Today (or, given time zones, yesterday) the best-selling drug of all time goes off patent in the USA.
Atorvastatin (Lipitor) became such a gigantic commercial success for two main reasons: it actually works slightly better than the earlier cholesterol-lowering drugs, and Pfizer funded several large clinical trials proving that it worked better. Despite the (often justified) cynicism about drug marketing and approval, the regulatory process does mean that effective treatments are more profitable than ineffective ones — in sharp contrast to supplements and herbals, where effective treatments don’t have any real marketing advantage.
The patent expired earlier in New Zealand: in June 2010, Pharmac found a generic supplier and reduced the price for a month’s supply from $18 (for the lowest dose) to $1.77. In the US, Lipitor costs more than US$3 per pill, so there’s even more room for price decreases.