A new web site, refined from one rushed together after Hurricane Katrina scattered Louisiana residents nationwide, is ready to help doctors and pharmacists get patients' prescription histories almost instantly after a disaster. It's called In Case of Emergency: Rx, or ICERx, after the acronym many agencies recommend people program into their cellular phones to make their personal emergency contacts easy for rescue workers to find. After an earthquake, hurricane or other disaster, representatives from the National Association of Chain Drug Stores and the National Community Pharmacists Association, which represents independent pharmacies, would decide during a conference call whether to open the site. Chains would make available prescription histories from affected ZIP codes. A company that processes claims for independent pharmacies would provide data for that group. Individual independent pharmacies also could sign on to provide information.