Cerebrolysin and stroke: what the trials found

Cerebrolysin is not a single peptide. It is a mixture of low-molecular-weight peptides and free amino acids prepared from porcine (pig) brain protein, manufactured in Austria. In laboratory and animal models it behaves like a neurotrophic factor: it protects neurons under stress, enhances neurogenesis after experimental stroke, and in stroke animal models reduced infarct volume and oedema[1]. Clinically it is given by intravenous infusion over courses of 10 to 21 days.

The 2023 Cochrane review describes it as widely used in the treatment of acute ischaemic stroke in Russia, Eastern Europe, China and other Asian and post-Soviet countries[6]. It is not approved by the US FDA, and its clinical culture has grown up largely outside the Western regulatory system — which is part of why its evidence base looks the way it does.

CASTA (2012) — large, neutral

The Cerebrolysin Acute Stroke Treatment in Asia trial randomised 1,070 patients within 12 hours of an acute ischaemic hemispheric stroke to 30 mL Cerebrolysin daily or saline for 10 days, on top of aspirin. The confirmatory endpoint — a combined test of modified Rankin, Barthel and NIHSS at 90 days — showed no significant difference. A post-hoc analysis of the most severe strokes (NIHSS >12) showed a favourable trend, including 90-day mortality of 10.5% vs 20.2%, which the authors said needed confirmation in a new trial[2]. Post-hoc subgroups are hypothesis-generating, not proof.

CARS (2016) — rehabilitation, positive but exploratory

The Cerebrolysin and Recovery After Stroke trial started 30 mL daily for 21 days between 24 and 72 hours after stroke, combined with a standardised early rehabilitation programme. On its primary endpoint — the Action Research Arm Test at day 90 — it reported a large effect in favour of Cerebrolysin (Mann-Whitney estimator 0.71), and a small-to-medium effect on global status across 12 scales, with safety comparable to placebo. The authors themselves called it exploratory with a relatively small sample and asked for a large confirmatory trial; several authors were affiliated with the manufacturer[3]. A later meta-analysis pooled the CARS trials for motor recovery[4], and a 2025 pilot study examined Cerebrolysin with speech therapy for non-fluent aphasia[5].

Cochrane (2023) — no survival benefit, a safety signal

The Cochrane review of acute ischaemic stroke included seven randomised trials with 1,773 participants. Its findings, at moderate certainty: Cerebrolysin or similar peptide mixtures probably make little or no difference to all-cause death (risk ratio 0.96), probably make no difference to the total number of people with serious adverse events, and may increase non-fatal serious adverse events (risk ratio 2.39; higher again, 2.87, in the 30 mL for 10 days schedule). The reviewers judged risk of bias unclear or high in many domains and noted manufacturer support for three of the multicentre studies[6].

How the manufacturer’s side reads it

A 2022 review by CARS and CAPTAIN investigators describes Cerebrolysin as a neurorestorative agent that improves outcomes after ischaemic stroke with a favourable safety profile, emphasising recovery and rehabilitation rather than survival[7]. Cochrane’s primary outcomes centre on death and serious harm. That is a genuine disagreement about endpoints — and it is why the honest summary is "unproven for survival, uncertain for recovery", not "proven" or "useless".

In Russia, Semax — a registered medicine derived from ACTH(4-10) — has its own stroke literature. A 1997 study added Semax to standard care in 30 patients with acute hemispheric ischaemic stroke and compared them with 80 conventionally treated patients, reporting faster neurological recovery[8]; a 2018 study of 110 post-stroke patients linked it to higher BDNF and better Barthel-index recovery[9]. Neither was a large placebo-controlled trial, and neither has been replicated outside Russia. See the Russian peptides hub for context.

A separate Cochrane review examined Cerebrolysin in vascular dementia, the cognitive decline that can follow strokes and small-vessel disease. Across six randomised trials (597 participants; conducted in China, Russia and Romania, and industry-supported where funding was stated) it found a beneficial effect on cognition (SMD 0.36) and on global function, with no difference in adverse effects — but rated all of it very low-quality evidence and called the data not definitive[10].