One of the science people on this board can probably give you a better answer. One simple answer is that its often hard to get as high bio-availability of the drug orally as can be achieved IV. I think often still when a drug comes available in both forms the IV is still far superior.
Register for free to join our community of investors and share your ideas. You will also get access to streaming quotes, interactive charts, trades, portfolio, live options flow and more tools.