For the second time in a week, the Food and Drug Administration on Thursday is scheduled to consider a controversial request to convert a prescription drug into an over-the-counter product. And if you thought last week's FDA advisory committees' ruling about a cholesterol drug provoked headlines, wait until you hear the reaction after the agency acts on a contraceptive product. The FDA is scheduled to rule on an application by Barr Pharmaceuticals ( BRL) to permit an emergency contraceptive -- known as Plan B or, more colloquially, the morning-after pill -- to be sold without a prescription for women age 16 and older. If taken within 72 hours of unprotected sex, Plan B can reduce the risk of pregnancy by 89%. Plan B is 95% effective when taken in the first 24 hours after intercourse. Last week, two FDA advisory committees soundly rejected an attempt by Merck ( MRK) and its marketing partner Johnson & Johnson ( JNJ) to turn the prescription cholesterol drug Mevacor into an over-the-counter medication. The two committees, meeting jointly, said the companies failed to show that patients could safely take the drug without a doctor's prescription. This was the second time in four years that Mevacor had been rebuffed as an OTC product. But Plan B is a more complicated and more politically incendiary story. In December 2003, two FDA advisory committees voted 23 to 4 to support the sale of Plan B as a nonprescription product for all women. In May 2004, however, the FDA, in a rare move, overruled the committees and rejected Plan B. The agency said Barr didn't provide "adequate data to support a conclusion that Plan B can be used safely by young adolescent women" for emergency contraception without a doctor's prescription. In this instance, a top FDA official, Dr. Steven Galson, signed the rejection letter. The agency noted that he "does not usually sign regulatory action letters," but he did so for Plan B because "his opinion of the adequacy of the data in young adolescents differed from that of the review staff."