With the cost of prescriptiondrugs being one of the fastest-growingcomponents of health carespending, seniors on Medicare, whogenerally don't have prescriptiondrug coverage, would welcome adrug benefit. So might investorswho hold shares in companies thatmake brand name prescription drugs,some market analysts say, especiallyif the Bush Administration could geta drug benefit passed that doesn'tinclude price caps. Although thegovernment would probably exact ahefty discount, higher volume saleswould counterbalance any lossesfrom lower prices. Drug firms withproduct lists that are heavy withdrugs for seniors will probably dobest, industry experts say. Pfizer andMerck, for example, which have bigsales in cardio and arthritis drugs,figure to get a boost from a Medicaredrug benefit.