Current strategies in the search for novel antiparasitic agents.

The market for antiparasitic products comprises the largest segment for sales of livestock and companion-animal healthcare agents. Despite the availability of highly effective, broad-spectrum agents, there remains a need for safer, more convenient and more environmentally friendly products that will overcome the ever-present threat of resistance development. The very high cost of discovering and developing a new drug, especially for use in livestock, is reflected in the limited number of new classes of antiparasitic agent launched on the market. New strategies are being adopted to minimise the cost of discovering potential drug candidates by maximising the chance of identifying a useful target mechanism of action and by speeding the time to discover and optimise a lead structure. These rely heavily on new technologies in target identification, screen development and lead optimisation. Examples of these will be discussed and speculation made about the possible factors that could influence the future shape of antiparasitic control.