I assume that your studies in economics identified what you are referring to as "cost-plus" pricing...which is not how any drug is priced. At the point of sales

I assume that your studies in economics identified what you are referring to as "cost-plus" pricing...which is not how any drug is priced. At the point of sales, R&D is a sunk cost and is not part of the pricing strategy, in most big modern companies. Companies price their product to maximize profit. That is not always the highest price they could charge, but is a function of total profits.