Rocuronium is a neuromuscular blocking agent acting as a competitive antagonist of acetylcholine. Results of an inhibition of eight individual liver microsomal cytochromes P450 (CYP) are presented. As the patients are routinely premedicated with diazepam, possible interaction of diazepam with rocuronium has been also studied. Results indicated that rocuronium interacts with human liver microsomal CYPs by binding to the substrate site. Next, concentration dependent inhibition of liver microsomal CYP3A4 down to 42% (at rocuronium concentration 189 μM) was found. This effect has been confirmed with two CYP3A4 substrates, testosterone (formation of 6β-hydroxytestosterone) and diazepam (temazepam formation). CYP2C9 and CYP2C19 activities were inhibited down to 75-80% (at the same rocuronium concentration). Activities of other microsomal CYPs have not been inhibited by rocuronium. To prove the possibility of rocuronium interaction with other drugs (diazepam), the effect of rocuronium on formation of main diazepam metabolites, temazepam (by CYP3A4) and desmethyldiazepam, (also known as nordiazepam; formed by CYP2C19) in primary culture of human hepatocytes has been examined. Rocuronium has caused inhibition of both reactions by 20 and 15%, respectively. The results open a possibility that interactions of rocuronium with drugs metabolized by CYP3A4 (and possibly also CYP2C19) may be observed.
- MeSH
- androstanoly metabolismus farmakologie MeSH
- cytochrom P-450 CYP3A metabolismus fyziologie MeSH
- cytochrom P450 CYP2C19 metabolismus fyziologie MeSH
- cytochrom P450 CYP2C9 metabolismus MeSH
- cytochromy metabolismus MeSH
- diazepam farmakologie MeSH
- hepatocyty metabolismus MeSH
- inhibitory cytochromu P450 MeSH
- jaterní mikrozomy enzymologie MeSH
- kultivované buňky MeSH
- lékové interakce MeSH
- lidé MeSH
- nedepolarizující myorelaxancia farmakologie MeSH
- systém (enzymů) cytochromů P-450 metabolismus MeSH
- vazebná místa MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
BACKGROUND: We studied the interaction of oxaliplatin derivatives involving cytotoxic adenine-based cyclin-dependent kinase inhibitors, with human liver microsomal cytochrome P450. METHODS AND RESULTS: The activities of 9 human liver microsomal CYP forms (CYPs 1A2, 7-ethoxyresorufin O-deethylation; 2A6, coumarin 7-hydroxylation; 2B6, 7-ethoxy-4-(trifluoromethyl) coumarin O-deethylation; 2C8, luciferin-6´ methyl ether demethylation; 2C9, diclofenac 4´-hydroxylation, 6´-deoxyluciferin hydroxylation; 2C19, (S)-mephenytoin 4´-hydroxylation; 2D6, bufuralol 1´-hydroxylation, 2E1, chlorzoxazone 6-hydroxylation; 3A4, testosterone 6β-hydroxylation, luciferin-6´ benzyl ether debenzylation) were tested using HPLC, fluorescence and luminescence product detection. At 100 µM platinum(II) oxalato complex concentration, CYP inhibition was in general 25%-50%, except for the CYP3A4 form which showed roughly twice the inhibition (72%-95%). At low complex concentration (10 µM), the difference in inhibition of CYP3A4 and other forms was even more pronounced. Dixon and Lineweaver-Burk plots indicated a partially noncompetitive mechanism of CYP3A4 inhibition. CONCLUSIONS: The tested complexes significantly inhibit human liver microsomal CYP3A4 activity even at clinically relevant concentrations. This could be a serious drawback for the use of these compounds in clinical practice.
Cílem in vitro studie bylo získat informace o možnosti interakce rokuronia s lidským jaterním mikrosomálním systémem cytochromů P450, zejména s formou cytochromu P450 3A4. Metody: Interakce rokuronia s mikrosomálními cytochromy P450 byla sledována spektrofotometricky pomocí diferenční absorpční spektroskopie. Interakce s cytochromem P450, formou CYP3A4, byla sledována pomocí inhibice specifické aktivity CYP3A4 (testosteron 6ß-hydroxylace). Výsledky: Rokuronium interaguje in vitro s lidskými jaterními mikrosomálními cytochromy P450 a inhibuje účinně aktivitu formy CYP3A4. Závěr: Vzhledem k tomu, že tato forma metabolizuje látky steroidní povahy, je možný vliv interakce rokuronia na další procesy v organizmu. Nelze rovněž vyloučit i možnost lékových interakcí rokuronia s léčivy metabolizovanými CYP3A4, které by mohly např. vést k prodloužení účinku rokuronia.
Aim of the study was to find whether human liver microsomal cytochromes P450 interact with rocuronium in vitro. Methods: Interaction of rocuronium with microsomal cytochromes P450 was followed spectrophotometrically using difference absorption spectroscopy. Interaction with cytochrome P450 form CYP3A4 was studied by determination of inhibition of a CYP3A4-specific enzyme activity (testosterone 6ß-hydroxylation) by HPLC. Results: Rocuronium interacts in vitro with human liver microsomal cytochromes P450 and inhibits effectively the CYP3A4 specific enzyme activity. Conclusion: Due to the fact that the CYP3A4 form is known to metabolize steroids and steroid-related compounds there is a possibility of an influence of rocuronium-CYP3A4 interactions on other processes in the organism. Moreover, a possibility of drug interactions with concomitantly administered drugs metabolized by CYP3A4 leading to e.g. prolongation of rocuronium effect cannot be excluded.
- MeSH
- androstanoly farmakokinetika farmakologie metabolismus MeSH
- financování organizované MeSH
- inhibitory cytochromu P450 MeSH
- jaterní mikrozomy enzymologie metabolismus MeSH
- nedepolarizující myorelaxancia farmakokinetika metabolismus MeSH
- systém (enzymů) cytochromů P-450 metabolismus MeSH
- techniky in vitro MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
The total content of rat liver microsomal cytochrome P450 (CYP) significantly decreased after repeated i.p. administration of the antiviral agent tenofovir ((R)-9-[2-(phosphonomethoxy)propyl] adenine) and tenofovir disoproxil at a daily dose 25 mg/kg, although the content of liver microsomal protein did not change. The decrease of the CYP content was accompanied by concomitant increase of the amount of inactive CYP form, cytochrome P420. This effect was confirmed by a parallel study of the activities of selected CYP forms, CYP2E1 (p-nitrophenol hydroxylation) and CYP1A2 (7-ethoxyresorufin deethylation). The activity (expressed relatively to the protein content) of both CYP forms decreased significantly following the decrease of the total CYP. On the other hand, the CYP2E1 activity expressed relatively to the decreasing total CYP content remained unchanged. However, CYP1A2 activity also decreased when calculated relatively to the total native CYP content indicating lower stability of this form. Semiquantitative RT-PCR showed no significant changes in expression of major rat liver microsomal CYP forms after tenofovir treatment. In conclusion, repeated administration of tenofovir in higher doses led to significant decrease of the relative proportion of active liver microsomal CYPs accompanied by a conversion of these enzymes to the inactive form (CYP420) maintaining the sum of CYP proteins unchanged.
- Klíčová slova
- PMPA, Cytochrome P450, CYP2E1, CYP1A2,
- MeSH
- adenin analogy a deriváty aplikace a dávkování farmakologie MeSH
- antivirové látky aplikace a dávkování farmakologie MeSH
- cytochrom P-450 CYP1A2 genetika metabolismus MeSH
- cytochrom P-450 CYP2E1 genetika metabolismus MeSH
- cytochromy metabolismus MeSH
- denaturace proteinů MeSH
- down regulace MeSH
- financování organizované MeSH
- injekce intraperitoneální MeSH
- jaterní mikrozomy MeSH
- játra enzymologie účinky léků MeSH
- krysa rodu rattus MeSH
- messenger RNA metabolismus MeSH
- organofosfonáty aplikace a dávkování farmakologie MeSH
- potkani inbrední LEW MeSH
- prekurzory léčiv aplikace a dávkování farmakologie MeSH
- tenofovir MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- ženské pohlaví MeSH
- zvířata MeSH
Cytochromes P450 2E1 of human and minipig origin were examined by absorption spectroscopy under high hydrostatic pressure and by resonance Raman spectroscopy. Human enzyme tends to denature to the P420 form more easily than the minipig form; moreover, the apparent compressibility of the heme active site (as judged from a redshift of the absorption maximum with pressure) is greater than that of the minipig counterpart. Relative compactness of the minipig enzyme is also seen in the Raman spectra, where the presence of planar heme conformation was inferred from band positions characteristic of the low-spin heme with high degree of symmetry. In this respect, the CYP2E1 seems to be another example of P450 conformational heterogeneity as shown, e.g., by Davydov et al. for CYP3A4 [Biochem. Biophys. Res. Commun. 312 (2003) 121-130]. The results indicate that the flexibility of the CYP active site is likely one of its basic structural characteristics.
- MeSH
- cytochrom P-450 CYP2E1 chemie metabolismus MeSH
- financování organizované MeSH
- lidé MeSH
- prasata MeSH
- Ramanova spektroskopie metody MeSH
- spektrofotometrie metody MeSH
- vazebná místa MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- srovnávací studie MeSH
