Objectives: To study the release of cupric ions and indomethacin from copper-bearing intrauterine devices (Cu-IUDs) and to assess the influence of their surface area of copper and the pH of the test medium on the release of cupric ions.
Methods: Cu-IUDs were incubated in simulated uterine fluid (SUF). The in vitro release of cupric ions and indomethacin was determined by means of a flame atomic absorption spectrometer and a UV 752 spectrophotometer, respectively, over a period of 220 days. The effect of indomethacin on the pH of the SUF was monitored during the cupric ions release study.
Results: The Cu-IUDs released cupric ions in vitro according to a biphasic pattern. After an initial burst release, the rate slowed down and then became steady. The release of indomethacin from two medicated Cu-IUDs was biphasic and, in both cases, in accordance with the in vitro dissolution model of the drug. The surface area of copper of Cu-IUDs and the pH change induced by indomethacin incorporated in their frame affected the release rate of copper (p < 0.05).
Conclusion: The surface area of the copper and the pH of the test medium modulate the in vitro release of cupric ions from Cu-IUDs.