MEDICAL DISCLAIMER: Educational research guidelines only. Lyophilized peptides are investigational chemical compounds and are NOT approved for human consumption, diagnosis, or therapy. Consult a licensed physician before any research application.
Thymopentin Dosage Chart, Schedule & Reconstitution Protocol
Quickstart Highlights
Thymopentin (TP-5, Timunox) is a synthetic immunomodulating pentapeptide, Arg-Lys-Asp-Val-Tyr, copying the active site (residues 32-36) of the thymic hormone thymopoietin [PMID 451537]. It drives prothymocyte-to-thymocyte differentiation and rebalances T-cell subsets and natural-killer activity, acting as an immunorestorative agent rather than a broad stimulant or suppressant. The standard regimen is 50 mg by subcutaneous or intramuscular injection three times weekly for 3-6 weeks, the schedule used in controlled atopic dermatitis and recurrent herpes simplex studies [PMID 8157786]. Its hallmark is a very short plasma half-life (under 30 seconds) from rapid proteolysis, which mandates frequent dosing and motivates modern sustained-release research [PMC6461748]. Thymopentin is approved for immunodeficiency in some countries (e.g., Italy) but is not FDA-approved in the US; the reconstitution figures here are an educational reference, not medical advice.
Reconstitute: Add 1 mL bacteriostatic water → 50 mg/mL concentration.
Typical dose: 50 mg SC/IM 3x/week
Easy measuring: At 50 mg/mL, 1 unit = 0.01 mL = 0.5 mg (500 mcg) on a U-100 insulin syringe.
Storage: Lyophilized powder stored frozen at −20 °C, protected from light and moisture. Thymopentin hydrolyzes readily once dissolved, so the reconstituted solution is kept refrigerated at 2-8 °C, protected from light, and ideally used the same day; discard within 24 hours of reconstitution given the peptide's instability in aqueous solution.
Half-life: Extremely short — under 30 seconds in plasma (native pentapeptide), due to rapid proteolytic cleavage; immune effects outlast the molecule.
Route: Subcutaneous or intramuscular injection from a reconstituted lyophilized vial; not orally bioavailable.
Status: Approved for immunodeficiency in some countries (e.g., Italy, as Timunox); not FDA-approved in the US (orphan-drug designation only). Educational reference.
About Thymopentin
Thymopentin (TP-5, brand name Timunox) is a synthetic immunomodulating pentapeptide — the sequence Arg-Lys-Asp-Val-Tyr that reproduces the active site (residues 32-36) of the thymic hormone thymopoietin [1]. Unlike many compounds modeled on this site, thymopentin's real-world route genuinely is parenteral: in the clinic it is given by subcutaneous or intramuscular injection from a reconstituted lyophilized vial, so the protocol below mirrors actual practice rather than serving only as a measurement convention [3].\n\nThe most studied Thymopentin dosage is 50 mg given three times per week for roughly 3-6 weeks, the regimen used in controlled trials of atopic dermatitis and recurrent herpes simplex [4][7]. This guide models a 50 mg vial reconstituted with 1.0 mL of bacteriostatic water (50 mg/mL), so a full 50 mg dose draws to 100 units — one complete U-100 insulin syringe — while a 25 mg sensitivity or lower-weight dose draws to 50 units. Because each 50 mg vial equals one dose, vials are reconstituted one at a time and used promptly.\n\nFrequency: Three times weekly (for example Monday, Wednesday, Friday), subcutaneously or intramuscularly, in repeated 3-6 week courses. Thymopentin is approved for immunodeficiency in several countries but is not FDA-approved in the United States; the figures here are an educational dosing reference, not medical advice.
Quick Protocol Navigation
Reconstitution Instruction & Mixing Step-by-Step
Lyophilized powder must be reconstituted carefully. Agitating peptide chains can shear disulfide bonds and render the peptide biologically inert.
Draw 1.0 mL of bacteriostatic water into a sterile syringe.
Inject the water slowly down the inner wall of the 50 mg thymopentin vial; do not aim the stream directly at the powder, and avoid vigorous shaking, which can denature the peptide.
Gently swirl or roll the vial until the solution is completely clear; the result is a 50 mg/mL concentration (500 mcg per insulin-syringe unit).
Draw the prescribed dose: a full 50 mg dose is 100 units (one complete U-100 syringe); a 25 mg dose is 50 units. Swab the injection site, then inject subcutaneously or intramuscularly.
Because thymopentin degrades quickly in solution, reconstitute one vial per dose, refrigerate at 2-8 °C if not used immediately, and discard any remainder within 24 hours.
Interactive Thymopentin Syringe Calculator
Currently visualizing the 50 mg vial reconstituted with 1 mL bacteriostatic water. Adjust the target dose to dynamically render syringe units.
Reconstitution Calculation: 50mg dry powder in 1mL water yields 50.00 mg/mL. To evaluate a 250mcg dose, pull to 0.5 units (1 syringe ticks).
U-100 Syringe Representation
Educational reference visual. Assumes standard U-100 insulin syringe where 1.0 mL volume = 100 units.
Titration & Dose Escalation Schedules
| Phase | Dose per injection | Units (per injection) |
|---|---|---|
| Sensitivity / lower-weight dose (optional first dose) | 25000 mcg (25 mg) | 50 units (0.50 mL) |
| Standard course (weeks 1-6, three times weekly) | 50000 mcg (50 mg) | 100 units (1.00 mL) |
| Repeat / maintenance cycles | 50000 mcg (50 mg) | 100 units (1.00 mL) |
Administration guidelines: Refer to guidelines | 1 mL Reconstitution
Research Supplies Quantity Planner
Scientific mathematical planning of syringes, bacteriostatic water and dry vials needed for extended research blocks using the 50 mg vial.
Peptide Vials (Thymopentin, 50 mg each):
- checkAt 50 mg per dose, three times weekly, each vial is reconstituted as a single full dose.
- check8-week course (~24 injections): about 24 vials.
- check12-week course (~36 injections): about 36 vials.
- check16-week course (~48 injections): about 48 vials.
Insulin Syringes (U-100):
- checkOne sterile U-100 syringe per injection; a 1 mL (100-unit) barrel holds a full 50 mg dose.
- check8-week course: about 24 syringes.
- check12-week course: about 36 syringes.
- check16-week course: about 48 syringes.
Bacteriostatic Water (30 mL bottles): Use 1.0 mL per vial for reconstitution.
- check1.0 mL reconstitutes each 50 mg vial to 50 mg/mL (500 mcg per unit).
- check8-week course: about 24 mL (one 30 mL bottle).
- check12-week course: about 36 mL (two bottles).
- check16-week course: about 48 mL (two bottles).
Alcohol Swabs: 70% isopropyl, single-use, for the vial stopper and injection site.
- checkUse two swabs per injection (vial top plus skin).
- check8-week course: about 48 swabs.
- check12-week course: about 72 swabs.
- check16-week course: about 96 swabs.
Mechanism of Action (MOA)
Thymopentin (TP-5) is a synthetic pentapeptide, Arg-Lys-Asp-Val-Tyr, with a molecular weight of roughly 679.8 Da. It corresponds to amino acid residues 32-36 of thymopoietin, a hormone secreted by thymic epithelial cells, and represents the smallest fragment that retains the parent hormone's immunological activity [1][8]. Thymopoietin itself is pleiotropic — affecting neuromuscular transmission, early T-cell differentiation and immune regulation — but thymopentin isolates the immunoregulatory component, which is why it was developed as a defined, fully synthetic immunorestorative agent [1].\n\nMechanistically, thymopentin acts on cells of the T lineage at two stages. In bone-marrow prothymocytes it triggers differentiation toward mature thymocytes, an action shared with the native hormone and demonstrated in the original murine assays [1]. In peripheral, already-committed T cells it modulates function, and this signaling has been linked to a rise in intracellular cyclic GMP, in contrast to the cyclic AMP elevation that drives precursor differentiation [2]. The net clinical effect is immunorestorative rather than broadly immunosuppressive or stimulatory: in immunodeficient or dysregulated states, thymopentin tends to normalize T-cell subset ratios (such as CD4/CD8), enhance natural-killer and lymphocyte responsiveness, and improve antibody responses, helping to rebalance an unbalanced immune system [2][3]. More recent work shows thymopentin-derived peptides can also engage innate pattern-recognition pathways, including the TLR2 receptor, broadening the understanding of how the sequence modulates immune responses [9].\n\nPharmacokinetics are the defining limitation. The native pentapeptide has an extremely short in vivo half-life — under 30 seconds — because it is rapidly cleaved by proteases present in human plasma [8]. It is not orally bioavailable (it is degraded in the gastrointestinal tract), so it is administered parenterally, by subcutaneous or intramuscular injection from a freeze-dried powder [8]. Interestingly, the route and rate of delivery matter: the immunostimulatory effect on antibody production seen with subcutaneous dosing can be lost when the same dose is given as a rapid intravenous bolus, and slow infusion outperforms bolus injection in animal models — observations that have driven research into sustained-release gels and stabilized retro-inverso analogs designed to extend exposure while preserving activity [8].\n\nBecause the molecule disappears from plasma within seconds, its pharmacodynamic footprint outlasts the peptide itself: a brief pulse of receptor engagement appears sufficient to influence T-cell maturation, so clinical regimens rely on repeated injections (typically three times weekly) rather than continuous presence of the drug [3][4]. This pulse-and-persist behavior, rather than a long circulating half-life, underlies the intermittent dosing schedule. The subcutaneous reconstitution scheme on this page reflects the genuine clinical route for thymopentin; the educational figures are provided for measurement reference and are not medical advice [3].
Clinical Trial Efficacy Highlights
- starGoldstein, Scheid, Boyse and colleagues (1979, Science) first reported that the synthetic pentapeptide Arg-Lys-Asp-Val-Tyr (residues 32-36 of thymopoietin) induced differentiation of murine prothymocytes into thymocytes while inhibiting differentiation of B-lineage cells, establishing thymopentin as a defined synthetic peptide carrying the immunological activity of the native thymic hormone [1].
- starAudhya and Goldstein and other early mechanistic work characterized thymopentin's immunoregulatory action on peripheral T cells as mediated by elevated intracellular cyclic GMP, distinct from the cyclic AMP elevation that drives precursor-cell differentiation, providing a biochemical basis for its immunorestorative effects on T-cell subsets and function [2].
- starA compilation of short- and long-term controlled studies of thymopentin (TP-5) in rheumatoid arthritis, including a six-month double-blind subcutaneous trial across several dosages and a three-week high-dose intravenous trial, did not confirm statistically significant clinical benefit, illustrating that the peptide's immunomodulation does not translate into efficacy in every indication [3].
- starStiller, Shupack and colleagues (1994, Journal of the American Academy of Dermatology) randomized 39 patients with severe atopic dermatitis to subcutaneous thymopentin 50 mg three times weekly or placebo; after 12 weeks the thymopentin group showed significantly greater clinical improvement than placebo, with no thymopentin-related adverse events reported [4].
- starLeung and colleagues (1990, Journal of Allergy and Clinical Immunology) reported that thymopentin therapy reduced the clinical severity of atopic dermatitis and was accompanied by measurable changes in lymphocyte subpopulations, supporting an immunologic mechanism for the observed dermatologic benefit [5].
- starAn open and partially randomized study in 16 children with severe atopic dermatitis used 50 mg thymopentin three times weekly for six weeks; total severity scores fell significantly from week three onward, and disease flared again in children switched to saline, indicating that benefit depended on continued dosing (Arch Dis Child, 1992) [6].
- starAn open, monitored, multicenter study treated 27 patients with severe, recurrent, treatment-refractory herpes simplex using thymopentin 50 mg subcutaneously three times weekly for six weeks; 13 of 14 with labial and 10 of 13 with genital infection improved markedly, with relapse rates cut by at least 50% and shorter, less symptomatic episodes [7].
- starFormulation research on a thymopentin-loaded phospholipid-based phase-separation gel (2019) confirmed the peptide's very short in vivo half-life (under 30 seconds) and demonstrated that sustained-release delivery produced prolonged immunomodulatory effects comparable to repeated daily injections of free thymopentin, underscoring that pharmacokinetic instability, not intrinsic activity, is the main therapeutic constraint [8].
Side Effects & Tolerability Profile
Clinical subjects transiently report mild side effects. Slowly escalating the titration dose represents the single most effective intervention to limit side effects.
- warningThymopentin is generally well tolerated in controlled trials; the most common issues are local injection-site reactions such as transient pain, redness, swelling or itching at the subcutaneous or intramuscular site.
- warningHypersensitivity and allergic reactions (rash, urticaria, and rarely more severe responses) can occur with any injected peptide; treatment should be stopped if signs of allergy appear.
- warningMild, transient systemic effects such as headache, low-grade flu-like symptoms or malaise have been reported infrequently around the time of injection.
- warningBecause thymopentin modulates T-cell function, caution is warranted in people with autoimmune disease, organ transplants, or those on immunosuppressive therapy, where altering immune balance could have unpredictable effects.
- warningThe extremely short plasma half-life (under 30 seconds) means systemic accumulation is unlikely, but it also necessitates frequent injections; the reconstituted solution is chemically unstable and loses potency if stored, so it should be used promptly and discarded within 24 hours.
- warningSafety in pregnancy and lactation has not been established, and the compound is not intended for use in those settings without specialist supervision.
- warningData in some indications are mixed or negative (for example rheumatoid arthritis), so immunomodulatory activity should not be assumed to equal clinical benefit for any given condition.
- warningRegulatory/research status: thymopentin is approved for immunodeficiency in some countries (e.g., Italy, as Timunox/Mepentil/Sintomodulina) but is NOT approved by the FDA or EMA for general use in the US/EU; the protocol here is presented for educational and research reference only.
Subcutaneous Injection Technique
Most research peptides require subcutaneous injection into fatty tissue. Never inject directly into a blood vessel or deep muscle tissue unless clinically detailed.
1. Site Selection
Common locations include the abdomen (2 inches from navel), outer upper arms, or thighs.
2. Sanitization
Thoroughly clean the selected site, stopper and vial top using 70% isopropyl alcohol prep swabs.
3. Angle & Push
Pinch the skin and insert the needle at a 45 to 90-degree angle. Depress plunger smoothly.
4. Site Rotation
Rotate injection sites continuously to avoid lipodystrophy or tissue scarring.
Frequently Asked Questions
What is the typical Thymopentin dosage?expand_more
The most common clinical Thymopentin dosage is 50 mg given by subcutaneous or intramuscular injection three times per week (for example Monday, Wednesday, Friday) for about 3-6 weeks, repeated in courses as needed. This is the regimen used in controlled trials for atopic dermatitis and recurrent herpes simplex. Some pediatric or sensitivity protocols start lower (around 25 mg). These figures are an educational reference, not a prescription.
Is Thymopentin FDA approved?expand_more
No. Thymopentin is not approved by the FDA for general therapeutic use in the United States; it received only an orphan-drug designation. It is, however, approved for immunodeficiency in several other countries — for example in Italy, where it is marketed as Timunox, Mepentil and Sintomodulina. In the US it is treated as an investigational/research compound, so this page is educational only.
How do you reconstitute Thymopentin?expand_more
Draw 1.0 mL of bacteriostatic water and inject it slowly down the wall of a 50 mg vial, then swirl gently until clear. This yields 50 mg/mL, so 500 mcg per insulin-syringe unit: a 50 mg dose is 100 units (a full U-100 syringe) and a 25 mg dose is 50 units. Because thymopentin degrades quickly in solution, reconstitute one vial per dose and discard any remainder within 24 hours.
What is the half-life of Thymopentin?expand_more
Thymopentin has an extremely short plasma half-life — under 30 seconds — because the pentapeptide is rapidly cleaved by proteases in human plasma. Despite this, a brief pulse of receptor engagement is enough to influence T-cell maturation, so the immune effects outlast the molecule. This pharmacokinetic instability is why it is dosed three times weekly and why researchers are developing sustained-release formulations and stabilized analogs.
How is Thymopentin administered, and can it be combined with other treatments?expand_more
Thymopentin is administered parenterally, by subcutaneous or intramuscular injection; it is not orally bioavailable because it is broken down in the gut. In its approved settings it has been used as an adjunct alongside conventional therapy (for example topical care in atopic dermatitis or antiviral measures in herpes). Any combination should only occur under qualified medical supervision, particularly in people with autoimmune disease or on immunosuppression.
Related Guides & Tools
Step-by-step references for reconstituting, measuring, and storing Thymopentin, plus the universal dosing calculator.
Academic References & Study Citations
Goldstein G, Scheid MP, Boyse EA, Schlesinger DH, Van Wauwe J. A synthetic pentapeptide with biological activity characteristic of the thymic hormone thymopoietin. Science. 1979;204(4399):1309-1310. View Scientific Paper →
Audhya T, Goldstein G. Thymopoietin to thymopentin: experimental studies. Surv Immunol Res. 1985;4 Suppl 1:17-25. View Scientific Paper →
Veys EM, et al. Thymopoietin pentapeptide (thymopentin, TP-5) in the treatment of rheumatoid arthritis. A compilation of several short- and longterm clinical studies. J Rheumatol. 1984. View Scientific Paper →
Stiller MJ, Shupack JL, Kenny C, et al. A double-blind, placebo-controlled clinical trial to evaluate the safety and efficacy of thymopentin as an adjunctive treatment in atopic dermatitis. J Am Acad Dermatol. 1994;30(4):597-602. View Scientific Paper →
Leung DYM, et al. Thymopentin therapy reduces the clinical severity of atopic dermatitis. J Allergy Clin Immunol. 1990;85(5):927-933. View Scientific Paper →
Thymopentin treatment in severe atopic dermatitis—clinical and immunological evaluations. Arch Dis Child. 1992;67(9):1095-1099. View Scientific Paper →
Thymopentin treatment of herpes simplex infections: an open, monitored, multicenter study. 1985. View Scientific Paper →
Thymopentin-loaded phospholipid-based phase separation gel with long-lasting immunomodulatory effects: in vitro and in vivo studies. Int J Nanomedicine. 2019. View Scientific Paper →
Targeting the TLR2 receptor with a novel thymopentin-derived peptide modulates immune responses. Front Immunol. 2021;12:620494. View Scientific Paper →