If you have been reading about TB-500 and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2026-04-30. Where a claim depends on a specific study, the study is described rather than over-claimed.
Lyophilized TB-500 is hygroscopic and should be kept dry before use. The usual storage recommendation for the solid is -20 °C, protected from light and moisture. Once dissolved, the peptide is less stable, and repeated freeze-thaw cycles can promote aggregation or degradation. Laboratories often divide a reconstituted solution into single-use aliquots and store them at -80 °C. Exact stability limits depend on buffer, pH, and concentration, so published data do not define a single universal condition.
Identity and purity are checked with chromatographic and mass spectrometric methods. Reverse-phase high-performance liquid chromatography separates the peptide from related impurities, while mass spectrometry confirms the expected molecular mass. A certificate of analysis may report a purity percentage, but the laboratory should still verify the material independently. Common quality concerns include truncated sequences, deamidation, oxidation, and residual solvents from synthesis. Because TB-500 is short, some impurities can differ from the target by only a few mass units.
Reconstitution practices affect downstream measurements. The dry powder is typically dissolved in sterile water or a suitable aqueous buffer, then mixed gently rather than vortexed at high speed. Visible particles or cloudiness suggest incomplete dissolution or contamination and should be investigated. For long-term storage, aliquots should be labeled with concentration, solvent, and date. Open questions include how different buffers alter peptide conformation and whether specific container materials adsorb the peptide. Those variables can change apparent concentration in assays even when the chemical identity is correct.
TB-500 is a synthetic peptide preparation marketed under a name derived from thymosin beta-4, a 43-residue actin-binding protein first isolated from thymus tissue. The full-length protein has a reported molecular mass near 4963 Da, while material sold as TB-500 is often described as a fragment containing the actin-binding motif LKKTETQ. Because suppliers use the name inconsistently, published sources sometimes refer to the same label as a fragment, a synthetic copy, or a related analog. This naming ambiguity complicates direct comparison of reports across studies.
Laboratory work on thymosin beta-4 describes binding to monomeric actin and effects on cell migration, angiogenesis, and inflammatory signaling in cultured cells. Animal models have examined skin, corneal, and cardiac repair after injury, with outcomes reported mainly in preclinical literature. Most of that evidence concerns the parent protein rather than preparations labelled TB-500, so extrapolation from animal findings to a specific commercial product remains uncertain. Whether the two behave identically in living systems has not been established in controlled human studies.
No major regulatory agency has approved TB-500 for therapeutic use, and it holds no pharmacopoeial monograph. The name appears on the World Anti-Doping Agency prohibited list within the class covering peptide hormones, growth factors, and related substances. Detection in doping control relies on mass spectrometric methods applied to urine, often after preparation steps that concentrate the analyte. Discussion of TB-500 therefore clusters in biochemistry, sports medicine, and anti-doping literature rather than in registered clinical trials.
| Property | Value | Notes |
|---|---|---|
| Storage temperature (dry) | -20 °C | Protected from light and moisture |
| Storage temperature (solution) | -80 °C | Single-use aliquots recommended |
| Identity assay | LC-MS or MALDI-TOF | Confirms mass near 889 Da |
| Purity assay | RP-HPLC | Reports main peak percentage |
| Common impurities | Truncated peptides, deamidated forms | Arise from synthesis or storage |
TB-500 is a laboratory label applied to a short synthetic peptide that is widely described as a fragment of thymosin beta-4, an actin-binding protein present in most mammalian cells. Suppliers and review articles usually present TB-500 as the N-terminal region of that protein, but the exact sequence attached to the name is not consistent across sources. Some product descriptions list a seven-residue chain; others use the label loosely for the parent protein itself. Because of that variation, any technical discussion of TB-500 needs to state which sequence is meant.
Thymosin beta-4 contains 43 amino acids and has a reported molecular mass near 4963 Da. The short fragment most often associated with the TB-500 label, an acetylated chain beginning LKKTETQ, has a reported mass near 889 Da, so the two are easily separated in analytical work. Mass spectrometry and amino acid analysis can confirm which material is present in a given sample. Statements treating TB-500 and thymosin beta-4 as interchangeable are therefore imprecise, even though the two appear together in much of the same literature.
Peptide bonds are susceptible to hydrolysis under extreme pH and to enzymatic cleavage if proteases are present. Heat, oxidising agents, and prolonged exposure to light also contribute to loss of material. Aggregation can occur at high concentrations or in certain buffer systems, and it may not be visible to the eye. Storage at -20 C or below is typical for both powder and aliquoted solutions, and desiccation of the powder is preferred.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography together with mass spectrometry. The chromatogram provides a purity estimate as a percentage of total peak area, while the mass spectrum confirms that the observed mass matches the expected value. Amino acid analysis or tandem mass spectrometry sequencing can provide additional confirmation. Reported purity figures depend on the column, gradient, and detection wavelength, so values from different laboratories are not directly comparable without method details.
== Unerwünschte Wirkungen == Häufig (unter 10 % der Patienten): Störungen im Magen-Darm-Trakt wie Appetitlosigkeit, Übelkeit, Erbrechen, Durchfall, weicher Stuhl, Bauchschmerzen sowie Bauchkrämpfe, Verdauungsstörungen und Verstopfung. Gelegentlich (unter 1 % der Patienten): Blähungen, Störungen des Geschmacksinns, Pilzinfektionen, Scheidenentzündungen, allergische Reaktionen mit Hautausschlag, Juckreiz und Nesselfieber, Nervosität, Benommenheit, Schläfrigkeit, Kopfschmerzen, Missempfindungen (Parästhesien) und Müdigkeit. Selten (unter 0,1 % der Patienten): Schwindel, Krämpfe, Krampfanfälle, Hyperaktivität, aggressive Reaktionen, Unwohlsein, Schwäche, Erregung, Angst, tiefer Blutdruck, Herzklopfen, Herzrhythmusstörungen, schwere anhaltende Durchfälle, Lichtempfindlichkeitsreaktionen (Hautreaktionen in Zusammenhang mit Sonnenlicht), Gelenkschmerzen und Zungenverfärbung. Sehr selten sind schwere allergische Reaktionen beobachtet worden. Unter einer Therapie mit Azithromycin kann es zu einem Anstieg der Transaminasen kommen. Bei schweren Leberfunktionsschäden ist Azithromycin daher kontraindiziert. Eine weitere Kontraindikation sind bekannte allergische Reaktionen gegen Azithromycin oder andere Antibiotika aus der Gruppe der Makrolide. Azithromycin hat ein ototoxisches Potential. Aus diesem Grund kommt es in seltenen Fällen zu einem Tinnitus. Die dabei entstandene Schädigung auf das Innenohr soll reversibel sein. In einer amerikanischen Studie wurde festgestellt, dass während einer 5-tägigen Therapie mit Azithromycin das Risiko für einen Herztod geringfügig steigt.
Dabei wurde ein zusätzlicher kardiovaskulärer Todesfall pro 21.000 behandelter Patienten (number needed to harm: 1:21.000) beobachtet, insbesondere bei Patienten, die schon vorher an kardiovaskulären Erkrankungen gelitten haben. Dies muss jedoch gegen die eventuell wirksamere Behandlung als durch andere Antibiotika abgewogen werden. Eine weitere große dänische landesweite Kohortenstudie konnte jedoch bei Patienten unter 65 Jahren kein erhöhtes Mortalitätsrisiko aufzeigen, so dass die Gabe bei herzgesunden jungen Patienten kein erhöhtes Risiko darstellt.
== Handelsnamen == Monopräparate Azyter (D), InfectoAzit (D), Ultreon (D), Zithromax (D, A, CH), Azi-Teva (D), Sumamed (HR, PL, RS), zahlreiche Generika (D, A, CH), Azitromicina (Costa Rica, Dominikanische Republik, Ecuador, Kolumbien, Mexiko, Peru), Azicip (Indien), Азимед/Azimed (Ukraine).
Sources: de.wikipedia.org
== Umwelt == Azithromycin wird unter normalen Bedingungen in der Kläranlage nicht vollständig abgebaut und gelangt so in die Gewässer. 2020 wurde in der Schweiz neben Clarithromycin und Diclofenac für Azithromycin ein Grenzwert in Oberflächenwässern festgelegt.
Sources: de.wikipedia.org
The dry powder is normally kept at -20 °C, protected from light and moisture. Reconstituted solutions are often divided into aliquots and stored at -80 °C to reduce freeze-thaw damage.
Reverse-phase HPLC assesses purity, and mass spectrometry confirms molecular mass. The combination helps distinguish the target peptide from truncated or modified impurities.
Buffer composition, pH, adsorption to containers, and freeze-thaw history can all affect the amount of intact peptide in solution. These factors may change results even when the starting material is chemically correct.
Not necessarily. TB-500 is a commercial label that suppliers apply to synthetic peptides described as thymosin beta-4 or a fragment of it. Published research most often studies the full-length protein, so statements about one do not automatically transfer to the other.