I saw in an old post from Spirit advice to someone to use homozone what is the same as Oxypowder and colosan. Homozone was the original one. It probably won't help for relaxing the ducts, but your intestines at least would be clean.
I would suggest to use it the 3 evenings before. On the old Ask Shelly forum was one poster named Alkilizingkatie (I hope I have it right), may be you can find her messages in the archive.
On the day of the flush she took 10 Oxypowder at 4 pm.
You also should first do a kidney cleanse before you do another flush.