Deep Eutectic Solvents and Their Possible Application in Transdermal Drug Delivery

Sammanfattning: Deep eutectic solvents, DES, is a type of solvent made by mixing a quaternary ammonium salt with a hydrogen bond donor at the eutectic point of the system. Most common quaternary ammonium salt is Choline Chloride, ChCl. A specific DES, Choline:CAGE has shown promise in delivering insulin through the skin of mice. Four different systems containing Choline chloride were chosen: ChCl:glycerol, ChCl: propylene glycol, ChCl:glucose and ChCl:sorbitol. Initial viscosity measurements were done to see if the viscosity of the DES would be a problem and how water would affect them. They all behaved like Newtonian liquids, but glucose and sorbitol had to high viscosity to continue work with in their pure form. The protein BSA were added to ChCl:glycerol and ChCl:propylene and it was found that to solve the protein, water was necessary to be present at low concentration in the DES. ChCl:glycerol kept stable the BSA solved and stable for a longer time compared to ChCl:glycerol. Since ChCl:gly had quite low viscosity and behaved like a liquid, time was put in to trying to change their properties to become suitable for topical use. Carbopol, polyacrylic acid, in combination with water made this possible as it formed a shear thinning gel. Franz cell diffusion test were made on ChCl:glycerol with fluorescent BSA to see if had any effect on skin penetration. Fluorescent BSA in PBS were used as control. On undamaged skin either had a significant penetration, 1-2 %. On damaged skin both penetrated the skin well, DES about 20%, but the PBS were about double as effective. Telling that DES had limited penetration through the skin but might be interesting for drug delivery to the skin.