And isn't it always when you are the farthest away from the toilet that you need to use one the most? Funny how the brain trys to screw with us.
I swear by Imodium, but be sure to take the Imodium Complete with the Anti-Gas feature. Sometimes the urge you feel in your belly is only gas (and the anti-gas simethicone will deal with that), but you certainly don't want to make a mistake.
Try taking Imodium the day before you know you will be away from a bathroom. With me it is even more effective the day after I take it.
Many years ago, when Imodium was not yet over-the-counter in America I visited England and found it on the shelf there and brought a bunch home with me. Now, in America, it is on the shelf, both brand-name, Imodium, with and without anti-gas simethicone, and generic. It's probably all in my head, but I don't believe the generic works as well. The over-the-counter Imodium the same drug as available by prescription, but at half the strength. If you want prescription strength (which I don't recommend, at least until you see how your body reacts) just take twice the over-the-counter dosage.