The adsorption of active pharmaceutical ingredients on the surface of medical devices such as polyvinl chloride, ethylene-vinyl acetate copolymer and glass often prevent the acuurate dose of drug. At dispensing of pharmaceuticals, mètre glass (MG) has been widely used for dispensing syrup. When measuring the viscous syrup, it often takes long time to dispense the accurate volume due to their adhesiveness on the glass surface. In this study, we investigate the adhesion of various syrups to MG made with uncoated glass or glass with a strongly hydrophobic silicone or fluorinated coating in terms of the following formulation parameters: viscosity, surface tension, contact angle, and surface free energy. The contact angles for syrups on the coated glass surfaces were significantly higher than those on the uncoated glass surface. In addition, the relationship between surface tension and contact angle was examined. We found that the contact angle was independent of surface tension for the uncoated glass, while it increased with increasing surface tension for the coated glasses. These results can be explained as follows: the silicone or fluorinated coatings inhibit the hydrogen bonding that usually takes place between water and silanol and siloxane groups at glass surfaces. The coatings reduced the surface free energy and increased the hydrophobicity of the glass, reduced its wettability by the syrups, and thus reduced the adhesion loss for the syrups. It was considered that as for the hydrophobic action, properties of matter of sample influence the coated device by coating in order that it is reinforced.
Keywords: fluorinated coating; glass; interaction; surface free energy; syrup.