Yes it does. For example, look at Clarinex. This drug is in no way advantageous over Claritin, and in fact is metabolized into Claritin in vivo. The only reason that it exists is because Schering-Plough's patent ran out on Claritin.
Or look at Vyvanse, a prodrug of Adderall. Shire Plc has been intentionally manipulating the market (using government amphetamine quotas) for years in order to push patients away from cheaper generic Adderall (despite the fact that many people find Vyvanse to be substantially inferior).
Or take the case of adrafinil, which metabolizes into modafinil (provigil). Adrafinil is just fine (not quite as effective, but nearly so), but its patent ran out. At that point, Cephalon pulled strings to get its approval revoked (this was in France; adrafinil is unapproved and unregulated in the US), so that people would have to move to their newer, patented drug. (And yes, adrafinil does tax the liver some, but no more so than plenty of other drugs).
Or look at Vyvanse, a prodrug of Adderall. Shire Plc has been intentionally manipulating the market (using government amphetamine quotas) for years in order to push patients away from cheaper generic Adderall (despite the fact that many people find Vyvanse to be substantially inferior).
Or take the case of adrafinil, which metabolizes into modafinil (provigil). Adrafinil is just fine (not quite as effective, but nearly so), but its patent ran out. At that point, Cephalon pulled strings to get its approval revoked (this was in France; adrafinil is unapproved and unregulated in the US), so that people would have to move to their newer, patented drug. (And yes, adrafinil does tax the liver some, but no more so than plenty of other drugs).