Abstract: The present invention provides a predictive method for selecting organic compounds having useful pharmaceutical activity in a mammal. The method uses volume areas of similar molecules. When specific substituents of the test compound file predetermined volumes, the compound is subject to a binding assay. Only when the binding assay is positive, is the experimental compound recommended for further pharmaceutical evaluation. Example compounds are derivatives of 4-substituted 2,6-diiodophenols of the structure: ##STR1## where R.sup.1 and R.sup.2 are defined as aliphatic or substituted aliphatic moieties or aromatic or substituted aromatic moieties. Useful structures are described. The compounds have useful pharmaceutical properties to treat conditions in a human being, including hyperthyroidism, angina pectoris, arrythmia, and the like.