Cytoflavin

Cytoflavin is a fixed-dose combination metabolic agent comprising succinic acid (the principal mass component and Krebs cycle substrate), inosine (a purine nucleoside and precursor to adenine nucleotides), nicotinamide (the amide form of vitamin B3 and precursor to nicotinamide adenine dinucleotide), and riboflavin (vitamin B2, the precursor to flavin adenine dinucleotide and flavin mononucleotide). Developed and manufactured by POLYSAN Scientific and Technological Pharmaceutical Company (Saint Petersburg, Russia), the product is formulated as enteric-coated tablets (300 mg succinic acid, 50 mg inosine, 25 mg nicotinamide, 5 mg riboflavin per tablet) and as a concentrate for intravenous infusion (1000 mg succinic acid, 200 mg inosine, 100 mg nicotinamide, 20 mg riboflavin sodium phosphate per 10 mL ampoule, with meglumine and sodium hydroxide as excipients). The pharmacological rationale is the simultaneous provision of four complementary metabolic substrates and cofactors whose intracellular availability becomes rate-limiting during ischemia, hypoxia, and oxidative stress: succinic acid feeds directly into mitochondrial Complex II (succinate dehydrogenase), bypassing the NAD-dependent steps of the Krebs cycle that fail under hypoxic conditions; inosine supports purine salvage and ATP resynthesis; nicotinamide replenishes the NAD+ pool consumed by poly(ADP-ribose) polymerase activation during ischemic injury; and riboflavin provides the FAD prosthetic group required for succinate dehydrogenase function and for multiple flavoprotein-dependent antioxidant enzymes including glutathione reductase.

The clinical evidence base for Cytoflavin spans ischemic stroke (acute and chronic cerebral ischemia), traumatic brain injury, diabetic polyneuropathy, postoperative cognitive decline in elderly surgical patients, post-COVID-19 asthenic syndrome, and organic asthenic disorder. The largest and most rigorous published trial is the CYLINDER study, a multicenter, double-blind, placebo-controlled, randomized trial in 216 patients with type 2 diabetes mellitus and symptomatic distal sensorimotor diabetic polyneuropathy conducted across 10 Russian clinical centers, which reported a statistically significant reduction in Total Symptom Score (TSS change of negative 2.65 points in the experimental group versus negative 1.73 points in the placebo group, p less than 0.001) after a sequential intravenous-then-oral treatment regimen. In acute ischemic stroke, multicenter studies have demonstrated marked reduction in neurological deficit severity by day 10 and higher probability of favorable functional outcome compared to standard-of-care controls. The CITADEL prospective randomized study demonstrated a pronounced anti-asthenic effect and correction of cognitive impairments in post-COVID-19 rehabilitation. An international, multicenter, randomized, single-blind, placebo-controlled trial (NCT04631484) evaluating Cytoflavin in moderate traumatic brain injury in adults was completed in 2024, with results published in Frontiers in Neurology in 2025, representing the first large-scale international trial of the compound outside the Russian Federation and Commonwealth of Independent States.

Cytoflavin is registered as a medicinal product in the Russian Federation and in Vietnam. The manufacturing facility holds GMP EU certification. The compound is not approved by the United States Food and Drug Administration, by the European Medicines Agency, or by other major Western regulatory authorities. The clinical literature is predominantly in Russian-language journals, with an expanding body of English-language publications in international peer-reviewed venues. The safety profile across published clinical studies is favorable; the principal adverse events are transient epigastric discomfort, headache, hyperuricemia (attributable to inosine-derived purine catabolism), and rare hypersensitivity reactions. No serious adverse events attributable to the drug have been reported in published controlled trials.

This monograph reviews the composition, identification, and formulation chemistry of Cytoflavin; the individual and composite pharmacology of its four active components; the pharmacokinetic considerations for each component; the preclinical pharmacology; the clinical evidence base across all studied indications; sourcing and quality verification; reconstitution and handling; stack interactions and combinations; adverse events and safety signals; and a comparative assessment of five alternative neuroprotective metabolic agents (Mexidol, Actovegin, Cerebrolysin, citicoline, and Reamberin) against Cytoflavin on five competency standards.