Corrosion of copper intrauterine devices: review and recent developments

Abstract

Abstract A systematic review of the literature about the corrosion of copper in intrauterine devices (IUDs) was conducted, an important topic of copper application that apparently may not be well known to a broad corrosion audience. Copper IUDs (Cu-IUDs) are one of the most widely used contraceptive methods around the world, particularly in China, India, and Latin America. The contraceptive method is based on the release of copper ions from a Cu-IUD. Copper ions enhance the inflammatory response in the uterine cavity and reach concentrations in the luminal fluids of the genital tract, which are toxic for spermatozoa and embryos. A description is made of the different types of Cu-IUD used, the traditional T-shaped device, copper nanoparticles inside a polymeric matrix, and other shapes. This review aims to discuss the main parameters affecting the efficiency of a Cu-IUD, the contraceptive mechanism, and the shape of the device. The high copper corrosion rate immediately after insertion in the uterus (“burst release”) is discussed, which presents values of the order of up to 296 μg/day, causing side effects such as bleeding and pain, with an exponential decay defining a steady-state plateau after 1–2 months of insertion with values of 40 μg/day for a 200 mm2 Cu-IUD. This plateau is maintained over the life span of a Cu-IUD, in which the copper dissolution rate is as low as 2 μg/day for a Cu-IUD with indomethacin keeping up the contraceptive action mechanism, the concentration of copper that needs to be higher than 10−6 mol/l.