5-hydroxydiclofenac and 4--hydroxydiclofenac

To investigate the respective roles of cytochromes P450 2C9 and 3A in drug oxidation in human livers, the

Topics: Animals; Cytochrome P-450 CYP2C9; Cytochrome P-450 CYP3A; Diclofenac; Hepatocytes; Humans; Hydroxylation; Mice; Transplantation Chimera

Diclofenac (DCF) is a widely used nonsteroidal anti-inflammatory drug, but it comes with a high risk of drug-induced liver injury (DILI). Despite the quinone-imine adduct pathways, the immunotoxicity is recently considered as another factor for DILI. However, such immune responses are still elusive. In the present study, investigation of the immune response in the acute hepatotoxicity model of TgCYP3A4/hPXR-humanized mice was conducted by administration of DCF and DCF metabolites, respectively. In a single dose intraperitoneal injection of 80 mg/kg DCF, the pharmacokinetic results showed the major DCF metabolites, including 4'-hydroxy-diclofenac (4'-OH-DCF), 5-hydroxy-diclofenac (5-OH-DCF) and diclofenac glucuronide (DCF-G) were generated after DCF treatment. Not only DCF, but those DCF metabolites could also directly cause different degrees of acute liver injury as significantly increased the serum ALT levels in a short time period in the TgCYP3A4/hPXR-humanized mice. Furthermore, the three DCF metabolites could directly stimulate the significant elevation of serum immune-related factors in varying degrees. Transcriptome analysis revealed the differentially expressed genes in the liver of DCF-G treated mice were mostly involved with the "immune system process" and "cell death" and related to "IL-17 signaling pathway" and "TNF-α signaling pathway", but 5-OH-DCF had little effect on the expressions of those genes. These results indicate that the metabolite DCF-G plays an important role in the activation of the hepatic immune system, which might be involved in the pathogenesis of DCF-induced acute liver injury.

Topics: Alanine Transaminase; Animals; Anti-Inflammatory Agents, Non-Steroidal; Cell Death; Chemical and Drug Induced Liver Injury; Cytokines; Diclofenac; Disease Models, Animal; Gene Expression Regulation; Glucuronides; Humans; Immunity; Injections, Intraperitoneal; Interleukin-17; Liver; Mice, Transgenic; Protein Interaction Maps; Signal Transduction; Tumor Necrosis Factor-alpha

The use of diclofenac (DCF), a nonsteroidal anti-inflammatory drug, is associated with a high prevalence of gastrointestinal side effects. In vivo studies in rodents suggested that reactive metabolites of DCF produced by the liver or the intestine might be responsible for this toxicity. In the present study, precision-cut intestinal slices (PCIS) prepared from the jejunum of 18 human donors were used as an ex vivo model to investigate whether DCF intestinal metabolites are responsible for its intestinal toxicity in man. PCIS were incubated with a concentration range of DCF (0-600 µM) up to 24 h. DCF (≥400 µM) caused direct toxicity to the intestine as demonstrated by ATP depletion, morphological damage, caspase 3 activation, and lactate dehydrogenase leakage. Three main metabolites produced by PCIS (4'-hydroxy DCF, 5-hydroxy DCF, and DCF acyl glucuronide) were detected by HPLC. Protein adducts were detected by immunohistochemical staining and showed correlation with the intestinal metabolites. DCF induced similar toxicity to each of the samples regardless of the variation in metabolism among them. Less metabolites were produced by slices incubated with 400 µM DCF than with 100 µM DCF. The addition of the metabolic inhibitors such as ketoconazole, cimetidine, or borneol decreased the metabolite formation but increased the toxicity. The results suggest that DCF can induce intestinal toxicity in human PCIS directly at therapeutically relevant concentrations, independent of the reactive metabolites 4'-OH DCF, 5-OH DCF, or diclofenac acylglucuronide produced by the liver or formed in the intestine.

Topics: Adenosine Triphosphate; Adult; Aged; Anti-Inflammatory Agents, Non-Steroidal; Caspase 3; Diclofenac; Female; Glucuronides; Humans; Immunohistochemistry; In Vitro Techniques; Jejunum; L-Lactate Dehydrogenase; Male; Middle Aged

Idiosyncratic adverse drug reactions due to the anti-inflammatory drug diclofenac have been proposed to be caused by the generation of reactive acyl glucuronides and oxidative metabolites. For the oxidative metabolism of diclofenac by cytochromes P450 at least five different reactive intermediates have been proposed previously based on structural identification of their corresponding GSH-conjugates. In the present study, the ability of four human glutathione S-transferases (hGSTs) to catalyze the GSH-conjugation of the different reactive intermediates formed by P450s was investigated. Addition of pooled human liver cytosol and recombinant hGSTA1-1, hGSTM1-1, and hGSTP1-1 to incubations of diclofenac with human liver microsomes or purified CYP102A1M11 L437N as a model system significantly increased total GSH-conjugation. The strongest increase of total GSH-conjugation was observed by adding hGSTP1-1, whereas hGSTM1-1 and hGSTA1-1 showed lower activity. Addition of hGSTT1-1 only showed a minor effect. When considering the effects of hGSTs on GSH-conjugation of the different quinoneimines of diclofenac, it was found that hGSTP1-1 showed the highest activity in GSH-conjugation of the quinoneimine derived from 5-hydroxydiclofenac (5-OH-DF). hGSTM1-1 showed the highest activity in inactivation of the quinoneimine derived from 4'-hydroxydiclofenac (4'-OH-DF). Separate incubations with 5-OH-DF and 4'-OH-DF as substrates confirmed these results. hGSTs also catalyzed GSH-conjugation of the o-iminemethide formed by oxidative decarboxylation of diclofenac as well as the substitution of one of the chlorine atoms of DF by GSH. hGSTP1-1 showed the highest activity for the formation of these minor GSH-conjugates. These results suggest that hGSTs may play an important role in the inactivation of DF quinoneimines and its minor reactive intermediates especially in stress conditions when tissue levels of GSH are decreased.

Topics: Anti-Inflammatory Agents, Non-Steroidal; Biocatalysis; Cytochrome P-450 Enzyme System; Diclofenac; Glutathione; Glutathione Transferase; Humans; Microsomes, Liver; Mutation; Oxidation-Reduction; Recombinant Proteins; Tandem Mass Spectrometry

Degradation of diclofenac sodium, a nonsteroidal anti-inflammatory drug widely found in the aquatic environment, was assessed using the white-rot fungus Trametes versicolor. Almost complete diclofenac removal (> or = 94%) occurred the first hour with T. versicolor pellets when the drug was added at relatively high (10 mg L(-1)) and environmentally relevant low (45 microg L(-1)) concentrations in a defined liquid medium. In vivo and in vitro experiments using the cytochrome P450 inhibitor 1-aminobenzotriazole and purified laccase, respectively, suggested at least two different mechanisms employed by T. versicolor to initiate diclofenac degradation. Two hydroxylated metabolites, 4'-hydroxydiclofenac and 5-hydroxydiclofenac, were structurally elucidated by nuclear magnetic resonance as degradation intermediates in fungal cultures spiked with diclofenac. Both parent compound and intermediates disappeared after 24 h leading to a decrease in ecotoxicity calculated by the Microtox test. Laccase-catalyzed transformation of diclofenac led to the formation of 4-(2,6-dichlorophenylamino)-1,3-benzenedimethanol, which was not detected in in vivo experiments probably due to the low laccase activity levels observed through the first hours of incubation.

Topics: Anti-Inflammatory Agents, Non-Steroidal; Biodegradation, Environmental; Cytochrome P-450 Enzyme System; Diclofenac; Hydroxylation; Laccase; Magnetic Resonance Spectroscopy; Trametes

Oral administration of the non-steroidal anti-inflammatory drug diclofenac (DCF) is associated with a high incidence of adverse drug reactions, some of which are thought to be mediated by the immune system. It has been proposed that metabolic activation of DCF and covalent binding to protein generates an antigenic determinant that stimulates immune cells; however, the nature of the metabolite remains ill-defined. The aim of this study was to synthesize and evaluate the antigenic potential of DCF metabolites in the mouse. DCF and DCF metabolites were administered via subcutaneous injection over a 5-day period to BALB/C strain mice to induce immune activation. Proliferation was measured by the addition of [(3)H] thymidine to ex vivo isolated draining auricular lymph node cells. Results were compared with those provoked by exposure to 2,4-dinitrochlorobenzene. Lymph node activation was observed following treatment with 2,4-dinitrochlorobenzene, 5-hydroxy DCF quinoneimine and 4'-hydroxy DCF quinoneimine, but not DCF acyl glucuronide or DCF itself. Interestingly, lymph node cells from 5-hydroxy DCF treated mice were also found to proliferate, when compared with cells from vehicle-treated mice, while 4'-hydroxy DCF did not stimulate lymph node cell activation. The reactivity of 5-hydroxy DCF quinoneimine was confirmed by synthesis and characterization of an N-acetyl cysteine adduct. These data show that formation of 5-hydroxy DCF and subsequent autoxidation provides an antigenic determinant for immune cell activation in the mouse.

Topics: Animals; Antigens; Cell Proliferation; Diclofenac; Female; Glucuronides; Local Lymph Node Assay; Lymph Nodes; Mice; Mice, Inbred BALB C

Data concerning metabolism of diclofenac in children are limited to intravenous and enteric coated oral formulations. There are no data examining diclofenac or its hydroxyl metabolite pharmacokinetics after rectal administration in children.. Infants (n = 26) undergoing tonsillectomy were given diclofenac 2 mg.kg(-1) followed by 1 mg.kg(-1) 8 h as suppository formulation for postoperative analgesia. Serum was assayed for diclofenac, 4'-hydroxydiclofenac and 5'-hydroxydiclofenac concentrations during the procedure and 1, 2 and 4 h postoperatively. The formation clearances of diclofenac to hydroxyl metabolites were estimated using nonlinear mixed effects models. A single compartment, first order absorption and first order elimination model was used to describe diclofenac pharmacokinetics. Published data from 11 children given enteric-coated diclofenac tablets were used to assess relative bioavailability.. Mean (sd) age and weight of the patients were 4.5 (1.5) years and 20.5 (4.1) kg. The formation clearance to 4'-hydroxydiclofenac (% CV) and to 5'-hydroxydiclofenac were 8.41 (8.1) and 3.41 (113) l.h(-1) respectively, standardized to a 70 kg person using allometric '1/4 power' models. Clearance by other routes contributed 33.0 (64) l.h(-1) 70 kg(-1). Elimination clearance of hydroxyl metabolites was fixed at 27.5 l.h(-1) 70 kg(-1). The volumes of distribution of parent diclofenac and its hydroxyl metabolite were 22.8 (19.0) and 45.3 (l.70) kg(-1). The suppository formulation had an absorption half-life of 0.613 (33.2) h with a lag time of 0.188 (24.9) h. Interoccasion variability of formation clearance to 4'-hydroxydiclofenac, diclofenac volume of distribution, absorption half-time and lag time for the suppository was 36%, 55%, 14% and 119%, respectively. The relative bioavailability of the suppository compared with an enteric-coated tablet was 1.26.. The formation clearance of the active metabolite 4'-hydroxydiclofenac contributed 19% of total clearance (44.82 l.h(-1) 70 kg(-1)). The rectum is a suitable route for administration of diclofenac in children 2-8 year of age and was associated with a higher relative bioavailabilty than enteric-coated tablets and an earlier maximum concentration (50 vs. 108 min). This pharmacokinetic profile renders diclofenac suppository a suitable formulation for short duration surgery.

Topics: Anti-Inflammatory Agents, Non-Steroidal; Biological Availability; Body Weight; Child; Child, Preschool; Chromatography, High Pressure Liquid; Diclofenac; Female; Half-Life; Humans; Male; Pain, Postoperative; Rectum; Suppositories; Tablets, Enteric-Coated; Tonsillectomy