Elucidation of the mechanism of inhibition of cyclooxygenases by acyl-coenzyme A and acylglucuronic conjugates of ketoprofen

Pharmacokinetic Criteria of Ketoprofen and its Cyclooxygenase-2 Inhibition in Mice: Influence of Xylazine Administration

The objective of this study was to examine the effect of ketoprofen with or without combination with xylazine on the level of cyclooxygenase-2 in mice. The intraperitoneal (i.p.) dose of ketoprofen and xylazine that caused an analgesic response in half of the mouse population was 1.26 mg/kg and 6.63 mg/kg, respectively. Serum cyclooxygenase-2 concentration (activity) in the control mice was 16.94 ng/ml. The ketoprofen-treated group (2.52 mg/kg, i.p.) decreased the cyclooxygenase-2 concentration by 58% (7.16 ng/ml). The combined ketoprofen and xylazine treatment (13.26 mg/kg, i.p.) decreased the cyclooxygenase-2 by 94% (0.98 ng/ml). The ketoprofen plasma concentration in the combined treatment group was significantly higher compared to the ketoprofen treatment group. Ketoprofen plasma concentrations measured at 0.25, 0.5, 1, 2, 4, and 24 hours were 19.07, 18.94, 14.66, 6.53, 5.44, and 5.54 µg/ml, respectively. Plasma concentrations of ketoprofen and xylazine were raised to 28.74, 29.74, 15.32, 13.04, 14.64, and 11.95 µg/ml or by 51%, 56%, 5%, 100%, 169%, and 116%, respectively. Ketoprofen pharmacokinetic variables were increased (AUC0-∞ (515%), AUMC0-∞ (2389%), MRT (305%), t1/2β (375%), Tmax (100%), and Cmax (55%)), while other values were decreased (Kel (79%), Vss (25%), and Cl (88%)). Our findings suggested a synergistic interaction between ketoprofen and xylazine on the level of cyclooxygenase-2 (pharmacodynamic interaction) which was exerted by modification of the ketoprofen pharmacokinetic properties in mice.

Aqueous extract of Paullinia cupana attenuates renal and hematological effects associated with ketoprofen

This study aimed to evaluate the effect of aqueous extract of Paullinia cupana (AEG) against ketoprofen side effects, through biochemical, hematological, and histological parameters. AEG showed antioxidant activity in the DPPH^• scavenging (IC₅₀  = 17.00 ± 1.00 µg/ml) and HPLC analysis revealed that this extract is constituted by antioxidants (caffeine, catechins, theobromine, and polyphenols). In vivo experiments in female Wistar rats demonstrated that alterations in urea, creatinine, and uric acid levels promoted (p < .05) by ketoprofen were reversed when AEG was co-administered. Ketoprofen significantly decreased the catalase levels of animal tissues (p < .05), which were restored when AEG was co-administered with the mentioned drug. Histological analysis showed that AEG protected tissues from damages caused by ketoprofen. Moreover, AEG reestablished the number of white blood cells, which had decreased when ketoprofen was administered. In conclusion, this study suggested that the association between ketoprofen and AEG may be an alternative to reduce health damages caused by this drug. PRACTICAL APPLICATIONS: Paullinia cupana, popularly known as guaraná, is commonly consumed as a beverage in Brazil and exhibits pharmacological and beneficial effects to humans. Ketoprofen is an efficacious drug employed in the treatment of inflammatory processes. However, this drug can cause several side effects in humans. Thus, the usage of natural products and plant extracts that can reduce such undesirable effects consists in a valuable strategy to be applied in therapeutic interventions.

Repeated dose of meloxicam induces genotoxicity and histopathological changes in cardiac tissue of mice

Meloxicam is the non-steroidal anti-inflammatory drug most used in small animals; however, studies on genotoxicity, oxidative stress, and histopathologic alterations in cardiac tissue are limited, especially at therapeutical doses used in these animals. This study evaluated the toxic effects caused by the treatment involving repeated low at higher doses of meloxicam in mice, by genotoxicity, oxidative stress, and histopathological parameters. Mice (CF1, male) received, by gavage, meloxicam at the therapeutic dose indicated for small animals (0.1 mg/kg) and at higher doses (0.5 and 1 mg/kg) for 28 days. Later, they were euthanized for blood and organ analysis. Oxidative stress was analyzed by the plasma ferric reduction capacity (FRAP) and catalase, and genotoxicity, by the comet assay and the micronucleus test. Heart, liver, lung, and kidney tissues were analyzed by the histology, and stomach and duodenum were analyzed with a magnifying glass. The relative weight of organs did not present significant alterations. However, congestion of duodenum vessels was observed at the three tested doses and caused hyperemia of stomach mucosa at 1 mg/kg. In the heart histology there was a reduction in the number of cardiomyocytes, accompanied by an increase in cell diameter (possible cell hypertrophy) dose-dependent. The highest tested dose of meloxicam also increased the DNA damage index, without alterations in the micronucleus test. Meloxicam did not affect the catalase activity but increased the FRAP (1 mg/kg). Meloxicam at the dose prescribed for small animals could potentially cause cardiac histopathologic alterations and genotoxic effects.

Impact of carprofen administration on stress and nociception responses of calves to cautery dehorning

The objective of this study was to investigate the effects of carprofen administered immediately before cautery dehorning on nociception and stress. Forty Holstein calves aged approximately 6 to 8 wk old were either placebo treated and sham dehorned ( = 10) or cautery dehorned following administration of carprofen (1.4 mg/kg) subcutaneously ( = 10) or orally ( = 10) or a subcutaneous and oral placebo ( = 10) in a randomized, controlled trial. All animals were given a cornual nerve block using lidocaine before dehorning. Response variables including mechanical nociception threshold, ocular temperature, heart rate, and respiratory rate were measured before and following cautery dehorning for 96 h. Blood samples were also collected over 96 h following dehorning and analyzed for plasma cortisol and substance P concentrations by RIA. Plasma carprofen concentration and ex vivo PGE concentrations were also determined for this time period. Average daily gain was calculated for 7 d after dehorning. Data were analyzed using a linear mixed effects model with repeated measures, controlling for baseline values by their inclusion as a covariate in addition to planned contrasts. Dehorning was associated with decreased nociception thresholds throughout the study and a stress response immediately after dehorning, following the loss of local anesthesia, and 48 h after dehorning compared with sham-dehorned calves. Carprofen was well absorbed after administration and reached concentrations that inhibited ex vivo PGE concentrations for 72 h (subcutaneous) and 96 h (oral) compared with placebo-treated calves ( < 0.05). Carprofen-treated calves tended to be less sensitive ( = 0.097) to nociceptive threshold tests. Overall, at the dosing regimen studied, the effect of carprofen on sensitivity and stress following cautery dehorning was minimal. Consideration of route of administration and dose determination studies may be warranted.

Interaction of the electrophilic ketoprofenyl-glucuronide and ketoprofenyl-coenzyme A conjugates with cytosolic glutathione S-transferases

Carboxylic acid-containing drugs are metabolized mainly through the formation of glucuronide and coenzyme A esters. These conjugates have been suspected to be responsible for the toxicity of several nonsteroidal anti-inflammatory drugs because of the reactivity of the electrophilic ester bond. In the present study we investigated the reactivity of ketoprofenyl-acylglucuronide (KPF-OG) and ketoprofenyl-acyl-coenzyme A (KPF-SCoA) toward cytosolic rat liver glutathione S-transferases (GST). We observed that KPF-SCoA, but not KPF-OG inhibited the conjugation of 1-chloro-2,4-dinitrobenzene and 4-nitroquinoline N-oxide catalyzed by both purified cytosolic rat liver GST and GST from FAO and H5-6 rat hepatoma cell lines. Photoaffinity labeling with KPF-SCoA suggested that the binding of this metabolite may overlap the binding site of 4-methylumbelliferone sulfate. Furthermore, high-performance liquid chromatography and mass spectrometry analysis showed that both hydrolysis and transacylation reactions were observed in the presence of GST and glutathione. The formation of ketoprofenyl-S-acyl-glutathione could be kinetically characterized (apparent K(m) = 196.0 +/- 70.6 microM). It is concluded that KPF-SCoA is both a GST inhibitor and a substrate of a GST-dependent transacylation reaction. The reactivity and inhibitory potency of thioester CoA derivatives toward GST may have potential implications on the reported in vivo toxicity of some carboxylic acid-containing drugs.

Irreversible inhibition of glucose-6-phosphate dehydrogenase by the coenzyme A conjugate of ketoprofen: a key to oxidative stress induced by non-steroidal anti-inflammatory drugs?

Oxidative damage by non-steroidal anti-inflammatory drugs (NSAIDs) has been considered relevant to the occurrence of gastro-intestinal side-effects. In the case of chiral arylpropionate derivatives like ketoprofen (KPF), this mechanism has been evidenced for the R-enantiomer, especially when chiral inversion was observed, and lets us suppose the involvement of CoA conjugates. Glucose-6-phosphate dehydrogenase (G6PD) is the crucial enzyme to regenerate the GSH pool and maintain the intracellular redox potential. This enzyme is known to be down-regulated by palmitoyl-CoA thioester. We hypothesised then that G6PD is the target of carboxylic NSAIDs, via their CoA metabolites. We used molecular docking to localise a putative site in the human G6PD then we chose the Yeast orthologue, as the most suitable species to study experimentally the precise molecular interaction. KPF-CoA was effectively shown to bind covalently to the unique cysteine residue of the yeast enzyme. Binding was found to occur in the same site as palmitoyl-CoA. It was decreased in the presence of an allosteric inhibitor of G6PD, phospho(enol)pyruvate, and was not detected with G6PD of Leuconostoc mesenteroides, which does not possess the allosteric site. This site is distinct from the catalytic site, and probably allosteric, explaining the observed non-competitive inhibition of its activity by KPF-CoA. KPF-CoA was shown to induce the production of reactive oxygen species in Caco-2 cells, where its inhibition of G6PD activity was observed.

Enantioseparation of flurbiprofen and ketoprofen in patches and in urine excretions by achiral gas chromatography

The enantiomeric composition tests on flurbiprofen and ketoprofen present in patch products and in urine excretions following patch applications were performed as diastereomeric (R)-(+)-1-phenylethylamides by achiral gas chromatography and by gas chromatography-mass spectrometry in selected ion monitoring mode. The method for determination of (R)- and (S)-enantiomers in the range from 0.1 to 5.0 microg was linear (r > or = 0.9996) with acceptable precision (% RSD < or = 5.2) and accuracy (% RE = 0.6 approximately -2.4). The enantiomeric compositions of flurbiprofen in one patch product and of ketoprofen in five different products were identified to be racemic with relatively good precision (< or = 6.4%). The urinary excretion level of (R)-flurbiprofen was two times higher than its antipode, while the comparable excretion levels of (R)- and (S)-enantiomers for ketoprofen were observed.