What goes up...

Sales of Viagra and other "Erectile Dysfunction" drugs are declining, according to data from NDC published in the New York Times. The drugs work and side effects are relatively minor. Market penetration is relatively low, with only about 15 percent of potentially eligible patients taking the drug. We may be seeing the beginning of the end of marketing induced sales growth of drugs.

The drop in prescriptions comes as sales of other heavily marketed medicines, like antidepressants, are also stalling, and it may be another sign of the limits of consumer advertising to drive demand for drugs. In the late 1990's, drug makers used television advertising to introduce treatments for chronic conditions like arthritis and heartburn. But today, with many patients angry about drug prices and worried that companies are downplaying side effects, drug advertising seems to have lost some of its power.

As advertising loses its ability to generate new users, look for pharma companies to try to improve the "compliance" and "persistency" of existing users.