the parts list ~ doses by species and route, never a protocol
Thymulin Dosage in the Research Literature
There is no established human dose. What follows is what researchers administered, to which species, by which route — clipped from the studies and labelled as findings, not instructions.
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Plainly, before any numbers: there is no human thymulin dose to report, because thymulin is not an approved medicine and has no validated human protocol. Every figure on this page is a study finding — a dose a researcher gave to an animal or added to a cell culture in a specific experiment. We write them as "administered at X in [species]" and nothing more. This is a research digest, not a how-to. Nobody should read a number here as a personal instruction, and we do not provide one.
Thymulin Dosage in the Research Literature
Across the published thymulin literature, reported doses span a nanogram-to-low-microgram range per animal, depending heavily on the model and the route [4][11]. In rodent anti-inflammatory and pain studies, figures in the literature include roughly 0.1-1 microgram given intracerebroventricularly and 1-1000 nanograms given intraperitoneally [4]. In a rat pulmonary-hypertension study, the cited dose is about 100 nanograms/kg/day subcutaneously [4]. For radioprotection in lethally irradiated mice, daily subcutaneous doses of 3-100 microgram/day were used [11].
Notice how small those numbers are. Nanograms and low micrograms per animal is a hormone-scale dose, not a drug-scale one — consistent with thymulin being an endogenous signaling peptide rather than something given in bulk. Notice also the spread: the doses are not standardized across studies, because each model was optimized on its own terms (a brain-injected analgesia study and a subcutaneous radioprotection study are answering different questions). There is no consensus "thymulin dose," even in animals — there is a scatter of model-specific amounts [4][11].
Mouse systemic-inflammation models typically gave thymulin in vivo, often daily or every other day, as pretreatment before the inflammatory challenge [6][10]. The timing is part of the design: several anti-inflammatory results came from pretreating before the insult, not from rescuing after it. These are research doses in named species — they are not converted to, and do not imply, a human dose.
Thymulin Peptide Dosage and Routes Studied
The thymulin peptide dosage question is really a question about routes, because the literature is a catalogue of administration methods rather than a settled protocol. Routes studied include intraperitoneal, subcutaneous, intracerebroventricular, intratracheal (for gene therapy), intramuscular (for a gene-therapy vector), and topical (a small zinc-thymulin pilot), plus a large body of in-vitro work [4][7]. The route was usually chosen to fit the model: intracerebroventricular for CNS analgesia work, intratracheal for lung gene therapy, subcutaneous for systemic dosing.
There are also a couple of less-common routes worth noting. A boar steroidogenesis study used intravenous thymulin (4.4-444.4 ng/kg) as well as in-vitro incubation (1-1000 ng/mL), generally raising circulating testosterone 2-3 hours after injection [13]. And a separate strand is purely topical: a small zinc-thymulin pilot in androgenetic alopecia, which the research record flags as low-tier, single-author, and not independently grounded — preliminary, in other words [4].
Worth flagging the bigger pattern: several of the most-cited "thymulin" delivery studies are gene therapy, where the "dose" is a single vector administration, not a peptide quantity [5][7]. The 2020 asthma reversal used a single intratracheal plasmid dose in nanoparticles [7]; the neuroendocrine work used adenoviral vectors [5]. So when a source reports a striking single-dose result, check whether it administered the peptide or a gene that makes the peptide — they are not the same dosing concept.
Thymulin Half-Life and Pharmacokinetics
As a small peptide, native thymulin has a short circulating half-life — but a precise human pharmacokinetic half-life is not well established in the public literature. There is no clean PK number to clip here, and we will not invent one. This is one of the places where consumer write-ups tend to fill the gap with a confident figure; we would rather leave the line blank than fake it.
The strongest evidence for the short-half-life picture is indirect but telling: the gene-therapy approaches were developed specifically to sustain circulating thymulin levels in animal models, because the peptide does not persist on its own [4][5]. A molecule you have to engineer a gene vector to keep around is, by design, not a long-acting one [5]. The same logic shows up in the dosing schedules of the animal literature — daily or every-other-day injection in the inflammation models — which is what you do with a short-lived signaling peptide rather than a depot drug [6][10]. Beyond that, standardized human dosing and pharmacokinetics simply are not characterized, and we flag that absence as a finding in itself.
Stability and the Zinc Caveat
One dosing-relevant property is not about quantity at all: thymulin's activity requires its bound zinc ion. Chelating the zinc (with EDTA or Chelex) abolishes activity, and the apopeptide stays inactive until zinc is restored [1]. So any handling that strips the metal effectively switches the molecule off, regardless of how much peptide is present.
That turns dose-response into a two-variable problem. The amount of peptide is one axis; the amount of available zinc to activate it is the other [2]. A figure reported as a "thymulin dose" is really the peptide half of that pair, and its real-world activity also depends on the zinc half — which is exactly why the human zinc-deficiency literature can move measured thymulin activity up and down without changing the peptide at all [3]. For interpreting any reported dose, the zinc status of the system is part of the dose.
The honest summary: no human dose, study doses only by species and route, a short and poorly-characterized half-life, and an activity that lives or dies by a bound zinc ion. We report the numbers researchers used and refuse to translate them into anything a person should do. For the studies behind these figures, see the thymulin references.