Why can’t we lay down right after taking the pill?

So the instructions for taking accutane/isotretinoin say to remain upright for at least 10min after taking the pills…

Why?

I tried googling it but the websites I found seem to have deleted their page on isotretinoin (why would they do that??) so I figured maybe someone here would know why…

Not that I do it, but I’m tryin to figure out just how “I HAVE GOT TO SIT UP” I need to be… like… if I need to be so stressed about it that I remain upright for at least 30min instead of 10 bc I can’t remember WHY I sit up, just that it’s… probably? Not great.

Edit- firstly, thank you for all the informative replies! Secondly… I’m realizing I had no idea how long the esophagus is (10-13in) for stuff to potentially be “stuck” without it causing a choking feeling!