There's some NDA that I am under that I cannot give very specific advice, but the exam has not changed formats between 2018 and 2019, however, there are possibilities that some questions may change due to updates in clinical paradigms (though the main ones have not changed). The very volatile ones like oncology and immunology tend not to be asked in specific depth as the science can literally change the answers between examination years (however, I'd absolutely prepare for both of these in terms of MOA, side effect profile, and usual therapeutic applications and differentials).
If I faced your position, I would keep the 2018 and study from it. The advice that I give all my students is that:
1. I would flatly memorize the Top 200
2. Know how to use the formulae
3. Know how to read basic lab values and the replacement/removal options for all of them (particularly, Renal, Hepatic, Hematology, and Electrolytes)
4. Then start on systems, but that's just me.
If I came from a different pharmacopeia (like the BP), you need specifically to learn the USP generic names and specifically dosing differences in the US from the BP style (the US tends to be less precise about dosing gradations than BP).
If you are from the PEBC license, frankly, you can even risk take the exam without studying, the PEBC is way harder. From the Council or Irish systems, our exam is actually harder than yours (sadly) and less basic science heavy.
