The Associated Press reports that Pfizer declined to comment on reports it hopes to start marketing an over-the-counter version of its cholesterol drug Lipitor, the world''s biggest-selling prescription drug, after the original version loses patent protection in November. The Wall Street Journal reported that Pfizer hopes to get the Food and Drug Administration to approve a version of Lipitor that could be dispensed without a doctor''s prescription. Lipitor brings the New York-based drugmaker about $11 billion in annual revenue, and sales are already declining as cheaper generic versions go on sale in some overseas markets. The U.S. patent supporting the drug expires Nov. 30, which will allow generics to reach the market and eat into Pfizer''s sales. The company could keep more of its revenue if it could sell a less-expensive OTC version. A month''s supply of Lipitor costs about $150, and generics are expected to cost about $10 per month in the U.S.