Kind of a stupid question to ask. You can simply go to the hospital and get a script for it. Yeah, it sounds weird saying "go to the hospital", but that is where everyone goes. You log in, answer a few questions, the doctor delivers a script to the desk and they call your name to come pick it up. You can have it filled at the hospital pharmacy right there.
Bring a book, as the wait is about two hours. If you don't want to wait, hire a local to get it. Nearly all customer service reps at hotels will have a friend that they can call to do it. Pay upon delivery. TIP THE ONE THAT HELPS YOU!!!