A combination of two medicines already approved by the Food and Drug Administration might help treat cocaine addiction, says neuroscientist Larry Reid of Rensselaer Polytechnic Institute. Used together, isradipine, a medication for high blood pressure, and naltrexone, used to treat alcoholism, block cocaines ability to sustain addiction in rats. Effectiveness does not diminish with use, Reid reports. One advantage: the two drugs are already approved for medical use. Testing the approach with people is the next step.