RESUMO
PURPOSE: Treatment options for chronic low back pain (CLBP) include cognitive behavioral interventions. Most of these interventions only have small and short-lived effects. Using strict inclusion criteria for participation in an intensive combined physical and psychological program, encouraging effects were reported at 1-year follow-up. This study evaluates the long-term follow-up results of the same program. The hypothesis is that previously reported results are maintained. METHODS: Structured interviews were conducted in a prospective extended cohort with a minimum of 5-year follow-up in a similar fashion as in the 1-year follow-up report. The median follow-up in this cohort was 6.5 years. The extended cohort consisted of 277 patients (85% response). RESULTS: Outcomes include daily functioning, quality of life, current pain intensity, pain disturbance in daily activities and indicators of the use of pain medication and healthcare services. The previously reported positive 1-year follow-up results were maintained at a minimum of 5-year follow-up. Disability as measured with the Oswestry disability index (ODIv2.1a) decreased from 40 to 27 in the first year. This positive result was maintained at the 6.5-year follow-up with an ODI of 28. Pain intensity (NRS 0-100) improved from 60 to 39 in the first year, and at 6.5 years, this had further improved to 33. Improvement in quality of life (SF 36) at 1-year follow-up was maintained at 6.5-year follow-up, and healthcare consumption had decreased substantially as measured with doctor visits and analgesics used for CLBP. CONCLUSION: Selected and motivated patients with longstanding CLBP improve fast after an intensive combined physical and psychological program in daily functioning, pain and quality of life. Positive 1-year results are maintained, and healthcare utilization was still reduced at a minimum of 5-year follow-up. These slides can be retrieved under Electronic Supplementary Material.
Assuntos
Dor Crônica/terapia , Terapia Cognitivo-Comportamental/métodos , Dor Lombar/terapia , Manejo da Dor/métodos , Adulto , Idoso , Dor Crônica/diagnóstico , Dor Crônica/psicologia , Feminino , Seguimentos , Humanos , Dor Lombar/diagnóstico , Dor Lombar/psicologia , Masculino , Pessoa de Meia-Idade , Medição da Dor , Estudos Prospectivos , Qualidade de Vida , Resultado do TratamentoRESUMO
Organic anion-transporting polypeptide 1B1 (OATP1B1) is an important hepatic uptake transporter, of which the polymorphic variant OATP1B1*15 (Asn130Asp and Val174Ala) has been associated with decreased transport activity. Rosuvastatin is an OATP1B1 substrate and often concomitantly prescribed with oral antidiabetics in the clinic. The aim of this study was to investigate possible drug-drug interactions between these drugs at the level of OATP1B1 and OATP1B1*15. We generated human embryonic kidney (HEK)293 cells stably overexpressing OATP1B1 or OATP1B1*15 that showed similar protein expression levels of OATP1B1 and OATP1B1*15 at the cell membrane as measured by liquid chromatography-tandem mass spectrometry. In HEK-OATP1B1*15 cells, the V(max) for OATP1B1-mediated transport of E(2)17ß-G (estradiol 17ß-d-glucuronide) was decreased >60%, whereas K(m) values (Michaelis constant) were comparable. Uptake of rosuvastatin in HEK-OATP1B1 cells (K(m) 13.1 ± 0.43 µM) was nearly absent in HEK-OATP1B1*15 cells. Interestingly, several oral antidiabetics (glyburide, glimepiride, troglitazone, pioglitazone, glipizide, gliclazide, and tolbutamide), but not metformin, were identified as significant inhibitors of the OATP1B1-mediated transport of rosuvastatin. The IC(50) values for inhibition of E(2)17ß-G uptake were similar between OATP1B1 and OATP1B1*15. In conclusion, these studies indicate that several oral antidiabetic drugs affect the OATP1B1-mediated uptake of rosuvastatin in vitro. The next step will be to translate these data to the clinical situation, as it remains to be established whether the studied oral antidiabetics indeed affect the clinical pharmacokinetic profile of rosuvastatin in patients.
Assuntos
Fluorbenzenos/metabolismo , Hipoglicemiantes/metabolismo , Hipoglicemiantes/farmacologia , Transportadores de Ânions Orgânicos/antagonistas & inibidores , Pirimidinas/metabolismo , Sulfonamidas/metabolismo , Administração Oral , Cromatografia Líquida , Relação Dose-Resposta a Droga , Interações Medicamentosas , Estradiol/análogos & derivados , Estradiol/metabolismo , Células HEK293 , Humanos , Hipoglicemiantes/administração & dosagem , Cinética , Transportador 1 de Ânion Orgânico Específico do Fígado , Transportadores de Ânions Orgânicos/genética , Transportadores de Ânions Orgânicos/metabolismo , Rosuvastatina Cálcica , Espectrometria de Massas em Tandem , TransfecçãoRESUMO
The clinical development of a candidate p38 kinase inhibitor was terminated because of its unexpectedly rapid clearance in human subjects. Its short half-life and metabolic profile in human beings were vastly different from that in rats, dogs, and monkeys characterized during routine pre-clinical studies. Mice generated the predominant drug (4-hydroxylated) metabolite produced in human beings, which was not found in other species. The data from a murine in vitro drug biotransformation assay that used liver extracts from 14 inbred mouse strains were analyzed by haplotype-based computational genetic analysis. This led to the identification of aldehyde oxidase-1 (AOX1) as the enzyme responsible for the rapid metabolism of this drug. Specific enzyme inhibitors and expressed recombinant enzymes were used to confirm that AOX catalyzed the formation of the 4-hydroxylated drug metabolite in mouse and man. Genetic variation within Aox1 regulated the level of hepatic Aox1 mRNA, AOX1 protein, and enzyme activity among the inbred strains. Thus, computational murine pharmacogenetic analysis can facilitate the identification and characterization of drug metabolism pathways that are differentially utilized by humans and other species.
Assuntos
Aldeído Oxidase/metabolismo , Farmacogenética/métodos , Inibidores de Proteínas Quinases/farmacocinética , Proteínas Quinases p38 Ativadas por Mitógeno/antagonistas & inibidores , Adolescente , Adulto , Aldeído Oxidase/biossíntese , Aldeído Oxidase/genética , Animais , Artrite Reumatoide/tratamento farmacológico , Cães , Feminino , Meia-Vida , Haplorrinos , Humanos , Fígado/enzimologia , Fígado/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos , Inibidores de Proteínas Quinases/química , Inibidores de Proteínas Quinases/farmacologia , Pirimidinonas/farmacologia , Ratos , Ratos Endogâmicos BB , Método Simples-Cego , Especificidade da Espécie , Adulto Jovem , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
Simeprevir, a hepatitis C virus (HCV) NS3/4A protease inhibitor, displays nonlinear pharmacokinetics (PK) at therapeutic doses. Using physiologically based PK modeling, various drug-drug interactions were simulated with simeprevir as victim drug to identify whether saturation of the predominant metabolic enzyme (CYP3A4) or the active hepatic transporters (organic anion-transporting polypeptide (OATP)1B1/3) could account for the nonlinear PK. Interactions with ritonavir, a strong CYP3A4 inhibitor that does not affect OATP (at 100 mg dose), erythromycin, a moderate CYP3A4 inhibitor, and efavirenz, a moderate CYP3A inducer that does not affect OATP, demonstrated the involvement of CYP3A4. Interaction studies with low-dose cyclosporine confirmed the role of OATP. The interplay between hepatic uptake and CYP3A4 metabolism was verified by simulations with rifampicin, a potent CYP3A4 inducer and OATP1B1/3 inhibitor, and maintenance doses of cyclosporine. Saturation of gut and liver metabolism by CYP3A4, and saturation of hepatic uptake by OATP1B1/3, seem to account for the observed nonlinear PK of simeprevir.
Assuntos
Antivirais/farmacocinética , Inibidores Enzimáticos/farmacocinética , Simeprevir/farmacocinética , Proteínas não Estruturais Virais/antagonistas & inibidores , Alcinos , Benzoxazinas/farmacologia , Ciclopropanos , Ciclosporina/farmacologia , Citocromo P-450 CYP3A/genética , Citocromo P-450 CYP3A/metabolismo , Relação Dose-Resposta a Droga , Interações Medicamentosas , Eritromicina/farmacologia , Hepatite C/tratamento farmacológico , Humanos , Fígado/efeitos dos fármacos , Fígado/metabolismo , Transportador 1 de Ânion Orgânico Específico do Fígado , Dinâmica não Linear , Transportadores de Ânions Orgânicos/genética , Transportadores de Ânions Orgânicos/metabolismo , Rifampina/farmacologia , Ritonavir/farmacologiaRESUMO
Based on ibrutinib pharmacokinetics and potential sensitivity towards CYP3A4-mediated drug-drug interactions (DDIs), a physiologically based pharmacokinetic approach was developed to mechanistically describe DDI with various CYP3A4 perpetrators in healthy men under fasting conditions. These models were verified using clinical data for ketoconazole (strong CYP3A4 inhibitor) and used to prospectively predict and confirm the inducing effect of rifampin (strong CYP3A4 inducer); DDIs with mild (fluvoxamine, azithromycin) and moderate inhibitors (diltiazem, voriconazole, clarithromycin, itraconazole, erythromycin), and moderate (efavirenz) and strong CYP3A4 inducers (carbamazepine), were also predicted. Ketoconazole increased ibrutinib area under the curve (AUC) by 24-fold, while rifampin decreased ibrutinib AUC by 10-fold; coadministration of ibrutinib with strong inhibitors or inducers should be avoided. The ibrutinib dose should be reduced to 140 mg (quarter of maximal prescribed dose) when coadministered with moderate CYP3A4 inhibitors so that exposures remain within observed ranges at therapeutic doses. Thus, dose recommendations for CYP3A4 perpetrator use during ibrutinib treatment were developed and approved for labeling.
Assuntos
Indutores do Citocromo P-450 CYP3A/farmacologia , Inibidores do Citocromo P-450 CYP3A/farmacologia , Cálculos da Dosagem de Medicamento , Pirazóis/farmacocinética , Pirimidinas/farmacocinética , Adenina/análogos & derivados , Alcinos , Azitromicina/farmacologia , Benzoxazinas/farmacologia , Carbamazepina/farmacologia , Ciclopropanos , Interações Medicamentosas , Fluvoxamina , Humanos , Cetoconazol/farmacologia , Masculino , Modelos Biológicos , Piperidinas , Pirazóis/sangue , Pirimidinas/sangue , Rifampina/farmacologiaRESUMO
Metabolism of xenobiotics is often seen as an exclusive function of the liver, but some current findings support the notion that the lungs, kidneys and intestine may contribute considerably. After the establishment of the use of liver slices as a useful in vitro model to study metabolism and toxicity of xenobiotics, the same concept is currently being used for slices from lung, kidney and intestine. It is the aim of this review to discuss the use of organ slices in biotransformation research. The basic idea behind the use of tissue slices in biomedical research is the assumption that the cells under study will function optimally in vitro if they are cultivated in an environment that is most alike to their natural in vivo embedding, which is the case in tissue slices. Advantages in the use of organ slices are the relatively easy preparation as well as the potential standardization of both the preparation and use. Moreover, a direct interspecies comparison can be made between liver, lungs, kidneys and intestines, for example with respect to their metabolic capacity and their sensitivity for toxicants. Of major importance is that organ slices can be made with a similar procedure from organs/tissues originating from different species, including man. This latter aspect is useful in drug development in general but also for a better insight in the metabolic fate of compounds in man. Importantly the use of slices may largely contribute to a reduction in the use of experimental animals.
Assuntos
Técnicas Citológicas , Xenobióticos/metabolismo , Xenobióticos/toxicidade , Animais , Criopreservação , Humanos , Técnicas In Vitro , Mucosa Intestinal/metabolismo , Rim/metabolismo , Fígado/metabolismo , Pulmão/metabolismo , Microtomia , Preservação de TecidoRESUMO
Pentoxifylline (PTX) has been shown to exert hepatoprotective effects in various liver injury models. However, little information is available about the effect of PTX on the hepatic acute phase response. In the present study, the effect of PTX on a lipopolysaccharide (LPS)-induced acute phase response in primary porcine liver cell cultures was examined. During 72 hr of incubation with or without LPS, the ability of PTX to influence the secretion of tumour necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), acute phase proteins, and nitric oxide (NO) was assessed. PTX completely inhibited LPS-induced TNF-alpha production and attenuated IL-6 only after 48 hr of incubation. In contrast, PTX potentiated NO production and the expression of inducible nitric oxide synthase (iNOS) in hepatocytes after stimulation with LPS. The increased expression of iNOS and concurrent production of NO was also observed when liver cell cultures were incubated with dibutyryl cyclic adenosine monophosphate. No effect of PTX on acute phase protein secretion was observed during 72 hr of incubation. The present results show that PTX differentially affects the endotoxin-induced inflammatory response in primary porcine liver cell cultures by suppressing TNF-alpha and IL-6 while potentiating NO production.
Assuntos
Expressão Gênica/efeitos dos fármacos , Fígado/efeitos dos fármacos , Óxido Nítrico Sintase/biossíntese , Pentoxifilina/farmacologia , Substâncias Protetoras/farmacologia , Proteínas de Fase Aguda/efeitos dos fármacos , Proteínas de Fase Aguda/metabolismo , Animais , Células Cultivadas , AMP Cíclico/metabolismo , Citocinas/efeitos dos fármacos , Citocinas/metabolismo , Citoproteção , Fígado/enzimologia , Fígado/fisiologia , Óxido Nítrico Sintase/efeitos dos fármacos , Óxido Nítrico Sintase/genética , Óxido Nítrico Sintase Tipo II , Nitritos/metabolismo , SuínosRESUMO
It is now established that inflammatory stimuli such as lipopolysaccharides (LPS) and polyinosinic acid:polycytidylic (polyIC) suppress hepatic expression of cytochrome P450 (P450) genes in rat liver. Previous studies have suggested that LPS- or polyIC-induced downregulation of P450 was due to endogenously released inflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha), interleukin-1, interleukin-6, and interferons (IFNs). To improve our understanding of the role of inflammatory cytokines in mediating P450 depression, we investigated the possibility of preventing P450 downregulation with pentoxifylline. Pentoxifylline has been shown to inhibit LPS-induced TNF-alpha production by suppression of TNF-alpha gene expression. The present study shows that in uninduced male rats pentoxifylline selectively prevents the downregulation of microsomal P4501A2 and P4502B caused by LPS. No protective effect of pentoxifylline on the downregulation of P4502E1 and P4503A1/2 was observed. PolyIC-induced downregulation of P4501A2, P4502B, P4502E1, and P4503A1/2 was not affected by pentoxifylline. These results suggest that the LPS-induced downregulation of P4501A2 and P4502B is mediated to a large extent by TNF-alpha. Other cytokines might be involved in the suppression of P4502E1 and P4503A1/2. The fact that polyIC-induced downregulation is not protected by pentoxifylline is further evidence that this agent acts via a selective induction of IFNs.
Assuntos
Sistema Enzimático do Citocromo P-450/genética , Sistema Enzimático do Citocromo P-450/metabolismo , Lipopolissacarídeos/farmacologia , Pentoxifilina/farmacologia , Animais , Citocromo P-450 CYP1A1/genética , Citocromo P-450 CYP1A1/metabolismo , Citocromo P-450 CYP1A2/genética , Citocromo P-450 CYP1A2/metabolismo , Citocromo P-450 CYP2E1/genética , Citocromo P-450 CYP2E1/metabolismo , Regulação para Baixo/efeitos dos fármacos , Indutores de Interferon/farmacologia , Fígado/efeitos dos fármacos , Fígado/metabolismo , Masculino , Inibidores de Fosfodiesterase/farmacologia , Poli I-C/farmacologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley , Fator de Necrose Tumoral alfa/biossíntese , Fator de Necrose Tumoral alfa/genéticaRESUMO
As an example of advanced testing in the field of metabolism in an industrial environment, the introduction of some novel approaches, including the use of genetically engineered cell lines for assessing CYP 2D6-related polymorphic effects is illustrated. In this paper, it is demonstrated that novel in vitro test systems can be developed by using these genetically engineered cell lines for evaluating the potential risks associated with proprietary drugs (especially if their metabolism depends to a high extent on CYP 2D6). Moreover, it is demonstrated that, by the use of these in vitro methods, issues such as polymorphism, for which no animal models are available, can be assessed in such a way that predictions can be made on adverse effects which, up to now, could only be detected during clinical trials. Through the use of these new biotechnological in vitro metabolism models, clinically relevant data can be obtained for a scientifically-based human risk assessment, and animal use can be reduced.
Assuntos
Linhagem Celular/enzimologia , Citocromo P-450 CYP2D6/genética , Engenharia Genética , Polimorfismo Genético/genética , Alternativas aos Testes com Animais , Animais , Linhagem Celular/efeitos dos fármacos , Cromatografia Líquida de Alta Pressão , Cricetinae , Cricetulus , Citocromo P-450 CYP2D6/classificação , Citocromo P-450 CYP2D6/metabolismo , Dextrometorfano/metabolismo , Dextrometorfano/farmacologia , Etanolaminas/metabolismo , Etanolaminas/farmacologia , Humanos , Pulmão/citologia , Espectrometria de Massas , Polimorfismo Genético/efeitos dos fármacosRESUMO
Despite the fact that pigs are increasingly used in pharmacological and toxicological studies, knowledge on the enzymes which metabolize xenobiotics, in particular cytochrome P450 (CYP) enzymes, in pigs is still very limited. Primary cultures of pig hepatocytes were used to characterize CYP enzymes. The characterization was performed at the level of enzymatic activities, apoprotein and mRNA analyses. Enzyme inducers investigated were beta-naphthoflavone (BNF), phenobarbital (PB), dexamethasone (DEX) and rifampicin (RIF). After 48hr of BNF treatment, CYP1A protein and mRNA levels were increased, and ethoxyresorufin O-deethylation and caffeine 3-demethylation were strongly induced. PB and RIF increased the levels of CYP3A apoprotein and mRNA, whereas BNF down-regulated CYP3A and related activities. PB and RIF treatment resulted in increased ethylmorphine N-demethylation and testosterone hydroxylation, which appears to be the result of CYP3A induction. Hybridization of pig RNA with a human CYP2C9 cDNA probe showed a PB and RIF inducible CYP, which was down-regulated by BNF. Similar inducing effects were observed for tolbutamide, a marker substrate for CYP2C. DEX was not a potent inducer, although some induction of CYP3A mRNA was observed. The present results indicate the absence of CYP2B and probably CYP2D enzymes and activities in pig liver. Despite some dissimilarities, the results indicate that pigs, apart from their very human-like physiology, might represent a more appropriate model species for oxidative drug metabolism in humans than rats.
RESUMO
A selective and specific high-pressure liquid chromatographic (HPLC) method for the simultaneous assay of Clanfenur and its metabolites in biological fluids of interest has been developed which is suitable for routine analysis, using micro volumes (0.1 ml) of plasma samples only. After protein precipitation the extract is analysed by reversed-phase HPLC with UV detection. Excellent recovery, linearity, accuracy and precision (less than 5% for plasma) are achieved by the assay which is able to quantify Clanfenur and its metabolites in plasma at concentrations between 0.025 and 5.0 mg l-1.
Assuntos
Diflubenzuron/análogos & derivados , Animais , Cromatografia Líquida de Alta Pressão , Diflubenzuron/sangue , Humanos , Indicadores e Reagentes , Ratos , Espectrofotometria UltravioletaRESUMO
Congener specific PCB and toxaphene (polychlorinated camphene, PCC) analyses were performed in seal blubber, collected in Svalbard, Norway. The concentration, body burden and metabolic index (PCB congener concentration in seal relative to their prey) were calculated. Multiple regression analyses were carried out to evaluate the influence of age, sex, blubber (as a percentage of total body weight) and cytochrome P450 activities on PCB and PCC levels. Levels of total PCBs found were five times higher than in ringed seals from the Canadian Arctic, corresponding with the relatively high contaminant levels in the European Arctic. The dominant PCB congeners (> 70% of the total PCBs measured) were 153, 138, 99, 180 and 101. The observed PCB and PCC accumulation patterns were very similar to patterns in seals from other studies, suggesting a large resemblance in contaminant metabolism. A decrease in the relative abundance of the lower chlorinated PCBs, was associated with higher concentrations of PCB 153. Since there was no indication for selective PCB excretion by lactating females, this suggests metabolism of these PCBs in ringed seals due to xenobiotic metabolising enzymes. The metabolic index confirmed the model of persistency of the different PCBs except for congener 128 and 138. These congeners, considered persistent in seals, could to some extent be metabolised in ringed seals. However, co-elution of PCB 138 with PCB 163 and of PCB 128 with TOX 50 possibly has resulted in an underestimation of the metabolic index for these congeners. Multiple regression analyses revealed a significant positive effect of age and a negative effect of the blubber content on the PCB concentrations. Since large fluctuations of body lipids occur between seasons in pinnipeds, PCB measurements should account for the total blubber content to avoid biased results. PCBs with vicinal H-atoms in the o, m or the m, p positions showed in addition a relation with cytochrome P450 enzyme activities. Surprisingly, no effect of sex on the PCB concentrations was observed, probably because female ringed seals, unlike other pinnipeds, continue feeding during lactation. This results in only small amounts of lipid and lipid-associated contaminants being mobilised from the blubber. Consequently, contaminant excretion with the milk will be low. Toxaphene concentrations found were low compared to levels found in the Canadian Arctic. Two congeners, TOX 26 and TOX 50 were predominant (15 and 18%, respectively of total toxaphene). There was no effect of sex, age, total blubber, or cytochrome P450 activities on the toxaphene levels. There was also no correlation between toxaphene and PCB levels, which may indicate differences in exposure and metabolism between these contaminants. Toxaphenes did not bioaccumulate to any substantial extent in ringed seals.
Assuntos
Poluentes Ambientais/análise , Bifenilos Policlorados/análise , Focas Verdadeiras/metabolismo , Toxafeno/análise , Tecido Adiposo/anatomia & histologia , Fatores Etários , Animais , Carga Corporal (Radioterapia) , Sistema Enzimático do Citocromo P-450/metabolismo , Poluentes Ambientais/farmacocinética , Feminino , Masculino , Noruega , Bifenilos Policlorados/farmacocinética , Focas Verdadeiras/anatomia & histologia , Fatores Sexuais , Toxafeno/farmacocinéticaRESUMO
The selective control of inflammatory reactions will continue to be a major issue in the development of new drugs. Many new molecular targets are coming up. This paper highlights a few key mediators that are nowadays considered as interesting therapeutic intervention points. Cytokines play an important regulatory role in the initiation, maintenance and termination of inflammatory reactions. More than 50 cytokines have been identified, and more and more has become known about their receptors and signal transduction pathways. Tumour necrosis factor-alpha (TNF-alpha) is still regarded as one of the initial cytokines of the cascade, and different approaches are followed to control its synthesis, release or effects. Lipopolysaccharide (LPS) is a one of the triggers that is able to induce a strong TNF-response. Inhibitors of cyclic nucleotide phosphodiesterases (PDEs), including rolipram and pentoxifylline suppress the LPS-induced TNF-alpha production in monocytes/macrophages. In our laboratory it has been shown that the alternative way to increase cAMP levels, via stimulation of beta-adrenergic receptors, also provides an effective way, both in vitro and in vivo, to inhibit TNF-alpha release. Other therapeutic ways include the use of antibodies directed to cytokines, TNF receptor fused to IgG, antibody therapy against TNF, the use of MAP kinase inhibitors. The different signal transduction pathways, including the NF-kappa B activation route may provide alternative pharmacological tools. We may surely expect anti-inflammatory drugs of much greater specificity to be developed in the next decade. Despite the relative limited investments in veterinary drug development this will also have consequences for veterinary therapy.
Assuntos
Doenças dos Animais/imunologia , Citocinas/farmacologia , Inflamação/tratamento farmacológico , Transdução de Sinais , Doenças dos Animais/terapia , Animais , Anti-Inflamatórios/farmacologia , Anti-Inflamatórios/uso terapêutico , Citocinas/uso terapêutico , Imunização PassivaRESUMO
Diseases are a major cause of variation in drug response. Although many different diseases are known that have an effect on the pharmacokinetics or sometimes the pharmacodynamics of a drug, disorders associated with a so-called acute phase response (APR) are the most important in this respect. During APR, for example caused by tissue damage or invasion of a pathogen, a group of symptoms can be observed that often include fever, lassitude, inhibition of gastric function and synthesis of acute phase proteins. All phases that together determine the pharmacokinetic profile of a drug, absorption, distribution, metabolism and excretion, can be affected during APR. From a clinical point of view however, the effects on absorption and metabolism are the most relevant. For drugs that are given orally, a slower absorption rate is often observed during APR due to a delayed gastric emptying. Even more important from a clinical point of view is the depression of biotransformation capacity in the liver during APR, especially affecting the enzymes of the cytochrome P450 (CYP450) complex. Although much has become known about the mechanism of this effect, a number of questions remain. Cytokines, nitric oxide and possibly the enzyme heme oxygenase are playing a role in a complex process that depends on a mutual interaction between Kupffer cells (macrophages) and hepatocytes in the liver. The clinician should be aware of unexpected changes in drug effects or residue levels due to cumulation of the compound during disease or after vaccination. In these situations, drugs that are excreted unchanged may be better alternatives.
Assuntos
Reação de Fase Aguda/veterinária , Citocinas/farmacologia , Drogas Veterinárias/farmacocinética , Reação de Fase Aguda/fisiopatologia , Doenças dos Animais/fisiopatologia , Animais , Sistema Enzimático do Citocromo P-450/metabolismo , Óxido Nítrico/metabolismo , Vacinação/veterinária , Drogas Veterinárias/farmacologiaRESUMO
In this study primary hepatocyte cultures (HC cultures) and cocultures comprised of hepatocytes and Kupffer cells (HC/KC cocultures) were compared to investigate the inflammatory response induced by lipopolysaccharide (LPS). In addition both culture types were compared to study the hepatotoxic effects of two frequently used drugs: tiamulin and chlorpromazine. The inflammatory response in both culture types was determined by measurement of tumour necrosis factor-alpha (TNF-alpha), interleukin 6 (IL-6) and nitric oxide (NO). The drug-induced hepatotoxic effects were determined by measuring production of intracellular reactive oxygen species (ROS) and cytotoxicity. Exposure of both cultures to LPS resulted in a significantly increased production of TNF-alpha, IL-6 and NO. However, the production of TNF-alpha, IL-6 and NO was substantially increased in culture supernatant of cocultures, compared to single HC-cultures. Both tiamulin and chlorpromazine were potent inducers of intracellular ROS production at concentrations > or = 50 microM. High ROS production was paralleled by increased cytotoxicity as observed in both culture types. Incubation of cocultures with chlorpromazine resulted in a significant increased ROS production as compared to HC cultures. In contrast, no significant differences between HC-cultures and HC/KC cocultures were observed for tiamulin induced ROS production or cytotoxicity. The present study demonstrates that cocultures between Kupffer cells and hepatocytes provide an excellent model for the study of hepatotoxic compounds which exert (part) of their toxic effects via the activation of Kupffer cells. Furthermore they offer a valuable tool to study increased susceptibility to intoxication from xenobiotic agents in case of a concurrent or pre-existing inflammation.
Assuntos
Células de Kupffer/fisiologia , Fígado/citologia , Fígado/efeitos dos fármacos , Drogas Veterinárias/toxicidade , Animais , Comunicação Celular , Técnicas de Cultura de Células/métodos , Modelos Animais de Doenças , Células de Kupffer/efeitos dos fármacos , Fígado/patologia , Suínos , Xenobióticos/toxicidadeRESUMO
During infection and inflammation drug disposition and hepatic metabolism are markedly affected in mammals. Pro-inflammatory mediators play an important role in the suppression of (cytochrome-P450-mediated) drug metabolism. Inflammatory mediators like cytokines, nitric oxide (NO), reactive oxygen species (ROS) and eicosanoids are released by activated macrophages from various sources, including liver and lung. It was the aim of this study to investigate ways to suppress the activation of macrophages during the onset of the inflammatory cascade. Therefore porcine lung and liver macrophages were isolated, and incubated with lipopolysaccharide (LPS) to initiate an acute inflammatory response, represented by the release of high amounts of tumour necrosis factor-alpha (TNF-alpha) into the culture medium. Additionally the primary macrophages were coincubated with phosphodiesterase-IV-(PDE-IV)-inhibitors or beta-adrenoceptor agonists that in previous studies demonstrated strong suppressive effects on TNF-alpha release. Especially the beta-adrenoceptor agonists showed to be very potent TNF-alpha suppressants, which indicates that the beta-adrenoceptor might be an interesting target for suppression of activation of macrophages. This was strengthened by the observation that the beta-adrenoceptor expression was not altered during the onset of the inflammatory cascade.
Assuntos
Inflamação/fisiopatologia , Ativação de Macrófagos/fisiologia , Macrófagos Alveolares/imunologia , Animais , Técnicas de Cultura de Células , Citocinas/farmacologia , Lipopolissacarídeos/farmacologia , Fígado/citologia , Óxido Nítrico/farmacologia , Espécies Reativas de Oxigênio , Receptores Adrenérgicos beta/fisiologia , SuínosRESUMO
The effects of novobiocin (range 0.0125-2 mmol/L) on the hydroxylation of testosterone, the N-demethylation of erythromycin, and the glucuronidation of alpha-naphthol and paracetamol were studied using pig hepatic microsomes, pooled from five animals. The final concentrations of these substrates in the incubation mixtures were selected to meet Vmax conditions. Novobiocin caused a concentration-dependent inhibition of the glucuronidation of paracetamol; the formation of alpha-naphthol-glucuronide was reduced to a lesser degree. These results confirm and extend earlier findings in laboratory animal species that novobiocin inhibits UDP-glucuronosyltransferases (UDPGTs). Moreover, novobiocin strongly inhibited 6 beta-hydroxylation of testosterone. The microsomal N-demethylation of erythromycin and hydroxylation of testosterone at the 15 alpha position were less affected by novobiocin. These results suggest that novobiocin inhibits not only UDPGTs, but also cytochrome P450 (CYP) enzyme activities, probably those belonging to the CYP3A subfamily. More research is needed to reveal which CYPs and UDPGTs are affected by novobiocin in vivo, in order to improve the understanding the probably the predictability of potential drug interactions with this antibiotic.
Assuntos
Inibidores das Enzimas do Citocromo P-450 , Inibidores Enzimáticos/farmacologia , Glucuronosiltransferase/antagonistas & inibidores , Microssomos Hepáticos/enzimologia , Novobiocina/farmacologia , Suínos/metabolismo , Acetaminofen/farmacologia , Animais , Cromatografia Líquida de Alta Pressão/veterinária , Relação Dose-Resposta a Droga , Interações Medicamentosas , Eritromicina/farmacologia , Masculino , Microssomos Hepáticos/efeitos dos fármacos , Naftóis/farmacologia , Testosterona/farmacologiaRESUMO
The effect of infection and inflammation of the central nervous system (CNS) on cytochrome-P450-dependent activities in brain, spinal cord and liver microsomes was determined. For this, two models were used: (1) the intracerebroventricularly injected lipopolysaccharide (LPS) model and (2) the experimental auto-immune encephalomyelitis (EAE) model. In the LPS model, aminopyrine N-demethylase (AMND) and ethoxycoumarin O-deethylase (ECOD) activities (both P450 dependent) were significantly decreased (35 and 20%, respectively) in brain microsomes. In the EAE model, only ECOD activity was significantly lower (18%). In the liver, a decrease in total P450, AMND and ECOD activities was only observed in the LPS model. In both models, tumour necrosis factor (TNF) was significantly elevated in brain and spinal cord tissues. In serum, TNF was only detectable in the LPS model. It is concluded that an infection or inflammation located in the CNS, which is accompanied by high TNF levels, results in a decrease in P450-dependent metabolism not only in the liver but in the brain as well.
Assuntos
Encéfalo/enzimologia , Inibidores das Enzimas do Citocromo P-450 , Encefalomielite Autoimune Experimental/enzimologia , Meningites Bacterianas/enzimologia , O-Dealquilase 7-Alcoxicumarina/metabolismo , Aminopirina N-Desmetilase/metabolismo , Animais , Encéfalo/imunologia , Sistema Enzimático do Citocromo P-450/metabolismo , Modelos Animais de Doenças , Encefalomielite Autoimune Experimental/imunologia , Ativação Enzimática/imunologia , Injeções Intraventriculares , Lipopolissacarídeos/administração & dosagem , Masculino , Meningites Bacterianas/imunologia , Microssomos Hepáticos/enzimologia , Microssomos Hepáticos/imunologia , Microssomos Hepáticos/metabolismo , Ratos , Ratos Endogâmicos Lew , Ratos Sprague-Dawley , Medula Espinal/enzimologia , Medula Espinal/imunologia , Medula Espinal/metabolismo , Fator de Necrose Tumoral alfa/metabolismoRESUMO
1. The pharmacokinetic interactions between paracetamol (PA) and antipyrine (AP) were studied in pigs in order to investigate the usefulness of this combination for the simultaneous assessment of oxidative and conjugative metabolism. 2. When both drugs were given at a dose of 5 mg/kg, AP plasma clearance was reduced from 2.22 to 0.96 lh-1 kg-1. PA clearance was not changed in comparison with control values. 3. At a dose of 2 mg/kg no pharmacokinetic interaction between the two drugs was observed. 4. The only oxidative AP metabolite found in urine was 4-hydroxyantipyrine (4-OHA). It accounted for 80% of the dose and, like PA, it was completely glucuronidated. 5. The glucuronidation of PA has been studied in vitro in pig liver microsomes. The apparent Km value for PA glucuronidation was 40 mM with a Vmax = 54 nmol min-1 mg protein-1. To determine if 4-OHA and PA competed for the same UDP-glucuronosyl-transferase, the effect of 4-OHA and AP on PA glucuronidation was studied. It appeared that 4-OHA was a competitive inhibitor with a Ki app = 0.07 microM, whereas AP had no effect. 5. Results suggest a dose-dependent interaction between AP and PA, which may be due to competition at the level of glucuronidation. Therefore, the usefulness of AP and PA in vivo in a cocktail for metabolism studies is limited.
Assuntos
Acetaminofen/farmacocinética , Antipirina/farmacocinética , Acetaminofen/administração & dosagem , Acetaminofen/metabolismo , Animais , Antipirina/administração & dosagem , Antipirina/metabolismo , Relação Dose-Resposta a Droga , Esquema de Medicação , Interações Medicamentosas , Glucuronatos/metabolismo , Glucuronosiltransferase/metabolismo , Infusões Intravenosas , Masculino , Taxa de Depuração Metabólica , Microssomos Hepáticos/enzimologia , Orquiectomia , SuínosRESUMO
The fluoroquinolone antibacterial agents have gained widespread use in the treatment of a broad range of bacterial infections. We recently described a possible interaction concerning the concomitant use of cyclosporine A and norfloxacin in pediatric renal transplant patients. We examined the effect of two common fluoroquinolone antibiotics on cytochrome P450-mediated drug biotransformations in human and rat liver microsomes. Rats were pretreated with inducers, which increased the levels of the P450 isozymes CYP3A2, CYP1A, CYP2E1, and CYP4A1. Ciprofloxacin and norfloxacin significantly depressed the N-demethylation of erythromycin by CYP3A4 in human microsomes and by CYP3A2 in rat microsomes. The inhibition was determined to be competitive in nature in rat microsomes, with ciprofloxacin and norfloxacin both exhibiting similar Ki values of 2.0 and 2.3 mM, respectively. Ciprofloxacin and norfloxacin also inhibited ethoxyresorufin-O-dealkylase (CYP1A). In contrast, ciprofloxacin and norfloxacin did not inhibit the metabolism of substrates that are specific for the P450 isozymes CYP2E1 and CYP4A1. Rats treated chronically with norfloxacin revealed no alterations in hepatic CYP3A2 protein levels or activity. These studies in hepatic microsomes demonstrate that fluoroquinolones can decrease CYP3A- and CYP1A-mediated biotransformation by competitive inhibition and that they have the potential to cause drug interactions with agents metabolized by these enzymes.