Shades of grey: radiopharmaceutical chemistry in the 1990s and beyond

The editorial briefly reviews future directions for pharmaceutical research, with particular reference to validation in the sense of correlation between in vivo values such as tissue ratios, binding potential, volume of distribution and in vitro measures of the same binding site or enzyme site densities as measured in different regions of an organ. Determination of the dose-response curve of radioligand binding in animals, using competition for sites by doses of identical or pharmacologically equivalent, but structurally different drugs. (UK)