Reduction of the “burst release” of copper ions from copper-based intrauterine devices by organic inhibitors

BackgroundThe copper intrauterine device is a contraceptive method that is based on the release of copper ions from a copper wire. Immediately after insertion, the dissolution of copper in the uterine fluid is markedly higher (“burst release”) than that necessary for contraception action, leading to a variety of harmful effects.Study DesignPretreatments with organic compounds [thiourea (TU) and purine (PU), 10−4–10−2 M concentration range, 1- and 3-h immersion times] were tested. The dissolution of copper with and without pretreatments in TU and PU solutions was analyzed by conventional electrochemical techniques and surface analysis.ResultsPretreatments in PU solutions reduced the initial corrosion rate of copper in simulated uterine solutions, with inhibitory efficiencies that depend on the PU concentration and on the immersion time assayed. Inhibitory efficiency values higher than 98% for pretreatments with ≥10−3 M PU were found. Conversely, after TU pretreatments, a high copper release was measured.ConclusionsIt was concluded that 10−3 M PU pretreatment is a promising strategy able to reduce the “burst release” of copper and to ensure contraceptive action.