Research on soft-tissue expander permeability to metronidazole and procaine

This in vitro study was designed to determine if in fact silicone expanders are readily permeable to metronidazole and procaine. The expanders were filled with 0.2% metronidazole or 2% procaine through the filler valves and then immersed wholly in normal saline. At several intervals over 120 hours, a certain amount of the surrounding saline was sampled and the drug levels subsequently determined. In this study, the silicone expanders were indeed readily permeable to the drugs, as measured with an ultraviolet spectrophotometer. A consistent diffusion curve was demonstrated. The rate of diffusion of a drug is inversely proportional to its molecular weight; i.e., the smaller the given drug's molecular weight, the greater is its ability to permeate an expander. In view of this, in the course of expansion, 0.2% metronidazole could be used in clinical expansion instead of normal saline, and a certain amount of antibiotic would diffuse out of the expander to prevent and control the infection.