Semax Peptide Dosage: Reading the Numbers on Research Documentation

By What Peptides Editorial Team · Updated 2026-09-14 · Part of Peptide Handling Guides: Reconstitution Arithmetic, Storage and Testing

Semax is a synthetic heptapeptide built on the adrenocorticotropic hormone fragment ACTH(4-7), Met-Glu-His-Phe, extended at the C-terminus with Pro-Gly-Pro to give the full sequence Met-Glu-His-Phe-Pro-Gly-Pro. That three-residue tail is there to slow enzymatic trimming of the short parent fragment, which on its own is cleared very quickly in biological matrices. Semax was developed in Russia, where it has been registered as a medicine; in most other markets it appears only as a research material, usually labelled research use only and not for human consumption. This page explains the numbers that appear on documentation for it. It gives no dose, no schedule and no outcome expectation, because none of those belong in an educational article.

What this page does instead is arithmetic and label literacy. A research document for semax typically states a mass (mg or mcg), a volume (mL), and sometimes a concentration (mg/mL) or a percentage. Those are three different quantities, and most of the confusion behind the search term comes from treating them as one. Below: what each quantity means, why intranasal and injectable research presentations are described with different concentration figures, and where a defensible dose figure would actually come from. This is educational content about laboratory and research documentation. It is not medical advice, and it is not a protocol for preparing or giving anything to a person or an animal.

Mass, Volume and Concentration Are Three Different Things

A milligram (mg) is one thousandth of a gram. A microgram, written mcg on most documents and ug on older ones, is one millionth of a gram, so there are 1000 mcg in 1 mg. Peptide documentation uses both, and the choice is usually arbitrary: suppliers tend to print whichever unit keeps the leading number between 1 and 1000. A vial described as 5 mg holds the same quantity as one described as 5000 mcg. Errors cluster around this conversion because a single misplaced zero moves the amount by a factor of ten, and because handwritten specifications sometimes abbreviate micrograms to a symbol that reads like milligrams. When you read a research document, rewrite every figure in one unit before you do anything else with it.

Volume and concentration are separate again. Volume is how much liquid is in the container, in millilitres (mL). Concentration is mass per unit volume, usually mg/mL, and it is a derived quantity: mass divided by volume. A specification sheet that lists 5 mg of peptide and 2 mL of diluent describes a 2.5 mg/mL solution. Double the diluent to 4 mL and the same 5 mg now sits in a 1.25 mg/mL solution. The amount of peptide has not changed; the concentration has. Most documentation confusion comes from quoting a concentration as if it were an amount, or the other way round, and the two are only interchangeable once you also know the volume. The same three-field discipline applies to activity measures, which is why we treat why a unit is not a mass as a separate problem.

• mg: a mass, one thousandth of a gram
• mcg (ug): a mass, one thousandth of a milligram
• mL: a liquid volume, independent of how much peptide is in it
• mg/mL: derived concentration, mass divided by volume
• % w/v: grams per 100 mL, common on nasal solution labels
• unit or IU: an activity measure, not a mass

Why Nasal and Injectable Research Forms Are Described Differently

Semax appears in research literature and in supplier catalogues in more than one presentation, and the concentration figures attached to them are not comparable. An intranasal research solution is typically described as a percentage weight per volume, such as 0.1% or 1%, which corresponds to 1 mg/mL or 10 mg/mL respectively, because a 1% w/v solution is 1 g per 100 mL. Injectable research material is more often lyophilised powder in a vial, with the amount stated as a mass on the vial and no concentration at all until a diluent volume is chosen by the laboratory. One describes a ready-made liquid, the other describes a solid, so the numbers mean different things even when both read as a single figure.

The formulation constraints differ too. A nasal solution has to stay inside a narrow window of pH, osmolality and preservative content to remain stable in an aqueous dropper or spray bottle, and the peptide concentration is whatever the formulation work settled on. A lyophilised vial has no such constraint; the concentration is set later by whoever reconstitutes it, which is why documentation for powders states mass and leaves concentration blank. A third wrinkle is peptide content: a vial marked 5 mg may contain 5 mg of solid material of which only part is peptide, the remainder being water, salts and counter-ions. Read how purity and peptide content are measured separately before treating a printed mass as the mass of peptide.

Where a Legitimate Dose Figure Comes From, and Why We Give None

There is one place where a dose figure for a medicine belongs: the approved prescribing information, sometimes called the summary of product characteristics or package insert, issued by the regulator that licensed it. Semax has been registered as a medicine in Russia, so an approved prescribing document exists for it there. It is not approved by the US Food and Drug Administration or the European Medicines Agency, and no equivalent document exists in those jurisdictions. Where a compound is a prescription medicine, the dose is a clinical decision made by a licensed clinician against that approved document. It is not something a website should supply, and this page does not.

For research material, the closest thing to an authoritative number is the methods section of a peer-reviewed paper or the protocol record on a public trial registry, both of which state what an investigator did under ethics approval and institutional oversight. Neither is a recommendation, and both describe a specific population under supervision. Vendor listings, forum posts and online calculators are not sources of dose information at all; they sit one step further from any document that was reviewed by anyone. This page is educational arithmetic for laboratory and research documentation and is not medical advice. For the molecule itself, start with how a peptide is defined and where the term ends, and for the wider set of explainers see the peptide guides collection.

This page is part of the Peptide Handling Guides: Reconstitution Arithmetic, Storage and Testing guide.