Therapeutic Deep Eutectic Systems: Synthesis and Spectroscopic Characterization

Therapeutic deep eutectic systems (THDESs) are emerging alternatives to improve the bioavailability, solubility, delivery, and pharmacokinetics properties of drugs. In therapeutic deep eutectic system, one of the key components should be active pharmaceutical ingredient (API) which is expected to be dissolved with a eutectic compound. In this study, therapeutics deep eutectic systems were synthesis incorporating active pharmaceutical ingredients including Ibuprofen, Citric Acid, and Phloroglucinol with eutectic components such as menthol, thymol, and camphor. In this case, APIs act as hydrogen bond acceptors (HBA) and menthol, thymol and camphor behave as hydrogen bond donors (HBD). THDESs were synthesized by heating the APIs with menthol, thymol, and camphor at 50-1000C for 30-60 minutes under constant stirring at 500 rpm until a homogeneous mixture was achieved. Various ratios from 1:1 to 1:3 were used for HBA: HBD components. All the tested THDESs, however, did melt below the melting points of their constituent parts. After synthesizing, they were immediately studied using an ATR-FTIR spectrophotometer. Some important observations include OH peak of thymol and menthol being significantly reduced indicating strong hydrogen bonds formed with the Ibuprofen carboxylic acid group. In addition, Ibuprofen has a strong C=O peak around 1700 cm-1 which was noticeably diminished in the THDES. Similar pattern of shifting the OH stretching peaks was observed for Phloroglucinol: Menthol and Citric Acid: Menthol. However, some THDESs were solidified below the room temperature (200C) which indicate that these THDESs may be liquid at the physiological temperature (37.50C)