In order to get a generic approved you need to do testing that shows your drug works in the same way as the original. In order to have a control you need to hav

In order to get a generic approved you need to do testing that shows your drug works in the same way as the original. In order to have a control you need to have the original drug, thus a pharma company can stop production on a drug while still under patent and replace it with this "new" drug (often the same drug with an antacid added) thus making generic approval much more difficult and costly.