Because aspirin and ibuprofen are NSAIDs
Because aspirin and ibuprofen are NSAIDs, both cause a variety of adverse effects, including stomach ulcers, stomach bleeding, coagulation disorders, mmp inhibitor and cerebral microbleeds . Moreover, both cause liver damage . Laster  reported a patient with pericarditis treated with aspirin who developed subsequent acute liver injury. Liver injuries are more dangerous than gastrointestinal injuries. Nevertheless, there have been few studies focusing on liver injury and the mechanism of that injury.
In a previous study , we showed that intragastric administration of aspirin (15 mg/kg) or ibuprofen (15 mg/kg) for 3 weeks caused metabolomic changes in blood and increased the level of alanine transaminase (ALT) and aspartate aminotransferase (AST), indicating there was liver injury with long-term administration of aspirin or ibuprofen. In the present study, we focused on the metabolic changes of liver CYP450 enzymes and ultrastructural morphological characteristics of liver cells. We developed a cocktail method and used it to evaluate the metabolic capacity of liver CYP450 isoenzymes. We also evaluated the values of liver CYP450 isoenzyme measurement for early diagnosis of liver injury. The whole schematic picture of study design was showed in supplemental Fig. 1.
Materials and methods
Discussion It is widely acknowledged that ibuprofen is better tolerated than is aspirin. A large-scale, randomized, investigator-blinded study showed that overall tolerability of ibuprofen was better than that of aspirin , especially in terms of gastrointestinal tolerability . Considering the risks of gastrointestinal reaction, aspirin is commonly used in enteric-coated dosage form. Nevertheless, whether enteric-coated aspirin is better than ibuprofen in terms of gastrointestinal tolerability remains unclear. Therefore, enteric-coated aspirin was selected in this study. According to the monitoring of body weight, rats in the Ibuprofen group were lighter than those in the Aspirin group, suggesting that ibuprofen caused more gastrointestinal damage than did aspirin. Although many studies have reported that ibuprofen had better gastrointestinal tolerability than did aspirin [10,19,20], our study showed that enteric-coated aspirin had better gastrointestinal tolerability than did ibuprofen. Further morphological examinations showed that the mucous layer of stomach became thin in aspirin group. Nevertheless, in ibuprofen group, there was ulcerous formation in the lesser and greater curvature of the stomach (supplemental Fig. 4). In the present study, we measured liver biochemical indexes, liver CYP450 enzymes and ultrastructure of liver cell to determine the influence of aspirin and ibuprofen on the liver. The metabolic ability of liver CYP450 enzymes was investigated by a cocktail method, consisting of co-administration of several probe drugs simultaneously [21,22]. Various probe drugs are specifically metabolized by various CYP450 isozymes, therefore, the metabolic ability of CYP450 isozymes can be evaluated according to the pharmacokinetics of probe drugs . Tolbutamide, bupropion, phenacetin and midazolam are used as probe drugs for CYP2C9, CYP2B6, CYP1A2 and CYP3A4. These CYP450 s are controlled by transcription factors in the nucleus, called nuclear receptors (NR), including thyroid and vitamin D receptors, constitutive androstane receptor (CAR) and the pregnane X receptor (PXR) [24,25]. The accelerated metabolism of these probe drugs suggested that the catalytic abilities of CYP2C9, CYP2B6, CYP1A2, and CYP3A4 were induced. One of the possible mechanisms is that the NR was activated by aspirin and ibuprofen, resulting in expression of these CYPs. Another mechanism may be related to the increased numbers of mitochondria according to ultrastructure examination. Ibuprofen promoted the opening of inner mitochondrial membrane pores by activating Ca2+ and phosphate . On day 28, there was no AUC(0–t), AUC(0–∞), Cmax decreased for tolbutamide and no AUC(0–t), AUC(0–∞), Cmax of increase for hydroxytolbutamide in the Aspirin and Ibuprofen groups. Although AUC(0–t), AUC(0–∞), Cmax of metoprolol decreased in the Aspirin and Ibuprofen groups, the t1/2 did not decrease and AUC(0–t), AUC(0–∞), Cmax for hydroxymetoprolol were also decreased, suggesting that the absorption of metoprolol was reduced. Although the AUC(0–t), AUC(0–∞) and Cmax of bupropion were increased in the Aspirin and Ibuprofen groups, there were no changes in AUC(0–t), AUC(0–∞) and Cmax for hydroxybupropion. Moreover, the AUC(0–t) and AUC(0–∞) for bupropion were 1570.7 ± 732.3 and 1615.5 ± 738.5 at day 28, respectively, lower than those of day 14. Therefore, the difference of bupropion was most likely caused by experimental error. As for phenacetin and midazolam, the AUC(0–t), AUC(0–∞), and Cmax were all decreased in the Aspirin and Ibuprofen groups. However, the AUC(0–t), AUC(0–∞), and Cmax of acetaminophen and 1-hydroxy-midazolam were not accordingly higher as on day 14. As a group, the metabolisms of tolbutamide, bupropion, phenacetin and midazolam on day 28 were not accelerated further with continuous administration of aspirin and ibuprofen. This situation may be correlated with damage of liver cells. The AST and ALT were higher in the Aspirin and Ibuprofen groups on day 28, in accordance with results from our previous work . Moreover, the ultrastructural examination showed that morphological characteristics of liver nuclei were altered to irregular, suggesting that there was damage to liver cells.