WASHINGTON

Gov. George W. Bush, who has promised on the campaign trail to make prescription drugs more affordable, signed legislation making it harder for Texas doctors to prescribe a cheaper generic version of a popular blood-thinning drug.
     The 1997 law was sought by DuPont Merck Pharmaceutical, the drug giant that manufactures the name-brand drug. DuPont tried to persuade states to block the new generic competition. Just three states, including Texas, adopted laws.
     Texas has since reversed course, agreeing with the Food and Drug Administration in 1999 that generic warfarin is just as safe and effective as name-brand Coumadin.
     The generic version is sold for 40% to 50% less than the name brand.
     A spokesman for Bush defended the law, saying the governor was protecting patients.
     "When we're talking about drugs that have the potential of life or death, we ought to have an extra safety measure for patients," said Dan Bartlett, a spokesman for the Republican presidential nominee.
     Many health experts say that risk was greatly exaggerated.
     "It's pretty clear the FDA has gone to extensive lengths to verify the quality and standards necessary for generic drugs," said one heart specialist, Dr. Raymond Woosley, the chairman of the pharmacology department at Georgetown University School of Medicine.
     With the cost of prescription drugs a major focus of the presidential race, Vice President Al Gore's campaign seized on the Coumadin legislation to renew its charge that Bush is a pawn of the industry.
     "This would be another example of Bush's heartless policies and failed leadership," said Gore spokeswoman Kym Spell. "When it comes to prescription drugs, Bush is proving he's coldblooded."
     Bartlett accused Gore of "grasping at straws in an attempt to change the dynamics of the election."
     "The fact that Al Gore would attack Gov. Bush for a patient safety bill sponsored by Democrats shows the lengths he will go to in order to mislead Americans about Gov. Bush's record in Texas," he said.
     The controversy surrounds Coumadin, a blood thinner taken by 2 million people, mostly heart disease sufferers, to prevent blood clots. DuPont had been the exclusive manufacturer of the drug for decades, although its patent expired in 1962.
     In 1996, the FDA approved a generic substitute, known as warfarin, concluding that it's identical to Coumadin and safe for patients.
     DuPont mounted a campaign to convince state legislatures that the two are not the same. Coumadin is part of a class of pharmaceuticals known as "narrow therapeutic index" drugs. That means the dosages must be tightly controlled. Slightly too little, and the medicine is ineffective; slightly too much, and it can be toxic.
     The generic version, DuPont told legislators, may not get the dosage just right. Barr Laboratories, manufacturer of the generic drug, made the opposite case. Overwhelmed with questions, the FDA in 1998 told doctors and state pharmacy boards that the generic warfarin was just as good as Coumadin.
     DuPont was motivated partly by profit and partly by concern for patients, argued Stuart Haines, an expert on drug therapy at the University of Maryland who gets some of his research money from DuPont.
     "Clearly they wanted to protect their market share," he said.
     Haines said he understands why doctors might be cautious about using a new generic drug, but he doesn't think states should intervene if a drug has been approved by the FDA.