Mistake 2 — Spraying water directly onto the lyophilizate

Causes dispersal of the peptide, foam formation, and aggregates. Water must flow down the wall of the vial, not directly onto the pellet.

Mistake 3 — Cold components

Cold peptide + cold water = poorer solubility, precipitation. Always equilibrate to room temperature before handling.

Mistake 4 — Inadequate stopper disinfection

Bacterial contamination may be invisible but significantly shorten the stability of the peptide after reconstitution. Always disinfect with an alcohol pad before every puncture.

Mistake 5 — Using the wrong solvent

Tap water, distilled water, “pure” water from a pharmacy — none of these is sterile and suitable for research peptides. Always use certified BAC or WFI water from a laboratory supplier or pharmacy.

Mistake 6 — Freezing the reconstituted solution

Freeze-thaw cycles denature the peptide. If you need longer storage, divide the solution into aliquots (small volumes) and freeze only once at −20 °C — but even so, for most peptides it is better to use BAC water and keep refrigerated.

Mistake 7 — Repeatedly removing from the refrigerator

Frequent temperature changes (refrigerator → room → refrigerator) accelerate degradation. Before drawing a dose, you do not need to equilibrate the vial — drawing is fast enough that the cold is not an issue.

Mistake 8 — Using a peptide showing signs of degradation

Yellow color, sediment, cloudiness — do not use. Better to discard one vial than to compromise an entire experiment.

Mistake 9 — Inaccurate solvent volume

Adding 2.2 mL instead of 2.0 mL, for example, changes the concentration by 10 %. Always measure the volume precisely on an insulin syringe or precision pipette.

Mistake 10 — Missing documentation

With multiple peptides in the refrigerator, it is easy to mix up vials. Always label with name, concentration, and reconstitution date.

10. Special cases — peptides with low solubility

Some peptides have worse solubility in standard BAC water and require a modified approach.

CJC-1295 without DAC (Modified GRF 1-29)

At high concentrations (>2 mg/mL) it may be opalescent. Solution: dilute to ≤2 mg/mL or use a slightly acidic solvent (0.1 % acetic acid).

Melanotan II

Slightly more difficult dissolution in a cold solution. Solution: equilibrate longer (45 min), use BAC water at room temperature.

TB-500 and other longer peptides (>40 aa)

Risk of aggregation at high concentrations. Solution: dilute to ≤2 mg/mL, strictly follow slow swirling.

GHK-Cu

Sensitive to light (copper-blue color). Solution: amber vial or wrap in aluminum foil, shorten light exposure.

Hydrophobic peptides (rare in research)

Some peptides with a high proportion of hydrophobic amino acids may not be fully soluble in water. Specific recommendations (DMSO, special buffers) should be in the technical datasheet from the supplier.

11. Sterility and contamination — why they matter

In the research context, the question of sterility is often underestimated, but it has a significant impact on experimental results:

Bacterial contamination

Even subvisual contamination can:

• Cause peptide degradation through bacterial proteases
• Induce anti-drug antibodies in animal models
• Skew inflammatory markers in the experiment
• Cause an endotoxin reaction in sensitive models

Fungal contamination

Most often manifests as visible growth or color change of the solution. The solution is completely unusable.

Endotoxins (LPS)

When purchasing a peptide, verify the LAL test in the CoA — the value should be <0.5 EU/mg. Endotoxins do not disappear with reconstitution, they are already present in the lyophilizate.

Cross-contamination between vials

When working with multiple peptides:

• Never use the same syringe for two different vials
• Disinfect the syringe between drawing from BAC water and applying to the peptide
• Maintain strict aseptic practice

12. Safety and practical tips

Handling needles

• Never re-cap a used needle into its protective cover (risk of needlestick injury)
• Dispose of needles into a certified sharps container
• In case of accidental needlestick — immediately wash, disinfect, follow local safety protocols

Handling alcohol

• 70 % isopropanol is flammable — keep away from open flame
• Let alcohol fully evaporate before piercing with a needle (risk of alcohol in the solution)

Disposal

• Used syringes and needles → sharps container
• Empty vials → regular waste (if entire contents have been used)
• Vials with residual peptide → according to local rules for laboratory waste
• Spoiled reconstituted peptide → best to autoclave before disposal

Health aspects

• Never use research peptides on yourself or others — they are intended exclusively for research purposes
• In case of skin contact — thoroughly wash with soap and water
• In case of eye contact — rinse with water for 15 minutes, seek medical attention

13. Frequently asked questions (FAQ)

Can I use distilled water from a drugstore or from a physics laboratory? No. Distilled water is not sterile and has no preservative. After piercing the vial, it rapidly becomes contaminated. Always use certified BAC or WFI water.

How long should I swirl the vial to dissolve the peptide? For most peptides, 30–60 seconds of gentle swirling is enough. Some peptides (especially longer ones) may require several minutes or 5–10 minutes of sitting at room temperature.

I see small particles in the solution after reconstitution. What should I do? Let the solution sit for 5–10 minutes at room temperature, then swirl gently again. If particles persist, they are probably impurities or aggregates — the peptide may not be fully functional, but is often still usable. A cloudy or milky solution, however, is a sign of degradation.

Can I dilute a reconstituted peptide with more BAC water? Yes — adding more BAC water lowers the concentration (useful for more precise dosing). Stability remains similar. Always work aseptically and label the new concentration.

What if I accidentally add too much solvent? The peptide will still be functional, just at a lower concentration. Recalculate the units on the syringe according to the new concentration. At extremely dilute solutions (<200 µg/mL), adhesion loss of the peptide on the syringe walls can be a problem.

Can I store peptides in the freezer before reconstitution? Yes — lyophilized peptide in its original sealed vial tolerates even long-term storage at −20 °C, extending shelf life by ~2×. Do not freeze the reconstituted solution.

What to do if the peptide vial is not under vacuum? The vial should be slightly negative-pressure (on first puncture the needle “draws in” air). If there is no vacuum, the seal may have been compromised — contact the supplier. It can probably still be used, but stability may be reduced.

Can I reconstitute a peptide with a drug solution (e.g., commercial insulin)? No — combination with other pharmaceutical products is outside the scope of research protocols and can be dangerous. Each peptide is reconstituted separately.

What is the difference between “reconstitution” and “dilution”? Reconstitution = bringing a lyophilizate into solution by adding a solvent. Dilution = lowering the concentration of an already dissolved peptide by adding more solvent. Reconstitution is performed only once at the start; dilution as needed.

Can I mix two peptides into one vial? Yes — this is described in the research literature (e.g., the regenerative combination BPC-157 + TB-500 or the CJC-1295 + Ipamorelin combination for growth hormone). Note: shorter stability (10–14 days) due to the different stabilities of individual components. Many prefer separate vials for greater flexibility.

How do I know that a peptide has lost its activity? In a research context, typically by loss of effect on experimental endpoints. Visually: cloudiness, discoloration, sediment, smell. For precise quantitative verification, HPLC analysis is required (most laboratories do not have this luxury for everyday dosing).

Do reconstituted peptides need to be protected from light? For most peptides, light is not critical, but GHK-Cu and some aromatic peptides (with high Trp, Tyr content) are sensitive. It is safer to always store the vial in a dark box in the refrigerator.

What is the optimal temperature during reconstitution? Room temperature, 20–25 °C, is optimal. Higher temperatures (>30 °C) can accelerate degradation; lower (<15 °C) worsen solubility.

14. Conclusion

Reconstitution of a lyophilizate is a technically simple but critical step in working with research peptides. The quality of reconstitution directly affects:

• Efficacy of the peptide in the experiment
• Reproducibility of results
• Safety and sterility of the solution
• Shelf life of the reconstituted product

Main rules in four points:

1. Sterility — disinfect stoppers, use new sterile syringes, work aseptically
2. Slow flow — water flows down the wall of the vial, not directly onto the lyophilizate
3. Gentle swirling, never shaking
4. Labeling — concentration, date, batch on every vial

With the correct procedure, a quality research peptide (HPLC ≥99 %, MS identity, LAL test) will provide a stable, reproducible, and sterile solution suitable for experimental work.

Further reading

Practical guides:

• Dose calculation on an insulin syringe
• Storage of research peptides
• How to read a Certificate of Analysis (CoA)
• Sterile work in an amateur laboratory

Educational articles:

• What are peptides? Complete guide
• How peptides are manufactured — SPPS vs recombinant production
• Stability of peptides in solution

Product pages with reconstitution instructions:

• BPC-157 — complete guide
• TB-500 — complete guide
• Semaglutide — complete guide
• Tirzepatide — complete guide
• Ipamorelin — complete guide
• CJC-1295 — complete guide

Peptide comparisons:

• BPC-157 vs TB-500 — regenerative peptides
• Semaglutide vs Tirzepatide — GLP-1 vs dual agonist

References and citations

1. Wang W. (2000). Lyophilization and development of solid protein pharmaceuticals. Int J Pharm. 203(1-2):1–60.
2. Carpenter J.F., Pikal M.J., Chang B.S., Randolph T.W. (1997). Rational design of stable lyophilized protein formulations. Pharm Res. 14(8):969–975.
3. Pikal M.J. (1990). Freeze-drying of proteins. Part I: Process design. BioPharm. 3(8):18–27.
4. Manning M.C., Chou D.K., Murphy B.M., et al. (2010). Stability of protein pharmaceuticals: An update. Pharm Res. 27(4):544–575.
5. United States Pharmacopeia (USP) — General Chapter <797> Pharmaceutical Compounding — Sterile Preparations.
6. European Pharmacopoeia (Ph. Eur.) — Monograph 0169: Water for injections; Monograph 0008: Parenteral preparations.
7. Costantino H.R., Pikal M.J. (Eds.) (2004). Lyophilization of Biopharmaceuticals. AAPS Press.
8. Akers M.J. (2002). Excipient–drug interactions in parenteral formulations. J Pharm Sci. 91(11):2283–2300.

Legal notice

This guide is intended exclusively for research, educational, and laboratory purposes. All peptides and Molequa® products are supplied solely for research use — they are not a medicinal product, dietary supplement, cosmetic product, or food. They are not intended for human or animal consumption, nor for intravenous, subcutaneous, or any other administration to human persons. Sale is restricted to qualified researchers, academic institutions, and laboratories. For clinical use of approved peptide medicines (Insulin, Semaglutide, Tirzepatide, and others), always consult a qualified physician. Before any handling, study the relevant scientific literature, the technical datasheet of the specific peptide, and comply with applicable legislation in your jurisdiction.

Author: Molequa® Research Team Publication date: 2026 Last updated: May 2026 Reading time: ~20 min

Key scientific figures and citations

Correct reconstitution determines whether a peptide survives without degradation. Below are the key stability figures and lyophilisation literature behind the recommended protocols.

“Lyophilisation remains the gold standard for long-term peptide and protein storage; however, careful selection of cryoprotectants, fill volume and reconstitution diluent is critical to preserve native structure and prevent aggregation, oxidation and deamidation during shelf life.” — Manning MC. et al. (2010), Pharmaceutical Research 27(4) — PubMed 20143256

Statistics and key facts

• Lyophilised peptide at −20 °C in the dark: typical stability 2 to 3 years (sequence-dependent)
• Reconstituted peptide in bacteriostatic water at 2–8 °C: typically 28 days (preservative-free sterile water only 7 to 10 days)
• Main degradation pathways: oxidation (Met, Cys, Trp), deamidation (Asn, Gln), peptide bond hydrolysis, aggregation
• Aseptic technique: USP <797> standard for sterile compounding, 70% isopropanol for stopper disinfection, single-use sterile needles
• Recommended diluent: 0.9% benzyl alcohol in bacteriostatic water for injection (BAC water) — preservative effect documented in USP/Ph. Eur. monographs
• “Do not refreeze after reconstitution” rule, ice crystallisation in freeze–thaw cycles disrupts secondary peptide structure

Reference sources (PubMed)

1. Wang W. (2000). “Lyophilization and development of solid protein pharmaceuticals.” Int J Pharm 203(1-2):1–60. PubMed 11086221
2. Manning MC. et al. (2010). “Stability of Protein Pharmaceuticals: An Update.” Pharm Res 27(4):544–575. PubMed 20143256
3. Ohtake S., Wang YJ. (2011). “Trehalose: current use and future applications.” J Pharm Sci 100(6):2020–2053. PubMed 21953728
4. Mensink MA. et al. (2017). “How sugars protect proteins in the solid state and during drying.” Eur J Pharm Biopharm 114:288–295. PubMed 28189621

Article scope: This article summarises the peer-reviewed literature on peptide lyophilisation and reconstitution in research settings and makes no therapeutic claims. Molequa® products are sold exclusively for laboratory scientific research (RUO).

Frequently asked questions about lyophilised peptide reconstitution

These questions address the most common research-context searches about the reconstitution process. For a detailed step-by-step protocol see the sections above.

What is bacteriostatic water and why is it used?

Bacteriostatic water (BAC water) is sterile water with 0.9 % benzyl alcohol, which prevents bacterial growth in multi-dose vials. It is the standard for peptide reconstitution in research because it extends solution stability to 28 days at 2 to 8 °C. Without preservative the solution deteriorates within 7 to 10 days.

Can I use saline instead of BAC water?

Yes, but only for single-use. Saline (0.9 % NaCl) is sterile but contains no preservative. Reconstituted peptide in saline is stable only 7 to 10 days at 2 to 8 °C, after which the risk of bacterial contamination grows significantly. For long-term storage use BAC water.

How long does reconstituted peptide last in the fridge?

With bacteriostatic water: 28 days at 2 to 8 °C protected from light. With sterile water or saline (no preservative): 7 to 10 days. After exceeding these timeframes degradation products (broken inactive fragments) and bacterial contamination risk can rise significantly. Do not freeze after reconstitution.

Why should I avoid shaking the vial?

Mechanical stress (shaking) can denature the peptide, breaking its three-dimensional structure and rendering it inactive. Always swirl gently in circular motions for 30 to 60 seconds until all lyophilisate dissolves. The solution should be clear, if cloudy or with floating particles, the peptide is damaged.

What final concentration should I aim for?

The standard is 2.5 to 5 mg/ml (suitable for most dosing). For small experimental doses choose a lower concentration (1 mg/ml = larger syringe volume = more precise measurement). For high-concentration injections choose higher (5 to 10 mg/ml). Higher reconstitution volume = smaller errors at small doses.

How do I sterilise without an autoclave?

Sterile filtration (0.22 µm syringe filter) is the simplest method for small volumes. Water and vials must be purchased sterile (USP grade). UV sterilisation of surfaces (vial rubber stoppers) is done with a 70 % isopropyl alcohol disinfectant swab (let evaporate). For laboratory peptide work never boil or heat the reconstituted solution.

Where can I buy bacteriostatic water in the EU?

Bacteriostatic water is available in the EU through veterinary and laboratory suppliers (e.g. Henke-Sass Wolf, B. Braun Vetivex). In Slovak and Czech pharmacies it is typically obtained on prescription as “Aqua bacteriostatica”. For research procurement USP grade with verified 0.9 % benzyl alcohol content is recommended. For Molequa® peptide reconstitution BAC water in 10 ml vials is recommended.