Screening lead compounds for QT interval prolongation

The late detection of cardiotoxic side effects, such as QT prolongation, in duced by compounds of pharmacological interest can dramatically impede drug discovery and development projects, and consequently increase their cost. The launch of new drugs with undetected cardiotoxic side effects could have hazardous consequences and could trigger lethal cardiac dysrhythmias in pa tients. It is desirable, therefore, to test for the potential cardiotoxic s ide effects of compounds at an early stage of drug development. Electrophys iological test systems and cellular-based fluorometric high-throughput assa ys are now available for cloned human cardiac ion channels. These test syst ems are important fools in the preclinical safety evaluation of drugs and n ewly developed compounds.