RESEARCH DIGEST / DOSE DATA
Thymulin Dosage in the Research Literature
No established human dose. The record reports nanogram-to-microgram amounts in named species, by route — 1/100/1000 ng i.p., 0.1-1 microg i.c.v., 3-100 microg/day s.c. Study findings, not guidance.
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There is no established human thymulin dosage, and nothing on this page is dosing guidance. What follows is a record of what researchers administered to animals, at what amount, by what route — reported so the figures can be read against their studies. The numbers are small: nanograms to a few micrograms per animal, given by injection into the abdomen, under the skin, or into the brain fluid, depending on the model. Where gene therapy was used, there is no peptide dose at all — a single vector dose makes the body produce thymulin itself. Read every figure as 'administered at X in this species,' never as a protocol.
Thymulin Dosage in the Research Literature
Searches for thymulin peptide dosage return no human protocol because none exists; what the record holds is a set of animal doses. Reported thymulin research doses span nanogram-to-low-microgram amounts per animal, by species and model [8][9][13]. The clearest dose ladder is the anti-hyperalgesia study: daily intraperitoneal thymulin at 1, 100, and 1000 ng produced dose-dependent reductions in hyperalgesia in mice, with a 1 microgram dose reversing skin IL-1beta and NGF increases [8]. Central-action studies used roughly 0.1-1 microg intracerebroventricular [8][12], and the thymulin analog PAT was given at 1-200 microg i.p. and 25 microg intraplantar in rats [9].
Other models scale similarly. Radioprotection in mice used daily subcutaneous serum thymic factor at 3-100 microg/day [13]. Endocrine work in boars used 4.4-444.4 ng/kg intravenous and 1-1000 ng/mL in vitro [14]. A pulmonary-hypertension rat model used roughly 100 ng/kg/day subcutaneous (per source). Every one of these is a study finding in a named species — not a human dose.
Thymulin Side Effects and Safety in Studies
Thymulin's safety profile is not characterized in modern human trials. The available controlled human data come from two double-blind placebo-controlled rheumatoid-arthritis trials of the synthetic analog nonathymulin at 1, 5, or 10 mg/day, which evaluated effects on disease activity — not native thymulin [15]. There is no established human side-effect profile for native thymulin, and it is not FDA-approved for any use [2][16]. Because activity is strictly zinc-dependent, any reported effect is also entangled with zinc status [16].
Routes Studied
Thymulin and its analogs have been administered by several routes, each tied to a model rather than a recommended practice. Documented routes include intraperitoneal, subcutaneous, intracerebroventricular, intratracheal (for inhaled gene therapy), intramuscular (gene-therapy vector), topical (a zinc-thymulin pilot), and in vitro [2][7][8][13].
The gene-therapy routes are a category apart. The inhaled-asthma study delivered a single intratracheal dose of thymulin-expressing plasmids in nanoparticles — a vector dose, not a peptide dose [7]. The neuroendocrine-aging work delivered regulatable adenovectors carrying the metFTS analog [5]. In those models the relevant quantity is vector dose and expression duration, not milligrams of peptide.
One stability note governs all of it: activity requires the bound zinc ion. Zinc chelation (for example by EDTA or Chelex) abolishes activity, and the apo-peptide is inactive until zinc is restored [2]. Any handling that strips zinc strips function.
Why a Human Dose Does Not Exist Yet
Two facts keep a human dosage out of reach. First, native thymulin has a short circulating half-life as a small peptide, and a precise human pharmacokinetic half-life is not well established in the public literature [2] — you cannot rationally set a dose without knowing the clearance. Second, there are no large modern human efficacy trials of native thymulin; the human record is sparse and dated, and several studies used the synthetic analog nonathymulin rather than the native peptide [16].
The field's response was not to escalate peptide doses but to change the delivery problem entirely — using gene therapy to sustain circulating thymulin from a vector [4][5]. For the dose figures behind specific findings, see the thymulin research findings; for how zinc gates all of it, see thymulin zinc dependence.