The numbers
Semax Dosage in the Research Literature
What was administered, to which species, by which route — and why the half-life shapes everything else. No human dosing.
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This page reports the Semax doses used in published animal studies. It does not tell anyone how much to take — there is no validated human dose outside Russian prescription formulations, and this is a research digest, not medical advice. Two facts shape everything. First, the doses in the literature are measured per kilogram of body weight in rats and mice, not as human amounts. Second, the intact peptide leaves the brain within minutes, which is why the effect people report is short and why a breakdown product, Pro-Gly-Pro, is credited with the longer action [6][8]. Below: the doses actually studied, the half-life, the routes, how the powder is handled, and a note on cycling — each tied to a study and stated as research, never as instruction.
Doses studied in animals
Semax dosage in the literature is reported in research-context terms only — expressed per kilogram in rodents. The recurring figures are: a single 50 microg/kg intranasal dose in rat neurotrophin gene-expression studies [2]; 50 and 250 microg/kg intranasal in the rat basal-forebrain BDNF binding and protein study [1]; and 0.15 mg/kg intraperitoneal (injected into the abdominal cavity) in mouse monoaminergic studies [20]. Daily intraperitoneal dosing has been used in rat stress models, and intranasal dosing over several consecutive days is standard in the rodent focal-ischemia neuroprotection work [4]. None of these is a human dose, and none should be read as one.
Semax half life
The Semax half life is very short, and that single fact explains most of the practical reports. After a 50 microg/kg intranasal dose in rats, only about 0.093% of the administered radioactivity per gram appeared in the brain at two minutes — roughly 80% of it still intact Semax, the remainder already metabolites — and the peptide undergoes rapid enzymatic degradation [6]. The intact heptapeptide therefore has a very short residence time. The longer behavioral effects reported in the literature are commonly attributed to the active Pro-Gly-Pro metabolite, which carries independent neurotrophic activity [8]. The stability of Semax acetate to proteolysis across biological media has been measured directly [16], confirming how quickly the unmodified peptide breaks down.
How long does semax last
How long Semax lasts depends on whether you mean the molecule or the effect. The molecule itself is gone fast — brain radioactivity is already measured at two minutes after an intranasal dose, with rapid degradation following [6]. The reported subjective effect is widely described by users as lasting a handful of hours before tapering, which is why many redose later in the day; this short duration is one of the most consistent community observations and lines up with the pharmacokinetic data. Any effect outlasting the parent peptide is attributed to the Pro-Gly-Pro metabolite rather than to lingering Semax [8].
Routes studied
Three routes appear in the literature. Intranasal is the primary clinical and preclinical route — it allows rapid brain access while bypassing first-pass liver metabolism, and it is the route in the BDNF, neurotrophin, and neuroprotection studies [1][2][4]. Intraperitoneal injection is common in rodent pharmacology, including the monoaminergic study at 0.15 mg/kg [20]. Systemic injection has been used in some rodent behavioral models. The intranasal route is also the one tied to the most frequently reported discomfort — nasal stinging — covered on the Semax effects page.
Semax reconstitution
Research peptide is typically supplied lyophilized — freeze-dried to a dry powder under vacuum, which removes water and yields a more stable solid that is dissolved before use. Beyond that general description, the published literature does not define a consumer reconstitution protocol, and the sterility and pH of self-prepared solutions are not controlled outside a pharmacy setting. The relevant chemistry that exists is about stability, not preparation: unmodified Semax is rapidly degraded from the N-terminus in blood, the engineered Pro-Gly-Pro tail slows that breakdown, and the proteolytic stability of Semax acetate in biological media has been studied directly [16]. This site does not provide a how-to-prepare procedure.
Semax cycle
There is no evidence-based Semax cycle. Eastern European protocols sometimes use short cycling courses, but the pharmacological rationale — for example, receptor-downregulation kinetics — is not well characterized in the published literature, and formal tolerance, dependence, and withdrawal studies are sparse. Some long-term users report the effect blunting with continuous daily use and choose to take breaks, sometimes citing neurotrophic-receptor downregulation; others report no acute tolerance. Because the underlying kinetics are uncharacterized, "how much, how often, and for how long" has no evidence-based answer, and the cycling question remains a community heuristic rather than an established finding.