Semax Peptide

## What it is Semax is a synthetic heptapeptide developed at the Institute of Molecular Genetics of the Russian Academy of Sciences and Moscow State University in the late 1980s. It is a stabilized analog of the adrenocorticotropic hormone fragment ACTH(4-10), with a Pro-Gly-Pro stabilizing tail that extends the in vivo half-life and abolishes the corticotropic activity of native ACTH. The result is a peptide that retains the cognitive and neurotrophic effects of the parent ACTH fragment without raising cortisol. The compound is approved in Russia for acute ischemic stroke, transient ischemic attack, post-stroke cognitive impairment, and other cerebrovascular and asthenic conditions. It is included in Russian stroke-care guidelines. It is not approved by the FDA, EMA, or other Western regulators, and Western stroke trials have not been conducted. Outside Russia and CIS countries Semax sits in the research-peptide grey market. Users tend to be biohackers seeking nootropic activation, students chasing focus, and a smaller cohort exploring it for ADHD-adjacent symptoms or post-concussion recovery. ## Mechanism of action Semax modulates BDNF and nerve growth factor (NGF) expression in hippocampus and cortex, with measurable upregulation in rodent models within hours of intranasal dosing. It enhances dopaminergic and serotonergic signaling, modulates the endogenous opioid system, and reduces oxidative stress markers in preclinical ischemia models. The Pro-Gly-Pro tail is not just a half-life extender: it shifts the receptor profile away from melanocortin/HPA-axis activation, which is why Semax does not raise cortisol the way native ACTH does. Plasma half-life is approximately 30 minutes, but behavioral and EEG effects persist for 6 to 24 hours after a single intranasal dose, indicating sustained downstream signaling rather than direct receptor occupancy. Onset after intranasal dosing is rapid: cognitive activation and EEG alpha/beta shifts are detectable within 15 to 30 minutes. ## Evidence base Russian acute-stroke trials are the strongest part of the evidence base. Gusev 1997 and follow-up studies through the 2000s reported improved NIHSS recovery scores in acute ischemic stroke patients receiving Semax 12 to 18 mg/day intravenously or intranasally over 5 to 10 days versus standard care. Cumulative Russian trial enrollment in stroke is estimated at 400 to 500 patients across multiple centers. Effect sizes in these trials are moderate, and meta-analytic synthesis from a 2011 Russian review reported consistent direction of effect. In healthy adults, smaller Russian studies (Kaplan 1996, Lebedeva 2008) tested intranasal Semax at 200 to 600 mcg/day on attention, reaction time, and memory tasks. Results showed modest reaction-time improvements and enhanced sustained attention versus placebo, with effect sizes in the range typical of mild stimulants. EEG studies documented increased alpha and beta band activity consistent with cognitive activation. Preclinical work supports the BDNF/NGF and monoaminergic mechanism. Rodent ischemia models show neuroprotection at clinically translatable doses, and rodent learning paradigms show improved acquisition and retention. Two small Russian pediatric open-label trials (n=80 combined) reported modest ADHD symptom reductions, but the evidence is far thinner than for stimulant therapy and lacks placebo control. Western replication is essentially absent. There is no completed Western RCT, no FDA review, and no large multi-center stroke trial outside Russia. Long-term safety data is limited to short-course Russian inpatient and outpatient trial windows. ## Dosage and administration Intranasal cognitive use is the standard outside acute stroke contexts: 200 to 600 mcg/day, divided into 2 to 3 doses, typically morning and early afternoon to align activation with the workday. Russian stroke protocols use much higher doses, up to 12 to 18 mg/day intravenously in acute inpatient care, reflecting the scale of CNS injury being treated. Intranasal sprays are typically formulated at 0.1% to 1% (1 to 10 mg/mL); 2 to 3 sprays per nostril delivers approximately 100 to 300 mcg per side. Alcohol-free saline-based sprays preserve nasal mucosal tolerance for daily use. Russian cognitive protocols run 10 to 14 day courses; acute stroke protocols are 5 to 10 day inpatient courses. Reference the existing typicalDoseMg of 0.6 as the daily total for cognitive use, dosed in 2 to 3 divided administrations. Start low (200 to 300 mcg/day) for the first week to assess activation tolerance. ## Side effects and safety Reported adverse effects are mild: nasal mucosal irritation, transient mild headache, and rare mild euphoria or activation. Higher doses can produce overactivation, particularly in users sensitive to stimulants. Because the Pro-Gly-Pro tail abolishes corticotropic activity, Semax does not raise cortisol; HPA axis disruption is not a concern at standard doses. Contraindications include pregnancy, lactation, acute psychotic disorder, and severe hypertension where mild activating effects could compound risk. Interactions are sparsely documented: concurrent stimulants (caffeine, amphetamines) may produce additive activation, and antipsychotics may theoretically antagonize the dopaminergic component. Long-term safety with chronic continuous use has not been established. The compound is not on the WADA Prohibited List as of 2026. ## Practical notes Lyophilized Semax and pre-formulated nasal sprays should be refrigerated. Reconstituted intranasal solution is typically stable for 30 days refrigerated; some users add bacteriostatic preservation for longer shelf life. Light protection is sensible but not strictly required. Expect cognitive activation within 15 to 30 minutes of an intranasal dose, peaking around 1 to 2 hours, with a useful window of 4 to 6 hours. Most users describe sharper sustained attention, faster verbal recall, and a quieter sense of mental effort. Effects on subjective mood and motivation accumulate over a 10 to 14 day course. Russian nootropic stacking pairs Semax with Selank for non-overlapping benefit (Semax activation plus Selank anxiolysis), though there is no controlled human data on the combination. Semax is not a substitute for evaluated treatment of ADHD, post-stroke cognitive impairment, or other approved indications outside Russian clinical practice.