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Benzodiazepines medazepam and midazolam are activators of pregnane X receptor and weak inducers of CYP3A4: investigation in primary cultures of human hepatocytes and hepatocarcinoma cell lines.

Abstract：

:Benzodiazepines have wide-spread used in pharmacotherapy for their anxiolytic, myorelaxant, hypnotic, amnesic and anticonvulsive properties. Despite benzodiazepines are used in clinics over 50 years, they have not been surprisingly tested for capability to induce major drug-metabolizing cytochromes P450. In the current study, we have examined the potency of Alprazolam, Bromazepam, Chlordiazepoxide, Clonazepam, Diazepam, Lorazepam, Medazepam, Midazolam, Nitrazepam, Oxazepam, Tetrazepam and Triazolam to induce CYP1A2 and CYP3A4 in primary cultures of human hepatocytes. Benzodiazepines were tested in therapeutic concentrations and in concentrations corresponding to their plasma levels in intoxicated patients. We found weak but significant induction of CYP3A4 mRNA by Midazolam and Medazepam, while other benzodiazepines did not induce CYP3A4 expression. None of the tested compounds induced CYP1A2 mRNA in three independent human hepatocytes cultures. In addition, employing gene reporter assays with transiently transfected hepatocarcinoma cells, we found that tested benzodiazepines did not activate aryl hydrocarbon receptor (AhR), whereas Midazolam and Medazepam slightly activated pregnane X receptor (PXR). Consistently, two-hybrid mammalian assay using hybrid fusion plasmids GAL4-PXR ligand-binding domain (LBD) and VP16-SRC-1-receptor-interacting domain (RID) confirmed PXR activation by Midazolam and Medazepam. In conclusion, Alprazolam, Bromazepam, Chlordiazepoxide, Clonazepam, Diazepam, Lorazepam, Nitrazepam, Oxazepam, Tetrazepam and Triazolam can be considered as safe drugs in term of their inability to induce PXR- and AhR-dependent cytochrome P450 enzymes CYP1A2 and CYP3A4. Medazepam and Midazolam slightly activated pregnane X receptor and displayed weak potency to induce CYP3A4 mRNA in human hepatocytes.

journal_name

Toxicol Lett

journal_title

Toxicology letters

authors

Vrzal R,Kubesova K,Pavek P,Dvorak Z

doi

10.1016/j.toxlet.2010.01.004

subject

Has Abstract

pub_date

2010-03-15 00:00:00

pages

183-8

issue

eissn

0378-4274

issn

1879-3169

pii

S0378-4274(10)00018-4

journal_volume

193

pub_type

杂志文章

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Benzodiazepines medazepam and midazolam are activators of pregnane X receptor and weak inducers of CYP3A4: investigation in primary cultures of human hepatocytes and hepatocarcinoma cell lines.