I wrote here last month about pharmaceutical supply chains, in the context of the (bizarre) threat by the Trump administration to start slapping tariffs on foreign-produced drugs. My main point was that it is tremendously hard (from the outside) to figure out just what a "foreign-made" drug even is, given the number of steps that everything goes through in manufacturing and distribution and the general reluctance of anyone to disclose all those to anyone else.
Here's an article ("Journey of a Pill") that illustrates that in great detail, and here's an article in the Globe and Mail that adds some more details. The authors picked clonazepam, a classic old benzodiazepine (often sold under the brand name of Klonopin) that has been on the market in North America since the mid-1970s. It is the very definition of a generic drug - off patent for decades but still in use, and produced by a number of suppliers around the world. In this case, the authors trace a path that starts with the API itself being produced in Bangalore, while the excipients that will also go into the pill are made in Guangzhou. The API is taken by truck to Mumbai and then shipped by boat to Rotterdam, while the excipients are similarly trucked to Shanghai and then are shipped to Mumbai. The API is analyzed and inspected in the EU and then shipped back to India itself, and the actual clonazepam tablets (API and excipients combined) are made in India. You'll note that this analysis skips over a good amount of the chemistry involved - for example, where do the ingredients used to make the clonazepam itself come from? The answer there is surely "other Chinese suppliers, and good luck figuring out which ones".
But wait, there's more, as they used to say on the old cable TV ads. The finished tablets are shipped to the US, where they undergo USP testing in New Jersey. They are then trucked to Tennessee, where they are repackaged into smaller consumer bottles, and these are then sent to a distribution center Toronto for the Canadian market. In the case the authors are using, trucks then take these to Vancouver, where they are delivered to individual pharmacies for prescription sale to consumers. The authors estimate that the clonazepam could travel over 30,000 miles before it gets into the hands of a patient, what with all that transoceanic shipping, which is pretty impressive. That's also why you see a lot of ocean shipping as opposed to air freight - the latter does occur, but the margins in the generic business are thin enough to make it less attractive. I've heard the expression in the shipping business that "air freight is for flowers and f**kups" (i.e. hasty overnight deliveries), and I think that applies here as well.
This example also illustrates the complexity (and potential fragility) of the whole enterprise. The authors emphasize (rightly) that this is just one drug, and one typical path out of many potential ones that it could take, depending on conditions. But in general this is not at all atypical, from what I know of the process. The authors also expressed surprise at just how difficult it was to piece together these routes from outside - they ended up doing a lot of calling and off-the-record discussions, from the look of it, and I think that's really the only way. No one wants to give their competition any kind of hand by revealing any particular good deals they've made in all those middle steps.
And it all shows as well how idiotic it is to come out saying that you're just going to slap a tariff on everything that's not made in the US. I mean, there are drugs that are (up to a point) made in the US, but even those are often going to have an overseas excursion somewhere in the process. Such tariffs would have the biggest impact on the cheapest drugs, the generics like the case discussed here, because those are almost invariably made by low-cost overseas suppliers. So if you want to hit the consumers of such medicines the hardest, on a percentage basis, that's the way to do it. But if you don't care about that and just want to make tough-guy noises about Them Foreigners, feel free, I guess. There are a lot of financial comparative-advantage reasons to get your generic drugs made overseas, but I also appreciate that there are disadvantages to relying exclusively on such routes for them as well. It's a tradeoff (and what isn't?) But that's not the level of thinking we're seeing here - not from a president who seems to think that a trade deficit means that people are stealing from you.