Timed Relase VC Tablets Question

[Blanko]

I noticed a timed-release vitamin C (1000 mg) I have has been irritating my GI if taken before I sleep, and then I wondered if maybe it's not a good idea taking something that is a very slow dissolving big tablet like that.

I put the tablet into a cup of water with some cider vinegar and still after 10 hours the tablet is almost as large as it is when taken right out of the bottle.

I put another regular vitamin C tablet (500 mg) in there and it dissolved very quickly.

Are these timed release tablets mostly sitting intact in my GI system for many hours?

Now that I think of it, I much prefer the idea of taking regular 500 tablets whenever I like rather than trying to benefit from such a slow dissolving timed-release tablet in a larger dose.

What happens if the tablet doesn't dissolve properly? It would be excreted and seen in a toilet?

Not sure how well these tablets have been studied and tested.

10 hours later it's still intact and large in size in the water-cider mixture in the cup.