The nation's largest medical association sought to halt distribution of a "smokeless cigarette," saying it should be removed from shelves until it is judged "safe for human consumption." The American Medical Assn. filed legal petitions with state health authorities in Arizona and Missouri--where the product is being test-marketed--contending that the smokeless cigarette is a "new, hazardous" drug that needs further testing. The product, dubbed Premier by manufacturer R. J. Reynolds Co., contains nicotine, an "addictive drug . . . which has been implicated in cardiovascular disease," high blood pressure and other medical problems, the AMA said. "The scientific evidence is crystal clear about the adverse health effects of nicotine and carbon monoxide," Dr. Roy Schwarz of the AMA said at a news conference. R. J. Reynolds responded with a news release contending that "Premier is a cigarette . . . not a drug-delivery system, as the AMA has alleged."