The use of polyoxyethylene (20) cetyl ether in assessing the hydrophobicity of compounds of biomedical importance and in the process of drug release from microemulsions

The creation and study of artificial membranes based on microemulsions is an important direction due to the similarity of the structure of both direct and reverse microemulsions with cell membranes. A microemulsion mobile phase prepared with a non-ionic surfactant in combination with a C18 type stationary phase creates a similar image of the cell membrane in a chromatographic column. In addition, the use of microemulsion systems to transport drugs with low bioavailability into the body can increase their bioavailability. The chromatographic behaviour of model substances of biomedical importance was investigated using micellar mobile phases containing polyoxyethylene (20) cetyl ether in biopartitioning micellar chromatography (BMC) in the concentration range of 1-5 %. Cholic acid was introduced into the polyoxyethylene (20) cetyl ether micellar mobile phase to approximate the structure of the cell membrane. The hydrophobicity of the model compounds was evaluated. Hydrophobicity indices in the micellar mobile phase with and without addition of cholic acid were compared. The release profile of promethazine hydrochloride from microemulsion systems with monomeric and polymeric surfactants was investigated. The kinetic properties of the release of promethazine hydrochloride from microemulsion systems were calculated. It was found that a microemulsion of polyoxyethylene (20) cetyl ether mixed with polyoxyethylene (4) lauryl ether reduced the release of promethazine hydrochloride in weight percent. The release of promethazine hydrochloride from microemulsions does not obey Fick's diffusion but follows a non-Fick's transport mechanism, as evidenced by the high values of the diffusion exponent (n > 0.5).