The design and synthesis of two photoactivable biotin-labeled analogues of verapamil (6 and 7) is reported. Preliminary evaluation of the biological profile of 6 (EDP 137) and 7 (EDP 141) shows that they have comparable affinities to that of verapamil for P-170, the protein responsible for multidrug resistance (MDR). Since both appear to bind irreversibly to the protein and the presence of biotin in their structure makes them easily detectable by avidin, they promise to be of great help in studying the protein and its mechanism of action.