When I saw that some major drug companies were being sued over coupon offerings, I had a suspicion what the concern would be.
I had to go back to January 2008 to find this post, but I addressed the same issue in regards to free samples. Patients are given samples or coupons to bypass the health insurance company when it will not cover the medicine or will cover it at a higher copay. The coupon can reduce the copay or coinsurance. Bear in mind, sometimes the generic IS the better medication. Generics are often brand named drugs that have gone off patent.
I worked in health care in the past, so I understand that the burden ends up on the patient. The very worst of this is that most of the time the cheaper medicine IS the better medicine. The worst -er is that the drug companies convince doctors and patients otherwise - through direct to consumer and provider advertising and manipulation.
Read about the lawsuit in the Boston Globe.