Drug interaction studies with esomeprazole, the (S)-isomer of omeprazole

Estimation of CDK inhibitors by RP-HPLC: application for pharmacokinetic interactions studies with PPIs

Background: The study investigated pharmacokinetic interactions between palbociclib and ribociclib with proton pump inhibitors (PPIs) using the reverse-phase high-performance liquid chromatography (RP-HPLC) method.Methods: Developed RP-HPLC method quantified palbociclib and ribociclib in biological matrices. In vitro metabolic stability assays and in vivo studies in rats evaluated effect of omeprazole and esomeprazole on pharmacokinetics of palbociclib and ribociclib.Results: The RP-HPLC method was sensitive, accurate and linear. Esomeprazole and omeprazole decreased metabolic clearance of palbociclib and ribociclib by several folds. In vivo, esomeprazole elevated Cmax of palbociclib and ribociclib by 90.1% and 86.4%, whereas omeprazole reduced it by 32.0% and 16.8%, respectively.Conclusion: The RP-HPLC method was used to analyze in vitro and in vivo samples. Long-term treatment with PPIs affects pharmacokinetics of palbociclib and ribociclib, necessitating optimal chemotherapy regimen.

Assessing and mitigating pH-mediated DDI risks in drug development - formulation approaches and clinical considerations

pH-mediated drug-drug interactions (DDI) is a prevalent DDI in drug development, especially for weak base compounds with highly pH-dependent solubility. FDA has released a guidance on the evaluation of pH-mediated DDI assessments using in vitro testing and clinical studies. Currently, there is no common practice of ways of testing across the academia and industry. The development of biopredictive method and physiologically-based biopharmaceutics modeling (PBBM) approaches to assess acid-reducing agent (ARA)-DDI have been proven with accurate prediction and could decrease drug development burden, inform clinical design and potentially waive clinical studies. Formulation strategies and careful clinical design could help mitigate the pH-mediated DDI to avoid more clinical studies and label restrictions, ultimately benefiting the patient. In this review paper, a detailed introduction on biorelevant dissolution testing, preclinical and clinical study requirement and PBPK modeling approaches to assess ARA-DDI are described. An improved decision tree for pH-mediated DDI is proposed. Potential mitigations including clinical or formulation strategies are discussed.

Evaluation of CYP2C19-Mediated Pharmacokinetic Drug Interaction of Tegoprazan, Compared with Vonoprazan or Esomeprazole

BACKGROUND AND OBJECTIVE

CYP2C19-mediated drug interactions of acid-reducing agents are clinically important given the high possibility of concomitant administration with CYP2C19 substrates. This study aimed to evaluate the effect of tegoprazan on the pharmacokinetics (PK) of a CYP2C19 substrate, proguanil, compared with vonoprazan or esomeprazole.

METHODS

A two-part, randomized, open-label, two-sequence, three-period crossover study was conducted in 16 healthy CYP2C19 extensive metabolizers (eight subjects per part). In each period, a single oral dose of atovaquone/proguanil 250/100 mg was administered alone or co-administered with tegoprazan 50 mg, esomeprazole 40 mg (Part 1 only) or vonoprazan 20 mg (Part 2 only). The plasma and urine concentrations of proguanil and its metabolite, cycloguanil, were measured up to 48 h post-dose. PK parameters were calculated using a non-compartmental method and compared between administered alone and co-administered with tegoprazan, vonoprazan or esomeprazole.

RESULTS

Co-administration of tegoprazan did not significantly affect the systemic exposure of proguanil and cycloguanil. In contrast, co-administration of vonoprazan or esomeprazole increased proguanil systemic exposure and decreased cycloguanil systemic exposure, and the magnitude of the corresponding change was greater with esomeprazole co-administration than vonoprazan co-administration.

CONCLUSION

Tegoprazan, unlike vonoprazan and esomeprazole, exhibited negligible CYP2C19-mediated PK interaction. It suggests that as an alternative to other acid-reducing agents, tegoprazan can be used concomitantly with CYP2C19 substrates in clinical settings.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT04568772 (Registered on September 29, 2020).

Evaluation of the pharmacokinetics of trazpiroben (TAK-906) in the presence and absence of the proton pump inhibitor esomeprazole

Trazpiroben, a dopamine D2 /D3 receptor antagonist under development to treat gastroparesis, displays decreasing solubility with increasing pH. This single-sequence, open-label, two-period, crossover study evaluated the effect of esomeprazole, a proton pump inhibitor that raises gastric pH, on the single-dose pharmacokinetics, safety, and tolerability of trazpiroben in healthy adults (NCT03849690). In total, 12 participants were enrolled and entered period 1 (days 1-3), receiving a single oral dose of trazpiroben 25 mg on day 1. After a 4-day washout, participants then entered period 2 (days 8-13) and received esomeprazole 40 mg once daily on days 8-12, with a single oral dose of trazpiroben 25 mg co-administered 1 h post esomeprazole dosing on day 11. Geometric mean area under the curve from time 0 extrapolated to infinity (AUC∞ ) and maximum plasma concentration (Cmax ) values were generally similar when trazpiroben was administered alone versus alongside esomeprazole (AUC∞ , 44.03 vs. 38.85 ng h/ml; Cmax , 19.76 vs. 17.24 ng/ml). Additionally, the associated geometric mean ratio (GMR; co-administration: administration alone) 90% confidence intervals (CIs) suggested no clinically meaningful difference between treatment groups (AUC∞ , GMR 0.88, 90% CI 0.78-1.00; Cmax , 0.87, 90% CI 0.70-1.09). Mean apparent first-order terminal elimination half-life values were similar between treatments, illustrating co-administration with esomeprazole had minimal effect on trazpiroben elimination. Trazpiroben was well-tolerated in healthy adults following administration alone and alongside esomeprazole, with no clinically relevant adverse events reported. The lack of evidence of any clinically meaningful drug-drug interaction supports the co-administration of esomeprazole with trazpiroben.

Pharmacokinetics of Esomeprazole in Critically Ill Patients

Background

Esomeprazole, a potent proton pump inhibitor (PPI), is widely used for the prevention of stress ulcers in intensive care unit (ICU) patients.

Objective

This study investigates the pharmacokinetics (PK) of esomeprazole in critically ill patients.

Methods

The study included eligible adult ICU patients who received endotracheal intubation assisted mechanical ventilation for more than 48 h and had at least an extra risk factor for stress ulcers. All enrolled patients received once-daily intravenous (IV) esomeprazole 40 mg. After the first dose of esomeprazole was administrated, serial blood samples were collected at 3, 5, 15, 30 min and 1, 2, 4, 6, 8, and 10 h. The total sample concentrations of esomeprazole were measured by UPLC-MS/MS. Esomeprazole PK parameters were analyzed using noncompartmental analysis.

Results

A total of 30 patients were evaluable. Mean age and body mass index (BMI) were 61.97 years and 23.14. PK sampling on the first dose resulted in the following median (IQR) parameters: AUC_0−∞ 8.06 (6.65–9.47) mg·h/L; MRT_0−∞ 4.70 (3.89–5.51) h; t_1/2 3.29 (2.7–3.87) h; V 24.89 (22.09–27.69) L; CL 6.13 (5.01–7.26) L/h; and C_max 2.56 (2.30–2.82) mg/L.

Conclusions

According to the label of esomeprazole, our study showed different esomeprazole PK parameters in ICU patients compared with healthy volunteers. Esomeprazole has unique pharmacokinetic parameters in critically ill patients.

Caffeine-clozapine interaction associated with severe toxicity and multiorgan system failure: a case report

BACKGROUND

Caffeine is a known inhibitor of Clozapine metabolism mediated by inhibition of CYP1A2. Hitherto, the effects of caffeine on Clozapine levels have always been modest, as have the clinical manifestations of toxicity resulting from their interaction. We present a case of severe toxicity associated with the co-consumption of caffeine and Clozapine culminating in life-threatening complications requiring management in Intensive Care.

CASE PRESENTATION

A 34 year old male with a history of chronic schizophrenia, who had been managed stably on 400 mg Clozapine for the previous 5 years, changed his dietary behaviour and began consuming caffeine-containing energy drinks over the course of 3 weeks. The total daily dose of caffeine was estimated as 600 mg/day (four cans of Red Bull). He subsequently presented to the Emergency Department with life-threatening Clozapine toxicity, resulting in a decreased level of consciousness, severe metabolic acidosis, acute respiratory failure, raised inflammatory markers and acute renal failure attributed to interstitial nephritis. Maximum recorded Clozapine level was 1796 ng/ml.

CONCLUSIONS

This case describes the interaction between a common caffeine-containing beverage and a commonly prescribed antipsychotic medication, associated with severe adverse effects. We call for clinical and scientific attention to the possible interaction between these substances and draw attention to the implications for prescribing practices and patient counselling.

Exploring the Effect of Esomeprazole on Gastric and Duodenal Fluid Volumes and Absorption of Ritonavir

Proton-pump inhibitors (PPIs), frequently prescribed to lower gastric acid secretion, often exert an effect on the absorption of co-medicated drug products. A previous study showed decreased plasma levels of the lipophilic drug ritonavir after co-administration with the PPI Nexium (40 mg esomeprazole), even though duodenal concentrations were not affected. The present study explored if a PPI-induced decrease in gastrointestinal (GI) fluid volume might contribute to the reduced absorption of ritonavir. In an exploratory cross-over study, five volunteers were given a Norvir tablet (100 mg ritonavir) orally, once without PPI pre-treatment and once after a three-day pre-treatment with the PPI esomeprazole. Blood samples were collected for eight hours to assess ritonavir absorption and magnetic resonance imaging (MRI) was used to determine the gastric and duodenal fluid volumes during the first three hours after administration of the tablet. The results confirmed that PPI intake reduced ritonavir plasma concentrations by 40%. The gastric residual volume and gastric fluid volume decreased by 41% and 44% respectively, while the duodenal fluid volume was reduced by 33%. These data suggest that the PPI esomeprazole lowers the available fluid volume for dissolution, which may limit the amount of ritonavir that can be absorbed. Although additional factors may play a role, the effect of PPI intake on the GI fluid volume should be considered when simulating the absorption of poorly soluble drugs like ritonavir in real-life conditions.

The number and kind of antiepileptics affect propofol dose requirement for anesthesia: observational study

The propofol dose requirement and the emergence time are affected by antiepileptic use. The effects on anesthesia of the number and kind of antiepileptic agents have not been reported. We investigated the relationship between the kind and number of antiepileptic agents and the propofol dose requirement for anesthesia and emergence time in intravenous general anesthesia for dental treatment for patients with neurological disorders. We studied 247 patients with neurological disorders who underwent dental treatment under intravenous general anesthesia. Patients were categorized according to the number of antiepileptics (none, single agent, two kinds, and three or more kinds of antiepileptics) and the kind of antiepileptic (carbamazepine, valproate, phenobarbital, phenytoin, zonisamide, clobazam, or topiramate) being received. The propofol dose requirement for anesthesia, emergence time, and predicted blood propofol concentration at emergence were evaluated. Patients on three or more kinds of antiepileptics had significantly lower propofol dose requirement (reduction in 25%, compare with no use) and predicted blood propofol concentration at emergence (reduction in 41%) and significantly longer emergence time (extension in 50%) (P < 0.05). Valproate and clobazam reduced the propofol dose (valproate 9% and clobazam 19%) and predicted blood propofol concentration at emergence (valproate 18% and clobazam 33%), while phenobarbital increased these parameters (30% and 125%) (P < 0.05). The number and kind of antiepileptics effects propofol dose requirement. In particular, valproate and clobazam reduce the propofol dose requirement, while phenobarbital increases this.Clinical trial registration UMIN No. UMIN000014179.

In Vitro Assessment of Potential for CYP-Inhibition-Based Drug-Drug Interaction Between Vonoprazan and Clopidogrel

BACKGROUND AND OBJECTIVES

It was recently proposed that CYP-mediated drug-drug interactions (DDIs) of vonoprazan with clopidogrel and prasugrel can attenuate the antiplatelet actions of the latter two drugs. Clopidogrel is metabolized to the pharmacologically active metabolite H4 and its isomers by multiple CYPs, including CYP2C19 and CYP3A4. Therefore, to investigate the possibility of CYP-based DDIs, in vitro metabolic inhibition studies using CYP probe substrates or radiolabeled clopidogrel and human liver microsomes (HLMs) were conducted in this work.

METHODS

Reversible inhibition studies focusing on the effects of vonoprazan on CYP marker activities and the formation of the [¹⁴C]clopidogrel metabolite H4 were conducted with and without pre-incubation using HLMs. Time-dependent inhibition (TDI) kinetics were also measured.

RESULTS

It was found that vonoprazan is not a significant direct inhibitor of any CYP isoforms (IC₅₀ ≥ 16 μM), but shows the potential for TDI of CYP2B6, CYP2C19, and CYP3A4/5. This TDI was weaker than the inhibition induced by the corresponding reference inhibitors ticlopidine, esomeprazole, and verapamil, based on the measured potencies (k_inact/K_I ratio and the R2 value). In a more direct in vitro experiment, vonoprazan levels of up to 10 µM (a 100-fold higher concentration than the plasma C_max of 75.9 nM after taking 20 mg once daily for 7 days) did not suppress the formation of the active metabolite H4 or other oxidative metabolites of [¹⁴C]clopidogrel in a reversible or time-dependent manner. Additionally, an assessment of clinical trials and post-marketing data suggested no evidence of a DDI between vonoprazan and clopidogrel.

CONCLUSIONS

The body of evidence shows that the pharmacodynamic DDI reported between vonoprazan and clopidogrel is unlikely to be caused by the inhibition of CYP2B6, CYP2C19, or CYP3A4/5 by vonoprazan.

Pantoprazole Does Not Reduce the Antiplatelet Effect of Clopidogrel: A Randomized Controlled Trial in Korea

Background/Aims

Concerns that proton pump inhibitors (PPIs) diminish the efficacy of clopidogrel could hamper the appropriate prescription of PPIs. We evaluated the influence of pantoprazole on the antiplatelet effect of clopidogrel compared with ranitidine, which is regarded as safe, after stratification of the population according to the presence of a cytochrome (CYP) 2C19 polymorphism in Korea.

Methods

Forty patients who underwent dual antiplatelet therapy were randomized to receive pantoprazole (n=20) or ranitidine (n=20). Platelet aggregation was evaluated by impedance aggregometry at baseline (D0) and 8 days after acid-lowering treatments (D9). CYP2C19 was genotyped by polymerase chain reaction restriction fragment length polymorphism.

Results

After co-treatment, the percentage of clopidogrel low-response was 11.1% (2/18) in the pantoprazole group and 10.5% (2/19) in the ranitidine group (p=0.954). The impedance values with adenosine diphosphate stimulus after acid-lowering treatments did not significantly differ between the two groups. In a multiple regression analysis, only ST-elevation myocardial infarction was marginally associated with a reduced antiplatelet effect (odds ratio, 12.07; 95% confidence interval, 0.84 to 173.78). However, pantoprazole use did not affect the antiplatelet effect after correction for the CYP2C19 polymorphism.

Conclusions

This study showed that pantoprazole does not increase platelet aggregation in patients receiving dual antiplatelet therapy (ClinicalTrials.gov number: NCT02733640).

The Gastric and Intestinal Microbiome: Role of Proton Pump Inhibitors

PURPOSE OF REVIEW

The discovery of Helicobacter pylori and other organisms colonizing the stomach and the intestines has shed some light on the importance of microbiome in maintaining overall health and developing pathological conditions when alterations in biodiversity are present. The gastric acidity plays a crucial role in filtering out bacteria and preventing development of enteric infections. In this article, we discuss the physiology of gastric acid secretion and bacterial contribution to the composition of gastric and intestinal barriers and review the current literature on the role of proton pump inhibitors (PPIs) in the microbial biodiversity of the gastrointestinal tract.

RECENT FINDINGS

Culture-independent techniques, such as 16S rRNA sequencing, have revolutionized our understanding of the microbial biodiversity in the gastrointestinal tract. Luminal and mucosa-associated microbial populations are not identical. Streptococcus is overrepresented in the biopsies of patients with antral gastritis and may also be responsible for the development of peptic ulcer disease. The use of PPIs favors relative streptococcal abundance irrespective of H. pylori status and may explain the persistence of dyspeptic symptoms in patients on PPI therapy. Increased risk of enteric infections has also been seen in patients taking PPIs. The overuse of PPIs leads to significant shift of the gastrointestinal microbiome towards a less healthy state. With the advent of PPIs, many studies have demonstrated the significant changes in the microbial composition of both gastric and intestinal microbiota. Although they are considered relatively safe over-the-counter medications, PPIs in many cases are over- and even inappropriately used. Future studies assessing the safety of PPIs and their role in the development of microbiome changes should be encouraged.

Risk of seizure associated with use of acid-suppressive drugs: An observational cohort study

OBJECTIVES

Previous, large, prescription-event monitoring studies in patients receiving PPI therapy recorded instances of convulsion or seizure. The objective of this study was to quantify the relative risk of seizure associated with the use of proton pump inhibitors (PPIs) and histamine-2 receptor antagonists (H2RAs) in a general population, overall and stratified by epilepsy status, and to determine the effects of demographics and comorbidities.

METHODS

In this observational study (NCT01744301), patients aged 20-84years in the study period from 1 January 2005 to 31 December 2011 were identified from The Health Improvement Network. In a nested case-control analysis, 8605 patients with seizure were matched to 40000 controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using logistic regression.

RESULTS

After adjustment, there were no associations between current PPI use and seizure risk in the overall population (OR: 1.05; 95% CI: 0.87-1.27), the subcohort with epilepsy (OR: 0.87; 95% CI: 0.49-1.53), and the subcohort without epilepsy (OR: 1.05; 95% CI: 0.87-1.28). There were no associations between current H2RA use and seizure risk in the overall population (OR: 1.16; 95% CI: 0.62-2.18) and the subcohort without epilepsy (OR: 1.02; 95% CI: 0.51-2.01). Seizures were less frequent in women than in men. Dementia/psychosis, anxiety, depression, and use of anxiolytics, antidepressants, and paracetamol were associated with an increased seizure risk.

CONCLUSIONS

Our study revealed that the use of PPIs and the use of H2RAs were not associated with an increased risk of seizures in the overall population or in the cohorts stratified by epilepsy status.

Effect of esomeprazole, a proton pump inhibitor on the pharmacokinetics of sonidegib in healthy volunteers

AIMS

This study aimed to evaluate the impact of esomeprazole on the pharmacokinetics of sonidegib.

METHODS

This Phase I study evaluated the impact of the proton pump inhibitor (PPI) esomeprazole on the oral absorption and pharmacokinetics (PKs) of a single dose of sonidegib under fasted conditions. A total of 42 healthy subjects were enrolled to receive either sonidegib alone (200 mg single dose) or sonidegib in combination with esomeprazole (40 mg pre-treatment 5 days and combination were given on day 6). Primary PK parameters assessed in the study were area under the concentration-time curve (AUC) from 0-14 days and 0-7 days and maximum observed plasma concentration (Cmax ).

RESULTS

The plasma exposure (AUC0-14d, AUC0-7d and Cmax ) of a single 200 mg oral dose of sonidegib was decreased by 32-38% when sonidegib was co-administered with esomeprazole compared with sonidegib alone, with no apparent change in elimination slope and tmax . Baseline gastric pH was similar between the two arms.

CONCLUSIONS

These results suggest a modest reduction in the extent of sonidegib absorption by esomeprazole. There was no obvious metabolic drug-drug interaction between the two agents. Both sonidegib and esomeprazole were well tolerated in the study population.

Rhabdomyolysis associated with single-dose intravenous esomeprazole administration: A case report

BACKGROUND

Proton pump inhibitors are usually safe, although serious adverse effects can occur. We report the first case of rhabdomyolysis associated with single-dose intravenous esomeprozole administration.

METHODS

A 45-year-old Korean male visited our emergency room because of persistent lower chest discomfort that started 10 hours before. He had been diagnosed with diabetes and coronary heart disease, but discontinued oral hypoglycemic agents 1 month earlier. He continued to take medications for coronary heart disease. There was no abnormality on an electrocardiogram or in cardiac enzymes. Initial laboratory findings did not show abnormalities for muscle enzymes. Esomeprozole 40 mg was administrated intravenously for the control of his ambiguous chest discomfort. Then, 12 hours later, he complained of abrupt severe right buttock pain. An area of tender muscle swelling 8 cm in diameter was seen on his right buttock area. Creatine kinase and lactate dehydrogenase were elevated to 40,538 and 1326 U/L, respectively. A bone scan using 20 mCi of Tc-hydroxymethylene diphosphonate was compatible with rhabdomyolysis.

RESULTS

His muscular symptoms, signs, and laboratory findings improved markedly with conservative management, including hydration and urine alkalinization. He is being followed in the outpatient department with no evidence of recurrence.

CONCLUSION

We should keep in mind that single-dose intravenous administration of esomeprazole can induce rhabdomyolysis.

Esomeprazole induced galactorrhea: a novel side effect

Proton pump inhibitors (PPIs) are one of the most frequently prescribed medications across the globe. Esomeprazole is the S-isomer of omeprazole, and it is currently the most widely prescribed PPI. The safety profile of esomeprazole is extremely favorable with only minor side effects, like headache and diarrhea, that are encountered in day to day practice. We report a case of a young female with symptoms of gastroesophageal reflux disease who developed galactorrhea after starting esomeprazole therapy. Resolution of galactorrhea after stopping the drug and self-rechallenge by the patient herself with reappearance of galactorrhea confirmed the culprit to be esomeprazole only. We postulate that esomeprazole may have a mild inhibitory effect on CYP3A4, which leads to decreased metabolism of estrogen, thereby increasing serum estrogen levels. Estrogen causes stimulation and production of prolactin release, which results in development of galactorrhea. This is the first case of esomeprazole induced galactorrhea, to the best of our knowledge.

Pharmacokinetic drug interaction profiles of proton pump inhibitors: an update

Proton pump inhibitors (PPIs) are used extensively for the treatment of gastric acid-related disorders, often over the long term, which raises the potential for clinically significant drug interactions in patients receiving concomitant medications. These drug–drug interactions have been previously reviewed. However, the current knowledge is likely to have advanced, so a thorough review of the literature published since 2006 was conducted. This identified new studies of drug interactions that are modulated by gastric pH. These studies showed the effect of a PPI-induced increase in intragastric pH on mycophenolate mofetil pharmacokinetics, which were characterised by a decrease in the maximum exposure and availability of mycophenolic acid, at least at early time points. Post-2006 data were also available outlining the altered pharmacokinetics of protease inhibitors with concomitant PPI exposure. New data for the more recently marketed dexlansoprazole suggest it has no impact on the pharmacokinetics of diazepam, phenytoin, theophylline and warfarin. The CYP2C19-mediated interaction that seems to exist between clopidogrel and omeprazole or esomeprazole has been shown to be clinically important in research published since the 2006 review; this effect is not seen as a class effect of PPIs. Finally, data suggest that coadministration of PPIs with methotrexate may affect methotrexate pharmacokinetics, although the mechanism of interaction is not well understood. As was shown in the previous review, individual PPIs differ in their propensities to interact with other drugs and the extent to which their interaction profiles have been defined. The interaction profiles of omeprazole and pantoprazole sodium (pantoprazole-Na) have been studied most extensively. Several studies have shown that omeprazole carries a considerable potential for drug interactions because of its high affinity for CYP2C19 and moderate affinity for CYP3A4. In contrast, pantoprazole-Na appears to have lower potential for interactions with other medications. Lansoprazole and rabeprazole also seem to have a weaker potential for interactions than omeprazole, although their interaction profiles, along with those of esomeprazole and dexlansoprazole, have been less extensively investigated. Only a few drug interactions involving PPIs are of clinical significance. Nonetheless, the potential for drug interactions should be considered when choosing a PPI to manage gastric acid-related disorders. This is particularly relevant for elderly patients taking multiple medications, or for those receiving a concomitant medication with a narrow therapeutic index.

Predictors of the clinical effects of pirfenidone on idiopathic pulmonary fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease with a poor prognosis. Recently, pirfenidone was reported to slow the rate of decline in vital capacity and improve progression-free survival in IPF. The purpose of this study was to clarify the factors that predicted a good response to pirfenidone, as well as its adverse effects.

METHODS

Forty-one IPF cases, treated with pirfenidone from January 2009 to January 2011, were enrolled in this investigation. Disease severity was classified into grades I-IV, as defined by the Japanese Respiratory Society (JRS). Short-term responsiveness to pirfenidone was evaluated by the modified criteria of the JRS. Predictors of nausea, anorexia, or both that represented important adverse effects were examined by multivariate Cox proportional hazard analyses. Predictors of short-time responsiveness were examined by multivariate logistic regression analyses.

RESULTS

Diagnosed by a surgical lung biopsy (SLB), the mild cases of grade I/II were predictors of good, short-term responsiveness. Patients taking acid-secretion inhibitors, including proton pump inhibitors and histamine H2-receptor antagonists, showed less anorexia, nausea, or both. Only 1 case was administered drugs to activate gastrointestinal motility.

CONCLUSIONS

We concluded that IPF patients with a mild disease, diagnosis by SLB, or both showed indications of a good response to pirfenidone. In addition, acid-secretion inhibitors may reduce the frequency of anorexia, nausea, or both from pirfenidone.

Esomeprazole and aspirin fixed combination for the prevention of cardiovascular events

Low dose aspirin therapy plays a fundamental role in both the primary and secondary prevention of cardiovascular events. Although the evidence using low dose aspirin for secondary prevention is well-established, the decision to use aspirin for primary prevention is based on an evaluation of the patient’s risk of cardiovascular events compared to their risk of adverse events, such as bleeding. In addition to the risk of bleeding associated with long term aspirin administration, upper gastrointestinal side effects, such as dyspepsia often lead to discontinuation of therapy, which places patients at an increased risk for cardiovascular events. One option to mitigate adverse events and increase adherence is the addition of esomeprazole to the medication regimen. This review article provides an evaluation of the literature on the concomitant use of aspirin and esomeprazole available through February 2013. The efficacy, safety, tolerability, cost effectiveness, and patient quality of life of this regimen is discussed. A summary of the pharmacokinetic and pharmacodynamic interactions between aspirin and esomeprazole, as well as other commonly used cardiovascular medications are also reviewed. The addition of esomeprazole to low dose aspirin therapy in patients at high risk of developing gastric ulcers for the prevention of cardiovascular disease, significantly reduced their risk of ulcer development. Pharmacokinetic and pharmacodynamic studies suggested that esomeprazole did not affect the pharmacokinetic parameters or the antiplatelet effects of aspirin. Therefore, for those patients who are at a high risk of developing a gastrointestinal ulcer, the benefit of adding esomeprazole likely outweighs the risks of longer term proton pump inhibitor use, and the combination can be recommended. Administering the two agents separately may also be more economical. On the other hand, for those patients at lower risk of developing a gastrointestinal ulcer, both the additional risk and cost make the inclusion of a proton pump inhibitor unwarranted.

Evaluation of the pharmacodynamics of acetylsalicylic acid 81 mg with or without esomeprazole 20 mg in healthy volunteers

BACKGROUND

The absence of a pharmacokinetic interaction between the proton pump inhibitor esomeprazole (40 mg) and acetylsalicylic acid (aspirin, ASA; 325 mg) has previously been established.

OBJECTIVE

This study set out to investigate the potential for pharmacodynamic interaction between low-dose ASA and esomeprazole in healthy volunteers, by measuring ASA antiplatelet activity.

STUDY DESIGN

This was a single-center, open-label, two-period, randomized crossover study.

PARTICIPANTS

Healthy male and female volunteers aged 18-75 years were included. All volunteers received ASA 81 mg once daily for 5 days prior to the study (pre-screen). Subjects were eligible for inclusion if they had aspirin reactivity units (ARU, as measured by the VerifyNow ASA assay) of <550 on Day 6.

INTERVENTION

After pre-screening and a washout period of at least 14 days, eligible volunteers received ASA 81 mg with or without esomeprazole 20 mg once daily for 5 days in randomized order, with a 14-day washout between treatments.

MAIN OUTCOME MEASURE

The main outcome measure was the antiplatelet activity of ASA, as assessed by ARU ratio relative to baseline in the VerifyNow ASA assay; suppression of serum thromboxane B(2) (TXB(2)) was a secondary endpoint. Statistical comparisons were made using linear mixed models.

RESULTS

A total of 29 volunteers (19 aged ≥50 years; 8 women; 21 men) were evaluable for pharmacodynamic analysis (per protocol). All volunteers on both treatments achieved ARU <550 at Day 6. The geometric mean ratio of Day 6 to Day 1 (baseline) platelet aggregation was 0.70 (95% confidence interval [CI] 0.68, 0.72) with ASA alone and 0.71 (95% CI 0.69, 0.74) with ASA + esomeprazole. The ratio of platelet aggregation (ASA + esomeprazole/ASA) was 1.02 (95% CI 0.99, 1.05). ASA administered alone or with esomeprazole reduced serum TXB(2) by more than 99.5%. The ratio of suppression of serum TXB(2) levels (ASA + esomeprazole/ASA) was 1.06 (95% CI 0.88, 1.29). The combination of ASA and esomeprazole was well tolerated.

CONCLUSION

No pharmacodynamic interaction between low-dose ASA and esomeprazole was found with regard to platelet function.

TRIAL REGISTRATION

Registered at ClinicalTrials. gov as NCT01199328.

Doubling the dose of clopidogrel restores the loss of antiplatelet effect induced by esomeprazole

INTRODUCTION

Concerns have been raised about the potential adverse interaction between clopidogrel and PPIs. We studied the impact of esomeprazole and ranitidine on the antiplatelet action of clopidogrel and aspirin and sought to determine whether doubling the dose of clopidogrel could restore its efficacy.

MATERIALS AND METHODS

In a randomized prospective crossover study, we tested platelet reactivity to aspirin and clopidogrel (75 and 150 mg) with and without esomeprazole or ranitidine using the VerifyNow system (Accumetrics Inc, San Diego, CA, USA) in 4 stages, each lasting 7 days: T1, 160 mg aspirin and 75 mg clopidogrel; T2 : 160 mg aspirin+75 mg clopidogrel+20 mg esomeprazole, T3 : 160 mg aspirin+150 mg clopidogrel+20 mg esomeprazole and T4 : 160 mg aspirin+75 mg clopidogrel+150 mg ranitidine. Results are expressed in P2Y12 Reaction Units (PRU%) and Aspirin Reaction Units (ARU).

RESULTS

In 21 patients with stable coronary artery disease, esomeprazole reduced the effect of clopidogrel with a 38.6%±24 loss in PRU% (p<0.001) (absolute mean difference -16.7 PRU% [-21;-12.5]), increasing 8-fold the prevalence of low responders to clopidogrel (defined as patients with PRU% below 20%). Doubling clopidogrel dosage to 150 mg restored the basal response. Ranitidine did not modify the antiplatelet effect of clopidogrel.

CONCLUSION

Our study demonstrates a strong negative clopidogrel/esomeprazole interaction, compensated by increasing the dose of clopidogrel to 150 mg or replacing esomeprazole with ranitidine. That could offer a simple solution to the PPI-induced clopidogrel resistance.

Effect of esomeprazole on the pharmacokinetics of carbamazepine

Objective:

Present study was carried out to evaluate effect of esomeprazole on the pharmacokinetics of carbamazepine in rabbits.

Materials and Methods:

Study was conducted at Department of Pharmacology, Postgraduate Institute of Medical Education and Research from March to October 2007. In a parallel design study, carbamazepine 40 mg/kg/day was given orally for 14 days. On day 15, blood samples were taken at various time intervals between 0 and 24 hours. In esomeprazole group, carbamazepine was administered for 14 days as above. On day 8, esomeprazole 2.8 mg/kg/day along with carbamazepine 40 mg/kg/day was administered till 14 days and blood samples were drawn on 15^th day. Plasma levels of carbamazepine were assayed by high-performance liquid chromatography and pharmacokinetic parameters were calculated.

Results:

In all groups there was a decrease in the AUC_0-24 when carbamazepine was coadministered with esomeprazole. The decrease in AUC_0-24 (22.78 ± 4.71 to 10.46 ± 2.29), C_max (2.76 ± 0.77 to 1.412±1.08), T_max (2.83 ± 0.17 to 3 ± 0.40) was statistically significant (P < 0.05) when esomeprazole was given along with carbamazepine. Additionally, absorption and elimination constant were also altered significantly.

Conclusions:

These results suggest that concomitant use of esomeprazole alters the pharmacokinetics of carbamazepine. Confirmation of these results in human studies will warrant changes in carbamazepine dose or frequency when esomeprazole is coadministered.

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.

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.

Esomeprazole: potent acid suppression in the treatment of acid-related disorders

Esomeprazole (S-omeprazole), an enantiomer of the racemate omeprazole, is the first proton pump inhibitor to be developed as an isomer. This confers improved pharmacokinetics and pharmacodynamics compared with the racemate R/S-omeprazole. The difference in the pharmacokinetics of esomeprazole compared with omeprazole and the R-isomer is due to reductions in total body clearance and first-pass metabolism in the liver. Pharmacodynamic studies showed that esomeprazole 40 mg provides greater intragastric acid control than respective doses of all the other proton pump inhibitors on the market. Several well-designed clinical trials, employing both endoscopic and symptomatic response criteria, have compared the efficacy of esomeprazole with that of other proton pump inhibitors in the management of gastroesophageal reflux disease patients, and in the eradication of Helicobacter pylori. In addition, the efficacy of esomeprazole for the healing and prevention of nonsteroidal anti-inflammatory drug-associated dyspeptic symptoms and ulcers has been established. The aim of this review is to provide an overview of the pharmacokinetics, pharmacodynamics and consequent clinical importance of esomeprazole in the treatment of acid-related disorders.

Transmucosal gastric leak induced by proton pump inhibitors

Despite their remarkable safety profile and lack of clinical side effects, proton pump inhibitors (PPIs) induce a transmucosal gastric leak to non-electrolyte probes of various sizes. The ex vivo addition of PPIs to isolated rat gastric corpus increases transmucosal permeability in a dose-dependent manner, which corresponds with PPIs' dose-dependent inhibition of acid secretion. Upon the addition of omeprazole, lansoprazole, or esomeprazole, a small decrease in transepithelial resistance and the concomitant stimulation of short circuit current was observed. Additionally, transepithelial flux of (14)C-[D]-mannitol (MW 182.17) across the gastric mucosa increased by a mean of 68% immediately following the addition of 200 microM omeprazole. This flux increase was bidirectional. Omeprazole also increased the paracellular permeability to larger radiolabeled probes, including (14)C-sucrose (MW 342.3) and (14)C-polyethylene glycol (MW 4,000) by 118% and 350%, respectively. However, the flux of still larger probes, 10,000 and 70,000 MW dextrans, was not increased. Because PPIs are so widely used and are assumed to be innocuous, this transmucosal gastric leak must be further investigated, as it may carry considerable biomedical implications.

Stress-induced ulcer bleeding in critically ill patients

Increased knowledge of risk factors and improved ICU care has decreased the incidence of stress-related bleeding. Not all critically ill patients need prophylaxis for SRMD and withholding such prophylaxis in suitable low-risk candidates is a reasonable and cost-effective approach. Mechanical ventilation for more than 48 hours and coagulopathy are the main risk factors for stress-induced upper GI bleeding. Although intravenous H2RAs can prevent clinically important bleeding, their benefits seem to be limited by the rapid development of tolerance. The availability of intravenous formulations of PPIs makes it possible to critically compare their prophylactic efficacy and safety to different classes of acid-suppressive agents, such as H2RAs, in critically ill patients. The appropriate dose of PPI and the role of newer PPI formulations need to be further defined along with proposed guidelines for the use of intravenous and oral/enteral formulations of PPIs in patients at risk for stress-related mucosal damage.

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.

Esomeprazole: a proton pump inhibitor

Proton pump inhibitors (PPIs) are the most potent inhibitors of gastric acid secretion available, and they are effective for treating all acid-related disorders. Esomeprazole is one of several most recent PPIs that became available to the market in 2001. Esomeprazole is indicated for the treatment of gastroesophageal reflux disease in adults and children, risk reduction of NSAIDs-associated gastric ulcer, Helicobacter pylori eradication and control of pathological hypersecretory conditions associated with Zollinger-Ellison syndrome. Esomeprazole is available in both oral and intravenous formulations. A number of studies have compared esomeprazole with other PPIs. While differences supporting esomeprazole have been reported, the magnitude of differences has been variable and of uncertain clinical importance. Cost plays a major role in prescribing patterns of PPIs.

Esomeprazole induces upper gastrointestinal tract transmucosal permeability increase

BACKGROUND

Proton pump inhibitors (PPIs) are one of the most widely used drug classes in the US and are now frontline medications for gastro-oesophageal reflux disease (GERD) and dyspepsia. In a previous work, we observed that a transmucosal, upper gastrointestinal (GI) leak exists in Barrett's oesophagus (BO) patients. PPI medications are commonly used by Barrett's patients.

AIM

To examine if the PPI, esomeprazole, affects the barrier function of the upper GI tract.

METHODS

The sucrose permeability test (SPT) was used to assess the possible effect of the PPI, esomeprazole, on upper GI leak in 37 first-time-presenting GERD patients and 25 healthy controls.

RESULTS

Esomeprazole induced a significant transmucosal leak in the upper GI tract of patients taking the drug for the first time. The leak occurred quickly, within days of first taking the drug. The leak was also reversed within days of stopping the medication.

CONCLUSIONS

This is the first patient-based study showing that a PPI compromises upper GI barrier function. There are potential implications for transmucosal leak of other medications that a patient on a PPI may be taking, as well as possible leak of endogenous peptides/proteins. The clinical consequences of this phenomenon are currently unknown, but are potentially important.

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.

Review article: The prevalence and clinical relevance of cytochrome P450 polymorphisms

BACKGROUND

Most drugs currently used in clinical practice are effective in only 25% to 60% of patients, while adverse drug reactions (ADRs) as a consequence of treatment are estimated to cost billions of US dollars and tens of thousands of deaths.

AIM

To review the prevalence and clinical significance of cytochrome P450 polymorphisms.

RESULTS

The cytochrome P450 enzyme families 1-3 are responsible for 70 to 80% of all phase I dependent drug metabolisms. In 90% metabolic activity dependents on six enzymes: CYP1A2, CYP3A, CYP2C9, CYP2C19, CYP2D6 and CYP2E1. Polymorphisms in the CYP450 gene can influence metabolic activity of the subsequent enzymes. A poor metabolizer (PM) has no or very poor enzyme activity. A consequence of PM is drug toxicity if no other metabolic route is available, or when multiple drugs are metabolized by the same cytochrome. In that case dose reduction is an option to prevent toxic effects.

CONCLUSIONS

In the future genotyping should be considered to identify patients who might be at risk of severe toxic responses, in order to guide appropriate individual dosage. Medical therapy should be a close cooperation between clinicians, pharmacologists and laboratory specialists, leading to reduced therapeutic errors, ADRs and health care costs.

Esomeprazole: prevention and treatment of NSAID-induced symptoms and ulcers

Non-steroidal anti-inflammatory drugs (NSAIDs) represent one of the most widely used drug classes. However, many patients complain of dyspeptic symptoms impairing their quality of life: ~ 20% of patients taking NSAIDs show endoscopic ulcers with or without symptoms, and up to 2% of chronic NSAID users will develop serious complications each year, such as bleeding or perforation, which are the cause of death in many patients. Coprescription of a proton pump inhibitor is one established option for the healing and prevention of NSAID-associated lesions of the upper gastrointestinal tract in patients at risk. Recent studies evaluated the clinical efficacy of esomeprazole in the management of gastrointestinal problems associated with the intake of selective and non-selective NSAIDs and aspirin.

[Clinical pharmacological aspects of the proton pump inhibitor therapy: importance of pharmacogenetic differences in the clinical practice]

Proton pump inhibitors (PPIs) are widely used for the treatment of gastroesophageal reflux disease, as well as other acid-related disorders. Omeprazole, lansoprazole, pantoprazole, rabeprazole and esomeprazole effectively suppress gastric acid secretion by blocking the gastric acid pump, H+/K+ -adenosine triphosphatase (ATPase). Understanding the pharmacokinetic properties of PPIs and examining the pharmacogenetic differences may help clinicians to optimize PPI therapy and to perform individual treatment, especially in non-responder patients with GERD or ulcer or after failed eradication therapy.

[Safety of proton pump inhibitors]

The significant inhibitory capacity of gastric acid secretion of PPIs makes them the drugs of choice for treating acid-related diseases. The considerable prevalence of these diseases and the need for maintaining the administration of the drug during considerably long periods results in this therapeutic group being one of the most widely used. However, in spite of their extensive use, there continue to emerge concerns about their potential toxicity; concerns surrounding the specificity of their mechanism of action and a consequential suspicion that something so potent must involve harmful effects. PPIs act selectively on the final stage of the process of gastric acid secretion, namely the H+/K+-ATPase or proton pump. This enzyme represents an essential step in the process of secretion of H+, and PPIs exert a very specific action on the parietal cell, as they need an environment with very low pH levels, which only exist in this cell. In the present article, the adverse effects of PPIs are reviewed, with special emphasis on those related to their continued administration and on the special circumstances of patients, as in the case of the elderly, those with liver failure, pregnant and breastfeeding mothers and children. All the PPIs on the market share a common chemical basis and there are no great differences in their potential adverse effects, the possibility of them promoting opportunist infections or their capacity to generate pharmacokinetic interactions with other drugs, which, if occur, are generally insignificant. After two decades of use, PPIs have proved to be very effective and safe drugs.

Gastrointestinal medications

Medications to address gastrointestinal disorders are among the most commonly dispensed somatic medications. The authors examine proton pump inhibitors, H(2) blockers, 5-HT(3) receptor-antagonists, and a few other drugs that are used to address this domain of medical concerns. The metabolic pathways, interactions with the P-glycoprotein transporter, and capabilities of inhibiting or inducing metabolic enzymes are elucidated for each drug. Specific drug-drug interactions with each agent are also detailed, including both psychotropic and non-psychotropic agents. Also, the article explores how different genotypic variants for specific cytochrome P450 enzymes have an impact on the effectiveness and likelihood of drug-drug interactions relating to specific gastro-intestinal medications.

Pharmacokinetic drug interaction profiles of proton pump inhibitors

Proton pump inhibitors are used extensively for the treatment of gastric acid-related disorders because they produce a greater degree and longer duration of gastric acid suppression and, thus, better healing rates, than histamine H(2) receptor antagonists. The need for long-term treatment of these disorders raises the potential for clinically significant drug interactions in patients receiving proton pump inhibitors and other medications. Therefore, it is important to understand the mechanisms for drug interactions in this setting. Proton pump inhibitors can modify the intragastric release of other drugs from their dosage forms by elevating pH (e.g. reducing the antifungal activity of ketoconazole). Proton pump inhibitors also influence drug absorption and metabolism by interacting with adenosine triphosphate-dependent P-glycoprotein (e.g. inhibiting digoxin efflux) or with the cytochrome P450 (CYP) enzyme system (e.g. decreasing simvastatin metabolism), thereby affecting both intestinal first-pass metabolism and hepatic clearance. Although interactions based on the change of gastric pH are a group-specific effect and thus may occur with all proton pump inhibitors, individual proton pump inhibitors differ in their propensities to interact with other drugs and the extent to which their interaction profiles have been defined. The interaction profiles of omeprazole and pantoprazole have been studied most extensively. A number of studies have shown that omeprazole carries a considerable potential for drug interactions, since it has a high affinity for CYP2C19 and a somewhat lower affinity for CYP3A4. In contrast, pantoprazole appears to have lower potential for interactions with other medications. Although the interaction profiles of esomeprazole, lansoprazole and rabeprazole have been less extensively investigated, evidence suggests that lansoprazole and rabeprazole seem to have a weaker potential for interactions than omeprazole. Although only a few drug interactions involving proton pump inhibitors have been shown to be of clinical significance, the potential for drug interactions should be taken into account when choosing a therapy for gastric acid-related disorders, especially for elderly patients in whom polypharmacy is common, or in those receiving a concomitant medication with a narrow therapeutic index.

Therapeutic Drug Monitoring and Pharmacogenetic Tests as Tools in Pharmacovigilance

Therapeutic drug monitoring (TDM) and pharmacogenetic tests play a major role in minimising adverse drug reactions and enhancing optimal therapeutic response. The response to medication varies greatly between individuals, according to genetic constitution, age, sex, co-morbidities, environmental factors including diet and lifestyle (e.g. smoking and alcohol intake), and drug-related factors such as pharmacokinetic or pharmacodynamic drug-drug interactions. Most adverse drug reactions are type A reactions, i.e. plasma-level dependent, and represent one of the major causes of hospitalisation, in some cases leading to death. However, they may be avoidable to some extent if pharmacokinetic and pharmacogenetic factors are taken into consideration. This article provides a review of the literature and describes how to apply and interpret TDM and certain pharmacogenetic tests and is illustrated by case reports. An algorithm on the use of TDM and pharmacogenetic tests to help characterise adverse drug reactions is also presented. Although, in the scientific community, differences in drug response are increasingly recognised, there is an urgent need to translate this knowledge into clinical recommendations. Databases on drug-drug interactions and the impact of pharmacogenetic polymorphisms and adverse drug reaction information systems will be helpful to guide clinicians in individualised treatment choices.

Safety of potent gastric acid inhibition

The proton pump inhibitors are a very effective drug group for the control of gastric acid secretion, which makes them of great use in the medical practice setting, while at the same time they represent one of the treatment groups widely used in Western European countries. These factors lead to this drug group being prescribed in all age populations, quite often in polymedicated patients and with pluripathology, and on many occasions during prolonged periods of time. All these determinant factors sometimes make the safety profile of proton pump inhibitors disputable. In this respect all of them have been shown to have little adverse events and are safe in long-term treatment. The risk of drug interactions when prescribed in association with other drugs is low and their repercussion in the medical practice setting is quite exceptional as they require few dosage adjustments in patients with severe concomitant diseases and in elderly patients. Finally, their safety is high in pregnant women and in children, although further studies in this population are required to corroborate this evidence.