Pharmacokinetic drug interaction profiles of proton pump inhibitors

Proton pump inhibitors, genetic polymorphisms and response to clopidogrel therapy

Clopidogrel has become part of the mainstay of therapy for acute coronary syndromes and in patients post stenting. Clopidogrel is a pro drug and is metabolised by liver enzymes, particularly CYP2C19, into its active form. A considerable proportion of patients have a poor response to clopidogrel and this may be due to several factors. Genetic polymorphisms involved in clopidogrel's absorption, metabolism and activity at the platelet may interfere with its antiplatelet actions. Further, proton pump inhibitors (PPI) may interfere with clopidogrel's actions by functionally reducing the ability of CYP2C19 to convert clopidogrel to its active metabolite. By attenuating clopidogrel's actions, both polymorphisms and drug interactions may increase the risk of thrombotic events during clopidogrel therapy. This review will explore the current evidence relating to the association between PPIs, genetic polymorphisms and poor response to clopidogrel. Routine genetic testing cannot be recommended for patients receiving dual antiplatelet therapy (DAPT). However, it may have a role for patients with an episode of stent thrombosis, prior to planned high-risk stenting or major bleeding. Regarding concomitant clopidogrel and PPI therapy, it is recommended that only patients with previous gastrointestinal (GI) bleeding or multiple risk factors for GI bleeding should be prescribed gastroprotection. This is due to the uncertainty surrounding the clinical significance of this interaction given the discordant biochemical and clinical data, conflicting results from observational studies and the limitations of the COGENT study. Pantoprazole seems least likely to interact with clopidogrel and most suitable for use in patients receiving DAPT.

Pharmacokinetics of the HIV integrase inhibitor S/GSK1349572 co-administered with acid-reducing agents and multivitamins in healthy volunteers

OBJECTIVES

To evaluate the effect of pH-altering agents on S/GSK1349572 exposure in healthy subjects.

METHODS

S/GSK1349572 is an unboosted, once-daily, next-generation HIV integrase inhibitor. In the first study, 16 subjects received four single-dose treatments: (i) S/GSK1349572 50 mg; (ii) S/GSK1349572 50 mg with a multivitamin (MVI; One A Day Maximum); (iii) S/GSK1349572 50 mg with a liquid antacid (Maalox Advanced Maximum Strength); and (iv) S/GSK1349572 50 mg 2 h before an antacid. In the second study, 12 subjects received a single dose of S/GSK1349572 alone and on day 5 of omeprazole.

RESULTS

All treatments were well tolerated. MVI co-administration modestly decreased S/GSK1349572 AUC by 33%. Concurrent antacid co-administration reduced S/GSK1349572 AUC by 74% and staggered antacid dosing significantly diminished this interaction, with a reduction in S/GSK1349572 AUC of 26%. Omeprazole did not significantly affect S/GSK1349572 exposure.

CONCLUSIONS

S/GSK1349572 can be taken with proton pump inhibitors and MVIs without dose adjustment but should be administered 2 h before or 6 h after antacids.

Adverse effects of long-term proton pump inhibitor therapy

Proton pump inhibitors have an excellent safety profile and have become one of the most commonly prescribed class of drugs in primary and specialty care. Long-term, sometimes lifetime, use is becoming increasingly common, often without appropriate indications. This paper is a detailed review of the current evidence on this important topic, focusing on the potential adverse effects of long-term proton pump inhibitor use that have generated the greatest concern: B12 deficiency; iron deficiency; hypomagnesemia; increased susceptibility to pneumonia, enteric infections, and fractures; hypergastrinemia and cancer; drug interactions; and birth defects. We explain the pathophysiological mechanisms that may underlie each of these relationships, review the existing evidence, and discuss implications for clinical management. The benefits of proton pump inhibitor use outweigh its risks in most patients. Elderly, malnourished, immune-compromised, chronically ill, and osteoporotic patients theoretically could be at increased risk from long-term therapy.

The influence of proton pump inhibitors on the antiplatelet potency of clopidogrel evaluated by 5 different platelet function tests

Proton pump inhibitors (PPIs) are metabolized by the cytochrome P450 enzyme system to a variable degree and may therefore interact with the metabolism of clopidogrel to its active form. The conflicting data on this potential interaction may be due to the use of different PPIs and platelet function tests in recent studies. We therefore evaluated the influence of different PPIs on the antiplatelet effect of clopidogrel by 5 platelet function tests in the same population. Adenosine diphosphate (ADP)-inducible platelet reactivity was assessed in 230 patients on dual antiplatelet therapy after angioplasty and stenting for cardiovascular disease by the light transmission aggregometry, VerifyNow P2Y12 assay, vasodilator-stimulated phosphoprotein phosphorylation assay, multiple electrode aggregometry, and Impact-R. ADP-inducible platelet reactivity showed no significant differences between patients without (n = 95, 41.3%) and with PPI therapy (n = 135, 58.7%) in each test system (all P > 0.05). Furthermore, we observed no significant differences of ADP-inducible platelet reactivity between patients without PPIs and patients with pantoprazole (n = 95, 70.4%), esomeprazole (n = 22, 16.3%), omeprazole (n = 9, 6.65%), or lansoprazole (n = 9, 6.65%) (all P > 0.3). High on-treatment residual ADP-inducible platelet reactivity occurred to a similar extent in patients without and with PPI therapy in each assay (all P > 0.05). In conclusion, concomitant treatment with PPIs did not attenuate the antiplatelet effect of clopidogrel in patients on dual antiplatelet therapy irrespective of the type of PPI and the used test system.

Clinical outcomes in patients with the concomitant use of clopidogrel and proton pump inhibitors after percutaneous coronary intervention: an analysis from the Guthrie Health Off-Label Stent (GHOST) investigators

BACKGROUND

The concomitant use of proton pump inhibitors (PPIs) with clopidogrel is suspected to be associated with an adverse impact on clinical outcomes in patients with coronary artery disease. We sought to evaluate whether the use of PPIs with clopidogrel was associated with worse clinical outcomes after percutaneous coronary intervention (PCI) compared with the use of clopidogrel alone.

METHODS AND RESULTS

We studied 2651 consecutive patients discharged alive after coronary stenting for stable or unstable coronary artery disease between 2001 and 2007. All patients received aspirin indefinitely and a thienopyridine for 1 to 12 months. Patients were categorized into 2 groups: those taking a PPI [PPI (+), n=751] and those not taking a PPI [PPI (-), n=1900] at discharge. The primary end points were the 6-month incidence of major adverse cardiovascular events (MACE) (composite of death, myocardial infarction, target vessel revascularization, and stent thrombosis) and net adverse clinical events (NACE) (composite of MACE and thrombolysis in myocardial infarction major or minor bleeding), which were evaluated using propensity-adjusted Cox regression analysis. In addition, propensity-matched analysis was performed in 685 pairs of patients. The PPI (+) group was older and had more comorbid conditions than the PPI (-) group. In propensity-adjusted as well as propensity-matched analyses, the use of PPIs was not associated with an increased risk of MACE or NACE.

CONCLUSIONS

The use of PPIs with dual antiplatelet therapy was not associated with any adverse influence on MACE or NACE after PCI.

Effect of omeprazole on the pharmacokinetics and toxicities of irinotecan in cancer patients: a prospective cross-over drug-drug interaction study

BACKGROUND

Omeprazole is one of the most prescribed medications worldwide and within the class of proton pump inhibitors, it is most frequently associated with drug interactions. In vitro studies have shown that omeprazole can alter the function of metabolic enzymes and transporters that are involved in the metabolism of irinotecan, such as uridine diphosphate glucuronosyltransferase subfamily 1A1 (UGT1A1), cytochrome P-450 enzymes subfamily 3A (CYP3A) and ATP-binding cassette drug-transporter G2 (ABCG2). In this open-label cross-over study we investigated the effects of omeprazole on the pharmacokinetics and toxicities of irinotecan.

METHODS

Fourteen patients were treated with single agent irinotecan (600mg i.v., 90min) followed 3weeks later by a second cycle with concurrent use of omeprazole 40mg once daily, which was started 2weeks prior to the second cycle. Plasma samples were obtained up to 55h after infusion and analysed for irinotecan and its metabolites 7-ethyl-10-hydroxycampothecin (SN-38), SN-38-glucuronide (SN-38G), 7-ethyl-10-[4-(1-piperidino)-1-amino]-carbonyloxycamptothecin (NPC) and 7-ethyl-10-[4-N-(5-aminopentanoic acid)-1-piperidino]-carbonyloxycamptothecin (APC) by high-performance liquid chromatography (HPLC). Non-compartmental modelling was performed. Toxicities were monitored during both cycles. Paired statistical tests were performed with SPSS.

RESULTS

The exposure to irinotecan and its metabolites was not significantly different between both cycles. Neither were there significant differences in the absolute nadir and percentage decrease of WBC and ANC, nor on the incidence and severity of neutropenia, febrile neutropenia, diarrhoea, nausea and vomiting when irinotecan was combined with omeprazole.

CONCLUSION

Omeprazole 40mg did not alter the pharmacokinetics and toxicities of irinotecan. This widely used drug can, therefore, be safely administered during a 3-weekly single agent irinotecan schedule.

Review article: combination of clopidogrel and proton pump inhibitors: implications for clinicians

OBJECTIVES

to evaluate the existing literature on a proposed interaction between clopidogrel and proton pump inhibitors (PPIs) and discuss its implications for clinicians treating patients with this combination therapy.

BACKGROUND

each year millions of patients receive antiplatelet therapy. A number of these patients are prescribed PPIs concomitantly to reduce the risk of gastrointestinal side effects associated with antiplatelet therapy. Several studies have been published recently addressing a potential adverse drug-drug interaction between clopidogrel and PPIs.

METHODS

literature was evaluated through Pubmed using the terms clopidogrel, PPI, prasugrel, cytochrome P450, genetic polymorphisms, H( 2) blockers, famotidine, genetic cytochrome P450 polymorphisms, and drug interaction. Articles with these terms were considered for evaluation. In addition, reference citations from publications identified in the searches were further reviewed and analyzed.

RESULTS

none of the currently published studies were specifically designed to evaluate this drug-drug interaction or address the clinical relevance of this interaction prospectively. Conflicting evidence raised concerns but the information did not conclude with certainty a cause-and-effect relationship between concomitant use of the drugs and emerging safety issues. However, the Food and Drug Administration issued a public-health warning on the possible interaction between clopidogrel and PPIs, predominantly with omeprazole, in November 2009.

CONCLUSIONS

controversies exist on a potential drug-drug interaction between clopidogrel and PPIs. Although further studies are warranted, several studies indicated that there was a drug-drug interaction through this combination therapy with detrimental clinical outcomes and increased costs. Studies suggested that the use of a PPI may make clopidogrel less effective resulting in a higher risk of myocardial infarction, stroke, or death. Until additional information becomes available clinicians should consider discontinuing PPI use if no clear indication is documented. Alternative options like H(2)-receptor antagonists should be considered. Upon availability, genetic testing may provide additional valuable information.

Pantoprazole does not influence the antiplatelet effect of clopidogrel-a whole blood aggregometry study after coronary stenting

Recent attention has been drawn to a potential drug-drug interaction observed between clopidogrel and proton pump inhibitors (PPIs). However, this potential interaction may not be a class effect of PPIs. We investigated if pantoprazole, which has a different metabolism than omeprazole, diminishes the effectiveness of clopidogrel. Our study included 336 patients (mean age 64.6 years; 106 women) 48 hours after percutaneous coronary stent implantation with a loading dose of 600 mg clopidogrel hydrogensulfate and 500 mg aspirin, followed by 75 mg clopidogrel and 100 mg aspirin daily. Whereas 188 patients (59 women) were not given any PPI comedication, 122 patients received pantoprazole and 26 either omeprazole or esomeprazole. The platelet aggregation followed by impedance aggregometry (in Ohm) was induced by 5 mmol/L adenosine diphosphate. The percentage of clopidogrel low-response (CLR) was similar between the non-PPI group [2.75 Ohm (confidence interval, CI: 2.25-3.26); 21.9% CLR] and the pantoprazole group [2.33 Ohm (CI: 1.79-2.87); 16.4% CLR] but higher in patients treated with omeprazole/esomeprazole (3.00 Ohm (CI: 1.49-4.51); 30.8% CLR). Multivariate regression analysis reveals that the risk of CLR in the pantoprazole comedication group was not increased compared with the group without any PPI [odds ratio 0.59 (CI: 0.31-1.13) 0.11]. Our data suggest that pantoprazole does not diminish the antiplatelet effectiveness of clopidogrel early after coronary stenting. Therefore, the use of pantoprazole seems preferable in patients treated with clopidogrel when a concomitant medication with a PPI is indicated.

Antacid effects of Chinese herbal prescriptions assessed by a modified artificial stomach model

AIM: To assess the antacid effects of the tonic Chinese herbal prescriptions, Si-Jun-Zi-Tang (SJZT) and Shen-Ling-Bai-Zhu-San (SLBZS).

METHODS: Decoctions of the tonic Chinese herbal prescriptions, SJZT and SLBZS, were prepared according to Chinese original documents. The pH of the prescription decoctions and their neutralizing effects on artificial gastric acids were determined and compared with water and the active controls, sodium bicarbonate and colloidal aluminum phosphate. A modified model of Vatier’s artificial stomach was used to determine the duration of consistent neutralization effect on artificial gastric acids. The neutralization capacity in vitro was determined with the titration method of Fordtran’s model.

RESULTS: The results showed that both SJZT and SLBZS have antacid effects in vitro. Compared with the water group, SJZT and SLBZS were found to possess significant gastric acid neutralizing effects. The duration for consistent neutralization of SLBZS was significantly longer than that of water. Also, SLBZS and SJZT exhibited significant antacid capacities compared to water.

CONCLUSION: SJZT and SLBZS were consistently active in the artificial stomach model and are suggested to have antacid effects similar to the active control drugs.

Differential effects of omeprazole and pantoprazole on the pharmacodynamics and pharmacokinetics of clopidogrel in healthy subjects: randomized, placebo-controlled, crossover comparison studies

Four randomized, placebo-controlled, crossover studies were conducted among 282 healthy subjects to investigate whether an interaction exists between clopidogrel (300-mg loading dose/75-mg/day maintenance dose) and the proton-pump inhibitor (PPI) omeprazole (80 mg) when they are administered simultaneously (study 1); whether the interaction, if any, can be mitigated by administering clopidogrel and omeprazole 12 h apart (study 2) or by increasing clopidogrel to 600-mg loading/150-mg/day maintenance dosing (study 3); and whether the interaction applies equally to the PPI pantoprazole (80 mg) (study 4). Relative to levels after administration of clopidogrel alone in studies 1,2,3, and 4, coadministration of PPI decreased the AUC(0-24) of the clopidogrel active metabolite H4 by 40, 47, 41, and 14% (P ≤ 0.002), respectively; increased maximal platelet aggregation (MPA) induced by 5 micromol/l adenosine diphosphate (ADP) by 8.0, 5.6, 8.1, and 4.3% (P ≤ 0.014), respectively; and increased the vasodilator-stimulated phosphoprotein phosphorylation-platelet reactivity index (VASP-PRI) by 20.7, 27.1, 19.0 (P < 0.0001), and 3.9% (P = 0.3319), respectively. The results suggest that a metabolic drug-drug interaction exists between clopidogrel and omeprazole but not between clopidogrel and pantoprazole.

Onset of relief of symptoms of gastroesophageal reflux disease: post hoc analysis of two previously published studies comparing pantoprazole 20 mg once daily with nizatidine or ranitidine 150 mg twice daily

BACKGROUND

Systematic assessments of the onset of symptom relief in the treatment of gastroesophageal reflux disease (GERD) are lacking.

OBJECTIVE

This work evaluated the time interval until complete symptom relief from heartburn (including both daytime and nighttime heartburn) and acid regurgitation in patients with GERD or endoscopy-negative GERD (NERD) during the first 7 days of treatment with pantoprazole, nizatidine, or ranitidine.

METHODS

This was a post hoc reanalysis of data from 2 previously published, multicenter, randomized, double-blind, active-controlled, parallel-group studies. Male and female patients aged >or=18 years with endoscopically proven GERD or NERD (Hetzel-Dent grade >or= [trial 1] or Savary-Miller grade 0 or 1 [trial 2]) were enrolled. Patients were required to have had reflux symptoms for the previous >or=3 months, with >or=1 symptom (ie, daytime heartburn, nighttime heartburn, or acid regurgitation) for >or=4 of the past 7 days in trial 1 or >or=1 symptom (ie, heartburn, acid eructation, or painful swallowing) of at least moderate intensity for the past 3 days in trial 2. The treatments were pantoprazole 20 mg once daily in both trials, nizatidine 150 mg BID in trial 1, or ranitidine 150 mg BID in trial 2. Presence and severity of symptoms were recorded on daily diary cards using a 4-point Likert-type scale.

RESULTS

In total, 114 patients from trial 1 and 307 patients from trial 2 were evaluable for heartburn, and 58 patients from trial l and 271 patients from trial 2 were evaluable for acid regurgitation. In both studies, there were no significant differences in baseline characteristics between pantoprazole recipients and nizatidine or ranitidine recipients, with the exception of more men than women in trial 1 compared with trial 2 (P < 0.001). On day 2 of trial 1, 23 (39.0%) and 8 (14.5%) of pantoprazole and nizatidine recipients, respectively, experienced complete relief from heartburn (P < 0.01). The differences between groups remained statistically significant through day 7, when 28 (47.5%) and 8 (14.5 %) of pantoprazole and nizatidine recipients had no heartburn (P < 0.001). There were no differences in control of acid regurgitation over 7 days with pantoprazole compared with nizatidine or ranitidine, except at days 2 and 4 of trial 1, when significantly more patients receiving pantoprazole experienced relief from acid regurgitation than those receiving nizatidine (day 2: 60.6% [n = 20] vs 20.0% [n = 5], P < 0.01; day 4: 48.5% [n =16] vs 24.0% [n = 6], P < 0.05).

CONCLUSION

In this post hoc reanalysis of data from 2 previously published clinical trials, use of pantoprazole 20 mg once daily was associated with effective early relief from heartburn and acid regurgitation among these patients with GERD and NERD; relief occurred as fast as and, in some cases, even faster than that seen with nizatidine or ranitidine.

Rebamipide: a gastrointestinal protective drug with pleiotropic activities

Rebamipide, a gastroprotective drug, was developed in Japan and was proven to be superior to cetraxate, the former most prescribed drug of the same category, in 1989 in the treatment for gastric ulcers. The initially discovered basic mechanisms of action of rebamipide included its action as a prostaglandin inducer and oxygen free-radical scavenger. In the last 5 years, several basic and clinical studies have been performed for functional dyspepsia, chronic gastritis, NSAID-induced gastrointestinal injuries, gastric ulcer following eradication therapy for Helicobacter pylori, gastric ulcer after endoscopic surgery and ulcerative colitis. In addition, several molecules have been identified as therapeutic targets of rebamipide to explain its pleiotropic pharmacological actions. The aim of this article is to provide an update on the pharmacological and clinical profile of rebamipide and to explore further possibilities for additional indications.

Safety of the long-term use of proton pump inhibitors

The proton pump inhibitors (PPIs) as a class are remarkably safe and effective for persons with peptic ulcer disorders. Serious adverse events are extremely rare for PPIs, with case reports of interstitial nephritis with omeprazole, hepatitis with omeprazole and lansoprazole, and disputed visual disturbances with pantoprazole and omeprazole. PPI use is associated with the development of fundic gland polyps (FGP); stopping PPIs is associated with regression of FGP. In the absence of Helicobacter pylori infection, the long-term use of PPIs has not been convincingly proven to cause or be associated with the progression of pre-existing chronic gastritis or gastric atrophy or intestinal metaplasia. Mild/modest hypergastrinemia is a physiological response to the reduction in gastric acid secretion due to any cause. The long-term use of PPIs has not been convincingly proven to cause enterochromaffin-like cell hyperplasia or carcinoid tumors. PPIs increase the risk of community acquired pneumonia, but not of hospital acquired (nosocomial) pneumonia. There is no data to support particular care in prescribing PPI therapy due to concerns about risk of hip fracture with the long-term use of PPIs. Long-term use of PPIs does not lead to vitamin B12 deficiencies, except possibly in the elderly, or in persons with Zollinger-Ellison Syndrome who are on high doses of PPI for prolonged periods of time. There is no convincingly proven data that PPIs increase the risk of Clostridium difficile-associated diarrhea in persons in the community. The discontinuation of PPIs may result in rebound symptoms requiring further and even continuous PPI use for suppression of symptoms. As with all medications, the key is to use PPIs only when clearly indicated, and to reassess continued use so that long-term therapy is used judiciously. Thus, in summary, the PPIs are a safe class of medications to use long-term in persons in whom there is a clear need for the maintenance of extensive acid inhibition.

Population pharmacokinetic modeling of pantoprazole in pediatric patients from birth to 16 years

The population pharmacokinetics of pantoprazole was characterized in pediatric patients from birth to 16 years using NONMEM and evaluated via bootstrap and predictive check. Data were described using a 2-compartment model with a typical parameterized in terms of clearance (CL) (95% CI) of 1.93 L per hour (1.53, 2.61), given the reference covariates (female, full term, extensive/unknown CYP2C19 metabolizer status, non-African American, 10 kg weight, intravenous or tablet administration). Pantoprazole pharmacokinetic parameters appear to be similar in pediatric patients compared to adults when allometrically scaled. The effect of age on allometrically scaled CL was best described by a sigmoid Emax model with the age effect reaching an asymptote approximately equal to the adult CL by 1 year. CYP2C19 poor metabolizers exhibited reduced CL with the point estimate and 95% CI more than 70% lower than the typical value. Simulations from the final model indicated that the 1.2-mg/kg dose provides the best comparison to adults.

Relation of proton pump inhibitor use after percutaneous coronary intervention with drug-eluting stents to outcomes

Recent evidence has shown that clopidogrel and proton pump inhibitors (PPIs) are metabolized by the same pathway and that patients taking both drugs have greater levels of platelet reactivity and more adverse outcomes than patients taking only clopidogrel. We sought to examine the effect of a PPI at discharge from the hospital after percutaneous coronary intervention with drug-eluting stents on the incidence of major adverse cardiac events (MACE) at 1 year. We compared 502 patients who were not prescribed a PPI at discharge and 318 patients who were prescribed a PPI. All patients were taking clopidogrel. We followed patients for 1 year with regard to MACE, including death, Q-wave myocardial infarction, target vessel revascularization, and stent thrombosis. We performed multivariate Cox regression to adjust for confounding variables, including compliance with clopidogrel, to assess the effect of a PPI at discharge on the 1-year outcomes. The baseline characteristics of patients discharged with a PPI were similar to those of patients discharged without a PPI. Univariate survival analysis of the outcomes showed a greater rate of MACE (13.8% vs 8.0%, p = 0.008) and overall mortality (4.7% vs 1.8%, p = 0.02) in the PPI group. After multivariate analysis, the adjusted MACE hazard ratio for PPI at discharge was 1.8 (95% confidence interval 1.1 to 2.7, p = 0.01). In conclusion, in patients undergoing percutaneous coronary intervention with drug-eluting stents and receiving clopidogrel, the prescription of a PPI at discharge was associated with a greater rate of MACE at 1 year.

Pantoprazole: a proton pump inhibitor

Pantoprazole is a proton pump inhibitor (PPI) that binds irreversibly and specifically to the proton pump, thereby reducing gastric acid secretion. Pantoprazole has a relatively long duration of action compared with other PPIs, and a lower propensity to become activated in slightly acidic body compartments. To date, no drug-drug interactions have been identified with pantoprazole in numerous interaction studies. Overall, in the short-term (8-10 weeks) initial treatment of gastro-oesophageal reflux disease (a condition that occurs when the reflux of gastric contents causes troublesome symptoms and/or complications) and long-term (6-24 months) maintenance therapy, oral pantoprazole 20 or 40 mg/day demonstrated similar efficacy to omeprazole, lansoprazole and esomeprazole and greater efficacy than histamine type 2 receptor antagonists. Pantoprazole is also effective in treating and preventing NSAID-related gastric and gastroduodenal injury. The optimal adult oral dose for gastric acid-related disorders is pantoprazole 40 mg once daily. Although data are limited, pantoprazole 20 or 40 mg/day was effective and well tolerated in the treatment of acid-related disorders in children and adolescents. Pantoprazole was also well tolerated in adults with acid-related disorders in short- and long-term studies. Thus, pantoprazole is a valuable agent for the management of acid-related disorders.

Clopidogrel pharmacogenomics and risk of inadequate platelet inhibition: US FDA recommendations

Antiplatelet therapy with clopidogrel is the current standard of care for coronary artery disease patients undergoing a percutaneous coronary intervention. However, approximately 25% of patients experience a subtherapeutic antiplatelet response. Clopidogrel is a prodrug that undergoes hepatic biotransformation by CYP2C19 into its active metabolite. Several studies have reported that, compared with wild-type individuals, CYP2C19 variant allele carriers exhibit a significantly lower capacity to metabolize clopidogrel into its active metabolite and inhibit platelet activation, and are therefore at significantly higher risk of adverse cardiovascular events. Consequently, the US FDA has recently changed clopidogrel's prescribing information to highlight the impact of CYP2C19 genotype on clopidogrel pharmacokinetics, pharmacodynamics and clinical response. Future studies remain necessary to develop effective personalized therapeutic strategies for CYP2C19 variant allele carriers and other individuals at risk for clopidogrel nonresponsiveness.

Advances in clinical research on the interaction between proton pump inhibitors and clopidogrel

As a new antiplatelet drug, clopidogrel is the cornerstone of drug treatment for coronary artery disease. However, clinical use of clopidogrel frequently leads to gastrointestinal injury or increases the risk of gastrointestinal bleeding. To prevent clopidogrel-associated gastrointestinal injury, concomitant proton pump inhibitors (PPIs) have been used widely in clinical practice. However, recent studies show that treatment with clopidogrel plus PPIs can increase the incidence of adverse cardiovascular events. Despite being controversial, this finding has attracted wide attention from clinicians. This article will review the recent advances in clinical research on the interaction between proton pump inhibitors and clopidogrel.

A comparative study of proton-pump inhibitor tests for Chinese reflux patients in relation to the CYP2C19 genotypes

BACKGROUND

The proton-pump inhibitor (PPI) test has been proposed as a valuable tool for diagnosing gastroesophageal reflux disease in Western populations.

GOALS

We aim to compare the diagnostic accuracy of the PPI test using rabeprazole and pantoprazole in a Chinese population with a higher prevalence of poor PPI metabolization.

STUDY

After diagnostic endoscopy, patients with gastroesophageal reflux disease symptoms were randomly assigned to a 2-week test with rabeprazole (20 mg b.i.d.) or pantoprazole (40 mg b.i.d.). Therapeutic response was assessed with a 5-grade daily record. Genotypes of cytochrome P450 (CYP) 2C19 polymorphism were determined.

RESULTS

Of the 178 patients who completed the study, 92 (51.7%) had erosive esophagitis and 78 (48.3%) were endoscopy-negative reflux disease. On the basis of 50% reduction of symptoms, there was a nonsignificant difference of diagnostic performances between rabeprazole and pantoprazole. For the CYP2C19 genotypes, 138 (87.3%) were determined to be extensive metabolizers (EMs) and 20 (12.7%) were poor metabolizers (PMs). When comparing the EMs and PMs, the diagnostic specificity in the prediction of erosive esophagitis was higher in the EMs (57.6% vs. 20.0%, P=0.040), as was the accuracy (74.6% vs. 50.0%, P=0.023). There were no differences in the sensitivity, positive predictive value, or negative predictive value.

CONCLUSIONS

CYP2C19 genotypic polymorphism was related to a higher possibility of false-positive results for patients who metabolized PPI poorly. High-dose rabeprazole and pantoprazole showed a similar diagnostic performance.

Rabeprazole: a review of its use in the management of gastric acid-related diseases in adults

Rabeprazole (Aciphex, Alfence, Pariet) is a proton pump inhibitor (PPI) used for the treatment of adults with conditions requiring a reduction of gastric acid secretion such as erosive or ulcerative gastro-oesophageal reflux disease (GORD), non-erosive reflux disease (NERD), duodenal and gastric ulcers, and pathological hypersecretory conditions including Zollinger-Ellison syndrome (ZES). It is also used as part of combination therapy for the eradication of Helicobacter pylori, a pathogen frequently implicated in the development of gastric and duodenal ulcers. Rabeprazole has a well established efficacy and safety profile in the treatment of gastric acid-related diseases. Rabeprazole is a useful, well tolerated and cost-effective option for the treatment of GORD, NERD, peptic ulcer and other gastric acid-related diseases (including ZES), and provides an appropriate alternative to other currently available PPIs, with the added benefits of having a consistent efficacy profile and low drug interaction potential due to its predominantly nonenzymatic metabolism.

Polymorphism of human cytochrome P450 enzymes and its clinical impact

Pharmacogenetics is the study of how interindividual variations in the DNA sequence of specific genes affect drug response. This article highlights current pharmacogenetic knowledge on important human drug-metabolizing cytochrome P450s (CYPs) to understand the large interindividual variability in drug clearance and responses in clinical practice. The human CYP superfamily contains 57 functional genes and 58 pseudogenes, with members of the 1, 2, and 3 families playing an important role in the metabolism of therapeutic drugs, other xenobiotics, and some endogenous compounds. Polymorphisms in the CYP family may have had the most impact on the fate of therapeutic drugs. CYP2D6, 2C19, and 2C9 polymorphisms account for the most frequent variations in phase I metabolism of drugs, since almost 80% of drugs in use today are metabolized by these enzymes. Approximately 5-14% of Caucasians, 0-5% Africans, and 0-1% of Asians lack CYP2D6 activity, and these individuals are known as poor metabolizers. CYP2C9 is another clinically significant enzyme that demonstrates multiple genetic variants with a potentially functional impact on the efficacy and adverse effects of drugs that are mainly eliminated by this enzyme. Studies into the CYP2C9 polymorphism have highlighted the importance of the CYP2C9*2 and *3 alleles. Extensive polymorphism also occurs in other CYP genes, such as CYP1A1, 2A6, 2A13, 2C8, 3A4, and 3A5. Since several of these CYPs (e.g., CYP1A1 and 1A2) play a role in the bioactivation of many procarcinogens, polymorphisms of these enzymes may contribute to the variable susceptibility to carcinogenesis. The distribution of the common variant alleles of CYP genes varies among different ethnic populations. Pharmacogenetics has the potential to achieve optimal quality use of medicines, and to improve the efficacy and safety of both prospective and currently available drugs. Further studies are warranted to explore the gene-dose, gene-concentration, and gene-response relationships for these important drug-metabolizing CYPs.

Effects of omeprazole on plasma levels of raltegravir

Raltegravir, a human immunodeficiency virus type 1 (HIV-1) integrase inhibitor, has pH-dependent solubility. Raltegravir plasma concentration increases with omeprazole coadministration in healthy subjects; this is likely secondary to an increase in bioavailability attributable to increased gastric pH. Increased gastric pH has been reported in HIV-1-infected individuals, and the effects of omeprazole in this intended population may be diminished. Further investigation is necessary.

Effect of the cytochrome P450 2C19 inhibitor omeprazole on the pharmacokinetics and safety profile of bortezomib in patients with advanced solid tumours, non-Hodgkin's lymphoma or multiple myeloma

BACKGROUND AND OBJECTIVE

Bortezomib, an antineoplastic for the treatment of relapsed multiple myeloma and mantle cell lymphoma, undergoes metabolism through oxidative deboronation by cytochrome P450 (CYP) enzymes, primarily CYP3A4 and CYP2C19. Omeprazole, a proton-pump inhibitor, is primarily metabolized by and demonstrates high affinity for CYP2C19. This study investigated whether coadministration of omeprazole affected the pharmacokinetics, pharmacodynamics and safety profile of bortezomib in patients with advanced cancer. The variability of bortezomib pharmacokinetics with CYP enzyme polymorphism was also investigated.

PATIENTS AND METHODS

This open-label, crossover, pharmacokinetic drug-drug interaction study was conducted at seven institutions in the US and Europe between January 2005 and August 2006. Patients who had advanced solid tumours, non-Hodgkin's lymphoma or multiple myeloma, were aged >/=18 years, weighed >/=50 kg and had a life expectancy of >/=3 months were eligible. Patients received bortezomib 1.3 mg/m2 on days 1, 4, 8 and 11 for two 21-day cycles, plus omeprazole 40 mg in the morning of days 6-10 and in the evening of day 8 in either cycle 1 (sequence 1) or cycle 2 (sequence 2). On day 21 of cycle 2, patients benefiting from therapy could continue to receive bortezomib for six additional cycles. Blood samples for pharmacokinetic/pharmacodynamic evaluation were collected prior to and at various timepoints after bortezomib administration on day 8 of cycles 1 and 2. Blood samples for pharmacogenomics were also collected. Pharmacokinetic parameters were calculated by noncompartmental analysis of plasma concentration-time data for bortezomib administration on day 8 of cycles 1 and 2, using WinNonlin version 4.0.1.a software. The pharmacodynamic profile was assessed using a whole-blood 20S proteasome inhibition assay.

RESULTS

Twenty-seven patients (median age 64 years) were enrolled, 12 in sequence 1 and 15 in sequence 2, including eight and nine pharmacokinetic-evaluable patients, respectively. Bortezomib pharmacokinetic parameters were similar when bortezomib was administered alone or with omeprazole (maximum plasma concentration 120 vs 123 ng/mL; area under the plasma concentration-time curve from 0 to 72 hours 129 vs 135 ng . h/mL). The pharmacodynamic parameters were also similar (maximum effect 85.8% vs 93.7%; area under the percent inhibition-time curve over 72 hours 4052 vs 3910 % x h); the differences were not statistically significant. Pharmacogenomic analysis revealed no meaningful relationships between CYP enzyme polymorphisms and pharmacokinetic/pharmacodynamic parameters. Toxicities were generally similar between patients in sequence 1 and sequence 2, and between cycle 1 and cycle 2 in both treatment sequences. Among 26 evaluable patients, 13 (50%) were assessed as benefiting from bortezomib at the end of cycle 2 and continued to receive treatment.

CONCLUSION

No impact on the pharmacokinetics, pharmacodynamics and safety profile of bortezomib was seen with coadministration of omeprazole. Concomitant administration of bortezomib and omeprazole is unlikely to cause clinically significant drug-drug interactions and is unlikely to have an impact on the efficacy or safety of bortezomib.

Drug-drug interaction between clopidogrel and the proton pump inhibitors

OBJECTIVE

To evaluate the interaction between clopidogrel and proton pump inhibitors (PPIs).

DATA SOURCES

Literature retrieval was accessed through PubMed (1980-January 2009), abstracts from 2008 American Heart Association and 2009 Society of Cardiovascular Angiography and Interventions Scientific Sessions, and media press releases using the terms clopidogrel, proton pump inhibitors, cytochrome 2C19, genetic cytochrome P450 polymorphisms, and drug interaction. In addition, reference citations from publications identified in the search were reviewed.

STUDY SELECTION AND DATA EXTRACTION

Relevant original research articles and review articles were evaluated. Articles were selected if they were published in English and focused on any of the key words or appeared to have substantial content addressing the drug interaction.

DATA SYNTHESIS

Recent attention has been placed on a potential interaction observed between clopidogrel and the widely used PPIs. Preliminary evidence suggests that omeprazole interacts with clopidogrel, reducing clopidogrel's antiplatelet effects as measured by various laboratory tests. Most data indicate that the interaction involves the competitive inhibition of the CYP2C19 isoenzyme. The interaction appears to be clinically significant, as several retrospective analyses have shown an increase in adverse cardiovascular outcomes when PPIs and clopidogrel are used concomitantly. However, this may not be a class effect.

CONCLUSIONS

Available data suggest that omeprazole is the PPI most likely to have a significant interaction with clopidogrel. Further studies are needed to determine that an interaction between the other PPIs and clopidogrel does not exist. In situations in which both clopidogrel and a PPI are indicated, pantoprazole should be used since it is the PPI least likely to interact with clopidogrel.

Drug interaction studies with dexlansoprazole modified release (TAK-390MR), a proton pump inhibitor with a dual delayed-release formulation: results of four randomized, double-blind, crossover, placebo-controlled, single-centre studies

BACKGROUND AND OBJECTIVE

Most proton pump inhibitors are extensively metabolized by cytochrome P450 (CYP) isoenzymes, as are many other drugs, giving rise to potential drug-drug interactions. Dexlansoprazole modified release (MR) [TAK-390MR] is a modified-release formulation of dexlansoprazole (TAK-390), an enantiomer of lansoprazole, which employs an innovative Dual Delayed Release technology designed to prolong the plasma dexlansoprazole concentration-time profile following once-daily oral administration. As with lansoprazole, dexlansoprazole is metabolized mainly by CYP3A and CYP2C19. Based on in vitro studies, dexlansoprazole has the potential to inhibit activity of these isoenzymes and also may induce human hepatic CYP1A and CYP2C9 activity. To determine whether dexlansoprazole has an effect on these isoenzymes in vivo, drug interaction studies with dexlansoprazole MR were conducted.

METHODS

Four separate randomized, double-blind, two-way crossover, placebo-controlled, single-centre studies were conducted in healthy volunteers to evaluate the effect of dexlansoprazole on the pharmacokinetics of four test substrates (diazepam, phenytoin, theophylline [administered as intravenous aminophylline] and warfarin), which were selected based on in vitro and/or in vivo data that suggest a potential drug interaction with CYP isoenzymes or potentially coadministered narrow therapeutic index drugs. In each study, dexlansoprazole MR 90 mg or placebo was administered once daily for 9 or 11 days in each period. Subjects received a single dose of test substrate in each study period. Pharmacokinetic parameters of the test substrates were estimated using noncompartmental methods. A conclusion of no effect of dexlansoprazole MR on the test substrate was made if the 90% confidence intervals (CIs) for the ratios of the central values for the observed maximum plasma drug concentration (C(max)) and the area under the plasma concentration-time curve (AUC) of test substrate administered with dexlansoprazole MR versus placebo were within 0.80-1.25 based on an analysis of variance model. The potential for a pharmacodynamic interaction was also assessed for warfarin using prothrombin time, measured as the international normalized ratio. Routine safety assessments were conducted in these studies.

RESULTS

Mean C(max) and AUC values were generally similar for each test substrate when administered with multiple once-daily doses of dexlansoprazole MR or placebo. The 90% CIs for the bioavailability of these test substrates administered with dexlansoprazole MR relative to that obtained when the substrates were administered with placebo were within the bioequivalency range of 0.80-1.25, indicating that multiple doses of dexlansoprazole MR had no effect on the pharmacokinetics of these drugs. Additionally, dexlansoprazole MR had no effect on the pharmacodynamics of warfarin. Administration of these drugs with dexlansoprazole MR 90 mg or placebo was well tolerated; the only serious adverse event, which led to a subject's discontinuation from the study, was considered unrelated to study drugs.

CONCLUSIONS

Coadministration of dexlansoprazole MR with diazepam, phenytoin or theophylline did not affect the pharmacokinetics of these drugs, and therefore is unlikely to alter the pharmacokinetic profile of other drugs metabolized by CYP2C19, CYP2C9, CYP1A2 and perhaps CYP3A. Additionally, dexlansoprazole MR coadministered with warfarin did not affect the pharmacokinetics of the warfarin enantiomers and had no effect on the anticoagulant activity of warfarin. Dexlansoprazole MR was well tolerated in these trials of healthy subjects.

Accelerated metabolism of voriconazole and its partial reversal by cimetidine

We report a case of accelerated metabolism of voriconazole during therapy for invasive pulmonary aspergillosis, resulting in subtherapeutic levels. Target voriconazole levels were restored with high dosages of voriconazole (up to 40 mg/kg of body weight/day) and the addition of cimetidine as a cytochrome P450 enzyme inhibitor.

Population pharmacokinetics of intravenous pantoprazole in paediatric intensive care patients

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

The use of intravenous pantoprazole, a proton pump inhibitor, has been increasing in the paediatric intensive care unit. Despite this increased use, data on the disposition of intravenous pantoprazole in paediatric intensive care patients are very scarce.

WHAT THIS STUDY ADDS

Our population approach has determined the pharmacokinetic parameters of intravenous pantoprazole in paediatric intensive care patients and the relative importance of factors influencing its disposition. Pantoprazole clearance was significantly influenced by developmental changes and by the presence of systemic inflammatory syndrome, hepatic dysfunction and CYP2C19 inhibitors.

AIMS

To characterize the pharmacokinetics of intravenous pantoprazole in a paediatric intensive care population and to determine the influence of demographic factors, systemic inflammatory response syndrome (SIRS), hepatic dysfunction and concomitantly used CYP2C19 inducers and inhibitors on the drug's pharmacokinetics.

METHODS

A total of 156 pantoprazole concentration measurements from 20 patients (10 days to 16.4 years of age) at risk for or with upper gastrointestinal bleeding, who received pantoprazole doses ranging from 19.9 to 140.6 mg/1.73 m(2)/day, were analysed using a population pharmacokinetic approach (nonmem program).

RESULTS

The best structural model for pantoprazole was a two-compartment model with zero order infusion and first-order elimination. Body weight, SIRS, age, hepatic dysfunction and presence of CYP2C19 inhibitors were significant covariates affecting clearance (CL), accounting for 75% of interindividual variability. Only body weight significantly influenced central volume of distribution (V(c)). In the final population model, the estimated CL and V(c) were 5.28 l h(-1) and 2.22 l, respectively, for a typical 5-year-old child weighing 20 kg. Pantoprazole CL increased with weight and age, whereas the presence of SIRS, CYP2C19 inhibitors and hepatic dysfunction, when present separately, significantly decreased pantoprazole CL by 62.3, 65.8 and 50.5%, respectively. For patients aged between 6 months and 5 years without SIRS, CYP2C19 inhibitor or hepatic dysfunction, the predicted pantoprazole CL is faster than that reported in adults.

CONCLUSION

These results provide important information for physicians regarding selection of a starting dose and dosing regimens of pantoprazole for paediatric intensive care patients based on factors frequently encountered in this population.

Metabolism and related human risk factors for hepatic damage by usnic acid containing nutritional supplements

Usnic acid is a component of nutritional supplements promoted for weight loss that have been associated with liver-related adverse events including mild hepatic toxicity, chemical hepatitis, and liver failure requiring transplant. To determine if metabolism factors might have had a role in defining individual susceptibility to hepatotoxicity, in vitro metabolism studies were undertaken using human plasma, hepatocytes, and liver subcellular fractions. Usnic acid was metabolized to form three monohydroxylated metabolites and two regio-isomeric glucuronide conjugates of the parent drug. Oxidative metabolism was mainly by cytochrome P450 (CYP) 1A2 and glucuronidation was carried out by uridine diphosphate-glucuronosyltransferase (UGT) 1A1 and UGT1A3. In human hepatocytes, usnic acid at 20 microM was not an inducer of CYP1A2, CYP2B6, or CYP3A4 relative to positive controls omeprazole, phenobarbital, and rifampicin, respectively. Usnic acid was a relatively weak inhibitor of CYP2D6 and a potent inhibitor of CYP2C19 (the concentration eliciting 50% inhibition (IC(50)) = 9 nM) and CYP2C9 (IC(50) = 94 nM), with less potent inhibition of CYP2C8 (IC(50) = 1.9 microM) and CYP2C18 (IC(50) = 6.3 microM). Pre-incubation of microsomes with usnic acid did not afford any evidence of time-dependent inhibition of CYP2C19, although evidence of slight time-dependent inhibition of CYP2C9 (K(I) = 2.79 microM and K(inact) = 0.022 min(-1)) was obtained. In vitro data were used with SimCYP(R)to model potential drug interactions. Based on usnic acid doses in case reports of 450 mg to >1 g day(-1), these in vitro data indicate that usnic acid has significant potential to interact with other medications. Individual characteristics such as CYP1A induction status, co-administration of CYP1A2 inhibitors, UGT1A1 polymorphisms, and related hyperbilirubinaemias, or co-administration of low therapeutic index CYP2C substrates could work alone or in consort with other idiosyncrasy risk factors to increase the risk of adverse events and/or hepatotoxicity. Thus, usnic acid in nutritional supplements might be involved as both victim and/or perpetrator in clinically significant drug-drug interactions.

A pharmacokinetic study of etravirine (TMC125) co-administered with ranitidine and omeprazole in HIV-negative volunteers

AIMS

Etravirine is a next-generation non-nucleoside reverse transcriptase inhibitor (NNRTI) with activity against wild-type and NNRTI-resistant HIV. Proton pump inhibitors and H(2)-antagonists are frequently used in the HIV-negative-infected population, and drug-drug interactions have been described with other antiretrovirals. This study evaluated the effect of steady-state omeprazole and ranitidine on the pharmacokinetics of a single dose of etravirine.

METHODS

In an open-label, randomized, one-way, three-period crossover trial, HIV-negative volunteers randomly received a single dose of 100 mg etravirine alone (treatment A); 11 days of 150 mg ranitidine b.i.d. (treatment B); and 11 days of 40 mg omeprazole q.d. (treatment C). A single dose of 100 mg etravirine was co-administered on day 8 of sessions 2 and 3. Each session was separated by a 14-day wash-out.

RESULTS

Nineteen volunteers (seven female) participated. When a single dose of etravirine was administered in the presence of steady-state ranitidine, etravirine least squares means ratios (90% confidence interval) for AUC(last) and C(max) were 0.86 (0.76, 0.97) and 0.94 (0.75, 1.17), respectively, compared with administration of etravirine alone. When administered with steady-state omeprazole, these values were 1.41 (1.22, 1.62) and 1.17 (0.96, 1.43), respectively. Co-administration of a single dose of etravirine and ranitidine or omeprazole was generally safe and well tolerated.

CONCLUSIONS

Ranitidine slightly decreased etravirine exposure, whereas omeprazole increased it by approximately 41%. The increased exposure of etravirine when co-administered with omeprazole is attributed to CYP2C19 inhibition. Considering the favourable safety profile of etravirine, these changes are not clinically relevant. Etravirine can be co-administered with proton pump inhibitors and H(2) antagonists without dose adjustments.

Proton pump inhibitors: an update of their clinical use and pharmacokinetics

BACKGROUND

Proton pump inhibitors (PPIs) represent drugs of first choice for treating peptic ulcer, Helicobacter pylori infection, gastrooesophageal reflux disease, nonsteroidal anti-inflammatory drug (NSAID)-induced gastrointestinal lesions (complications), and Zollinger-Ellison syndrome.

RESULTS

The available agents (omeprazole/esomeprazole, lansoprazole, pantoprazole, and rabeprazole) differ somewhat in their pharmacokinetic properties (e.g., time-/dose-dependent bioavailability, metabolic pattern, interaction potential, genetic variability). For all PPIs, there is a clear relationship between drug exposure (area under the plasma concentration/time curve) and the pharmacodynamic response (inhibition of acid secretion). Furthermore, clinical outcome (e.g., healing and eradication rates) depends on maintaining intragastric pH values above certain threshold levels. Thus, any changes in drug disposition will subsequently be translated directly into clinical efficiency so that extensive metabolizers of CYP2C19 will demonstrate a higher rate of therapeutic nonresponse.

CONCLUSIONS

This update of pharmacokinetic, pharmacodynamic, and clinical data will provide the necessary guide by which to select between the various PPIs that differ-based on pharmacodynamic assessments-in their relative potencies (e.g., higher doses are needed for pantoprazole and lansoprazole compared with rabeprazole). Despite their well-documented clinical efficacy and safety, there is still a certain number of patients who are refractory to treatment with PPIs (nonresponder), which will leave sufficient space for future drug development and clinical research.

Efficacy and safety of pantoprazole 20 mg once daily treatment in patients with ulcer-like functional dyspepsia

OBJECTIVE

To investigate the efficacy of pantoprazole 20 mg once daily (o.d.) in relieving epigastric pain associated with ulcer-like functional dyspepsia.

RESEARCH DESIGN AND METHODS

In this double-blind, placebo-controlled, multicentre study, patients experiencing ulcer-like functional dyspepsia, with epigastric pain as the predominant symptom, were randomised to receive pantoprazole 20 mg or placebo o.d. for 28 days. Primary endpoint was the complete relief (i.e. absence) from epigastric pain after 28 days' treatment. The odds ratio (OR) for pantoprazole/placebo and its 95% confidence intervals (CIs) were determined. Significant superiority of pantoprazole was concluded if the value 1.0 was above this interval.

RESULTS

Of 419 patients (intention-to-treat [ITT]) randomised to treatment, 207 received pantoprazole and 212 received placebo. Epigastric pain relief was achieved after 28 days' treatment in 55% of pantoprazole recipients and 45% of placebo recipients (per-protocol [PP]: 58% and 47%, respectively). Pantoprazole demonstrated statistically significant superiority compared with placebo in the ITT (OR: 0.68; 95% CI: 0.46-0.99) and PP populations (OR: 0.64; 95% CI: 0.42-0.98). Pantoprazole was more efficacious than placebo in relieving heartburn and acid regurgitation after 7, 14 and 28 days of treatment. The sum score of gastrointestinal symptoms after 28 days was statistically significantly lower in the pantoprazole than placebo group. Fewer patients receiving concomitant psychotropic medication experienced relief from epigastric pain than those not receiving such medication. Adverse events did not significantly differ between pantoprazole and placebo.

CONCLUSIONS

Results of this study suggest that pantoprazole 20 mg is more efficacious than placebo, and is a well-tolerated treatment for relieving epigastric pain in patients with ulcer-like functional dyspepsia. Further research is needed to confirm these findings.

Clinical efficacy of esomeprazole in the prevention and healing of gastrointestinal toxicity associated with NSAIDs in elderly patients

NSAIDs are widely prescribed for the treatment of pain, inflammation and rheumatic disorders, but their use is associated with adverse gastrointestinal effects, ranging from dyspeptic symptoms and peptic ulcers to more serious complications. Elderly patients are at high risk of experiencing NSAID-induced gastrointestinal tract injury and should be considered candidates for prophylactic pharmacological therapy. In studies conducted in adult patients, proton pump inhibitors (PPIs) such as esomeprazole have been shown to prevent or reduce NSAID-induced gastrointestinal injury. The beneficial effects of esomeprazole can be ascribed largely to its ability to maintain sustained inhibition of gastric acid secretion, although there is evidence to suggest that pharmacodynamic properties unrelated to acid inhibition may also contribute to the gastroprotective effects of this agent. Although there are limited data on the use of esomeprazole specifically in elderly patient populations, studies of patients at high risk of NSAID-induced gastrointestinal toxicity because of advanced age indicate that this PPI is both effective and well tolerated when administered in conjunction with NSAIDs. Thus, esomeprazole can be regarded as a useful option for prophylactic therapy in elderly patients receiving long-term NSAID therapy.

Comparison of esomeprazole enteric-coated capsules vs esomeprazole magnesium in the treatment of active duodenal ulcer: A randomized, double-blind, controlled study

AIM: To evaluate the efficacy and tolerability of two different preparations of esomeprazole in healing duodenal ulcers.

METHODS: A total of 60 patients with active duodenal ulcers were enrolled and randomized to receive esomeprazole enteric-coated capsules (40 mg) or esomeprazole magnesium (40 mg), once daily, for 4 consecutive wk, with ulcer healing being monitored by endoscopy. Safety and tolerability were also assessed.

RESULTS: Fifty seven patients completed the whole trial. The ulcer healing rates at the end of wk 2 were 86.7% and 85.2% in the esomeprazole enteric-coated capsules and esomeprazole magnesium groups, respectively (P = 0.8410), and reached 100% at the end of wk 4 in both groups. Symptom relief at the end of wk 2 was 90.8% in the esomeprazole enteric-coated capsules group and 86.7% in the esomeprazole magnesium group (P = 0.5406); at the end of wk 4 symptom relief was 95.2% and 93.2%, respectively (P = 0.5786). Adverse events occurred in 16.7% of the esomeprazole enteric-coated capsules group and 14.8% of the esomeprazole magnesium group (P = 1.0000).

CONCLUSION: The efficacies of esomeprazole enteric-coated capsules and esomeprazole magnesium in healing duodenal ulcer lesions and relieving gastrointestinal symptoms are equivalent. The tolerability and safety of both drugs were comparable.

Comparison of four proton pump inhibitors for the short-term treatment of esophagitis in elderly patients

AIM

To compare efficacy and tolerability of four proton pump inhibitors (PPIs) commonly used in the short-term therapy of esophagitis in elderly patients.

METHODS

A total of 320 patients over 65 years with endoscopically diagnosed esophagitis were randomly assigned to one of the following treatments for 8 wk: (1) omeprazole 20 mg/d; (2) lansoprazole 30 mg/d; (3) pantoprazole 40 mg/d, or (4) rabeprazole 20 mg/d. Major symptoms, compliance, and adverse events were recorded. After 8 wk, endoscopy and clinical evaluation were repeated.

RESULTS

Per protocol and intention to treat healing rates of esophagitis were: omeprazole = 81.0% and 75.0%, lansoprazole = 90.7% (P = 0.143 vs omeprazole) and 85.0%, pantoprazole = 93.5% (P = 0.04 vs omeprazole) and 90.0% (P = 0.02 vs omeprazole), rabeprazole = 94.6% (P = 0.02 vs omeprazole) and 88.8% (P = 0.04 vs omeprazole). Dividing patients according to the grades of esophagitis, omeprazole was significantly less effective than the three other PPIs in healing grade 1 esophagitis (healing rates: 81.8% vs 100%, 100% and 100%, respectively, P = 0.012). Pantoprazole and rabeprazole (100%) were more effective vs omeprazole (89.6%, P = 0.0001) and lansoprazole (82.4%, P = 0.0001) in decreasing heartburn. Pantoprazole and rabeprazole (92.2% and 90.1%, respectively) were also more effective vs lansoprazole (75.0%, P < 0.05) in decreasing acid regurgitation. Finally, pantoprazole and rabeprazole (95.2% and 100%) were also more effective vs lansoprazole (82.6%, P < 0.05) in decreasing epigastric pain.

CONCLUSION

In elderly patients, pantoprazole and rabeprazole were significantly more effective than omeprazole in healing esophagitis and than omeprazole or lansoprazole in improving symptoms. H pylori infection did not influence the healing rates of esophagitis after a short-term treatment with PPI.

Long-term management of gastroesophageal reflux disease with pantoprazole

Gastroesophageal reflux disease (GERD) is a chronic, relapsing disease that can progress to major complications. Affected patients have poorer health-related quality of life than the general population. As GERD requires continued therapy to prevent relapse and complications, most patients with erosive esophagitis require long-term acid suppressive treatment. Thus GERD results in a significant cost burden and poor health-related quality of life. The effective treatment of GERD provides symptom resolution and high rates of remission in erosive esophagitis, lowers the incidence of GERD complications, improves health-related quality of life, and reduces the cost of this disease. Proton pump inhibitors are accepted as the most effective initial and maintenance treatment for GERD. Oral pantoprazole is a safe, well tolerated and effective initial and maintenance treatment for patients with nonerosive GERD or erosive esophagitis. Oral pantoprazole has greater efficacy than histamine H(2)-receptor antagonists and generally similar efficacy to other proton pump inhibitors for the initial and maintenance treatment of GERD. In addition, oral pantoprazole has been shown to improve the quality of life of patients with GERD and is associated with high levels of patient satisfaction with therapy. GERD appears to be more common and more severe in the elderly, and pantoprazole has shown to be an effective treatment for this at-risk population.