I'm a gastroenterologist. Most of the serious comments above are pretty accurate.
I get the trots due to anxiety associated with riding. There are all sorts of strategies to combat that. Waking up early and having your motivational coffee works. Imodium works. One tab is fine. For people sensitive to it, the liquid lets you titrate it.
You have to experiment to see how your blood-deprived gut handles input during the ride. I don't like Gatorade or PowerAde. I do better with water and cookies. YMMV.
The response to fiber supplements are inconsistent. You just have to see if they work.
Anticholinergics of any kind are a bad idea at our ages.
The antidiarrheals stay within the gut unless you take massive doses of them, in which case you can get a buzz from them. I've only seen someone do that once.
Having a small packet of hygienic towelettes and a small tube of pramoxine can work wonders on long rides.
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Momento mori, amor fati.