# Has the Toxicity of Therapeutic Deep Eutectic Systems
## 3 Animal Models
### Oral Administration  
Regarding in vivo pharmacokinetic studies, [PERSON] et al. administered RA-XII dissolved in 5-20% \(v/v\) Betaine and Mandelic acid (NADES) solution in rats. The authors observed that the oral absorption of RA-XII dissolved in 20% NADES solution was significantly increased. They concluded that NADES solutions were effective approaches for improving solubility, permeability, and oral bioavailability of the anti-tumor candidate RA-XII [89]. [PERSON] et al. prepared a novel eutectic of Diacerein with fumaric acid (FMA) as a coformer in various molar ratios. Diacerein and its active metabolite, called rhein, are anthraquinone derivatives used for treating osteoarthritis. Healthy Sprague Dawley rats were distributed in two groups and administered pure Diacerein and prepared eutectic suspension orally, respectively. Blood samples were collected, and pharmacokinetic parameters were analyzed after oral administration. The results of the pharmacokinetic evaluation suggested greater oral bioavailability of the prepared eutectic versus pure Diacerein [90]. These authors repeated the same study but changed the fumaric acid for 2,4- dihydroxybenzoic acid (DHA) as coformer, and again, the pharmacokinetic study in the rats proved higher oral bioavailability of the prepared eutectic [91]. Berberine is a quaternary benzylisoquinoline alkaloid with huge properties as an antihypertensive, antiarrhythmic, anti-inflammatory, and hypolipidemic, among other properties. Despite its therapeutic properties, berberine is poorly absorbed after oral administration and its plasma concentration in pharmacokinetic studies is extremely low. In this study, several NADESs were prepared and used to solubilize berberine. The NADESs selected were urea or organic acids (malic and lactic acid), and proline. The berberine solubilized in the selected eutctics mixtures were used to evaluate their pharmacokinetic properties in the female Balb/c mice and were compared with berberine. The plasma levels were determined up to 6 h after oral administration via gavage in the mice. The administration of NADESs with berberine yielded in a significant increase in the plasma level of berberine [36]. These authors were in concordance with another recent report that observed that the pharmacokinetic parameters of berberine were improved in the liver and indicated that NADES dilutions promoted the intestinal absorption of oral berberine by increasing solubility in mice. The authors suggested that NADESs may help to promote its use in oral drug delivery [75]. Another natural compound, the salvianolic acid B with anti-inflammatory and antioxidant properties, was studied, adding the model drug in ChCl/glycerol with the common molar ratio (ChCl/glycerol 1:2) as a drug vehicle for this poorly soluble compound. The results obtained demonstrated that the oral administration using gavage of ChCl/glycerol (1:2) was non-toxic with LD50 7733 mg/kg in mice. The results indicated that ChCl/glycerol (1:2) could accelerate the absorption and elimination of salvianolic acid B, maybe because the eutectic system could enhance the membrane penetration ability of drugs [92]. [PERSON] et al. also studied the efficacy of insulin-CAGE administered through the oral route. For the oral efficacy in in vivo studies, enterically coated capsules were administered via oral gavage to adult nondiabetic male rats. In vivo, when 10 U/kg insulin-CAGE was administered, a 45% decrease in blood glucose was observed, and by delivering insulin-CAGE, the authors evade gastric degradation of insulin and enhance its intestinal permeability [93]. Other authors reported the fabrication of a biodegradable polymeric patch for the buccal delivery of insulin using CAGE, as DESs, to transport facilitator and chitosan as mucoadhesive matrix. They applied ex vivo and in vivo studies. The ex vivo permeation was performed using porcine buccal tissue to study the extent of drug transport.