Iontophoresis of amoxicillin and cefuroxime: rapid therapeutic concentrations in skin

Context: Amoxicillin (AMX) and cefuroxime (CFX) are antibiotics used often to treat skin bacterial infections. Typically, high oral doses are required to achieve minimum inhibitory concentration (MIC) at the site of infection that may affect only a very small area of skin. Objectives: To lower side effects and increase therapeutic effectiveness, the percutaneous absorption and retention of AMX and CFX administered by iontophoresis was investigated in a rabbit model by measuring dermis concentrations via microdialysis. Methods: Iontophoresis was performed using a stainless steel electrode and a non-woven polypropylene pad. The cartridge pad was soaked with a solution of AMX in glycerin or of CFX in glycerin/water (60:40). Constant current density of 0, 100, 200 or 300 mu A/cm(2) was applied for 60 min. Results: For AMX, therapeutically effective skin concentrations were detected immediately after the application of electrical current for any of the current density tested and remained above it for at least 2 h from the end of iontophoresis. For CFX, skin concentrations rose above MIC only at the higher current densities and fell below the MIC by the end of the experiment. Conclusion: Iontophoresis is a promising method to obtain a fast and sustained concentration of AMX and CFX in skin.