Semax

What it is

Semax is a synthetic heptapeptide, Met-Glu-His-Phe-Pro-Gly-Pro, derived from the 4-10 fragment of adrenocorticotropic hormone [4]. Russian researchers describe it as a synthetic melanocortin derivative used in the treatment of ischaemic stroke, and the published human work uses the intranasal route [2][1]. It is also written ACTH(4-7)PGP [2]. A 2026 review summarises its position bluntly: not approved in the West, with a clinical literature that is Russian and no independent Western validation [4]. In the United States it is not an FDA-approved drug, and compounded preparations are not FDA-approved [10]. FDA’s advisory committee discussed it in July 2026 for cerebral ischaemia, migraine and trigeminal neuralgia [8].

How it works

The most consistent reported mechanism is upregulation of brain-derived neurotrophic factor: in animals Semax raises hippocampal BDNF protein about 1.4-fold and BDNF messenger RNA about 3-fold, with increased activation of the TrkB receptor [4]. In a rat model of cerebral ischaemia and reperfusion, Semax altered brain expression of proteins tied to inflammation and cell death and raised active CREB, a transcription factor linked to neuroprotection and recovery [2]. Reviews also describe modulation of dopamine and serotonin systems and antioxidant and anti-neuroinflammatory properties [4]. In the human stroke study the same BDNF signal was visible from outside the brain, as a rise in plasma BDNF [1].

What the evidence shows

The strongest human report is a Russian study of 110 people recovering from ischaemic stroke, 43 men and 67 women with a mean age of 58, divided into early and late rehabilitation groups, each split into subgroups with and without Semax [1]. Adding Semax raised plasma BDNF, which stayed elevated for the whole study period, alongside motor performance scoring on the British Medical Research Council scale and Barthel index scores [1]. The report is published in Russian, which limits independent scrutiny [1]. A 2026 review reaches a similar conclusion: human stroke trials report improved neurological function, but there is no independent Western validation [4]. FDA staff proposed that Semax not be listed [7].

Regulatory status

Not an FDA-approved drug. On Jul 23–24 2026 the FDA Pharmacy Compounding Advisory Committee voted to recommend adding it to the 503A bulk drug substances list; FDA has not finalized that listing (as of Sep 24 2026). [6] The Semax vote, held on 24 July 2026, was 8 in favour and 5 against, for proposed uses in cerebral ischaemia, migraine and trigeminal neuralgia [8]. FDA scientists had proposed the opposite, citing insufficient safety, efficacy and characterisation information across the nominated peptides [7][9]. In April 2026 FDA removed Semax from Category 2 after the nomination was withdrawn, which did not place it on the bulks list [11]. Formal listing requires rulemaking and is not approval [9].

Half-life and what it means for a level curve

No human pharmacokinetic study of Semax has been published that reports an elimination half-life, so only animal data exist [3]. In rats given labelled Semax intranasally, 0.093% of the introduced radioactivity per gram was found in brain 2 minutes after administration, and 80% of that radioactivity was still intact peptide rather than metabolites [3]. Separate rat work shows rapid enzymatic cleavage of the molecule in the presence of brain cells and plasma membranes [5][3]. STACK has no reference half-life for this compound because no human value has been published; you can enter your own estimate. A level then decays between doses and approaches about 97% of steady state after roughly five half-lives. STACK’s curve is an estimate from this published half-life, not a blood level.

Reported side effects

No FDA-approved label exists for Semax, so there is no regulated adverse-reaction list [10]. The 110-patient stroke study measured BDNF, motor performance and Barthel index rather than reporting a formal safety analysis, so it is weak evidence about harm [1]. A 2026 review notes that non-approved peptides in this group lack long-term safety data and systematic validation [4]. At the July 2026 meeting FDA scientists argued against inclusion of every nominated peptide, citing insufficient safety and efficacy information and incomplete characterisation of the molecules [9]. Compounded drugs are not FDA-approved, and FDA does not verify their safety, effectiveness or quality before they are marketed [10]. Tell your prescriber about anything unexpected.

Storage and handling

Semax has no FDA-approved label, so the label supplied with your preparation governs storage, beyond-use date and handling [10]. Drugs compounded under section 503A are exempt from current good manufacturing practice requirements, and state boards of pharmacy carry most of the day-to-day oversight of state-licensed pharmacies, so the printed label and the pharmacist’s instructions stand in for a package insert [10]. FDA warns that poor compounding practice can cause contamination or a preparation containing too much or too little active ingredient [10]. Because the published human use is intranasal, storage temperature and any in-use limit for a nasal solution come from that label [1]. STACK’s reconstitution calculator does the mixing arithmetic if your preparation needs it.

What STACK tracks for it

STACK logs each dose as your prescriber wrote it, with date, time and route, and treats intranasal as a first-class route rather than assuming an injection [1]. The estimated-level chart stays off unless you enter your own half-life, because no human value has been published [3]. You can record the schedule your prescriber gave you and mark doses against it, and track symptoms, sleep, headache days or whatever your prescriber is watching. Container inventory is tracked alongside. Everything exports as a plain summary for your next appointment. STACK shows what you logged; it does not prescribe and does not suggest amounts.

The reference half-life in STACK

STACK ships Semax without a default half-life: No human value published; rat kinetics only. You enter your own estimate before a curve is drawn.

Estimate only. Modelled from the published half-life you selected and the doses you logged — not a measured blood level. Do not use it to make medication decisions.

Free tools for Semax

Read next

Sources

Every URL below was fetched and checked on 2026-09-24. Bracketed numbers in the text link here.

1. TrialThe efficacy of semax in the treatment of patients at different stages of ischemic stroke
2. OtherBrain Protein Expression Profile Confirms the Protective Effect of the ACTH(4-7)PGP Peptide (Semax) in a Rat Model of Cerebral Ischemia-Reperfusion
3. OtherKinetics of Semax penetration into the brain and blood of rats after its intranasal administration
4. ReviewTherapeutic peptides in gerontology: mechanisms and applications for healthy aging
5. OtherDegradation of the ACTH(4-10) analog Semax in the presence of rat basal forebrain cell cultures and plasma membranes
6. FDAJuly 23-24, 2026: Meeting of the Pharmacy Compounding Advisory Committee
7. FDAFDA Briefing Document, Pharmacy Compounding Advisory Committee, July 23-24 2026
8. OtherFDA advisory committee backs two more peptides, rejects one for compounding list
9. OtherBulk List Bound: PCAC Backs Majority of Peptides in Two-Day Public Meeting
10. FDACompounding and the FDA: Questions and Answers
11. OtherFDA Announces Removal of 12 Peptides from Category 2 and Schedules PCAC Meetings