Empirical vs. "rational" methods of discovering new drugs

Empirical and theoretical approaches to drug discovery have often been perceived as mutually exclusive. Our experience has rather demonstrated that they can be complementary. The structure-based approach to design of compound libraries is clearly helpful; however, testing large libraries continues to reveal unanticipated actives in many of our programs. A rationale for these observations is offered.

Three-dimensional molecular modeling and drug design

A discussion of drug-receptor theory is used to show that the three-dimensional structure, or shape, of molecules is important for biological activity. The computer-assisted molecular modeling system at Merck is described, and it is shown that this system is useful for generating and storing molecular structures, determining preferred conformation, comparing molecular shapes, and computing molecular properties. Applications of the system to the study of anti-inflammatory drugs, somatostatin-like compounds, and dihydrofolate reductase inhibitors are summarized.

A model for the prostaglandin synthetase cyclooxygenation site and its inhibition by antiinflammatory arylacetic acids

Conformational analysis of indomethacin and other nonsteroidal antiinflammatory drugs leads to formulation of a hypothetical complementary receptor site model. The same model can serve to describe the prostaglandin cyclooxygenase active site, and, indeed, arachidonic and other polyunsaturated fatty acids could be folded on the model in a manner which rationalizes their stereospecific transformation to cyclic endo-peroxides (PGG). The model rationalizes the structure-activity relationships of enzyme substrates and inhibitors and appears to be in agreement with biochemical studies of the enzyme.

Anticoccidial 1-substituted 4(1H)-pyridinone hydrazones

4-Chlorobenzaldehyde 1-(4-chlorophenyl)-4(1H)-pyridinylidene hydrazone fluorusulfonate (4) was found to have excellent anticoccidial activity in chickens. The synthesis and biological evaluation of related analogues are presented. Presumably 4 shares a common mechanism of action with robenidine (25) since it was not active on a robenidine tolerant strain of E. tenella. Structural comparisons of the two molecules are presented.