Some of these estimates also take into account the opportunity cost of investing capital many years before revenues are realized (see Time-value of money). Because of the very long time needed for discovery, development, and approval of pharmaceuticals, these costs can accumulate to nearly half the total expense. A direct consequence within the pharmaceutical industry value chain is that major pharmaceutical multinationals tend to increasingly outsource risks related to fundamental research, which somewhat reshapes the industry ecosystem with biotechnology companies playing an increasingly important role, and overall strategies being redefined accordingly. Some approved drugs, such as those based on re-formulation of an existing active ingredient (also referred to as Line-extensions) are much less expensive to develop.

What drugs are the least expensive to develop?