They can be motivated by profit, as all businesses are. The problem is they aren't regulated by any means - for example, the amount of "ask your Doctor is blahblah is right for you" kind of ads need to stop. It's not the patient who needs to ask the doctor which medicine is right for him, it's the doctor who needs to act in the patients' best interest to provide the right medicine. Not to mention the kickbacks doctors get for prescribing certain drugs.