Retinalamin

1. Overview

Retinalamin is a polypeptide complex extracted from bovine retinal tissue, developed in the 1990s by Vladimir Khavinson and Svetlana Trofimova at the Saint Petersburg Institute of Bioregulation and Gerontology. It is part of Khavinson's broader program of organ-specific peptide bioregulators -- preparations isolated from various animal organs that are proposed to restore tissue function through direct interaction with gene regulatory elements [11] [12].

The preparation contains a mixture of low-molecular-weight peptides (up to 10 kDa) obtained through acid hydrolysis and ultrafiltration of bovine retinal tissue. Each vial contains 5 mg of the polypeptide complex with 17 mg glycine as a stabilizer, supplied as a lyophilized powder for reconstitution [7]. Unlike single-entity pharmaceuticals, Retinalamin is a multi-component biological extract, and the specific peptide sequences responsible for its activity have not been fully characterized, though they are proposed to act through the same peptide-DNA interaction mechanisms described for other Khavinson bioregulators [13].

Retinalamin was approved for clinical use in Russia by the Ministry of Health in 1999 and has been in continuous clinical use in Russian ophthalmological practice since then [9] [12]. It is indicated for retinal dystrophies (including retinitis pigmentosa), diabetic retinopathy, primary open-angle glaucoma, age-related macular degeneration, and post-traumatic retinal conditions. It is not approved by the FDA, EMA, or any other Western regulatory agency. The clinical evidence base, while spanning over two decades and including long-term follow-up studies, originates almost exclusively from Russian and former Soviet research institutions [1] [14].

Type

Polypeptide complex (bovine retinal extract); MW fractions up to 10,000 Da

Source

Bovine retinal tissue (acid hydrolysis and ultrafiltration)

Formulation

Lyophilized powder, 5 mg per vial, with glycine 17 mg (stabilizer)

Routes Studied

Intramuscular, parabulbar injection

Russian Approval

Approved by Russian Ministry of Health (clinical use since 1999)

FDA/EMA Status

Not approved by any Western regulatory agency

Developer

V.Kh. Khavinson and S.V. Trofimova, St. Petersburg Institute of Bioregulation and Gerontology

2. Mechanism of Action

Retinalamin is proposed to act through several interconnected pathways targeting retinal and optic nerve tissue.

Retinal Cell Proliferation and Differentiation

In vitro studies demonstrated that Retinalamin tissue-specifically stimulates proliferation of both retinal cells and retinal pigment epithelial (RPE) cells in culture [2]. This proliferative effect was selective: Retinalamin showed preferential activity on retinal-derived cells compared to non-retinal tissue cultures, consistent with Khavinson's theory of organ-specific peptide bioregulation [11]. Additionally, Retinalamin demonstrated inductive activity, triggering the formation of new retinal cells from multipotent ectodermal cell precursors in experimental models [3].

Neuroprotection of the Optic Nerve

Clinical studies in glaucoma patients have demonstrated that Retinalamin provides neuroprotective effects on the optic nerve head and retinal ganglion cells. In primary open-angle glaucoma, treatment courses produced positive dynamics in visual field parameters as measured by standard automated perimetry (SAP), with effects most pronounced in early-stage disease (stages IA and IIA) [5]. The neuroprotective mechanism is proposed to involve stabilization of retinal ganglion cell function and reduction of apoptotic signaling in the inner retinal layers.

Peptide-DNA Interaction (Bioregulator Theory)

According to Khavinson's bioregulator framework, the short peptides contained in Retinalamin penetrate retinal cells, enter the nucleus, and interact directly with DNA and histone proteins to modulate gene expression in a tissue-specific manner [13]. This theoretical mechanism, while extensively described for other Khavinson peptides such as Epithalon and Vilon, has not been validated specifically for the individual peptide components of Retinalamin by independent laboratories.

Retinal Electrophysiology

Clinical electrophysiological assessments have shown that Retinalamin improves bioelectrical activity of the retina, including electroretinogram (ERG) amplitudes and critical flicker fusion frequency, indicating enhanced functional capacity of photoreceptors and inner retinal neurons following treatment [1] [6].

3. Researched Applications

Retinal Dystrophies (Retinitis Pigmentosa)

The most extensive clinical data for Retinalamin involves its use in hereditary retinal degenerative disorders. In a landmark long-term retrospective study, patients with retinal pigment degeneration received Retinalamin treatment courses (1-2 times per year) for periods spanning 23-25 years [1]. Key findings include:

• First course of treatment improved visual acuity in 58.1% of patients
• Visual fields improved in 64.5% of cases
• Repeated annual courses preserved residual vision in 55.6% of patients over 23-25 years
• Object vision was maintained in 11.1% of long-term treated patients

These results suggest that Retinalamin may slow the natural progression of retinal degenerative disease, though the observational study design and absence of untreated controls followed for equivalent periods limit causal interpretation.

Diabetic Retinopathy

A clinical study of 56 patients (112 eyes) with type 1 and type 2 diabetes and diabetic retinopathy (without macular edema) evaluated Retinalamin using optical coherence tomography and electrophysiological monitoring [6]. Twenty-eight patients received intramuscular Retinalamin while 28 served as untreated controls. The treatment group demonstrated significant improvements in retinal structural and functional parameters, including preservation of retinal layer thickness and improved electrophysiological responses.

Primary Open-Angle Glaucoma

Retinalamin has been studied as a neuroprotective agent in glaucoma management. Clinical studies demonstrated that a course of 10 intramuscular injections, with a second course repeated after 6 months, produced prolonged neuroprotective effects with greatest efficacy in early-stage glaucoma (stages IA and IIA) [5]. Visual field parameters showed positive dynamics following treatment, suggesting preservation of retinal ganglion cell function.

Age-Related Macular Degeneration (Dry Form)

Clinical experience from Russian ophthalmological centers has demonstrated Retinalamin's application in dry (non-exudative) age-related macular degeneration. Studies reported improvements in visual acuity and contrast sensitivity following treatment courses, with meta-analytic data supporting the use of Retinalamin for retinoprotective therapy in dry AMD [4] [9].

Retinal Detachment (Adjunctive Therapy)

Retinalamin has been investigated as an adjunctive neuroprotective agent in the complex treatment of rhegmatogenous retinal detachment, supporting retinal recovery following surgical repair [10].

4. Clinical Evidence

The clinical evidence for Retinalamin exists primarily in Russian-language ophthalmological literature, with a smaller number of publications in international peer-reviewed journals.

Long-term Observational Data: The principal dataset involves patients followed for up to 25 years with repeated annual treatment courses, demonstrating preservation of visual function in a substantial proportion of patients with progressive retinal degeneration [1]. While the duration of follow-up is remarkable, the study was retrospective and observational.

Controlled Clinical Studies: The diabetic retinopathy study (n=56 patients, 112 eyes) used a controlled design with untreated comparators, demonstrating measurable structural and functional improvements [6]. Glaucoma studies similarly employed before-and-after treatment comparisons with objective electrophysiological and perimetric endpoints [5].

In Vitro Studies: Cell culture studies demonstrated tissue-specific proliferative and inductive activity of Retinalamin on retinal-derived cells [2] [3].

Animal Studies: The related synthetic peptide Epithalon (AEDG) preserved retinal morphological structure and increased bioelectrical activity by 43.9% in Campbell rats with hereditary retinal pigmentary dystrophy [8], providing mechanistic support for the retinal bioregulator concept.

A critical limitation is that no multicenter, double-blind, placebo-controlled Phase III trials conducted by independent research groups have been published. All major clinical studies originate from Russian ophthalmological institutions affiliated with or collaborating with Khavinson's institute.

5. Dosing in Published Research

The following doses have been reported in published research. These are not recommendations and should not be interpreted as therapeutic guidance.

In Russian clinical practice, the standard protocol involves 5 mg Retinalamin reconstituted in 0.5-1.0 mL of 0.9% NaCl or water for injection, administered either intramuscularly or via parabulbar injection once daily for 10 consecutive days [1] [6]. Courses are typically repeated 1-2 times per year. The parabulbar route (injection through the skin of the lower eyelid to a depth of approximately 1 cm) is used when direct periocular drug delivery is desired, while intramuscular administration provides systemic delivery. Long-term protocols spanning decades have used repeated annual courses without reported dose escalation requirements.

6. Safety and Side Effects

Retinalamin has been described as well-tolerated in published clinical literature spanning over two decades of use in Russian ophthalmological practice. No serious adverse events attributable to Retinalamin have been reported in published studies [1] [6] [9].

In the long-term retinal degeneration study (23-25 years of repeated annual courses), no adverse reactions or complications were documented [1]. The diabetic retinopathy study similarly reported no treatment-related adverse events [6].

However, several important caveats apply:

• No systematic toxicology studies meeting current ICH/FDA regulatory standards have been published.
• Safety data originate predominantly from the same research groups that developed the drug.
• As a bovine-derived biological extract, theoretical concerns exist regarding immunogenic reactions, prion disease transmission, and batch-to-batch variability, though no such events have been reported.
• Long-term consequences of repeated peptide bioregulator administration have not been evaluated by independent researchers.
• Drug interaction studies have not been published.

7. Regulatory Status

Russia: Retinalamin has been approved by the Russian Ministry of Health for clinical use since 1999 [9] [12]. Approved indications include retinal pigment degeneration, diabetic retinopathy, primary open-angle glaucoma (compensated), central retinal vein thrombosis, and age-related macular degeneration. It is manufactured as a lyophilized powder for injection.

International: Retinalamin is not approved by the FDA, EMA, Health Canada, TGA, or any other major Western regulatory agency. It is not listed in the United States Pharmacopeia or European Pharmacopoeia. Outside Russia and former Soviet states, it is available only through specialized import or research chemical suppliers.

8. Context Within Peptide Bioregulation

Retinalamin is one of six peptide-based pharmaceutical preparations developed by Khavinson's group that have achieved regulatory approval in Russia, alongside Thymalin (thymus), Prostatilen (prostate), Cortexin (brain cortex), Epithalamin (pineal gland), and Thymogen (synthetic thymic dipeptide) [9] [12]. It represents the retinal-specific member of this organ-targeted peptide bioregulator family.

The theoretical foundation proposes that the retina, like other organs, produces characteristic short peptides that decline with aging and disease, contributing to functional deterioration. Exogenous administration of retina-derived peptides is proposed to restore youthful gene expression patterns and cellular function in retinal tissue [7] [11] [14]. While the clinical results in ophthalmological practice have been described as positive by Russian investigators, the fundamental mechanism -- direct peptide-DNA interaction as the basis for tissue-specific gene regulation -- remains outside the mainstream of Western molecular biology and has not been independently validated [14].

9. Limitations and Transparency

Several important limitations should be considered:

• All published clinical data originates from Russian ophthalmological institutions, with no independent Western replication.
• Retinalamin is a multi-component extract with incompletely characterized composition, making it difficult to attribute effects to specific molecular entities.
• The longest-term study (25 years) is retrospective and observational, without concurrent untreated controls followed for the same period.
• No dose-response studies or formal pharmacokinetic analyses have been published.
• The proposed mechanism of action (tissue-specific peptide-DNA interaction) has not been validated specifically for Retinalamin's constituent peptides.
• Publication bias cannot be assessed given the concentration of research within affiliated Russian institutions.

10. Pharmacokinetics

Retinalamin's pharmacokinetics are better understood than most Khavinson bioregulators due to its pharmaceutical status and defined injection routes, though formal PK parameters meeting Western regulatory standards have not been published.

Two administration routes are used clinically: intramuscular and parabulbar injection [1][6]. Intramuscular administration delivers the polypeptide complex systemically, requiring transit through the bloodstream and crossing the blood-retinal barrier to reach target tissue. The blood-retinal barrier (analogous to the blood-brain barrier) is a selective permeability barrier formed by retinal capillary endothelial tight junctions and retinal pigment epithelial tight junctions. Whether systemically administered polypeptides of 1,000-10,000 Da cross this barrier at therapeutically relevant concentrations is unknown.

Parabulbar injection (through the skin of the lower eyelid to approximately 1 cm depth) delivers the preparation to the periocular space, providing proximity to the target tissue with reduced systemic dilution. This route may achieve higher retinal tissue concentrations than intramuscular injection, though comparative tissue-level pharmacokinetic data have not been published.

The preparation's polypeptide components (MW 1,000-10,000 Da) would be susceptible to proteolytic degradation both at the injection site and in plasma. The 17 mg glycine stabilizer may provide some protection during reconstitution and injection but would not significantly extend peptide half-lives in vivo. No plasma half-life, ocular tissue distribution, or elimination kinetics have been reported.

11. Dose-Response

The standard dose of 5 mg daily for 10 days has been used consistently across published clinical studies without dose comparison [1][5][6]. No dose-response studies have been published for Retinalamin.

The protocol of 1-2 courses per year for long-term maintenance (up to 25 years) [1] implies that the effects of a single course are transient and require periodic reinforcement. The 6-month inter-course interval used in glaucoma studies [5] was presumably chosen clinically rather than optimized through dose-frequency analysis.

The stroke protocol for Cortexin (a related preparation) uses double-frequency dosing (10 mg twice daily versus once daily for standard indications), suggesting that dose-response relationships may differ by disease severity. Whether similar dose adjustment applies to Retinalamin for severe versus mild retinal disease has not been studied.

The 58.1% improvement rate after the first Retinalamin course and 55.6% long-term vision preservation rate after 23-25 years of repeated annual courses [1] suggest that the treatment benefits a majority but not all patients. Whether non-responders might benefit from higher doses, more frequent courses, or different administration routes has not been investigated.

12. Comparative Effectiveness

Retinalamin vs. Epithalon (AEDG)

Epithalon preserved retinal morphological structure and increased bioelectrical activity by 43.9% in rats with hereditary retinal pigmentary dystrophy [8], demonstrating that the synthetic pineal tetrapeptide also has retinal effects. This overlap raises the question of whether Retinalamin's effects are partially mediated by AEDG-like sequences within the extract. No head-to-head comparison exists.

Retinalamin vs. Anti-VEGF Therapy

Anti-VEGF injections (ranibizumab, aflibercept, bevacizumab) are the standard of care for wet AMD and diabetic macular edema, with extensive RCT evidence from MARINA, ANCHOR, VIEW, and DRCR.net trials. Retinalamin is studied primarily in dry AMD and retinal dystrophies (conditions where anti-VEGF has limited efficacy), making the two approaches complementary rather than directly competitive. No comparative studies exist for overlapping indications such as diabetic retinopathy.

Retinalamin vs. Neuroprotective Agents in Glaucoma

Neuroprotection in glaucoma is an active area of research with no globally approved agents. Candidates include brimonidine (alpha-2 agonist with possible neuroprotective properties), memantine (failed in Phase III for glaucoma), and citicoline. Retinalamin's neuroprotective effects in glaucoma [5] place it in this investigational category, though its evidence base is limited to Russian clinical data.

Retinalamin vs. Cortexin

Both are Khavinson polypeptide extracts from animal neural tissue with pharmaceutical approval in Russia. Cortexin (brain cortex) has broader neurological indications, while Retinalamin (retina) targets ophthalmological conditions specifically. The tissue-specific extraction provides a rationale for their different clinical applications within the same bioregulator framework.

13. Enhanced Safety

Retinalamin has the longest documented safety record among Khavinson preparations, with patients treated for up to 25 years with repeated annual courses and no reported adverse events [1]. This extended observational safety data, while not meeting ICH standards, provides meaningful reassurance about long-term tolerability.

No serious adverse events attributable to Retinalamin have been reported across published clinical literature spanning over two decades [1][6][9]. The diabetic retinopathy study (56 patients, 112 eyes) [6] and the glaucoma studies [5] similarly documented no treatment-related adverse effects.

As a bovine-derived biological extract, Retinalamin carries the standard theoretical risks of prion contamination, immunogenicity, and batch-to-batch variability. The parabulbar injection route introduces additional risks specific to periocular procedures, including orbital hemorrhage, globe perforation, and local infection, though these are procedural risks rather than drug-related adverse effects.

The preparation's interaction potential with standard ophthalmological medications (anti-VEGF agents, IOP-lowering drops, corticosteroids) has not been studied. Many patients receiving Retinalamin for glaucoma or diabetic retinopathy would be simultaneously using topical or intravitreal medications, making drug interaction data clinically important.

No formal toxicology studies, reproductive safety evaluations, or carcinogenicity assessments have been published. The glycine stabilizer (17 mg per vial) contributes approximately 227 mg/mmol of amino acid per injection, which is pharmacologically negligible systemically but adds to the local amino acid load at the injection site.

14. Related Peptides

See also: Epithalon, Thymalin

15. References

1. [1] Razumovskiy MI, Trofimova SV, Khavinson VK (2019). Long-term outcomes of retinal degenerative disorder treatment with peptide bioregulators. Ophthalmology in Russia. PubMed
2. [2] Khavinson VK, Trofimova SV (2003). Effects of peptides on proliferative activity of retinal and pigmented epithelial cells. Bull Exp Biol Med. PubMed
3. [3] Khavinson VK, Trofimova SV (2003). Inductive activity of retinal peptides. Bull Exp Biol Med. PubMed
4. [4] Astakhov YuS, Gobedzhishvili MV, Dal NV (2018). An experience of Retinalamin use in glaucomatous optic neuropathy and age-related macular degeneration. Ophthalmology Reports. PubMed
5. [5] Erichev VP et al. (2019). Results of neuroprotective therapy in primary open-angle glaucoma. Vestn Oftalmol. PubMed
6. [6] Khavinson VK et al. (2024). Objective structural and functional monitoring of polypeptide retinal neuroprotective therapy in diabetic retinopathy. Vestn Oftalmol. PubMed
7. [7] Khavinson VK, Trofimova SV (2019). Molecular-physiological aspects of regulatory effect of peptides on the function of the retina. Springer. DOI
8. [8] Khavinson VK, Razumovsky MI, Trofimova SV, Grigorian RA, Razumovskaya AM (2002). Effect of epithalon on age-specific changes in the retina in rats with hereditary pigmentary dystrophy. Bull Exp Biol Med. PubMed
9. [9] Khavinson VK, Kuznik BI, Ryzhak GA (2013). Peptide bioregulators: a new class of geroprotectors. Report 2. Clinical studies results. Adv Gerontol. PubMed
10. [10] Astakhov YuS et al. (2020). Efficacy of retinalamin in the complex treatment of rhegmatogenous retinal detachment. Ophthalmology Reports. PubMed
11. [11] Khavinson VK (2002). Peptides and ageing. Neuro Endocrinol Lett. PubMed
12. [12] Khavinson VK (2020). Peptide medicines: past, present, future. Klin Med (Mosk). PubMed
13. [13] Khavinson VK, Popovich IG, Linkova NS, Mironova ES, Ilina AR (2021). Peptide regulation of gene expression: a systematic review. Molecules. DOI PubMed
14. [14] Anisimov VN, Khavinson VK (2010). Peptide bioregulation of aging: results and prospects. Biogerontology. DOI PubMed
15. [15] Morozov VG, Khavinson VK (1997). Natural and synthetic thymic peptides as therapeutics for immune dysfunction. Int J Immunopharmacol. DOI PubMed
16. [16] Khavinson VK, Linkova NS, Kvetnoy IM (2020). Peptides: prospects for use in the treatment of COVID-19. Molecules. DOI PubMed