Evaluation of dermal corrosion and irritation by Cytoreg in rabbits

Cytoreg is an experimental therapeutic platform consisting of an aqueous solution of six acids (hydrofluoric, hydrochloric, sulfuric, phosphoric, citric, and oxalic) with oncolytic, antiviral, immune modulatory and antibacterial activities. Cytoreg may be formulated for topical, oral, and parenteral administration. In the present study, a skin corrosion/irritation screen was conducted on three albino rabbits for the Cytoreg topical formulation at three dilutions; one animal each received a dilution of 100 %, 4 %, or 2 % in physiological saline solution. Three intact skin test sites per animal/concentration were evaluated. Each test site was treated with 0.5 mL of the appropriate test substance solution. Site one was dosed for 3 min, then observed. Dose site two was wrapped for 1 h, then both first and second test sites were observed. Dose site three was wrapped for 4 h. One hour after unwrapping the third site, all three test sites were observed for skin irritation and/or corrosion, and again at 24, 48 and 72 h after final unwrap. Based on the 4 -h dose scores through 72 h, the primary irritation index (PII) for Cytoreg is 0.00 at 2 % and 4 %, with a descriptive rating of non-irritating, and 0.25 PII with slightly irritating rating at 100 %.

Predictability of in vitro dermal assays when evaluating fatty amine derivatives

It is widely accepted that skin assays based on reconstructed human epidermis (RhE) models can be used in place of in vivo testing to accurately predict corrosivity and/or irritancy of commodity chemicals. Due to REACH legislation, substances from various categories of fatty amines derivatives have been evaluated for dermal corrosion applying either the EpiDerm™ (EPI-200) or EpiSkin™ assay. Available data and practical experience indicated that these substances are corrosive to the skin. The substances tested are cationic surfactants which dermal effects are characterized by a delayed severe inflammatory reaction. The mechanism is thought to be related to disruption of the cellular membrane following diffusion of the long apolar tails of the molecules into the lipid bilayers. However, unexpectedly almost all obtained study results indicated that these substances are NOT corrosive in these in vitro RhE test systems. Since these results did not align with the experiences on such substances, limited in vivo rabbit studies were employed additionally. These studies confirmed that after some delay full skin tissue destruction occurs, requiring classification as Corrosive Cat.1B or 1C for GHS. The results obtained for various fatty amine derivatives shows that RhE assays do not always predict corrosivity correctly.