Abstract
CYP2D6 substrate status is a critical Go/No Go decision criteria in central nervous system (CNS) drug discovery efforts because the polymorphic nature of CYP2D6 can lead to variable patient safety and drug efficacy. In addition, CYP2D6 is disproportionately involved in the metabolism of CNS drugs compared with other drug classes. Therefore, identifying trends in small molecule properties of CNS-penetrant compounds that can help discriminate potential CYP2D6 substrates from nonsubstrates would allow additional prioritization in the synthesis and biological evaluation of new therapeutic candidates. We report here the conversion of the CNS drug minaprine from substrate to nonsubstrate, as well as the conversion of the related CNS drug minozac from nonsubstrate to substrate, through the use of analog synthesis and CYP2D6 enzyme kinetic analyses. No single molecular property strongly correlated with substrate status for this 3-amino-4-methyl-6-phenylpyridazine scaffold, although molecular volume and charge appeared to be indirectly related. A parsed database of CYP2D6 substrates across diverse chemical structures was assembled and analyzed for physical property trends correlating with substrate status. We found that a complex interplay of properties influenced CYP2D6 substrate status and that the particular chemical scaffold affects which properties are most prominent. The results also identified an unexpected issue in CNS drug discovery, in that some property trends correlative with CYP2D6 substrates overlap previously reported properties that correlate with CNS penetrance. These results suggest the need for a careful balance in the design and synthesis of new CNS therapeutic candidates to avoid CYP2D6 substrate status while maintaining CNS penetrance.
- CNS, central nervous system
- LogP, log10 of the octanol/water partition coefficient
- KM, Michaelis-Menten constant
- HPLC, high-performance liquid chromatography
- ESI, electrospray ionization
- kdep, depletion rate constant (per minute)
- [S], substrate concentration (micromolar)
- MW, molecular weight
- LogD7.4, log10 of the distribution coefficient at pH 7.4
- PSA, polar surface area (Å2)
- MV, molar volume (cm3)
- TP, true positive
- TN, true negative
- FP, false positive
- FN, false negative
- Eq, equivalent
- MW01-1-085HAB, N-(2-morpholinoethyl)-6-phenylpyridazin-3-amine
- DMSO, dimethyl sulfoxide
- MW01-7-121HAB, 4-methyl-6-phenyl-N-(2-(tetrahydro-2H-pyran-4-yl)ethyl)pyridazin-3-amine
- MW01-7-103HAB, 4-methyl-6-phenyl-N-(2-(piperidin-1-yl)ethyl)pyridazin-3-amine
- tr, retention time (minutes)
- MW01-8-071HAB, 4-methyl-6-phenyl-N-(2-(piperazin-1-yl)ethyl)pyridazin-3-amine
- MW01-8-019HAB, 4-methyl-6-phenyl-3-(4-(pyridin-3-yl)piperazin-1-yl)pyridazine
- MW01-2-068ZGF, N1,N2-dimethyl-N1-(4-methyl-6-phenylpyridazin-3-yl)-N2-(pyrimidin-2-yl)ethane-1,2-diamine.
Footnotes
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This work was supported in part by the National Institutes of Health National Institute on Aging [Grants AG000260 and AG031311]; and the National Institutes of Health National Institute of Neurological Disorders and Stroke [Grant NS056051].
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Article, publication date, and citation information can be found at http://dmd.aspetjournals.org.
doi:10.1124/dmd.109.028134
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The online version of this article (available at http://dmd.aspetjournals.org) contains supplemental material.
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↵1 Current affiliation: Astellas Research Institute of America, Skokie, Illinois.
- Received April 21, 2009.
- Accepted July 31, 2009.
- Copyright © 2009 by The American Society for Pharmacology and Experimental Therapeutics
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