" I can buy foreign antibiotics for 90% discount to US counterpart in the NYC pharmacy with a prescription from the US doctor. I didn't know you could do that until several months ago. "
That works for off-patent drugs (very few antibiotics are still under patent). There you have 3 tiers: the branded product is still sold, then there are US-label generices and there are outside-US-label generics. The OUS-label generics take a bit of play-acting to make legal-ish.
In the case of under-patent drugs, the patent owner controls both domestic supply and importation. Any non-royalty-paid dose is plenty illegal enough to cost any physician who knowingly uses it his license. Hell, it's illegal enough so side effects are probably aggravated battery.
Give it 3 years and maybe a black market in pirfenidone might be financially important. But only extreme optimists expect pirfenidone to have a market lifetime much over 3 years. It really is a lousy drug.