Recommended Storage Conditions (Post-Reconstitution)

Use Bacteriostatic Water for multi-dose vials: Tesamorelin (a GHRH analog) is typically supplied as a lyophilized powder, intended to be mixed with Bacteriostatic Water for Injection (0.9% benzyl alcohol) for multi-dose use[1][2]. After reconstitution of a 20 mg vial in ~3 mL bacteriostatic water, the manufacturer’s best-practice guidance is to store the solution at controlled room temperature (20–25 °C) and use it within a defined timeframe[3][4]:

  • Room-temperature storage: Keep the reconstituted Tesamorelin vial at 20–25 °C (68–77 °F). The EGRIFTA® WR prescribing information (11.6 mg multi-dose vials) specifies that once mixed with bacteriostatic water, the vial can be stored at room temp in its box (protect from light) and used for up to 7 days[3][4]. Any unused solution should be discarded 7 days after reconstitution to avoid potency loss or contamination[3]. This 7-day limit is an official stability guideline based on studies of the drug’s integrity and preservative effectiveness.
  • Do not freeze the solution: Freezing is explicitly advised against. The manufacturer warns not to freeze reconstituted Tesamorelin[3]. Freezing and thawing can cause peptide denaturation or aggregation, and freeze-thaw cycles are known to degrade peptides[5][6]. Keep the vial in the provided container, away from extreme cold or heat, and shielded from light to preserve stability[7].
  • Immediate use vs short storage: If Tesamorelin were reconstituted with sterile water (no preservative) – as in the single-use EGRIFTA SV® 2 mg vials – it should be injected immediately and not stored. The product labeling for those sterile-water vials indicates to inject right after reconstitution and discard any unused solution[8]. Without a preservative, even refrigeration will not safely extend the usable life of a sterile-water mixture due to risk of microbial growth. In contrast, bacteriostatic water allows short-term storage (multi-dose use) because the benzyl alcohol inhibits bacterial contamination[9].

Effects of Temperature on Stability (Room-Temp vs Refrigeration)

Avoid refrigerating reconstituted Tesamorelin – counterintuitive as it may seem for peptides – because cold temperatures can cause this peptide to precipitate or “gel” out of solution. Users have reported that Tesamorelin solutions turn cloudy and form a hard gel-like solid when stored in the refrigerator, rendering the dose non-homogeneous and unusable[10][11]. This occurs because lowering the temperature can reduce the peptide’s solubility in the diluent, especially at higher concentrations, leading to aggregation/solidification. The official EGRIFTA® WR instructions therefore emphasize keeping the reconstituted vial at room temp (not in the fridge)[3]. In summary:

  • At room temperature (20–25 °C): Tesamorelin stays in a clear, fully dissolved state and remains chemically stable for the recommended 7-day period[3]. The benzyl alcohol preservative helps keep the solution sterile during this time[9]. Chemical degradation is minimal over a week at room temp as per product stability data.
  • At refrigerator temperature (~4 °C): The peptide may precipitate as a white solid or gel inside the vial, due to its solubility limits being exceeded at low temperature. If this happens, the solution will appear cloudy or clumped (not clear), and should not be injected[10][12]. Warming it back to room temp sometimes redissolves mild precipitates, but full “gelling” indicates significant aggregation that likely cannot be reliably reversed. Moreover, even aside from precipitation, Tesamorelin’s official stability in solution hasn’t been established beyond 7 days, so extended refrigeration is not an approved practice.
  • Chemical stability vs physical stability: It’s worth noting that generally many reconstituted peptides are chemically more stable at 2–8 °C than at room temp, potentially lasting a couple of weeks if kept soluble[13]. However, Tesamorelin’s formulation and concentration make cold storage problematic due to physical stability (aggregation) issues. The manufacturer chose room-temperature storage for the multi-dose vial to avoid this precipitation problem while still ensuring at least 7 days of potency. In other words, keeping it at room temp strikes a balance between preventing precipitation and maintaining acceptable stability. Do not freeze the vial under any circumstance, as freezing can cause irreversible peptide denaturation or particle formation upon thawing[6].

Bacteriostatic Water vs. Other Diluents

When reconstituting Tesamorelin, the choice of diluent affects both usability and stability:

  • Bacteriostatic Water (0.9% benzyl alcohol): This is the recommended diluent for multi-dose use. The benzyl alcohol acts as a preservative, suppressing bacterial growth in the vial so that the solution can be used for multiple injections over several days[9]. Storage up to 7 days at room temp is supported when using bacteriostatic water[3]. In fact, clinical kits of EGRIFTA WR™ are supplied with a 30 mL bottle of bacteriostatic water, specifically for weekly reconstitution and multi-dose storage[2][14]. Note: While BA extends usability, it is not meant for indefinite storage – multi-dose injectables with BA are typically limited to ~28 days of use once opened[9]. Also, BA can mildly accelerate peptide/protein aggregation over time (this has been observed in other protein drugs)[15], which is one reason the Tesamorelin solution is discarded after 1 week despite the preservative.
  • Sterile Water for Injection (no preservative): This diluent is used in single-use vials (EGRIFTA SV®). It contains no antimicrobial agent, so any reconstituted solution should be used immediately and not stored[8]. If one were to reconstitute a 20 mg vial with plain sterile water, the entire volume would ideally need to be injected right away or divided into sterile single-use aliquots. Storing a sterile-water mix, even in the fridge, is unsafe because bacteria can grow and the peptide can degrade without protection. Thus, sterile water is only appropriate if you plan to use the full vial (or each aliquot) within hours of mixing. For human administration, this typically means using sterile water only in scenarios of daily reconstitution of small vials, not for a large multi-dose vial.
  • Normal Saline (0.9% NaCl) or other diluents: The manufacturer does not provide saline; they instruct to use the supplied diluent only[16]. Nonetheless, some practitioners or compounding pharmacies might reconstitute peptides with bacteriostatic 0.9% saline or a buffered solution. An isotonic saline diluent could reduce injection-site burning (since water alone is hypotonic), and many peptides remain stable in saline. However, saline lacks a preservative unless it’s a “bacteriostatic saline.” If using plain saline, the same single-use rule as sterile water applies. Bacteriostatic saline (if available, containing benzyl alcohol) would similarly allow multi-dose use. In any case, pH and compatibility must be considered: Tesamorelin is formulated to dissolve in water at roughly neutral pH; using a strongly acidic or basic solvent could damage the peptide[16]. It’s safest to stick with Water for Injection (with or without BA) as provided or recommended. Using unapproved diluents or additives isn’t advised without evidence of stability.
  • Sensitivity considerations: Patients sensitive or allergic to benzyl alcohol may need to avoid bacteriostatic water. In such cases, one alternative is to use sterile water and administer single doses (discarding any remainder). The trade-off is convenience and shelf-life – no ability to store the mixed solution. According to peptide therapy guidelines, bacteriostatic water affords convenience (multi-dose over days)[9], whereas preservative-free water avoids any BA exposure but requires more frequent vial use or meticulous sterile handling.

Long-Term Stability and Additional Tips

  • Lyophilized (dry) peptide stability: Unreconstituted Tesamorelin (the freeze-dried powder) is much more stable. Store the dry vials per the manufacturer’s instructions (original Tesamorelin vials were stored refrigerated 2–8 °C prior to dispensing, though newer formulations are room-temp stable)[17][18]. In general, keep the vials in a cool, dark place. Dry peptides can tolerate room temperature for a short time (days to weeks) without issue, but for long-term storage (months/years) refrigeration or freezing is preferred[19]. Always protect lyophilized peptides from moisture and light, and allow a cold vial to come to room temp before opening (to prevent condensation)[19].
  • If longer storage of the reconstituted solution is required: The officially recommended limit is 7 days at room temp[3]. If, for some reason, one needs to extend the use beyond a week, one approach (in research settings) is to aliquot and freeze the solution. By splitting the reconstituted peptide into sterile small vials or syringes and freezing at –20 °C (or colder), you can prolong stability for a few months[13][20]. This must be done carefully under sterile conditions, and each aliquot should only be thawed once (no repeated freeze–thaw cycles)[5][6]. Keep in mind that this is not an FDA-approved practice for Tesamorelin intended for human injection – it’s a laboratory storage method. The thawed peptide might still aggregate or lose some potency, and one should never inject a solution that has visible particles or cloudiness[10][21]. For human use, the safest course is to adhere to the 7-day room-temp rule and reconstitute fresh vials as needed, rather than attempting to extend the solution’s life.
  • Signs of degradation or contamination: Regardless of storage method, always inspect the solution before use. Tesamorelin in solution should be clear, colorless, and free of any particles[22]. If you see cloudiness, fibers/threads, or precipitate that doesn’t dissolve by gentle warming, the vial should be discarded. Likewise, any significant color change could indicate oxidation or contamination. Bacterial growth in a contaminated vial might cause cloudiness as well – another reason to discard any vial past its recommended window, even if it looks fine.

In summary, for a 20 mg Tesamorelin vial reconstituted with bacteriostatic water, store it at room temperature, use it within about one week, and do not refrigerate or freeze the mixed solution[3]. This ensures the peptide remains soluble and potent for your daily injections. If you follow these best practices – and compare diluent options as noted (using bacteriostatic water for multi-day use vs immediate use if using sterile water) – you will maintain the integrity and safety of the Tesamorelin for human administration. Yes, the peptide can “gel up” in cold temperatures, so keeping it at room temp is actually the recommended approach to prevent precipitation[23][11]. By adhering to the manufacturer’s guidelines and the above storage tips, you’ll maximize stability and efficacy of the reconstituted Tesamorelin solution while minimizing any waste or loss of activity.