Ohta's Isan is one of those Japanese powdered hybrid medicines containing a mixture of Western pharmaceutical chemicals and traditional Chinese herbs. Some newer formulations of Ohta's also have digestive enzymes mixed in.
Like most Japanese powdered medicines, you're supposed to mix it with water then drink it. Some people will instead just put the powder in the mouth (holding nose optional) and then quickly swallow it with a drink of water (less time spent tasting the bitterness, basically).
Alternative
Another method is to wrap them up in dedicated starch/gelatin-based sachet wraps, called "oblaat", before swallowing them. Some of the newer ones are also flavored like candy. DIY your own pills, basically.
You DO NOT want to take such medicines via the nasal route. Especially not antacids (these work on the stomach!).
Updated
Seeeee?
I'm saaaaaved...
It feels like a disciplinary problem!
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Please use them according
to recommended dosage and
administration guidelines.
It's jus' some O*ta's Isan antacid! Folks say it's more effective if you take it thru the nasal epithelium! It's pretty well known from where I come from!
Please don't do this at home, kids.
We ain't doing anything sketchy!
You're giving me a heart attack, so would you please stop!?