Cerebrolysin is unlike every synthetic peptide in this encyclopaedia: it is not a single molecule but a mixture of short peptides and free amino acids obtained from pig brain. It is an authorised medicine — in Poland among other countries — for adjunctive treatment of dementia, post-stroke deficits and traumatic brain injury, given only by injection or infusion. It has dozens of clinical trials behind it, including randomised studies with more than a thousand participants and several Cochrane reviews. It is also an example of how results can diverge: manufacturer-supported trials show improvement, while independent reviews find no effect on survival and a possible increase in serious adverse events. In 2025–2026 part of the preclinical literature on the preparation was retracted by journals. This review sorts out what is known.
What Cerebrolysin is
According to the Summary of Product Characteristics, 1 ml of solution contains 215.2 mg of a peptide mixture obtained from pig brain. The Cochrane reviews describe it as “a mixture of low-molecular-weight peptides and amino acids derived from porcine brain that has potential neuroprotective properties”, widely used for stroke in Russia, Eastern Europe, China and other Asian and post-Soviet countries. The manufacturer is the Austrian company EVER Neuro Pharma.
In the Polish Register of Medicinal Products Cerebrolysin is listed under number 08135 as a medicine authorised by the national procedure, as a solution for injection and infusion, with the indication “adjunctive treatment” in dementia of the Alzheimer and vascular type, in post-stroke deficits and in craniocerebral trauma. The word “adjunctive” matters — it is not a first-line medicine for any of these conditions. In the USA the preparation is not approved by the FDA.
How it is meant to work
To keep neurons alive and repair them the brain uses neurotrophic factors — proteins such as NGF and BDNF that act as “fuel and repair instructions” for nerve cells. According to the manufacturer and the reviews, Cerebrolysin is meant to mimic those factors: the peptide fragments it contains would stimulate the same pathways and increase the brain's own production of neurotrophic factors. The active composition is not defined — it is a mixture, so nobody knows which fragments are responsible for which effect.
The second proposed mechanism is suppression of inflammation in the brain. In a study from China (Guan et al., 2019), in rats with temporary occlusion of the middle cerebral artery the preparation given 3 hours after the ischaemia reduced the infarct area and improved motor performance, and in microglia (the brain's immune cells) it lowered the expression of pro-inflammatory genes and raised anti-inflammatory ones through the CREB/PGC-1α pathway. The phrase popular in marketing copy, “switches microglia from the M1 to the M2 phenotype”, is a simplification of that result; PubMed has no paper that uses such a description for Cerebrolysin.
What was studied — cells and animals, and what was retracted
The preclinical literature is extensive: models of stroke, brain injury, Alzheimer's disease, spinal cord injury and even nanoparticle poisoning. A large part of it, however, came from two centres collaborating with the manufacturer, and that is precisely the part with a serious problem. In 2025–2026 journals retracted a series of animal papers on Cerebrolysin from a laboratory at the University of California San Diego, published jointly with company employees; in a 2025 retraction note the editor writes of overlapping band fragments and edited backgrounds in figures that “call into question the article's overall scientific soundness” (Rockenstein et al., note 2025). PubMed currently tags ten records of animal studies in which Cerebrolysin was the intervention or the comparator as retracted.
This does not invalidate the whole literature — the study by Guan et al. comes from a different centre — but it means that the mechanistic stories about “lowering amyloid and tau”, repeated in many reviews, rest partly on data in which editors have lost confidence. The animal evidence now has to be read with that correction.
Human data — ischaemic stroke
The largest trial is CASTA (Heiss et al., 2012): 1,070 patients with acute ischaemic stroke in Asia, randomly assigned to 30 ml of Cerebrolysin a day or placebo by infusion for 10 days and followed for 90 days. The primary endpoint — a combined assessment of three disability scales — showed no significant difference between the groups. Only a post hoc analysis in patients with more severe stroke (NIHSS above 12) showed a trend in favour of the drug and lower mortality (10.5 % versus 20.2 %); the authors themselves wrote that this needed confirmation in a further trial.
The CARS trial (Muresanu et al., 2016) was smaller: 208 patients, 21 days of infusions started 24–72 hours after the stroke, alongside rehabilitation. Here the result was positive: arm function at day 90 (the ARAT test) was clearly better in the drug group (Mann-Whitney estimator 0.71; p below 0.0001). The authors described the trial as exploratory and small, requiring confirmation — and the author list included manufacturer employees.
The independent Cochrane review (Ziganshina et al., 2023) gathered 7 randomised trials with 1,773 participants, CASTA included. Its conclusion: Cerebrolysin probably does not change all-cause mortality (risk ratio 0.96; moderate-certainty evidence) or the total number of people with serious adverse events, but it increases the number of people with non-fatal serious adverse events (risk ratio 2.39; interval 1.10–5.23), most clearly with the 30 ml for 10 days schedule. None of the trials reported what matters most to a patient — the share of deaths or dependence at the end of follow-up. The Cochrane authors also noted that the manufacturer supported three of the multicentre trials.
Human data — dementias and brain injury
In vascular dementia the Cochrane review (Cui et al., 2019) gathered 6 trials with 597 participants and found improved cognition (standardised difference 0.36) and global function, but rated the evidence as very low quality; no new trial has appeared since 2013. The authors wrote plainly that if there is a benefit, it “may be too small to be clinically meaningful”.
In Alzheimer's disease a meta-analysis of six trials (Gauthier et al., 2015), prepared with manufacturer employees among the authors, showed superiority over placebo on cognition at 4 weeks, but at 6 months the cognitive difference was no longer significant (p = 0.17). An independent review from Glasgow (Alsulaimani and Quinn, 2021), covering 8 trials and 793 people with all types of dementia, found a small effect (standardised difference −0.16) and judged it “probably less than would be considered clinically relevant”, with moderate to high risk of bias in the trials.
After traumatic brain injury the best-described trial is CAPTAIN II (Muresanu et al., 2020): 142 patients with moderate or severe injury (GCS 7–12), one centre, double-blind, placebo-controlled. The primary endpoint — a combined assessment of 13 scales — showed a “small-to-medium” effect in favour of the drug at day 90 (estimator 0.59; p = 0.012). The earlier multicentre trial CAPTAIN I was terminated after enrolling 46 people, so the whole strength of the evidence in brain injury rests on a single centre.
Safety and the limits of the evidence
Cerebrolysin is a preparation of animal origin, and therefore a mixture of foreign protein fragments — which sets it qualitatively apart from synthetic peptides. The Summary of Product Characteristics lists hypersensitivity as a contraindication, calls for caution in allergic diseases, and among adverse reactions gives very rare allergic reactions up to a “shock-like state”. In 2024 a well-documented, life-threatening anaphylaxis was described in an 85-year-old patient after intravenous administration in the subacute phase of stroke (Trimmel et al.); the authors stress that such cases have rarely been published, and that the drug is usually given to people in a serious condition.
The second contraindication in the Summary is epilepsy, especially with grand mal seizures — the document says the drug “may increase the frequency of seizures”, and among very rare adverse reactions it lists isolated seizures after administration. The third is severe renal failure. On top of this comes the Cochrane signal of more frequent non-fatal serious adverse events in stroke.
The limits of the evidence matter as much as the results: most trials were supported by the manufacturer, the most positive ones (CARS, CAPTAIN II) were small or single-centre and called themselves exploratory, and the largest (CASTA) missed its primary goal. Part of the animal data has been retracted as well. We deliberately give no methods of use and no doses — this is a medicine given under medical supervision, not a substance for self-administration.
The wider context — “neurotrophics” from different worlds
Cerebrolysin occupies a special place in this encyclopaedia: it is the only preparation with a medicine authorisation in Poland and the only one with randomised trials counted in hundreds and thousands of participants. It is worth setting it beside two other “neuropeptides” from the same shelf of promises — P21 (P021), a synthetic mimetic of the CNTF factor studied only in rodents in one laboratory, and the Russian Pinealon, a tripeptide without a single randomised trial. The difference is not that Cerebrolysin “works”, but that in its case an effect can at least be argued about on the basis of data.
Summary
Cerebrolysin is an authorised medicine made from pig brain, with an undefined active composition and a large but uneven evidence base. In stroke the largest trial missed its primary goal, and the independent Cochrane review of 2023 sees no effect on survival and flags more frequent serious adverse events; smaller, manufacturer-supported trials show better arm function. In dementias the effect is small and, according to independent analyses, probably without clinical relevance; in brain injury the evidence comes from a single centre. Add to this a real risk of anaphylaxis, a contraindication in epilepsy and retracted animal papers. State of the evidence: moderate in quantity, weak in quality and internally contradictory — and the question of whether a patient gains lasting benefit has still not been answered.
Sources
- Ziganshina LE, Abakumova T, Nurkhametova D, Ivanchenko K. Cerebrolysin for acute ischaemic stroke. Cochrane Database of Systematic Reviews. 2023;10(10):CD007026. PMID: 37818733. DOI: 10.1002/14651858.CD007026.pub7. pubmed.ncbi.nlm.nih.gov/37818733
- Cui S, Chen N, Yang M, Guo J, Zhou M, Zhu C, He L. Cerebrolysin for vascular dementia. Cochrane Database of Systematic Reviews. 2019;2019(11):CD008900. PMID: 31710397. DOI: 10.1002/14651858.CD008900.pub3. pubmed.ncbi.nlm.nih.gov/31710397
- Alsulaimani RA, Quinn TJ. The efficacy and safety of animal-derived nootropics in cognitive disorders: Systematic review and meta-analysis. Cerebral Circulation - Cognition and Behavior. 2021;2:100012. PMID: 36324709. DOI: 10.1016/j.cccb.2021.100012. pubmed.ncbi.nlm.nih.gov/36324709
- Gauthier S, Proaño JV, Jia J, Froelich L, Vester JC, Doppler E. Cerebrolysin in mild-to-moderate Alzheimer's disease: a meta-analysis of randomized controlled clinical trials. Dementia and Geriatric Cognitive Disorders. 2015;39(5-6):332-347. PMID: 25832905. DOI: 10.1159/000377672. pubmed.ncbi.nlm.nih.gov/25832905
- Heiss WD, Brainin M, Bornstein NM, Tuomilehto J, Hong Z; Cerebrolysin Acute Stroke Treatment in Asia (CASTA) Investigators. Cerebrolysin in patients with acute ischemic stroke in Asia: results of a double-blind, placebo-controlled randomized trial. Stroke. 2012;43(3):630-636. PMID: 22282884. DOI: 10.1161/STROKEAHA.111.628537. pubmed.ncbi.nlm.nih.gov/22282884
- Muresanu DF, Heiss WD, Hoemberg V, et al. Cerebrolysin and Recovery After Stroke (CARS): A Randomized, Placebo-Controlled, Double-Blind, Multicenter Trial. Stroke. 2016;47(1):151-159. PMID: 26564102. DOI: 10.1161/STROKEAHA.115.009416. pubmed.ncbi.nlm.nih.gov/26564102
- Muresanu DF, Florian S, Hömberg V, et al. Efficacy and safety of cerebrolysin in neurorecovery after moderate-severe traumatic brain injury: results from the CAPTAIN II trial. Neurological Sciences. 2020;41(5):1171-1181. PMID: 31897941. DOI: 10.1007/s10072-019-04181-y. pubmed.ncbi.nlm.nih.gov/31897941
- Trimmel H, Tauber W, Zikeli M. Life-Threatening Anaphylaxis due to Cerebrolysin®. Case Reports in Neurological Medicine. 2024;2024:2332908. PMID: 39055722. DOI: 10.1155/2024/2332908. pubmed.ncbi.nlm.nih.gov/39055722
- Guan X, Wang Y, Kai G, et al. Cerebrolysin Ameliorates Focal Cerebral Ischemia Injury Through Neuroinflammatory Inhibition via CREB/PGC-1α Pathway. Frontiers in Pharmacology. 2019;10:1245. PMID: 31695614. DOI: 10.3389/fphar.2019.01245. pubmed.ncbi.nlm.nih.gov/31695614
- Rockenstein E, Ubhi K, Trejo M, et al. Retraction Note: Cerebrolysin™ efficacy in a transgenic model of tauopathy: role in regulation of mitochondrial structure. BMC Neuroscience. 2025;26(1):67. PMID: 41382024. DOI: 10.1186/s12868-025-00985-1. pubmed.ncbi.nlm.nih.gov/41382024
For in-vitro laboratory research only. It is not a human medicine and is not for treatment.