WHAT IT MEANS AND WHY ITS IMPORTANT Some investors quoted in published reports foresee huge gains for such retail pharmacy chains as CVS and Walgreens, as blockbuster drugs like Pfizer’s Lipitor (atorvastatin) and Sanofi-Aventis’ and Bristol-Myers Squibb’s Plavix (clopidogrel bisulfate) come off patent and face generic competition, but they would do well to remember an important factor: the patent cliff.