Mintel
Note that Mintel has some coverage for Europe and other regions in addition to the US. The easy way to navigate Mintel is to search the Insights section -- or for a broad view there is a browse feature for Insights, by category, region, trend drivers, and demographics.
MarketResearch Academic
Note that MarketResearch Academic is mostly US focused. The easy way to navigate MarketResearch Academic is to search. While each named drug/drug class brings back results, explore alternate terminology after trying the name of your drug.
Note that there is a note that gives the price at the start of each report, such as: "250 pages - $5,500.00 (Student downloads are FREE of charge – the price is shown for informational purposes only)". No worries, we are not charged this amount when you access the report - Ship pays a flat fee for all access to MarketResearch Academic reports.
US Data & Statistics
Searches US government websites and reports, covers each approved topic for class (and a whole lot more)