WHAT IS KNOWN AND OBJECTIVE: Paroxetine is both a substrate and an inhibitor of CYP2D6. The objective of the presented study was to determine the persistence of CYP2D6 inhibition after short term (6 weeks) and long term (18·7 ± 10·6 weeks) paroxetine treatment. METHODS: Two the studies consisted of 30 depressive/anxiety patients each. In the first study, patients were subdivided into three groups treated with paroxetine (A1), alprazolam (A2) and paroxetine + alprazolam (A3). After 6 weeks, all the patients (A1+A2+A3) were switched to alprazolam treatment; metabolic activity was evaluated at the beginning, after 6 weeks of paroxetine/alprazolam/alprazolam + paroxetine treatment (A1/A2/A3) and 4 weeks after the switch to alprazolam treatment (Week 0, 6, 10). In the second study patients on previous long term paroxetine treatment were subdivided into two groups treated with mirtazapine (B1) or paroxetine (B2); metabolic activity of CYP2D6 was evaluated at the beginning and after 6 weeks of therapy. RESULTS AND DISCUSSION: Metabolic ratio of dextromethorphan to dextrorphan has normalized in all subjects after 4 weeks of paroxetine wash out in the first study. In the second study, 6 weeks after paroxetine discontinuation, restoration of metabolic activity of CYP2D6 was observed in only five of eight originally poor metabolizers. WHAT IS NEW AND CONCLUSION: We conclude that a wash-out period of 4 weeks seems to be sufficient for CYP2D6 disinhibition after short-term paroxetine treatment (6 weeks). On the other hand, treatment with a CYP2D6 substrate less than 6 weeks after long-term paroxetine treatment (18·7 weeks on average) could result in elevated drug plasma levels and occasionally also in drug toxicity.
- Klíčová slova
- CYP2D6, disinhibition, paroxetine,
- MeSH
- alprazolam farmakologie MeSH
- cytochrom P-450 CYP2D6 metabolismus MeSH
- deprese farmakoterapie enzymologie metabolismus MeSH
- dextromethorfan farmakologie MeSH
- dextrorfan farmakologie MeSH
- dospělí MeSH
- dvojitá slepá metoda MeSH
- inhibitory cytochromu P450 CYP2D6 * MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladiství MeSH
- mladý dospělý MeSH
- paroxetin farmakologie MeSH
- senioři MeSH
- úzkost farmakoterapie enzymologie metabolismus MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladiství MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- randomizované kontrolované studie MeSH
- Názvy látek
- alprazolam MeSH
- cytochrom P-450 CYP2D6 MeSH
- dextromethorfan MeSH
- dextrorfan MeSH
- inhibitory cytochromu P450 CYP2D6 * MeSH
- paroxetin MeSH
WHAT IS KNOWN AND OBJECTIVE: Accurate prediction of actual CYP2D6 metabolic activity may prevent some adverse drug reactions and improve therapeutic response in patients receiving CYP2D6 substrates. Dextromethorphan-to-dextrorphan metabolic ratio (MR(DEM/DOR)) is well established as a marker of CYP2D6 metabolizer status. The relationship between urine and plasma or serum MR(DEM/DOR) is not well established nor is there evidence of antimode for separation of intermediate and especially poor metabolizers (PM) from extensive metabolizers (EM). This study addressed whether CYP2D6 phenotyping using molar metabolic ratio of dextromethorphan to dextrorphan (MR(DEM/DOR)) in serum is usable and reliable in clinical practice as urinary MR(DEM/DOR). METHODS: We measured MR(DEM/DOR) in serum and CYP2D6 genotype in 51 drug-naive patients and 30 volunteers. Receiver-operator characteristic (ROC) analysis was used for the evaluation of optimum cut-off value for discriminating between extensive, intermediate and PM. In addition, we studied the correlation of serum MR(DEM/DOR) with urine MR(DEM/DOR) in the 30 healthy volunteers. RESULTS AND DISCUSSION: A trimodal distribution of log MR(DEM/DOR) in serum was observed, with substantial overlap between extensive and intermediate metabolizer groups. We obtained an acceptable cut-off serum MR(DEM/DOR) value to discriminate between PM and either extensive or extensive + intermediate metabolizers. Using serum MR(DEM/DOR), it seems to be unreliable to discriminate EM from intermediate metabolizers (IM). A strong correlation between serum MR(DEM/DOR) and urine MR(DEM/DOR) was found. WHAT IS NEW AND CONCLUSION: Serum MR(DEM/DOR) (3 h) correlated with MR(DEM/DOR) in urine (0-8 h). Serum MR(DEM/DOR) discriminated between extensive and PM and between extensive + intermediate and PM. Our CYP2D6 phenotyping using serum dextromethorphan/dextrorphan molar ratio appears reliable but requires independent validation.
- MeSH
- cytochrom P-450 CYP2D6 genetika MeSH
- dextromethorfan aplikace a dávkování farmakokinetika MeSH
- dextrorfan farmakokinetika MeSH
- dospělí MeSH
- fenotyp MeSH
- genotyp MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladiství MeSH
- mladý dospělý MeSH
- ROC křivka MeSH
- senioři MeSH
- studie případů a kontrol MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladiství MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- klinické zkoušky MeSH
- práce podpořená grantem MeSH
- Názvy látek
- cytochrom P-450 CYP2D6 MeSH
- dextromethorfan MeSH
- dextrorfan MeSH
OBJECTIVES: Differences in the metabolism between males and females have been seen over time. Hormonal regulation of cytochrome P450 activity is understood to be involved. Trans-resveratrol (RES) is an estrogenically active plant polyphenol with many protective biological activities including neuroprotection. The present report studied the influence of sex and RES on variances in rat's cytochrome P450 2D2 hepatic metabolic activity. METHODS AND DESIGN: Isolated perfused rat liver was used for determination of cytochrome P450 2D2 activity. Wistar albino rats of both sexes were treated with RES at the dose of 5 mg/kg/day for 10 days prior to liver isolation. Levels of marker substance dextromethorphan (DEM) and its 2D2 specific metabolite dextrorphan (DEX) were measured during perfusion. The metabolic ratios (DEM/DEX) and the levels of DEM and DEX in perfusate were compared. RESULTS: In the controls, the activity of CYP2D2 was found to be higher in male rats compared to females. RES produced inhibition of CYP2D2, expressed by significant changes of both DEM and DEX levels in males and significant increase of only DEM levels in females. There were no gender changes in DEX levels in RES treated animals whilst DEM levels were significantly increased during the whole perfusion in females. CONCLUSION: The results confirmed gender differences in the metabolic activity of CYP450 2D2 with a higher rate in male rats. RES acted as an inhibitor, however again with greater impact in males than in females. This metabolic divergence could be a cause for different sensitivity or even toxicity of drugs metabolized by the CYP450 2D2.
- MeSH
- aromatické hydroxylasy antagonisté a inhibitory metabolismus MeSH
- dextromethorfan chemie metabolismus MeSH
- dextrorfan chemie metabolismus MeSH
- inhibitory cytochromu P450 MeSH
- inhibitory enzymů farmakologie MeSH
- játra účinky léků metabolismus MeSH
- krysa rodu Rattus MeSH
- pohlavní dimorfismus * MeSH
- potkani Wistar MeSH
- resveratrol MeSH
- stilbeny farmakologie MeSH
- systém (enzymů) cytochromů P-450 metabolismus MeSH
- zvířata MeSH
- Check Tag
- krysa rodu Rattus MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- aromatické hydroxylasy MeSH
- Cyp2d2 protein, rat MeSH Prohlížeč
- dextromethorfan MeSH
- dextrorfan MeSH
- inhibitory cytochromu P450 MeSH
- inhibitory enzymů MeSH
- resveratrol MeSH
- stilbeny MeSH
- systém (enzymů) cytochromů P-450 MeSH
Changes in the immune system induced by exogenous or endogenous factors may be accompanied with modifications of the activity of the drug metabolising enzymes in the liver. Some immunostimulatory agents are known to suppress the oxidative metabolism mediated by cytochromes P450. Possible effects of substances which suppress the immune responses of the organism have not been fully understood yet. The present study was undertaken to investigate the influence of immunosuppressants cyclophosphamide and dexamethasone on the CYP2D 1-dependent metabolism of dextromethorphan (DEM) in the isolated perfused liver from male rat donors (Wistar albino, 250-310 g). Recirculatory perfusion system was used with Williams' medium E (Sigma Chemicals Co.) as a perfusion medium (120 mL). DEM was administered as a 1 mg bolus into the perfusion solution at the start of each experiment after 20 min preperfusion. Samples of perfusate for HPLC determination of DEM and its O-demethylated metabolite dextrorphan (DOR) were taken at 15 min intervals for 120 min. The results have shown a rapid conversion of DEM to DOR in the isolated rat liver preparations. Pharmacokinetic parameters in the livers from intact rats were as follows: t1/2 DEM = 19.1+/-4.10 min, k(m) = 0.035+/-0.008 min(-1), Cl(m) = 4.21+/-0.97 mL x min(-1), AUC(DOR) = 2160+/-201 microg x min x L(-1). Pretreatment of rats with dexamethasone (4 mg/kg/day, iv, x 3 days) led to a significant increase in the concentration of dextrorphan in the recirculating solution, but it did not substantially change the kinetic constants of DOR formation (km = 0.036+/-0.004 min(-1), Cl(m) = 4.27+/-0.43 mL x min(-1)). Cyclophosphamide (100 mg/kg, ip, 1 dose on day 5 before perfusion) induced nearly twofold increase in the DOR concentrations in perfusate and thus highly significant (p < 0.01) changes of the kinetic parameters characterizing the increased rate of conversion of DEM to DOR (t1/2 DEM = 12.1+/-0.90 min, km = 0.055+/-0.004 min(-1), Cl(m) = 7.09+/-1.37 mL x min(-1), AUC(DOR) = 3602+/-154 microg x min x L(-1)). Considering that both cyclophosphamide and dexamethasone belong to the most widely used immunosuppressive drugs, their potential to promote the CYP2D-mediated metabolism might have a clinical impact in combined therapy of autoimmune or other diseases.
- MeSH
- alkoholoxidoreduktasy MeSH
- aromatické hydroxylasy * MeSH
- cyklofosfamid farmakologie MeSH
- dexamethason farmakologie MeSH
- dextromethorfan metabolismus MeSH
- dextrorfan metabolismus MeSH
- imunosupresiva farmakologie MeSH
- játra účinky léků metabolismus MeSH
- kinetika MeSH
- krysa rodu Rattus MeSH
- metylace MeSH
- potkani Wistar MeSH
- rodina 2 cytochromů P450 MeSH
- systém (enzymů) cytochromů P-450 metabolismus MeSH
- vysokoúčinná kapalinová chromatografie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu Rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- alkoholoxidoreduktasy MeSH
- aromatické hydroxylasy * MeSH
- cyklofosfamid MeSH
- Cyp2d1 protein, rat MeSH Prohlížeč
- dexamethason MeSH
- dextromethorfan MeSH
- dextrorfan MeSH
- imunosupresiva MeSH
- rodina 2 cytochromů P450 MeSH
- systém (enzymů) cytochromů P-450 MeSH
