The development of drug metabolism research as expressed in the publications of ASPET: part 1, 1909-1958

Human Absorption, Distribution, Metabolism, and Excretion Studies: Origins, Innovations, and Importance

Human absorption, distribution, metabolism, and excretion (hADME) studies represent one of the most important clinical studies in terms of obtaining a comprehensive and quantitative overview of the total disposition of a drug. This article will provide background on the origins of hADME studies as well as provide an overview of technological innovations that have impacted how hADME studies are carried out and analyzed. An overview of the current state of the art for hADME studies will be provided, the impacts of advances in technology and instrumentation on the timing of and approaches to hADME studies will be discussed, and a summary of the parameters and information obtained from these studies will be offered. Additionally, aspects of the ongoing debate over the importance of animal absorption, distribution, metabolism, and excretion studies versus a "human-first, human-only strategy" will be presented. Along with the information above, this manuscript will highlight how, for over 50 years, Drug Metabolism and Disposition has served as an important outlet for the reporting of hADME studies. SIGNIFICANCE STATEMENT: Human absorption, distribution, metabolism, and excretion (hADME) studies have and will continue to be important to the understanding and development of drugs. This manuscript provides a historical perspective on the origins of hADME studies as well as advancements resulting in the current-state-of the art practice for these studies.

The Evolution of Drug Metabolism and Disposition: A Perspective From the Editors

This article was solicited to commemorate the 50th anniversary of Drug Metabolism and Disposition (DMD) and features perspectives from five former editors spanning the years 1994 to 2020. During that time frame the journal underwent significant changes in manuscript submission and processing as well as multiple generational changes in the composition of the editorial board and associate editors. A constant, however, has been the commitment to be the premier journal for publications of articles in the areas of drug metabolism, absorption, distribution, excretion, and pharmacokinetics. Advances in some of those areas during the past 3 decades have been monumental. Two cases in point involve cytochromes P450 and drug transporters. In 1994 rigorous characterization of human cytochrome P450 enzymes was in its infancy, there were no proven selective inhibitors, and the idea of solving a human P450 X-ray crystal structure was just a fantasy. Likewise, little was known about individual drug transporters. Today, detailed knowledge of individual human P450 enzymes and drug transporters is integral in drug design and drug discovery and in avoiding drug interactions. In the face of these huge advances in knowledge, each editor has been charged with maintaining the caliber and significance of the journal and its financial solvency while serving the needs of individual authors. We present 5 individual perspectives on the challenges and rewards of serving as DMD editor and hope that, by humanizing the job, we will encourage others to assume positions of responsibility in publication of society journals. SIGNIFICANCE STATEMENT: The 5 most recent former editors of DMD describe their experiences and perspectives on the position in the context of constantly changing scientific emphases, technology, and publishing practices. The article offers subscribers, authors, and future editors and editorial board members valuable insights into the inner workings of the journal.

New insights on the consequences of biotransformation processes on the distribution and pharmacodynamic profiles of some neuropsychotropic drugs

The metabolic processes frequently trigger highly complex pharmacokinetic (PK) and pharmacodynamic (PD) characteristics for the coexisting entities, parent drug and its active or inactive metabolites. The interpretation of both individual and cumulative profiles, frequently used in the therapeutic drug monitoring procedures, must take into consideration the biological coherence of the changes of the molecular descriptors characterizing the metabolites versus the parent drugs, and further qualitative and quantitative consequences on permeability processes across highly specialized biological barriers (e.g. blood-brain barrier [BBB]). This paper analyzes the correlation of molecular descriptor differences and the PK/PD consequences for three representative psychotropic drugs (risperidone, clozapine and tramadol) and their active metabolites, underlying the safety and efficacy concerns of using the products of metabolic processes as potential new drugs. The minimal structural changes are correlated with the predicted or experimental penetrability across the biological membranes, with a special emphasis on BBB penetration, as the limiting phase for the effect at central nervous system level. The PD characteristics related to the active metabolites are compared to the ones reported for the parent drugs, concerning mainly the affinity for cerebral receptors and the type of activity at a specific level. For the neuropsychotropic substances, with BBB penetrability as a sine qua non condition, the comparative analysis of PK/PD properties for the parent drug and its metabolites generates a complete and highly complex image of the consequences of their coexistence, since these entities must be conceived and analyzed not separately, but by inclusion of usually complementary properties generating a unique therapeutic profile.

The development of drug metabolism research as expressed in the publications of ASPET: Part 2, 1959-1983

In 25 years, drug metabolism research went from using subcellular particles of undefined content to an understanding of metabolism at the molecular level. The discoveries of cytochrome P450, enzyme induction, reactive intermediates, and genetic polymorphisms were milestones in the field. New publications from the American Society for Pharmacology and Experimental Therapeutics chronicled the discoveries and provided communications to advance the science of drug metabolism.