Therapeutic switching: a new strategic approach to enhance R&D productivity.

New chemical entity discovery and development is a long, expensive and risky way of producing new therapeutics. An alternative approach, namely finding new uses for existing drugs, offers substantial advantages in terms of cost, time and risk, and represents a highly attractive strategy to drug discovery. Patents protecting the new use may also be obtained. There are multiple different classes of such R and D programs, depending on whether the original development is still protected by composition of matter patents, and whether the compound was ever fully developed/marketed for its original indication. There are also shortened R and D programs for new uses for stereoisomers and metabolites of existing drugs. Case histories in all areas are presented.