Feeding predators people dosed with new drugs is something that must be done with great care. You may not care about the prisoner - if you did, he wouldn't be inside the pred - but you have to be sure the pred can safely metabolize the material.

There was even a famous incident on the Run TV show in which a prisoner consumed a lethal dose of slow acting poison, knowing she was about to be eaten. The two preds who consumed her were lucky to survive and needed several weeks of treatment to recuperate.