The government is considering whether a drug that treats high cholesterol should be sold over-the-counter. Those in favor say low-dose cholesterol medicine could get treatment to millions at risk of heart disease. Opponents say direct sale to consumers would allow patients to skip doctors visits. They might avoid hearing that diet and exercise are needed, and they're both critical in reducing cholesterol. Johnson & Johnson and Merck Consumer Pharmaceuticals have joined in asking the Food and Drug Administration for permission to sell a low-dose version of Mevacor over the counter. A panel of FDA advisers is considering the request today and tomorrow. The agency usually follows the recommendations of its advisers.