Effect of Aspirin and ibuprofen either alone or in combination on gastric mucosa and bleeding time and on serum prostaglandin E2 and thromboxane A2 levels in the anaesthetized rats in vivo.

There is much evidence that a combination of ibuprofen (IBU) and Aspirin (ASA) can antagonize the irreversible inhibition of platelet function. This study was designed to investigate the degree of gastric damage, bleeding time (BT) and fluctuations in the serum levels of prostaglandin E2 (PGE2) and thromboxane A2 (TXA2) after oral administration of ASA (200 mg/kg) and IBU (50 mg/kg) either alone or in combination in rats in vivo. The stomach was assessed for any damage either after 6 h, 18 h or 6 days and carboxymethylcellulose (1% CMC) served as a vehicle and control. ELISA was used to measure TXA2 and PGE2 in serum. Bleeding time was assessed using tail blood. The results show that ASA and IBU either alone or in combination can cause gastric ulceration in 25-100% of the rats at 6 and 18 h. In contrast, gastric ulceration was seen in 50% of rats with a combination of ASA given before IBU only after 6 days of oral administration. BT was unaffected either by ASA or IBU when administered alone except after 18 h for IBU. In contrast, BT was significantly reduced when IBU was administered before ASA after 18 h and 6 days (P < 0.001). Serum PGE2 levels decreased significantly after ASA administered either alone or in combination with IBU for 6 h, 18 h and 6 days (P < 0.05). Serum TXA2 levels were significantly reduced after 6 h, 18 h and 6 days following ASA and IBU administration except for IBU alone which caused a significant increase in serum TXA2 6 days after its administration (P < 0.01). It can be concluded that ASA and IBU administered either alone or in combination can cause gastric ulcers in the rat stomach after 6 h and 18 h, but less severe after 6 days. IBU either alone or in combination with ASA reduced BT only after 18 h and 6 days of administration. Together, the results show that gastric ulceration correlated well with the inhibition of serum PGE2 and TXA2 levels.

Association of myocardial infarctions with COX-2 inhibition may be related to immunomodulation towards a Th1 response resulting in atheromatous plaque instability: an evidence-based interpretation.

Cyclooxygenase (COX) inhibitors remain a major class of drugs in rheumatology and their widespread use is expected to continue. The view that a prothrombotic effect explains the increase in myocardial infarction (MI) associated with both COX-2 selective and traditional NSAIDs (tNSAIDs) has been increasingly questioned. We review the evidence that prostanoids direct the immune response away from a Th1 response and that consequently inhibition of prostaglandin synthesis results in augmentation of the Th1 response by limiting prostanoid synthesis. Although the role of prostanoids as mediators of inflammation in the periphery is well understood, the systemic immunomodulatory role of prostanoids shifting the immune response away from a Th1 type is less appreciated. Atherosclerosis is an inflammatory arterial disease driven by a Th1 type immune response. Moreover, the vulnerable phenotype of atheroma is associated with the cellular Th1 immune response in contrast to the stable plaque phenotype associated with a Th2 type response. We propose a class effect of COX-2 selective and tNSAIDs, which results in augmentation of Th1-mediated atherogenesis/ production of pro-atherogenic cytokines associated with detrimental plaque remodeling, instability, rupture and embolization resulting in MI. Understanding of the Th1 mediated immunity, which underlies the cardiovascular, and the non-Th1, which underlies gastrointestinal adverse effects associated with the use of COX inhibitors, should lead to better risk assessment and the development of anti-inflammatory treatments with improved safety. Our explanation also emphasizes the pharmacological effects and consequences of immunomodulation in the inflammation associated with atherosclerosis and other Th1- as well as non-Th1-driven diseases.

The effect of CYP2C19 polymorphisms on H. pylori eradication rate in dual and triple first-line PPI therapies: a meta-analysis.

PREMISE: It has been suggested that proton pump inhibitor (PPI)-related differences in Helicobacter pylori eradication rates are partly because of CYP2C19 polymorphisms and there have been conflicting data in this area. We conducted a meta-analysis to investigate the evidence relating CYP2C19 to first-line H. pylori eradication rates. METHODS: A search of the literature was conducted up to June 2005 using Medline, EMBase, and Cochrane Register of Controlled Trials (CENTRAL). Twenty-eight arms from 17 papers were extracted for omeprazole, lansoprazole, and rabeprazole, collectively. Review Manager 4.2.8 was used for analysis. RESULTS: When all eradication rates, regardless of PPI used, were combined there was no significant difference between poor metabolizers (PM) and heterozygous extensive metabolizers (HetEMs) (odds ratio [OR]= 1.35, 95% confidence interval [CI] 0.89-2.07, p = 0.15); however, there was a significant difference between HetEM and homozygous extensive metabolizers (HomEMs) (OR = 1.90, 95% CI 1.38-2.60, p < 0.0001). Significant heterogeneity was observed in a HomEM and PM comparison, hence additional subanalysis of individual PPIs revealed that dual and triple omeprazole therapies significantly favored higher H. pylori eradication rates in PM over HomEM (OR = 4.03, 95% CI 1.97-8.28, p = 0.0001), and also over HetEM (OR = 2.24, 95% CI 1.09-4.61, p = 0.03). Dual and triple rabeprazole and triple lansoprazole therapies did not show significantly different H. pylori eradication rates between PM and HomEM (OR = 1.04, 95% CI 0.44-2.46, p = 0.25) and (OR = 1.80, 95% CI 0.67-4.85, p = 0.93), respectively. CONCLUSIONS: The impact of CYP2C19 polymorphisms on H. pylori eradication rates in studied populations appears clinically relevant in patients prescribed omeprazole as a component of their dual- or triple-drug therapy, whereas regimens that include lansoprazole or rabeprazole are unaffected. The choice of PPI and/or dose rather than CYP2C19 genotyping could be a more practical approach to assure the highest H. pylori eradication rates in clinical settings.

Peptic ulcer disease today.

Over the past few decades, since the introduction of histamine H(2)-receptor antagonists, proton-pump inhibitors, cyclo-oxygenase-2-selective anti-inflammatory drugs (coxibs), and eradication of Helicobacter pylori infection, the incidence of peptic ulcer disease and ulcer complications has decreased. There has, however, been an increase in ulcer bleeding, especially in elderly patients. At present, there are several management issues that need to be solved: how to manage H. pylori infection when eradication failure rates are high; how best to prevent ulcers developing and recurring in nonsteroidal anti-inflammatory drug (NSAID) and aspirin users; and how to treat non-NSAID, non-H. pylori-associated peptic ulcers. Looking for H. pylori infection, the overt or surreptitious use of NSAIDs and/or aspirin, and the possibility of an acid hypersecretory state are important diagnostic considerations that determine the therapeutic approach. Combined treatment with antisecretory therapy and antibiotics for 1-2 weeks is the first-line choice for H. pylori eradication therapy. For patients at risk of developing an ulcer or ulcer complications, it is important to choose carefully which anti-inflammatory drugs, nonselective NSAIDs or coxibs to use, based on a risk assessment of the patient, especially if the high-risk patient also requires aspirin. Testing for and eradicating H. pylori infection in patients is recommended before starting NSAID therapy, and for those currently taking NSAIDs, when there is a history of ulcers or ulcer complications. Understanding the pathophysiology and best treatment strategies for non-NSAID, non-H. pylori-associated peptic ulcers presents a challenge.

Host-specific differences in the physiology of acid secretion related to prostaglandins may play a role in gastric inflammation and injury.

Immune mediators are involved in strain-specific manifestations of Helicobacter pylori infection, and the type of immune response is associated with production of PGE(2), which in turn influences gastric acid secretion. Acid secretion plays a pivotal role, not only in the pattern of H. pylori-induced gastritis and its consequences, but also in nonsteroidal anti-inflammatory drug (NSAID)-induced gastropathies. Mice and their transgenic modifications are widely used in Helicobacter and eicosanoid research. Using [(14)C]aminopyrine accumulation and pylorus ligation, we aimed to study acid secretion in gastric gland preparations from the commonly used strains of BALB/c and C57BL/6 mice. We found that PGE(2) does not inhibit acid secretion in gastric glands from C57BL/6 mice, in contrast to the expected antisecretory effect of PGE(2) observed in BALB/c mice. In BALB/c mice the effect of histamine and carbachol was reduced by PGE(2), whereas in C57BL/6 mice dose-response curves to these secretagogues were not affected. EP(3) receptors are not involved in acid secretion in C57BL/6 mice, as confirmed by significantly lower expression of mRNA for the EP(3) receptor. These contrary findings are important to the interpretation of the antisecretory role of eicosanoids in BALB/c and C57BL/6 mouse strains and the involvement of prostanoids in the etiology of Helicobacter-induced inflammation and NSAID-induced gastropathies. We propose that the lack of antisecretory effect of PGE(2) observed in C57BL/6 mice could reflect the extent of Helicobacter-induced inflammation and status of acid secretion in response to anti-inflammatory drugs.