Atorvastatin, marketed in the US by Pfizer under the brand name Lipitor, is a blockbuster drug that is consistently the world's top-selling prescription medication. The introduction of generic versions of Lipitor in Canada and other countries in 2010 eroded Pfizer's market share, but US sales alone were still close to $2.5 billion last year.

A member of the drug class statins, atorvastatin is prescribed to treat high cholesterol and to reduce the risk of heart attack in people with heart disease or other risk factors. Like all statins, Lipitor works by blocking the action of an enzyme involved in cholesterol production in the liver, lowering the levels of LDL ("bad") cholesterol, while raising the levels of HDL ("good") cholesterol.

Atorvastatin was first synthesized in the US by Parke-Davis Warner-Lambert (now Pfizer) in 1985. Pfizer holds the US patent on Lipitor until June 2011, when other companies will be allowed to produce and market cheaper generic versions. The Indian generic company Ranbaxy Laboratories was first-filer, giving it a six-month period of exclusivity. However, Pfizer has reached an agreement with Ranbaxy to delay the launch of an American generic until November 2011.

Generic versions of Lipitor have been available in other countries including India, Spain, Australia, and Germany for several years at significantly lower prices. By law, generic versions of brand name prescription medications must contain the same active ingredients at the same dosage, and have the same pharmaceutical effects.

Health Canada approved the roll out of several generic versions of Lipitor in Canada in May of 2010. Paul Bisaro, chief executive of one of the companies winning generic approval, Watson Pharmaceuticals, says atorvastatin is the largest product to be offered as a generic in the history of the Canadian pharmaceutical industry.

Canadian officials have been actively pursuing ways to cut the cost of healthcare, including cutting the price of generic drugs from Canada. Health Canada's authorization of the low cost generic drugs means online Canadian pharmacies can now offer their many American customers atorvastatin from Canada instead of sourcing it from overseas.

Currently, there are at least three Canadian drug companies manufacturing 10, 20, 40 and 80 mg atorvastatin tablets. Drug giant Pfizer company spokeswoman Sally Beatty says the company plans to offer its own "alternative versions" of Lipitor soon, although she could not say when, or what the generic atorvastatin would be priced at.

Paul Bisaro, chief executive of Watson Pharmaceuticals, says the block-busting cholesterol lowering drug Lipitor is the largest product ever to be offered as a generic in the history of the Canadian pharmaceutical industry. Online Canadian pharmacies are passing the savings on to their American customers.