Is it permissible for a Muslim Ph.D. student in pharmacology in Britain to test a drug on tissue taken from the mouth of a pig after it has been slaughtered, knowing that the tissue will be used for testing purposes only and will not be incorporated into the drug's composition?

If the purpose of the experiments is to test a permissible medicine for humans or for animals that are permissible to own, then there is no harm in that, provided that direct contact with pork is avoided due to its impurity. However, it is not permissible to conduct these experiments to produce medicine for treating pigs themselves or for improving their production, because they are a prohibited animal.