What are the unopened shelf life and use-by limits after opening multidose containers or sachets of the Sovereign Medical calcium polystyrene sulfonate 99.75% powder for oral and rectal suspension product?

The Sovereign Medical calcium polystyrene sulfonate 99.75% powder for oral and rectal suspension product has an unopened shelf life of 5 years; after opening, 300 g or 400 g multidose containers have a shelf life of 1 month, while single-use 15 g sachets must be used immediately.