Abstract
E2101 orN-methyl-[1-[1-(2-fluorophenethyl)piperidine-4-yl]-1H-indol-6-yl] acetamide, an antagonist of 5-hydroxytryptamine receptor subtypes 1A and 2, is currently under development for the potential treatment of skeletal muscle associated spasticity. Here we characterized the in vitro metabolism of E2101 using human liver enzymes including human liver microsomal preparations, human liver S9 fractions, and individual forms of recombinant cytochromes P450 (P450s). Our results showed that E2101 was metabolized by P450s to form monohydroxylated (M1 and M2), dihydroxylated (M3), andN-dealkylated metabolites (M4). The structures of these major microsomal metabolites were proposed based on LC/MS/MS analyses. All four metabolites, M1–M4, were formed by CYP3A4. Metabolites, M1, M2, and M4, were also formed by CYP2C19 and M2 and M3 by CYP2D6. The potential P450 inhibition and induction of E2101 were also evaluated. E2101 was determined to be a competitive inhibitor of CYP2C19 and CYP2D6 with Ki of 15 and 48 μM, respectively, as determined by both Dixon plots and simultaneously nonlinear regression analyses. Induction of major P450 expression was not detected immunochemically after 72-h exposure to 10 or 50 μM E2101 in primary hepatocyte cultures obtained from three subjects. Taken together, E2101 is expected to metabolically interact with major human P450 enzymes including CYP2C19, CYP2D6, and CYP3A4, and a low risk of drug-drug interaction would be anticipated in clinical studies.
Footnotes
-
↵1 Present address: Department of Pharmacokinetic and Pharmacodynamic Sciences, Genetics Institute, Andover, Massachusetts
- Abbreviations used are::
- E2101
- N-methyl-[1-[1-(2-fluorophenethyl)piperidine-4-yl]-1H-indol-6-yl] acetamide
- 5-HT
- 5-hydroxytryptamine
- CNS
- central nervous system
- SSRI
- serotonin-selective reuptake inhibitor
- TRIZMA
- tris(hydroxymethyl)aminomethane
- TCDD
- 2,3,7,8-tetrachlorodibenzo-p-dioxin
- HPLC
- high-performance liquid chromatography
- LC/MS
- liquid chromatography/mass spectrometry
- MS/MS
- triple quadrupole mass spectrometer
- HLM
- human liver microsomal preparations
- IS
- internal standard
- SNLR
- simultaneously nonlinear regression analyses
- CID
- collision-induced dissociation
- PBS
- phosphate-buffered saline
- PDA
- photodiode array detector
- ESI
- electrospray ionization
- MRM
- multiple reaction monitoring
- HLS9
- human liver S9 fractions
- P450
- cytochrome P450
- GC
- gas chromatography
- Received January 14, 2002.
- Accepted March 21, 2002.
- The American Society for Pharmacology and Experimental Therapeutics
DMD articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|