Abstract
Biotransformation of cerivastatin was investigated in mice, rats, and dogs in vivo using the 14C-labeled drug. Marked species differences exist, both in pathways and extent of cerivastatin metabolism. Unchanged drug, together with its lactone, predominates in dog plasma and represents 40% of the dose in the excreta, whereas in rat bile they account for approximately 10% of the dose. In mice, the drug is metabolized rapidly and almost completely. Biotransformation of cerivastatin occurs by three distinct phase I routes and by phase II conjugation with sugar-type moieties and taurine. Phase I routes are demethylation of the pyridinyl methyl ether, β-oxidation of the 3,5-dihydroxy acid side chain, and reductive removal of the side chain 3-hydroxy group. In dogs, demethylation is the dominating phase I biotransformation. Phase II conjugation is equally important. In dog bile, different regioisomeric drug glucuronides and the benzylic glucuronide and glucoside conjugate of the demethylated drug were found. In rats, besides demethylation, β-oxidation of the dihydroxy acid side chain—followed by reductive removal of the 5-hydroxy group—is the major reaction. The resulting pentenoic acid derivatives are observed in plasma and liver homogenate. These metabolites are subsequently conjugated with taurine and excreted in the bile. This metabolic sequence is also important in mice. Furthermore, only in mice, cerivastatin is subject to reductive removal of the 3-hydroxy group, together with demethylation. The 5-hydroxyheptenoic acids formed predominate in plasma and liver homogenate, whereas the corresponding taurine conjugates are excreted in the bile.
Footnotes
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Send reprint requests to: Dr. M. Boberg, Bayer AG, PH-PD P Drug Metabolism and Isotope Chemistry, D-42096 Wuppertal, Germany.
- Abbreviations used are::
- HMG-CoA
- 3-hydroxy-3-methylglutaryl-coenzyme A
- HPLC
- high-performance liquid chromatography
- TBAH
- tetrabutylammonium hydrogensulfate
- MSTFA
- N-methyl-N-trimethylsilyltrifluoroacetamide
- EtOAc
- ethyl acetate
- THF
- tetrahydrofuran
- PE
- petroleum ether
- FAB
- fast atom bombardment
- GC/MS
- gas chromatography/mass spectrometry
- EI
- electron impact ionization
- CI
- chemical ionization
- ESI
- electrospray ionization
- LC/MS
- liquid chromatography/mass spectrometry
- NMR
- nuclear magnetic resonance
- TLC
- thin-layer chromatography
- HEPES
- N-2-hydroxyethyl-piperazine-N′-2-ethanesulfonic acid
- Ph3P
- triphenylphosphonium
- HONB
- N-hydroxy-5-norbornene-2,3-dicarboximide
- DCC
- dicyclohexylcarbodiimide
- PBS
- phosphate buffered saline
- Received October 15, 1997.
- Accepted March 9, 1998.
- The American Society for Pharmacology and Experimental Therapeutics
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