SEEING THROUGH THE MIST: ABUNDANCE VERSUS PERCENTAGE. COMMENTARY ON METABOLITES IN SAFETY TESTING

@article{Smith2005SEEINGTT,
  title={SEEING THROUGH THE MIST: ABUNDANCE VERSUS PERCENTAGE. COMMENTARY ON METABOLITES IN SAFETY TESTING},
  author={Dennis A. Smith and R. Scott Obach},
  journal={Drug Metabolism and Disposition},
  year={2005},
  volume={33},
  pages={1409 - 1417}
}
Recent attention has been given to the potential roles that metabolites could play in safety evaluations of new drugs. In 2002, a proposal was published on “metabolites in safety testing” (“MIST”) [T. A. Baillie, M. N. Cayen, H. Fouda, R. J. Gerson, J. D. Green, S. J. Grossman, L. J. Klunk, B. LeBlanc, D. G. Perkins, and L. A. Shipley (2002) Toxicol Appl Pharmacol 182:188–196], which suggested some guidelines regarding when it is necessary to provide greater assessment of the safety of… 

Figures and Tables from this paper

Metabolites in safety testing (MIST): considerations of mechanisms of toxicity with dose, abundance, and duration of treatment.
TLDR
The present review updates the enzymatic basis for the differences between species and how these relate to MIST considerations, and practical considerations of human ADME data, to determine which metabolites should be further evaluated for safety.
A holistic strategy for characterizing the safety of metabolites through drug discovery and development.
TLDR
A key principle in striking this balance is to build stepwise information on metabolites through the drug discovery and development continuum, which allows assessments to be made from early nonclinical studies onward as to whether or not metabolite safety is underwritten by exposure in toxicology species.
Metabolite Testing in Drug Development
TLDR
A number of key considerations apply, notably the specific structure, pharmacological activity, abundance, pharmacokinetics and physicochemical properties of individual metabolites, together with the administered dose of the parent compound, to ensure that the safety and efficacy profiles of candidate compounds are properly understood.
Metabolites in Safety Testing: Issues and Approaches to the Safety Evaluation of Human Metabolites in a Drug that is Extensively Metabolized
TLDR
The application of alternative strategies to 2008 FDA MIST guidance, such as those suggested by scientific literature and by the recent revision of the International Conference of Harmonisation M3 guidance, allowed us to focus on one metabolite for additional safety evaluation.
Metabolites in safety testing: metabolite identification strategies in discovery and development.
TLDR
It is argued that increased diligence should be applied to metabolism studies in the early stages of both drug discovery and drug development, in order to more routinely impact chemical design and to comply with the concepts of the MIST guidance without re-positioning the definitive radiolabelled studies from there typical place in late development.
Current opinion: safety evaluation of drug metabolites in development of pharmaceuticals.
Safety assessment of drug metabolites in the development of pharmaceuticals was discussed in January 2007 at the kick-off meeting of a "Drug Evaluation Forum", with reference to the views of
Metabolites: have we MIST out the importance of structure and physicochemistry?
TLDR
The analysis of circulating metabolites is driven by the need to complete a comprehensive PK/PD exploration of the activity of a drug to determine the likelihood of the metabolites exerting on and off target pharmacology, which may contribute to the overall efficacy and side effects of the drug.
Obtaining exposures of metabolites in preclinical species through plasma pooling and quantitative NMR: addressing metabolites in safety testing (MIST) guidance without using radiolabeled compounds and chemically synthesized metabolite standards.
The recent guidance on "Safety Testing of Drug Metabolites" issued by the U.S. Food and Drug Administration, Center for Drug Evaluation and Research (CDER) has highlighted the importance of
Drug Metabolism in Drug Safety Evaluation
TLDR
The different experimental approaches employed to study these two groups are outlined, and the implications for lead optimization efforts in drug discovery, and for later phase clinical development programs, are discussed in the context of establishing the human safety of the NCE.
...
1
2
3
4
5
...

References

SHOWING 1-10 OF 57 REFERENCES
Drug metabolites in safety testing.
TLDR
A number of points to consider emphasize the need to treat drug metabolite issues on a case-by-case basis, and define practical and scientifically based approaches to the use of metabolite data that address contemporary issues in the safety evaluation of drug candidates.
In vitro metabolism of tolcapone to reactive intermediates: relevance to tolcapone liver toxicity.
TLDR
Examination of the ability of M1 and M2 to undergo in vitro bioactivation by electrochemical and enzymatic methods and experiments with chemical P450 inhibitors and cDNA-expressed P450 enzymes reveal that this oxidation is catalyzed by several P450s, and that P450 2E1 and 1A2 play the primary role in the formation of C1 while P4501A2 is most important for the production of C2.
Assessment of the relative in vivo potency of the hydroxylated metabolite of darifenacin in its ability to decrease salivary flow using pooled population pharmacokinetic-pharmacodynamic data.
AIMS To describe the population pharmacokinetic-pharmacodynamic relationship between darifenacin (UK-88,525) and its hydroxylated metabolite (UK-148,993), and the reduction in salivary flow (SF, a
A mechanistic approach to understanding species differences in felbamate bioactivation: relevance to drug-induced idiosyncratic reactions.
TLDR
The result of the first 34 patients screened suggests that a patient with poor UGT activity is not necessarily at risk for FBM toxicity, and a relative 5-fold increase in mercapturate excretion in patient urine as a result of differences in metabolism through P450-, esterase-, and aldehyde dehydrogenase-mediated pathways.
Paracetamol hepatotoxicity at therapeutic doses
  • S. Vitols
  • Medicine, Biology
    Journal of internal medicine
  • 2003
TLDR
Hepatotoxicity within recommended dosage guidelines can be a dose-dependent phenomenon and not an idiosyncratic reaction in the setting of recent fasting and malnutrition because hepatotoxicity appeared after 4 g day but not after the lower doses.
Clinical and experimental studies linking oxidative metabolism to phenytoin-induced teratogenesis.
The research presented in this article concerns the proposed mechanism of phenytoin-induced teratogenicity that focuses on oxidative metabolites as sources of reactive species in clinical studies and
Acetaminophen-induced hepatotoxicity.
TLDR
The recent finding that NADPH oxidase knockout mice were equally sensitive to acetaminophen and had equal nitration of tyrosine suggests that the superoxide is not from the activation of Kupffer cells.
Metabolism and excretion of tolcapone, a novel inhibitor of catechol-O-methyltransferase.
TLDR
Tolcapone is almost completely metabolized and excreted in urine and faeces (only 0.5% of tolcapone was excreting unchanged); glucuronidation is the most important route of metabolism.
...
1
2
3
4
5
...