It isn't a subsidy to bargain for a lower price, which the Government here does - yet drug companies choose to sell the drugs anyway, because they still make a profit.
The US could bargain prices for its purchases too, but it's prohibited by law from doing so. The higher prices are not a "subsidy", they are the result of little or no bargaining power on the part of most drug consumers.
Sigh... Yes, it is a subsidy. Just not a direct payment one. This is what is called an "uneven playing field". Companies have somewhat fixed costs. Production equipment, R&D, overhead (IT people, finance, etc), etc. The material cost of making a pill is stupid cheap. The infrastructure to MAKE the pill is stupid expensive. Any country engaged in price-fixing drugs engages in logical fallacy and says "It costs you TWO CENTS to make this pill. We'll be insanely generous and allow you to sell it at 50 cents per." (They're generally not actually that stupid, but that's what they publicly claim.) Reality is, they know companies would rather make a little profit instead of no profit (and usually more importantly, it ups the revenue they can claim) and they knew the drug companies can 'overprice' the US drugs to pay for the infrastructure costs.
Don't get me wrong. Any company probably has inefficiencies. You could claim that drug companies waste too much money on some internal factor. Might even be right. Management fads are supposed to identify and remove these, but oddly rarely do. But yea, drug companies are forced to make the US pay for the bulk of these ancillary costs, or stop selling drugs to socialist countries, or stop R&D/testing/development. I'm sure if the majority of the drug companies stopped selling to said countries, they wouldn't face a PR campaign "zOMG! merchants of death! Refusing to sell medicine CUZ THEY'RE GREEDY CAPITALISTS!" or whatnot. Or simply called racists or whatnot. Ask companies that are more or less blackmailed into providing AIDS drugs to be sent to Africa, which often never actually reach the intended sick folks, at below market rates. It's a subsidy.
As expensive as drugs are, they're stupid cheap in the long run compared to surgery or death. I should actually thank the socialist countries for price-fixing. It killed the European pharmacology, and led to a significant boom in US pharmacology. One of the few manufacturing industries were America is kicking tail and taking names. I'm aware of two posters here that did/are working for such companies, they could probably explain better than I could.