"In the U.S., prescription drug spending increased from US $50.6 billion in 1993 to $93.4 billion in 1998, an 84% increase over a five-year period. Four categories of drugs accounted for 30.8% of this increase: oral antihistamines used to treat allergy, antidepressants, cholesterol-lowering drugs and ulcer treatments. These categories include seven of the ten drugs most heavily advertised to the public in 1998. That means that direct-to-consumer advertising could have added more than $13 billion to the US drug bill in 1998. In 1999, two thirds of the increase in spending on prescription drugs in the US was for 25 drugs with the most intensive DTC advertising campaigns"
Click on link for more interesting tidbits. Still trying to crunch some numbers here....