Animal pharm
Making drugs to treat animals is potentially lucrative – but also difficult, as Clare Sansom discovers
Chocolates, grapes, raisins and onions are some of our favourite foods: eating them is unlikely to make many of us very ill. But leave a piece of your favourite chocolate cake within reach of your dog, and you may find your beloved pet suffering from acute renal failure.
These examples illustrate the significant biochemical and metabolic differences between humans, dogs and cats – and, indeed, between all mammalian species – that make the design of medicines for use in animals a challenging endeavour. And veterinary drug development is further complicated for animals that are to enter the human food chain. The development process for livestock drugs involves long-term toxicity tests in rodents – often encompassing the whole of the natural rodent lifespan – as well as in other mammals, so that farmers and consumers can be wholly confident that the meat, milk or eggs will contain no potentially harmful drugs or metabolites. Furthermore, as Jonathan Elliott, professor of clinical pharmacology at the Royal Veterinary College in London, UK, explains, ‘all drugs to be prescribed for livestock are labelled with a minimum withdrawal period after treatment ends before an animal may be sent for slaughter, or milk may be sold’.