I was listening to an NPR special about a year ago on how, for some high-end medications which now have generics on the market, patients can receive 'coupons' for medications that cover their copays.
What does this mean? Well, for the generic the patient would have paid $7 and the insurance company would have paid maybe $50, for a total cost of $57 (hypothetically. In the case of the branded medication, the patient pays nothing (they would have paid more than the generic, usually twice or thrice the generic copay, but they pay nothing because they have a 'coupon'), but the insurance company might pay out upwards of $850 now, for a medication for which they may have paid $50.
This happens all over the country, and if it's even effecting one tenth of one percent of the US, you're looking at over a billion dollars in unnecessary healthcare spending.
The insurance companies are definitely not the Robin Hoods of the healthcare world, but they're also certainly not the worst aspect of that wasteful industry.
And I know for a fact that sometimes pharmacists will give you a different size pill than the doctor requests, if it's substantially cheaper. They tell people to just break them in half, or take 2, or whatever.
Which is hardly the most effective channel. In fact, studies have shown an inverse correlation between how much time a physician spends being "educated" by drug reps, and patient outcomes. Of course, while the patients' quality of care goes down the cost of care goes up, because they're paying out the nose for expensive new drugs instead of equivalent (or, as is often the case, superior) generics.