Abstract
With increasing numbers of drugs tested in oncology for smaller patient populations, fewer patients are available to answer important clinical pharmacological questions in the timeframe of clinical drug development. The quality and efficiency of trials to assess the pharmacokinetics of new drugs can be improved by making better use of available resources. One approach to do this is by making more effective use of isotopic tracer techniques. With increasing sensitivity of liquid chromatography-tandem mass spectrometry analyzing equipment over the years, it has now become possible to generate much more rich, high-quality pharmacokinetic data than before. In particular we want to make a plea here for a hybrid trial approach, where both radiolabeled drug and stable isotopically labeled drug are administered to patients to assess both the absolute bioavailability and absorption, distribution, metabolism and excretion in a single clinical trial experiment.