Semi-solid extrusion 3D-printing of eucalypt extract-loaded polyethylene oxide gels intended for pharmaceutical applications

In pharmaceutics, 3D printing is considered as a promising future technology for fabricating more complex patient-specific drug delivery systems (DDSs). An anti-staphylococcal herbal preparation, “Chlorophyllipt”, is produced mainly in a liquid form by the pharmaceutical industry in Ukraine, and it is composed of an ethanolic eucalypt extract (EE). Since staphylococcal infections have become a true challenge for the health care in all over the world, it would be relevant and justified to develop the aqueous gels of the present EE applicable for the 3D printing of the corresponding solid DDSs. The aim of the present study was to develop a novel polyethylene oxide (PEO) gel loaded with EE for a semi-solid extrusion (SSE) 3D printing and to print the corresponding oral solid DDSs with different sizes and shapes. For SSE 3D printing, we prepared and tested total ten (10) different aqueous PEO gel formulations loaded with EE. Prior to 3D printing, the physical appearance, homogeneity, injection force and viscosity of the gels were investigated. The EE-PEO gels were printed to lattice- and round-shaped solid DDSs with the head speed of 0.5 mm/s, and the weight (mass uniformity) and effective surface area of the printed systems were determined. The most feasible EE-PEO gel for SSE 3D printing comprised of 10 mg/ml of EE, 30 mg/ml of eumulgin and 20 mg/ml of ascorbic acid in a 20-% aqueous PEO gel. The key process parameters of the SSE 3D printing were identified and verified. The printing quality of EE-PEO DDSs were very good, thus showing compatibility of a plant extract and carrier polymer. Such 3D-printed antimicrobial DDSs can be used for example in the treatment of skin wounds and infections of the oral cavity.