To precise, pharmaceutical companies are concerned that bad counterfeits will harm the reputation of their products, which will cut into order volume and profits.
Either way it's a legitimate concern. If you want to produce your own products, sell them under your own name. Counterfeits are piggybacking on the hard work of other people and I have no sympathy for people doing it.
It's interesting that some companies supporting SOPA do so because of sheer cluelessness on the matter. And it's ironic because SOPA will not stop the phenomenon.
