Abstract
Buprenorphine is a partial μ-opioid receptor agonist used for the treatment of opioid dependence that has several advantages over methadone. The principal route of buprenorphine disposition has been well established; however, little is known regarding the potential for buprenorphine to influence the metabolism and clearance of other drugs by affecting the expression of drug-metabolizing enzymes (DMEs). Here, we investigate the effects of buprenorphine on the activation of pregnane X receptor (PXR) and constitutive androstane receptor (CAR), as well as the induction of DMEs, in both HepG2 cells and human primary hepatocytes (HPHs). In HepG2 cells, buprenorphine significantly increased human PXR-mediated CYP2B6 and CYP3A4 reporter activities. CYP2B6 reporter activity was also enhanced by buprenorphine in HepG2 cells cotransfected with a chemical-responsive human CAR variant. Real-time reverse transcription-polymerase chain reaction analysis revealed that buprenorphine strongly induced CYP3A4 expression in both PXR- and CAR-transfected HepG2 cells. However, treatment with the same concentrations of buprenorphine in HPHs resulted in literally no induction of CYP3A4 or CYP2B6 expression. Further studies indicated that buprenorphine could neither translocate human CAR to the nucleus nor activate CYP2B6/CYP3A4 reporter activities in transfected HPHs. Subsequent experiments to determine whether the differential response was due to buprenorphine's metabolic stability revealed a dramatically differential rate of elimination for buprenorphine between HPHs and HepG2 cells. Taken together, these studies indicate that metabolic stability of buprenorphine defines the differential induction of DMEs observed in HepG2 and HPHs, and the results obtained from PXR and CAR reporter assays in immortalized cell line require cautious interpretation.
Footnotes
This work was supported by the National Institutes of Health National Institute of Diabetes and Digestive and Kidney Diseases [Grant DK061652].
Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
doi:10.1124/jpet.110.173187.
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ABBREVIATIONS:
- MD
- methadone
- BUP
- buprenorphine
- DDI
- drug-drug interaction
- P450
- cytochrome P450
- UGT
- UDP-glucuronosyl transferase
- RIF
- rifampicin
- DME
- drug-metabolizing enzyme
- NR
- nuclear receptor
- PXR
- pregnane X receptor
- CAR
- constitutive androstane receptor
- RT-PCR
- reverse transcription-polymerase chain reaction
- HPH
- human primary hepatocyte
- DIP
- diprenorphine
- PK11195
- 1-(2-chlorophenyl-N-methylpropyl)-3-isoquinoline-carboxamide
- SFN
- sulforaphane
- PB
- phenobarbital
- CITCO
- 6-(4-chlorophenyl)imidazo[2,1-b][1,3]thiazole-5-carbaldehyde-O-(3,4-dichlorobenzyl) oxime
- HPLC
- high-performance liquid chromatography
- h
- human
- PBREM
- phenobarbital-responsive enhancer module
- XREM
- xenobiotic-responsive enhancer module
- PXRE
- pregnane X receptor response element
- GAPDH
- glyceraldehyde-3-phosphate dehydrogenase
- bp
- base pair(s)
- DMSO
- dimethyl sulfoxide
- Ad/EYFP-hCAR
- adenovirus expressing enhanced yellow florescence protein-tagged human CAR.
- Received July 21, 2010.
- Accepted September 8, 2010.
- Copyright © 2010 by The American Society for Pharmacology and Experimental Therapeutics
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