... through the kidneys like the Oxycontin he is currently taking, is this true? If this is true about the Opana it would be much better and safer for him to take than the Oxycontin ER he is currently taking as it does filter through the kidneys. Can anybody tell me if this is true about the Opana ER or IR not going through the kidneys like we have been told? If anyone knows for sure about this I would greatly appreciate it if they would tell me! Thank you from Curiouscatwoman