Pharmacokinetics of orally administered omeprazole in children. International Pediatric Omeprazole Pharmacokinetic Group

Management of Helicobacter pylori infection in paediatric patients in Europe: results from the EuroPedHp Registry

Purpose

The EuroPedHp-registry aims to monitor guideline-conform management, antibiotic resistance, and eradication success of 2-week triple therapy tailored to antibiotic susceptibility (TTT) in Helicobacter pylori-infected children.

Methods

From 2017 to 2020, 30 centres from 17 European countries reported anonymized demographic, clinical, antibiotic susceptibility, treatment, and follow-up data. Multivariable logistic regression identified factors associated with treatment failure.

Results

Of 1605 patients, 873 had follow-up data (53.2% female, median age 13.0 years, 7.5% with ulcer), thereof 741 (85%) treatment naïve (group A) and 132 (15%) after failed therapy (group B). Resistance to metronidazole was present in 21% (A: 17.7%, B: 40.2%), clarithromycin in 28.8% (A: 25%, B: 51.4%), and both in 7.1% (A: 3.8%, B: 26.5%). The majority received 2-week tailored triple therapy combining proton pump inhibitor (PPI), amoxicillin with clarithromycin (PAC) or metronidazole (PAM). Dosing was lower than recommended for PPI (A: 49%, B: 41%) and amoxicillin (A: 6%, B: 56%). In treatment naïve patients, eradication reached 90% (n = 503, 95% CI 87–93%) and 93% in compliant children (n = 447, 95% CI 90–95%). Tailored triple therapy cured 59% patients after failed therapy (n = 69, 95% CI 48–71%). Treatment failure was associated with PAM in single clarithromycin resistance (OR = 2.47, 95% CI 1.10–5.53), with PAC in single metronidazole resistance (OR = 3.44, 95% CI 1.47–8.08), and with low compliance (OR = 5.89, 95% CI 2.49–13.95).

Conclusions

Guideline-conform 2-weeks therapy with PPI, amoxicillin, clarithromycin or metronidazole tailored to antibiotic susceptibility achieves primary eradication of ≥ 90%. Higher failure rates in single-resistant strains despite tailored treatment indicate missed resistance by sampling error.

Ontogeny of Drug-Metabolizing Enzymes

Almost 50% of prescription drugs lack age-appropriate dosing guidelines and therefore are used "off-label." Only ~10% drugs prescribed to neonates and infants have been studied for safety or efficacy. Immaturity of drug metabolism in children is often associated with drug toxicity. This chapter summarizes data on the ontogeny of major human metabolizing enzymes involved in oxidation, reduction, hydrolysis, and conjugation of drugs. The ontogeny data of individual drug-metabolizing enzymes are important for accurate prediction of drug pharmacokinetics and toxicity in children. This information is critical for designing clinical studies to appropriately test pharmacological hypotheses and develop safer pediatric drugs, and to replace the long-standing practice of body weight- or surface area-normalized drug dosing. The application of ontogeny data in physiologically based pharmacokinetic model and regulatory submission are discussed.

Rectal Omeprazole in Infants With Gastroesophageal Reflux Disease: A Randomized Pilot Trial

BACKGROUND AND OBJECTIVE

Omeprazole is a proton pump inhibitor that is used in acid suppression therapy in infants. Infants cannot swallow the oral tablets or capsules. Since, infants require a non-standard dose of omeprazole, the granules or tablets are often crushed or suspended in water or sodium bicarbonate, which may destroy the enteric coating. In this study we explore the efficacy and pharmacokinetics of rectally administered omeprazole in infants with gastroesophageal reflux disease (GERD) due to esophageal atresia (EA) or congenital diaphragmatic hernia (CDH) and compare these with orally administered omeprazole.

METHODS

Infants (6-12 weeks postnatal and bodyweight > 3 kg) with EA or CDH and GERD were randomized to receive a single dose of 1 mg/kg omeprazole rectally or orally. The primary outcome was the percentage of infants for whom omeprazole was effective according to predefined criteria for 24-h intraesophageal pH. Secondary outcomes were the percentages of time that gastric pH was < 3 or < 4, as well as the pharmacokinetic parameters.

RESULTS

Seventeen infants, 4 with EA and 13 with CDH, were included. The proportion of infants for whom omeprazole was effective was 56% (5 of 9 infants) after rectal administration and 50% (4 of 8 infants) after oral administration. The total reflux time in minutes and percentages and the number of reflux episodes of pH < 4 decreased statistically significantly after both rectal and oral omeprazole administration. Rectal and oral administration of omeprazole resulted in similar serum exposure.

CONCLUSIONS

A single rectal omeprazole dose (1 mg/kg) results in consistent increases in intraesophageal and gastric pH in infants with EA- or CDH-related GERD, similar to an oral dose. Considering the challenges with existing oral formulations, rectal omeprazole presents as an innovative, promising alternative for infants with pathological GERD.

CLINICAL TRIAL REGISTER

ClinicalTrials.gov Identifier: NCT00226044.

Drugs in Focus: Proton Pump Inhibitors

Proton pump inhibitors (PPIs) are amongst the most commonly prescribed drugs in infants and children with the last decades witnessing a dramatic rise in their utilization. Although PPIs are clearly effective when used appropriately and have been regarded as safe drugs, there is growing evidence regarding their potential adverse effects. Although, largely based on adult data it is clear that many of these are also relevant to pediatrics. PPI use potentially affects gastrointestinal microbiota composition and function, decreases defence against pathogens resulting in increased risk for infections, interferes with absorption of minerals and vitamins leading to specific deficiencies and increased risk for bone fractures as well as interferes with protein digestion resulting in increased risk of sensitization to allergens and development of allergic diseases and eosinophilic esophagitis. An association with gastric, liver and pancreatic cancer has also been inferred from adult data but is tenuous and causation is not proven. Overall, evidence for these adverse events is patchy and not always compelling. Overall, the use of PPIs, for selected indications with a good evidence base, has significant potential benefit but carries more caution in infants and children. Pediatricians should be aware of the concerns regarding the potential adverse events associated with their use.

Biopharmaceutical considerations in paediatrics with a view to the evaluation of orally administered drug products - a PEARRL review

OBJECTIVES

In this review, the current biopharmaceutical approaches for evaluation of oral formulation performance in paediatrics are discussed.

KEY FINDINGS

The paediatric gastrointestinal (GI) tract undergoes numerous morphological and physiological changes throughout its development and growth. Some physiological parameters are yet to be investigated, limiting the use of the existing in vitro biopharmaceutical tools to predict the in vivo performance of paediatric formulations. Meals and frequencies of their administration evolve during childhood and affect oral drug absorption. Furthermore, the establishment of a paediatric Biopharmaceutics Classification System (pBCS), based on the adult Biopharmaceutics Classification System (BCS), requires criteria adjustments. The usefulness of computational simulation and modeling for extrapolation of adult data to paediatrics has been confirmed as a tool for predicting drug formulation performance. Despite the great number of successful physiologically based pharmacokinetic models to simulate drug disposition, the simulation of drug absorption from the GI tract is a complicating issue in paediatric populations.

SUMMARY

The biopharmaceutics tools for investigation of oral drug absorption in paediatrics need further development, refinement and validation. A combination of in vitro and in silico methods could compensate for the uncertainties accompanying each method on its own.

Cytochrome P450 and flavin-containing monooxygenase families: age-dependent differences in expression and functional activity

BackgroundAge-dependent differences in pharmacokinetics exist for metabolically cleared medications. Differential contributions in the cytochrome P450 3A (CYP3A), CYP2C, and flavin-containing monooxygenases (FMOs) families have an important role in the metabolic clearance of a large number of drugs administered to children.MethodsUnlike previous semiquantitative characterization of age-dependent changes in the expression of genes and proteins (western blot analysis), this study quantifies both gene and absolute protein expression in the same fetal, pediatric, and adult hepatic tissue. Expression was then correlated with the corresponding functional activities in the same samples.ResultsCYP3A and FMO families showed a distinct switch from fetal (CYP3A7 and FMO1) to adult isoforms (CYP3A4 and FMO3) at birth, whereas CYP2C9 showed a linear maturation from birth into adulthood. In contrast, analysis of CYP2C19 revealed higher expression and catalytic efficiency in pediatric samples compared with that in fetal and adult samples. Further, CYP3A and FMO enzymes exhibited an unexpectedly higher functional activity in fetal samples not entirely explained by protein expression.ConclusionThese surprising findings suggest that CYP and FMO enzymes may encounter development-related differences in their microenvironments that can influence the enzyme activity in addition to protein expression levels.

Obese Children Require Lower Doses of Pantoprazole Than Nonobese Peers to Achieve Equal Systemic Drug Exposures

OBJECTIVE

To assess appropriate pantoprazole dosing for obese children, we conducted a prospective pharmacokinetics (PK) investigation of pantoprazole in obese children, a patient population that is traditionally excluded from clinical trials.

STUDY DESIGN

A total of 41 obese children (6-17 years of age), genotyped for CYP2C19 variants *2, *3, *4, and *17, received a single oral dose of pantoprazole, ~1.2 mg/kg lean body weight (LBW), with LBW calculated via a validated formula. Ten post-dose pantoprazole plasma concentrations were measured, and PK variables generated via noncompartmental methods (WinNonlin). Linear and nonlinear regression analyses and analyses of variance were used to explore obesity, age, and CYP2C19 genotype contribution to pantoprazole PK. PK variables of interest were compared with historic nonobese peers treated with pantoprazole.

RESULTS

Independent of genotype, when normalized to dose per kg total body weight, pantoprazole apparent clearance and apparent volume of distribution were significantly lower (P < .05) and systemic exposure significantly higher (P < .01) in obese vs nonobese children. When normalized per kg LBW, these differences were not evident in children ≥12 years of age and markedly reduced in children <12 years of age.

CONCLUSIONS

LBW dosing of pantoprazole led to pantoprazole PK similar to nonobese peers. Additional factors, other than body size (eg, age-related changes in CYP2C19 activity), appear to affect pantoprazole PK in children <12 years of age.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02186652.

Dose-Finding Study of Omeprazole on Gastric pH in Neonates with Gastro-Esophageal Acid Reflux Using a Bayesian Sequential Approach

Objective

Proton pump inhibitors are frequently administered on clinical symptoms in neonates but benefit remains controversial. Clinical trials validating omeprazole dosage in neonates are limited. The objective of this trial was to determine the minimum effective dose (MED) of omeprazole to treat pathological acid reflux in neonates using reflux index as surrogate marker.

Design

Double blind dose-finding trial with continual reassessment method of individual dose administration using a Bayesian approach, aiming to select drug dose as close as possible to the predefined target level of efficacy (with a credibility interval of 95%).

Setting

Neonatal Intensive Care unit of the Robert Debré University Hospital in Paris, France.

Patients

Neonates with a postmenstrual age ≥ 35 weeks and a pathologic 24-hour intra-esophageal pH monitoring defined by a reflux index ≥ 5% over 24 hours were considered for participation. Recruitment was stratified to 3 groups according to gestational age at birth.

Intervention

Five preselected doses of oral omeprazole from 1 to 3 mg/kg/day.

Main outcome measures

Primary outcome, measured at 35 weeks postmenstrual age or more, was a reflux index <5% during the 24-h pH monitoring registered 72±24 hours after omeprazole initiation.

Results

Fifty-four neonates with a reflux index ranging from 5.06 to 27.7% were included. Median age was 37.5 days and median postmenstrual age was 36 weeks. In neonates born at less than 32 weeks of GA (n = 30), the MED was 2.5mg/kg/day with an estimated mean posterior probability of success of 97.7% (95% credibility interval: 90.3–99.7%). The MED was 1mg/kg/day for neonates born at more than 32 GA (n = 24).

Conclusions

Omeprazole is extensively prescribed on clinical symptoms but efficacy is not demonstrated while safety concerns do exist. When treatment is required, the daily dose needs to be validated in preterm and term neonates. Optimal doses of omeprazole to increase gastric pH and decrease reflux index below 5% over 24 hours, determined using an adaptive Bayesian design differ among neonates. Both gestational and postnatal ages account for these differences but their differential impact on omeprazole doses remains to be determined.

Population pharmacokinetics of omeprazole in critically ill pediatric patients

BACKGROUND

To develop a population pharmacokinetic model for intravenous omeprazole in critically ill children.

METHODS

One hundred eighty-six omeprazole concentration-time data from 40 critically ill children were analyzed using the nonlinear mixed-effects approach with the nonlinear mixed-effects modeling software, version 7.2 software. Patients were randomized into 2 groups and received intravenous omeprazole at a dose of 0.5 or 1 mg/kg twice daily. Blood samples were drawn at 0.5, 2, 6, 12, 24, and 48 hours after the first infusion.

RESULTS

The pharmacokinetic profile was best described by a 2-compartment model with a first-order elimination process. Between-patient variability could only be associated with plasma clearance (CL). The typical values for plasma CL were 24.9 L·h·70 kg (10.08%), with a distributional clearance of 53.9 L·h·70 kg (11.00%) and central and peripheral compartment distribution volumes of 4.23 L/70 kg (19.62%) and 674 L/70 kg (0.89%), respectively. Allometric size models seemed to predict changes adequately in all the pharmacokinetic parameters. High values of between-patient variability of CL [75.50% (2.60%)] and residual variability [130.0% (5.26%)] were still found in the final model. Model-based simulations suggested that the most suitable dose was 1 mg/kg because this yielded similar exposure (defined by the area under the concentration-time curve) to that obtained in adults after a 20-mg dose of omeprazole intravenously.

CONCLUSIONS

An allometric size model allows changes to be predicted in all the pharmacokinetic parameters, making dose adjustment by body weight important to achieve the most effective omeprazole exposure. This is the first step toward a population pharmacokinetic study, including more data to develop a predictable model to be used during therapeutic drug monitoring.

Gastroesophageal reflux disease: exaggerations, evidence and clinical practice

OBJECTIVE

there are many questions and little evidence regarding the diagnosis and treatment of gastroesophageal reflux disease (GERD) in children. The association between GERD and cow's milk protein allergy (CMPA), overuse of abdominal ultrasonography for the diagnosis of GERD, and excessive pharmacological treatment, especially proton-pump inhibitors (PPIs) are some aspects that need clarification. This review aimed to establish the current scientific evidence for the diagnosis and treatment of GERD in children.

DATA SOURCE

a search was conducted in the MEDLINE, PubMed, LILACS, SciELO, and Cochrane Library electronic databases, using the following keywords: gastroesophageal reflux; gastroesophageal reflux disease; proton-pump inhibitors; and prokinetics; in different age groups of the pediatric age range; up to May of 2013.

DATA SYNTHESIS

abdominal ultrasonography should not be recommended to investigate gastroesophageal reflux (GER). Simultaneous treatment of GERD and CMPA often results in unnecessary use of medication or elimination diet. There is insufficient evidence for the prescription of prokinetics to all patients with GER/GERD. There is little evidence to support acid suppression in the first year of life, to treat nonspecific symptoms suggestive of GERD. Conservative treatment has many benefits and with low cost and no side-effects.

CONCLUSIONS

there have been few randomized controlled trials that assessed the management of GERD in children and no examination can be considered the gold standard for GERD diagnosis. For these reasons, there are exaggerations in the diagnosis and treatment of this disease, which need to be corrected.

A double-blind placebo-controlled randomized trial on probiotics in small bowel bacterial overgrowth in children treated with omeprazole

OBJECTIVE

To evaluate the incidence of small bowel bacterial overgrowth (SBBO) in children treated with omeprazole, and to test whether probiotics influence the incidence.

METHODS

A double-blinded, placebo-controlled trial was performed in 70 children treated orally during four weeks with 20mg omeprazole per day. Lactobacillus rhamnosus R0011 (1.9×10(9) cfu) and Lactobacillus acidophilus R0052 (0.1×10(9) cfu) were simultaneously given daily to 36 subjects (probiotic group), while 34 subjects received placebo (placebo group). The diagnosis of SBBO was based on the development of suggestive symptoms, in combination with a positive glucose breath test.

RESULTS

After one month of proton pump inhibitor (PPI) treatment, 30% (21/70) had a positive breath test suggesting SBBO; of these 62% were symptomatic. Five children developed SBBO-like symptoms, but had a negative breath test; and 44 (63%) were symptom free and had a negative breath test. There was no difference in the incidence of positive breath tests in the probiotic versus the placebo group (33% vs 26.5%; p=0.13).

CONCLUSIONS

Since symptoms suggesting SBBO developed in 26% of PPI-treated children, and since the glucose breath test was abnormal in 72% of these, this side-effect should be more frequently considered. The probiotic tested did not decrease the risk to develop SBBO.

Proton pump inhibitors in pediatrics : mechanism of action, pharmacokinetics, pharmacogenetics, and pharmacodynamics

Proton pump inhibitors (PPIs) have become some of the most frequently prescribed medications for treatment of adults and children. Their effectiveness for treatment of peptic conditions in the pediatric population, including gastric ulcers, gastroesophageal reflux disease (GERD), and Helicobacter pylori infections has been established for children older than 1 year. Studies of the preverbal population of neonates and infants have identified doses that inhibit acid production, but the effectiveness of PPIs in the treatment of GERD has not been established except for the recent approval of esomeprazole treatment of erosive esophagitis in infants. Reasons that have been proposed for this are complex, ranging from GERD not occurring in this population to a lack of histologic identification of esophagitis related to GERD to questions about the validity of symptom scoring systems to identify esophagitis when it occurs in infants. The effectiveness of PPIs relates to their structures, which must undergo acidic activation within the parietal cell to allow the PPI to be ionized and form covalent disulfide bonds with cysteines of the H(+)-K(+)-adenosine triphosphatase (H(+)-K(+)-ATPase). Once the PPI binds to the proton pump, the pump is inactivated. Some PPIs, such as omeprazole and rabeprazole bind to cysteines that are exposed, and their binding can be reversed. After irreversible chemical inhibition of the proton pump, such as occurs with pantoprazole, the recovery of the protein of the pump has a half-life of around 50 h. Cytochrome P450 (CYP) 2C19 and to a lesser degree CYP3A4 clear the PPIs metabolically. These enzymes are immature at birth and reach adult levels of activity by 5-6 months after birth. This parallels studies of the maturation of CYP2C19 to adult levels by roughly the same age after birth. Specific single nucleotide polymorphisms of CYP2C19 reduce clearance proportionally and increase exposure and prolong proton pump inhibition. Prolonged treatment of pediatric patients with PPIs has not caused cancer or significant abnormalities.

Pharmacokinetics of two formulations of omeprazole administered through a gastrostomy tube in patients with severe neurodevelopmental problems

AIMS

Omeprazole is often administered through a gastrostomy tube as either (i) a Multiple Unit Pellet System (MUPS®) tablet disintegrated in water (MUPS® formulation), or (ii) a suspension in 8.4% sodium bicarbonate (suspension formulation). This bioavailability study evaluates this practice in tube-fed patients with severe neurodevelopmental problems.

METHODS

Nonblinded, two-phase cross-over trial.

RESULTS

In seven of 10 patients, bioavailability was higher for the suspension formulation than for the MUPS® formulation. Median (90% confidence interval) area under the plasma concentration-time curve ratio (MUPS® over suspension) was 0.5 (0.06-2.37).

CONCLUSIONS

In this population, omeprazole MUPS® formulation has no apparent advantage over the more easily administered suspension formulation.

New effective treatment regimen for children infected with a double-resistant Helicobacter pylori strain

BACKGROUND

The increasing number of pediatric patients infected with multiresistant Helicobacter pylori strains calls for evaluation of treatment regimens. Second-line antibiotics such as tetracycline or quinolones are not licensed for children. Because in vivo resistance to metronidazole may be overcome in vivo by a high dose and prolonged intake, we evaluated the eradication rate and side effects of a high-dose triple therapy in pediatric patients with culture-proven double resistance.

PATIENTS AND METHODS

In this open multicentre trial, 62 children (<18 years, body weight >15 kg) infected with an H pylori strain resistant to metronidazole and clarithromycin were treated according to body weight classes with amoxicillin (∼ 75 mg/kg/day), metronidazole (∼ 25 mg/kg/day) and esomeprazole (∼ 1.5 mg/kg/day) for 2 weeks. Adherence and adverse events were assessed by a 2-week diary and telephone interviews at days 7 and 14 of treatment. Primary outcome was a negative C-urea breath test after 6 weeks.

RESULTS

Of 62 patients, 5 were lost to follow-up, 12 were nonadherent, and 45 treated per protocol. Eradication rates were 66% (41/62) [confidence interval 54-78] (intention to treat) and 73% (33/45) [confidence interval 60-86] (per protocol). Success of treatment was not related to dose per kilogram body weight. Mild to moderate adverse events were reported by 21 patients, including nausea (10.8%), diarrhoea (8.9%), vomiting (7.1%), abdominal pain (5.4%), and headache (3.6%), and led to discontinuation in 1 child.

CONCLUSION

High-dose amoxicillin, metronidazole, and esomeprazole for 2 weeks is a good treatment option in children infected with a double resistant H pylori strain.

A multicenter, randomized, open-label, pharmacokinetics and safety study of pantoprazole tablets in children and adolescents aged 6 through 16 years with gastroesophageal reflux disease

Children with gastroesophageal reflux disease (GERD) may benefit from gastric acid suppression with proton pump inhibitors such as pantoprazole. Effective treatment with pantoprazole requires correct dosing and understanding of the drug's kinetic profile in children. The aim of these studies was to characterize the pharmacokinetic (PK) profile of single and multiple doses of pantoprazole delayed-release tablets in pediatric patients with GERD aged 6 to 11 years (study 1) and 12 to 16 years (study 2). Patients were randomly assigned to receive pantoprazole 20 or 40 mg once daily. Plasma pantoprazole concentrations were obtained at intervals through 12 hours after the single dose and at 2 and 4 hours after multiple doses for PK evaluation. PK parameters were derived by standard noncompartmental methods and examined as a function of both drug dose and patient age. Safety was also monitored. Pantoprazole PK was dose independent (when dose normalized) and similar to PK reported from adult studies. There was no evidence of accumulation with multiple dosing or reports of serious drug-associated adverse events. In children aged 6 to 16 years with GERD, currently available pantoprazole delayed-release tablets can be used to provide systemic exposure similar to that in adults.

Delayed-release oral suspension of omeprazole for the treatment of erosive esophagitis and gastroesophageal reflux disease in pediatric patients: a review

Omeprazole is a proton-pump inhibitor indicated for gastroesophageal reflux disease and erosive esophagitis treatment in children. The aim of this review was to evaluate the efficacy of delayed-release oral suspension of omeprazole in childhood esophagitis, in terms of symptom relief, reduction in reflux index and/or intragastric acidity, and endoscopic and/or histological healing. We systematically searched PubMed, Cochrane and EMBASE (1990 to 2009) and identified 59 potentially relevant articles, but only 12 articles were suitable to be included in our analysis. All the studies evaluated symptom relief and reported a median relief rate of 80.4% (range 35%–100%). Five studies reported a significant reduction of the esophageal reflux index within normal limits (<7%) in all children, and 4 studies a significant reduction of intra-gastric acidity. The endoscopic healing rate, reported by 9 studies, was 84% after 8-week treatment and 95% after 12-week treatment, the latter being significantly higher than the histological healing rate (49%). In conclusion, omeprazole given at a dose ranging from 0.3 to 3.5 mg/kg once daily (median 1 mg/kg once daily) for at least 12 weeks is highly effective in childhood esophagitis.

Pharmacokinetics of intravenous omeprazole in critically ill paediatric patients

The proton pump inhibitors are first-line drugs for the treatment of a number of gastrointestinal diseases. These drugs have a good safety profile, making it possible to use them in paediatric patients. Although their pharmacokinetics in children has not been extensively studied, research performed suggests that the dose used should be varied as a function of age, as this factor affects the drug's metabolism. Proton pump inhibitors can be used in critically ill children for the prophylaxis and treatment of gastrointestinal haemorrhage, although there is still little experience with this. The most widely used proton pump inhibitor at the present time is omeprazole. As there are specific characteristics of these patients that could alter the pharmacokinetics of the drugs, studies need to be performed to determine the most suitable dose and dosage interval.

Pediatric gastroesophageal reflux clinical practice guidelines: joint recommendations of the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition (NASPGHAN) and the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition (ESPGHAN)

OBJECTIVE

To develop a North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition (NASPGHAN) and European Society for Pediatric Gastroenterology, Hepatology, and Nutrition (ESPGHAN) international consensus on the diagnosis and management of gastroesophageal reflux and gastroesophageal reflux disease in the pediatric population.

METHODS

An international panel of 9 pediatric gastroenterologists and 2 epidemiologists were selected by both societies, which developed these guidelines based on the Delphi principle. Statements were based on systematic literature searches using the best-available evidence from PubMed, Cumulative Index to Nursing and Allied Health Literature, and bibliographies. The committee convened in face-to-face meetings 3 times. Consensus was achieved for all recommendations through nominal group technique, a structured, quantitative method. Articles were evaluated using the Oxford Centre for Evidence-based Medicine Levels of Evidence. Using the Oxford Grades of Recommendation, the quality of evidence of each of the recommendations made by the committee was determined and is summarized in appendices.

RESULTS

More than 600 articles were reviewed for this work. The document provides evidence-based guidelines for the diagnosis and management of gastroesophageal reflux and gastroesophageal reflux disease in the pediatric population.

CONCLUSIONS

This document is intended to be used in daily practice for the development of future clinical practice guidelines and as a basis for clinical trials.

Step-up and step-down approaches to treatment of gastroesophageal reflux disease in children

The single biggest change in the approach to treating pediatric gastroesophageal reflux disease (GERD) in recent years has been the empiric use of proton pump inhibitors (PPIs) for symptoms suspected to be those of GERD. In other words, PPIs have been used increasingly as a first-line concurrent diagnostic test and treatment before any investigation. Although this approach is useful for some patients, there are a number of caveats about its application to children. In general, these caveats are related to age per se (eg, infancy) and to age-related symptoms and severity of GERD itself. The most important caveats relate to the prescription of empiric PPI therapy in infants--which generally is to be avoided--and to how PPIs are used in older children--specifically, the advisability of empiric trials being of limited duration. Even in children with proven reflux esophagitis, GERD is not chronic and relapsing in all; thus, trials of therapy withdrawal are warranted. In light of many factors, including the burgeoning literature on potential risks of infections in acid-suppressed children and adults, caution with dose and duration of acid-suppressive drugs in children is urged. The role of antireflux surgery is also mentioned.

Long-term proton pump inhibitor use in children: a retrospective review of safety

The objective of this work was to assess the efficacy of continuous proton pump inhibitor (PPI) therapy in children and to evaluate changes in biochemical, endoscopic, and histologic parameters during such treatment. A retrospective review of children receiving PPI therapy continuously for 1 year or more with baseline and follow-up esophageal and gastric biopsies on treatment was conducted to assess type, frequency, and duration of PPI dosing, symptom relief, gastrin levels, histologic findings, and adverse events. A total of 113 children (59 male, median age 4.5 years) were identified. Of these, 31% (35/113) were neurologically impaired. The median treatment duration was 35.2 months. Elevated serum gastrin levels occurred in 73% of children with no statistically significant differences in gastrin level by PPI type, dose, and dosing frequency or treatment duration. Adverse events were reported by 12% of children: diarrhea (5%) and constipation (4%) were the most frequent. Long-term PPI therapy appears to be effective, safe and well tolerated in children despite some biochemical, endoscopic, and histologic changes.

Effect of MDR1 C3435T polymorphism on cure rates of Helicobacter pylori infection by triple therapy with lansoprazole, amoxicillin and clarithromycin in relation to CYP 2C19 genotypes and 23S rRNA genotypes of H. pylori

BACKGROUND

Polymorphism in MDR1 is associated with variation in the plasma level of a proton pump inhibitor.

AIM

To investigate whether MDR1 polymorphism is associated with eradication rates of Helicobacter pylori by a triple therapy with lansoprazole, amoxicillin and clarithromycin in relation to CYP2C19 genotype status and bacterial susceptibility to clarithromycin.

METHODS

A total of 313 patients infected with H. pylori completed the treatment with lansoprazole 30 mg b.d., clarithromycin 200 mg b.d. and amoxicillin 750 mg b.d. for 1 week. MDR1 C3435T polymorphism and CYP2C19 genotypes of patients and sensitivity of H. pylori to clarithromycin were determined.

RESULTS

Logistic regression analysis revealed that the MDR1 polymorphism as well as CYP2C19 genotypes of patients and clarithromycin-resistance of H. pylori were significantly associated with successful eradication. Eradication rates for H. pylori were 82% (83/101: 95% CI = 73-89), 81% (112/139: CI = 73-87), and 67% (44/73: CI = 48-72) in patients with the MDR1 3435 C/C, C/T and T/T genotype, respectively (P = 0.001).

CONCLUSIONS

Polymorphism of MDR1 is one of the determinants of successful eradication of H. pylori by the triple therapy with lansoprazole, amoxicillin and clarithromycin, together with CYP2C19 genotype and bacterial susceptibility to clarithromycin.

Personalized medicine for eradication of Helicobacter pylori

Regimens for eradication of Helicobacter pylori consist of a proton-pump inhibitor (PPI) and one or two antimicrobial agents, such as amoxicillin, clarithromycin or metronidazole. As the pharmacokinetics and pharmacodynamics of PPIs are affected by polymorphism of CYP2C19, doses and dosing schemes of a PPI should be optimized based on genotype status of each patient in order to yield higher eradication rates. PPIs affect the pharmacokinetics of other substrates of CYP2C19, such as warfarin and diazepam. Acid inhibition induced by a PPI also affects the pharmacokinetics of some drugs, such as itraconazole. Clarithromycin, one of the most frequently used antimicrobial agents in eradication of H. pylori, inhibits activity of CYP3A4, meaning that the pharmacokinetics of substrates of CYP3A4 are affected by clarithromycin. Therefore, clinicians must pay attention to the other drugs dosed to each of their patients. Therefore, the eradication regimen for H. pylori infection should be designed with the CYP2C19 genotype status, bacterial susceptibility to antimicrobial agents, and other drugs being taken by each patient having been taken into consideration.

Maintenance therapy for erosive esophagitis in children after healing by omeprazole: is it advisable?

OBJECTIVES

To evaluate the efficacy of acid-suppressive maintenance therapy for gastroesophageal reflux disease (GERD) in children, after the healing of reflux esophagitis.

METHODS

Forty-eight children (median age 105 months, range 32-170) with erosive reflux esophagitis were initially treated with omeprazole 1.4 mg/kg/day for 3 months. Patients in endoscopic remission were assigned in a randomized, blinded manner by means of a computer-generated list to three groups of 6-month maintenance treatment: group A (omeprazole at half the starting dose, once daily before breakfast), group B (ranitidine 10 mg/kg/day, divided in two doses), and group C (no treatment). Endoscopic, histological, and symptomatic scores were evaluated at: T0, enrollment; T1, assessment for remission at 3 months after enrollment (healing phase); T2, assessment for effective maintenance at 12 months after T0 (3 months after the completion of the maintenance phase). Relapse was defined as the recurrence of macroscopic esophageal lesions. After the completion of the maintenance phase, patients without macroscopic esophagitis relapse were followed up for GERD symptoms for a further period of 30 months.

RESULTS

Of 48 initially treated patients, 46 (94%) healed and entered the maintenance study. For all patients, in comparison to T0, the histological, endoscopic, and symptomatic scores were significantly reduced both at T1 and T2 (P<0.0001, for each). No significant difference was found in these three scores, comparing group A, B, and C at T1 and T2. A relapse occurred in one patient only, who presented with macroscopic esophageal lesions at T2. Three months after the completion of the maintenance phase, 12 (26%) patients complained of symptoms sufficiently mild to discontinue GERD therapy, excluding the patient who showed macroscopic esophagitis relapse. Three of 44 (6.8%) patients reported very mild GERD symptoms within a period of 30 months after maintenance discontinuation.

CONCLUSIONS

Our pediatric population showed a low rate of erosive esophagitis relapse and GERD symptom recurrence long term after healing with omeprazole, irrespective of the maintenance therapy.

Pharmacokinetic properties of esomeprazole in children aged 1 to 11 years with symptoms of gastroesophageal reflux disease: a randomized, open-label study

OBJECTIVE

The aim of this study was to assess the overall exposure, other pharmacokinetic (PK) properties, and tolerability of esomeprazole magnesium after repeated oral doses of 5, 10, and 20 mg in pediatric patients who had symptoms of gastroesophageal reflux disease (GERD).

METHODS

This randomized, open-label study was conducted at West Coast Clinical Trials, Long Beach, California. Boys and girls aged 1 to 11 years who had a clinical diagnosis of GERD were included and stratified by age (1-5 years [younger group] and 6-11 years [older group]). For this 5-day study, children in the younger group were randomly assigned to receive 1 esomeprazole 5- or 10-mg capsule p.o. QD, and those in the older group were randomly assigned to receive 1 esomeprazole 10- or 20-mg capsule p.o. QD. On days 1 to 4, study medications were administered with the supervision of the study personnel 1 hour before breakfast. Blood samples were collected within 0.5 hour before and 0.5, 1, 1.5, 2, 3, 4, 5, and 6 hours after study drug administration on day 5. Plasma concentrations of esomeprazole were measured using reverse-phase liquid chromatography and mass-spectrometric detection. Tolerability assessments were performed by reviewing the number and severity of adverse events (collected via spontaneous reporting and direct questioning) and findings from the physical examination, which included vital-sign measurements and laboratory analysis (hematology, biochemistry, and urinalysis). Site personnel supervised the administration of the study drug to ensure compliance with treatment.

RESULTS

The study included 31 children (17 boys, 14 girls; mean age, 5 years; 18 children in the younger group, 13 in the older group). A total of 27 children were included in the PK analysis. In the younger group, the geometric mean AUC(0-infinity) and Cmax values in the esomeprazole 10-mg group were >2-fold that in the 5-mg group (AUC(0-infinity), 4.83 and 0.74 pmol x h/L [0.32 and 0.04 micromol x h x L(-1)/kg], respectively; Cmax, 2.98 and 0.62 micromol/L [0.19 and 0.03 micromol/L x kg(-1)], respectively). In the older group, the geometric mean AUC(0-infinity) and Cmax values for the 20-mg dose group were approximately 2-fold those for the 10-mg dose group (AUC(0-infinity), 6.28 and 3.70 micromol x h/L [0.21 and 0.12 pmol x h x L(-1)/kg], respectively; Cmax, 3.73 and 1.77 micromol/L [0.13 and 0.06 micromol/L x kg 1], respectively). For the 10-mg esomeprazole dose, the geometric mean body-weight-normalized apparent oral clearance was approximately 50% higher in the younger group compared with the older group (0.40 and 0.25 L/h x kg(-1), respectively). Thirty patients were included in the tolerability analysis. The adverse events that occurred were skin excoriation, discolored feces, and skin laceration (1 [3.3%] patient each); none were considered related to treatment.

CONCLUSIONS

The results of this small study suggest that, in children aged 1 to 11 years who had GERD, the PK properties of esomeprazole may be both dose and age dependent and that younger children might have a more rapid metabolism of esomeprazole per kilogram of body weight compared with older children. Esomeprazole was well tolerated at doses of 5, 10, and 20 mg in the pediatric patients studied.

Pharmacokinetics and pharmacodynamics of lansoprazole in children 13 to 24 months old with gastroesophageal reflux disease

OBJECTIVES

To evaluate the pharmacokinetics and pharmacodynamics of lansoprazole in children between 13 and 24 months of age with gastroesophageal reflux disease (GERD).

METHODS

From the population of 66 children with symptomatic GERD, erosive esophagitis (> or = grade 2) or esophageal pH < 4 for > 4.2% of the 24-h period who participated in a phase I/II, open-label, multicenter (11 sites) US study, a subanalysis of 8 toddlers between 13 and 24 months of age was performed. All children were treated, based on body weight, with lansoprazole 15 mg once daily for 8 to 12 weeks. If a child were still symptomatic after 2 weeks of treatment, then the dose of lansoprazole could be increased to twice daily at the discretion of the investigator. Pharmacokinetic parameters were assessed at day 5. Twenty-four-hour median intragastric pH and the percentage of time intragastric pH > 3 or > 4 were assessed at baseline and at day 5 of treatment. Symptom response was assessed by investigator interview and daily diary. Safety was monitored by physical examinations including vital signs, adverse event assessments and laboratory evaluations.

RESULTS

Pharmacokinetic analysis of 5 children found a mean time to reach maximum concentration of 1.4 h, maximal plasma concentrations of 894 ng/mL, area under the concentration time curve of 1906 ng * h/mL and a half-life of 0.66 h. Significant (P < or = 0.027) increases from baseline to day 5 were observed in mean 24-h intragastric pH (2.76-3.52) and the percentages of time pH were > 3 (29.46%-55.36%) and pH was > 4 (16.96%-40.77%). Six of the 8 children had improvement in their overall GERD symptom severity on the basis of investigator assessment, and a reduction was seen in the percentage of days with moderate, severe or very severe GERD symptoms compared with baseline. The dosage of lansoprazole was increased in 3 of the 8 children. Median fasting serum gastrin level increased from 65.0 pg/mL at baseline to 136.5 pg/mL at the final visit. Treatment-related events were mild constipation (1 subject) and mild diarrhea (1 subject).

CONCLUSIONS

Although larger studies are needed to confirm these results, lansoprazole displays pharmacokinetic and pharmacodynamic parameters in children between 13 and 24 months of age that are similar to those results observed in older children as well as adults.

Multicenter, randomized, double-blind study comparing 20 and 40 mg of pantoprazole for symptom relief in adolescents (12 to 16 years of age) with gastroesophageal reflux disease (GERD)

An age-appropriate questionnaire (GASP-Q) was used to assess the frequency and severity of the gastroesophageal reflux disease (GERD) symptoms: abdominal/belly pain, chest pain/heartburn, pain after eating, nausea, burping/belching, vomiting/regurgitation, choking when eating, and difficulty swallowing, in adolescents age 12 to 16 years. The primary objective was to compare the mean composite symptom score (CSS) at week 8 with baseline after treatment with 20 or 40 mg of pantoprazole. Statistically significant (p < 0.001) improvement in CSS occurred in both groups. Safety was comparable between the 2 groups. Pantoprazole was safe, well tolerated, and effective in reducing symptoms of GERD in adolescents.

Pharmacokinetic properties of esomeprazole in adolescent patients aged 12 to 17 years with symptoms of gastroesophageal reflux disease: A randomized, open-label study

OBJECTIVE

The aim of this study was to assess the pharmacokinetic (PK) properties and tolerability of esomeprazole 20 and 40 mg after single and repeated oral doses in adolescents with symptoms of gastroesophageal reflux disease (GERD).

RESULTS

The study included 15 boys and 13 girls (mean age, 14.3 years). Geometric mean AUC(0-infinity) values (overall drug exposure) were 1.58 and 5.57 micromol . h/L (0.027 and 0.083 pmol x h x L(-1)/kg) after single-dose administration of esomeprazole 20 and 40 mg, respectively, on day 1. Corresponding values with repeated doses (day 8) were 3.65 and 13.86 micromol x h/L (0.064 and 0.207 micromol x h x L(-1)/kg). Geometric mean Cmax values were 0.67 and 2.78 micromol/L (0.012 and 0.041 micromol/L x kg(-1)) with single-dose administration of esomeprazole 20 and 40 mg, respectively, and 1.45 and 5.13 micromol/L (0.026 and 0.075 micromol/L x kg(-1)), respectively, with repeated doses (day 8). These mean AUC(0-infinity) and CmaX values were >2-fold with the 40 mg dose compared with the 20-mg dose with single- and repeated-dose administration. The most common adverse event was headache (2 [7.1%] patients).

CONCLUSIONS

The results of this study suggest that the PK parameters of esomeprazole were both dose- and time-dependent in these adolescents with GERD. Both doses of esomeprazole were well tolerated in this study population.

Gastroesophageal reflux in infancy and childhood

GER is a common reason for pediatric office visits and referrals to a pediatric gastroenterologist. This condition frequently is benign, and it is self-limited in most infants. Although a thorough history and complete physical examination usually are adequate to diagnose GER, a high index of suspicion must be maintained for other diagnoses associated with recurrent emesis, including metabolic disorders, as well as for other gastrointestinal conditions, such as pyloric stenosis and abnormalities of intestinal rotation. Behavioral or lifestyle modification usually can be implemented empirically to diagnose and manage a suspected case of uncomplicated GER. When this fails, medical therapy can be initiated, employing either a step-up or step-down approach with a PPI or H2RA. With the proven efficacy of PPIs and their availability to children, medical treatment has become the mainstay of therapy in severely affected patients; nevertheless, anti-reflux surgery is still widely performed in children with GER. Pediatricians and other primary care providers often manage infants and children who have gastrointestinal complaints, prior to referral to a pediatric gastroenterologist. Hence, they have the responsibility to educate children and families about GER, its natural history, complications, and therapeutic options. A careful history and physical examination, informed use of diagnostic studies, and a consistent approach to medical treatment are important principles that are required to guarantee the success of GER management in infants and children.

Possible Interethnic Differences in Omeprazole Pharmacokinetics

BACKGROUND AND OBJECTIVE

Considerable ethnic differences have been reported in the incidence of the poor metaboliser (PM) genotype of cytochrome P450 (CYP) 2C19. The frequency of this genotype was found to be much higher in Oriental persons (13-23%) than in American or European populations (3-5%). There are, however, no valid data published for Arabic subjects. The present study was conducted to evaluate pharmacokinetic parameters of omeprazole after a single dose in healthy Jordanian Arabic subjects and to compare the results with data published for other populations.

METHODS

Seventy-four healthy male Jordanian Arabic volunteers contributed to the study, which was performed at Al Essra Hospital in Amman, Jordan. After an overnight fast, omeprazole was administered as a single Losec 20mg capsule. A total of 20 blood samples were collected over a 10-hour period after administration. Omeprazole pharmacokinetic parameters were determined from the plasma concentration-time profiles using the WinNonlin software. Kolmogorov-Smirnov's test and probit plots of omeprazole area under the plasma concentration-time curve (AUC) data were used to analyse the frequency distribution of phenotypic data.

RESULTS

The mean pharmacokinetic parameters and their corresponding coefficient of variation (CV%) for peak plasma concentration (Cmax), AUC from time zero to infinity (AUCinfinity), time to reach Cmax (tmax), apparent oral clearance (CL/F) and elimination half-life (t(1/2)) were 314.96 ng/mL (56%), 923.2 ng . h/mL (108.6%), 2.1h (44%), 0.66 L/h/kg (92%) and 1.5 h (56.6%), respectively. Interindividual differences in the current study were high for all pharmacokinetic parameters, yet comparable to CVs reported in nonphenotyped subjects identified within other ethnic groups (40.3-159% for AUC and 39-48.2% for Cmax). The frequency distribution of all parameters, particularly the AUC, was shown to be trimodal. This has proposed the presence of three distinct phenotypes, designated as extensive metabolisers (EMs), slow-extensive metabolisers (SEMs), and PMs, with corresponding frequency of 36.5%, 39.2% and 24.3%, respectively. After stratification, the relative mean AUCs of omeprazole in EMs, SEMs and PMs were 1 : 2.7 : 9.3 (all p < 0.001). Accordingly, the CL/F of omeprazole showed a ratio of 9.8 : 3.6 : 1 for three phenotype groups, respectively. For other pharmacokinetic parameters including Cmax, t1/2, AUC normalised for bodyweight (AUCN), Cmax/dose and AUC/dose, there were also significant differences between the three groups.

CONCLUSIONS

The current pharmacokinetic study revealed that the majority of the Jordanian Arabics seemed to be more properly classified within the EM phenotype. More specifically, the observed metabolic rates of heterozygous and homozygous Jordanian Arabic EMs were more comparable to those of Caucasian EMs than Oriental EMs. Consequently, higher dosage requirements can be expected among most of the Jordanian Arabics. Yet, the incidence of PMs is significant and they seemed to exhibit a similar pharmacokinetic pattern to Chinese PMs in terms of long-term exposure (clearance and AUC) as well as short-term exposure (Cmax) parameters, after adjustment for dose and bodyweight. Therefore, further clinical application of CYP2C19 polymorphism is anticipated in Jordanian Arabic mixed population, particularly if long-term use of omeprazole is intended.

Changes in liver volume from birth to adulthood: a meta-analysis

A diversity of equations is available for the estimation of liver volume (LV), derived from studies in populations of ethnically homogeneous individuals and using a variety of methods of measurement. The aim of this study was to integrate all published pediatric data and to define a general equation for estimating LV from birth onward. Data were collated from 5,036 subjects (birth to 18 yr old). Equations were developed based on simple regression against body surface area (BSA) and multiple regression of LV with weight, height, BSA, age, gender, race, methodology, and year of publication as covariates. These equations, together with those reported in the literature, were compared for accuracy of prediction of LV from birth to 18 yr old. The most parsimonious equation to describe LV was selected according to the Akaike information criteria (AIC), precision and bias and following visual inspection of residual errors and observed vs. predicted plots: LV = 0.722 * BSA(1.176). The multiple regression models indicated that Japanese have up to 19% larger livers compared to Caucasians for a given body weight. Radiographic and ultrasonic measurements were associated with up to 8% lower estimates of liver size compared to measurements made at autopsy. There was no evidence that gender or the year in which a study was published (1933-1999) influenced the estimation of LV. The general equation was also applied to predict adult LV, and its precision and accuracy was found to be superior to those of 10/11 published adult models. In conclusion, we have developed a more general model to predict LV in pediatric populations and young adults, and have investigated a range of covariates.

The diagnosis and management of gastro-oesophageal reflux in infants

Gastro-oesophageal reflux (GOR) and gastro-oesophageal reflux disease (GORD) occur frequently during the first months of life. Gastro-oesophageal reflux may be a primary gastro-intestinal motility disorder, but it may also be secondary to other conditions such as cow's milk protein allergy. Objective diagnosis can be difficult because there may be absence of correlation between history, results of pH monitoring and histology. Severe GORD may cause minor symptoms, and minor GOR may cause severe symptoms. Several different therapeutic interventions exist. Simply stated, thickened formula reduces regurgitation and alginates and proton pump inhibitors can be used to decrease acid GOR, depending on the severity of the GORD. Efficacy data of prokinetic drugs are either lacking or disappointing. Regarding side-effects, interest has been focused on cisapride, although other molecules have similar effects. Long-term side-effects such as the nutritional consequence of therapeutic management have been insufficiently studied, especially for the acid-reducing molecules.

Outcomes of fundoplication: causes for concern, newer options

Antireflux surgery has been a mainstay of treatment for gastro-oesophageal reflux disease in children for some 40 years. In recent years, enthusiasm for antireflux surgery seems only to have increased, despite its often poor outcome, and the availability of highly effective medical therapy in the form of proton pump inhibitors (PPIs). Reports show that many children undergo surgery without reflux disease as the demonstrable cause of their symptoms/signs, and without evidence of having failed optimised medical management. Very few studies report objective testing postoperatively--those that do show high rates of failure within the first 1-3 years following surgery. Treatment with PPIs is an effective and safe alternative to surgery in many cases.

Effect of orally administered omeprazole on abomasal luminal pH in dairy calves fed milk replacer

The objective of this study was to determine whether oral administration of omeprazole, a proton-pump inhibitor, increased abomasal luminal pH in calves fed milk replacer. Four male dairy calves with cannulae in the abomasal body suckled milk replacer (60 ml/kg body weight every 12 h) and were administered a non-enteric-coated omeprazole (4 mg/kg body weight every 24 h) in a paste formulation for five successive days. Abomasal luminal pH was continuously measured using miniature glass pH electrodes. On the first day of omeprazole administration, there was a significant (P<0.05) increase in mean 24-h pH from 2.89 to 4.17. The mean 24-h pH on days 2, 3, 4 and 5 of omeprazole administration were 3.85, 4.02, 3.97 and 3.39 respectively. We conclude that oral administration of non-enteric-coated omeprazole increased abomasal luminal pH in calves fed milk replacer, but that the effect may decrease over time.

Pharmacokinetics of proton pump inhibitors in children

The use of proton pump inhibitors (PPIs) has become widespread in children and infants for the management of paediatric acid-related disease. Pharmacokinetic profiles of only omeprazole and lansoprazole have been well characterised in children over 2 years of age with acid-related diseases. Few data have been recently published regarding the pharmacokinetics of pantoprazole in children, and none are available for rabeprazole or esomeprazole. The metabolism of PPI enantiomers has never been studied in the paediatric population. A one-compartment model best describes the pharmacokinetic behaviour of omeprazole, lansoprazole and pantoprazole in children, with important interindividual variability for each pharmacokinetic parameter. Like adults, PPIs are rapidly absorbed in children following oral administration; the mean time to reach maximum plasma concentration varies from 1 to 3 hours. Since these agents are acid labile, their oral formulations consist of capsules containing enteric-coated granules. No liquid formulation is available for any of the PPIs. Thus, for those patients unable to swallow capsules, extemporaneous liquid preparations for omeprazole and lansoprazole have been reported; however, neither the absolute nor the relative bioavailabilities of these oral formulations have been studied in children. Intravenous formulations are available for omeprazole (in Europe), lansoprazole and pantoprazole. PPIs are rapidly metabolised in children, with short elimination half-lives of around 1 hour, similar to that reported for adults. All PPIs are extensively metabolised by the liver, primarily by cytochrome P450 (CYP) isoforms CYP2C19 and CYP3A4, to inactive metabolites, with little unchanged drug excreted in the urine. Similar to that seen in adults, the absolute bioavailability of omeprazole increases with repeated dosing in children; this phenomenon is thought to be due to a combination of decreased first-pass elimination and reduced systemic clearance. The apparent clearance (CL/F) of omeprazole, lansoprazole and pantoprazole appears to be faster for children than for adults. A higher metabolic capacity in children as well as differences in the extent of PPI bioavailability are most likely responsible for this finding. This may partly account for the need in children for variable and sometimes considerably greater doses of PPIs, on a per kilogram basis, than for adults to achieve similar plasma concentrations. Furthermore, no studies have been able to demonstrate a statistically significant correlation between age and pharmacokinetic parameters among children. Despite the small number of very young infants studied, there is some evidence for reduced PPI metabolism in newborns. The limited paediatric data regarding the impact of CYP2C19 genetic polymorphism on PPI metabolism are similar to those reported for adults, with poor metabolisers having 6- to 10-fold higher area under the concentration-time curve values compared with extensive metabolisers. Finally, because a pharmacokinetic/pharmacodynamic relationship exists for PPIs, the significant interindividual variability in their disposition may partly explain the wide range of therapeutic doses used in children. Further studies are needed to better define the pharmacokinetics of PPIs in children <2 years of age.

Asthma and gastroesophageal reflux disease in children: exploring the relationship

Asthma is a well-recognized disease and one of the most common illnesses in childhood. More recently, gastroesophageal reflux disease has increasingly been appreciated as a common daily occurrence in children and adolescents. These two diagnoses often present in tandem, with their coexistence being more frequent than would be expected for a chance occurrence. The mainstay of asthma management is the regulation and control of chronic airway hyperreactivity and inflammation. Children who do not respond to standard asthma regimens should be evaluated for other sources of their pulmonary symptoms, most notably gastroesophageal reflux. Baseline assessment of pulmonary function tests followed by an empiric trial of proton pump inhibitor therapy, using double the standard doses commonly used in acid-related disorders and administered for 3 months, is a cost-effective, noninvasive diagnostic strategy. Children who fail to exhibit pulmonary symptom improvement should be evaluated for both medication compliance and proper administration. Twenty-four-hour esophageal pH monitoring with concurrent dairy recordings of their symptoms is recommended to ascertain adequacy of acid suppression and confirm the diagnosis in those who continue to have symptoms. Children with acid-related causes of their pulmonary symptoms often require long-term treatment. Studies have confirmed the efficacy, safety, and tolerability of proton pump inhibitors in the treatment of children and adolescents. Surgery should be reserved for those with severe disease and those who are unable to comply with pharmacologic treatment.

Decisions in diagnosing and managing chronic gastroesophageal reflux disease in children

Gastroesophageal reflux disease (GERD) presents in different ways in children, most commonly with vomiting, or with esophageal symptoms such as regurgitation, heartburn, or dysphagia. Extraesophageal symptoms and signs also frequently occur. Less well recognized is that abdominal pain is a relatively common mode of presentation. Although abdominal pain is common in school-aged children, GERD and other acid-related disorders such as peptic ulcer disease are relatively uncommon causes of such. A careful history will usually determine whether an acid-related disorder is in the differential diagnosis of abdominal pain. Early detection and treatment of GERD in children may prevent, attenuate, or heal complications such as failure to thrive or feeding refusal as well as pulmonary, ear-nose-and-throat disorders, erosive esophagitis, and peptic stricture. In children with persistent or severe symptoms and/or complications of GERD such as erosive esophagitis, the major treatment options are pharmacologic management with acid-suppressing medication, specifically proton pump inhibitors (PPIs), or antireflux surgery. For many patients, PPI treatment offers advantages over surgery. When given in adequate doses, PPIs can safely effect relief of GERD symptoms and healing of esophagitis in children. Antireflux surgery may work well in selected patients, but it carries significant risk of morbidity, including high failure rates, even in the short term. Some postoperative studies report that more than 60% of patients are back on medical treatment with proton pump inhibitors for recurrence of GERD symptoms, and a similar percentage have new symptoms that were not present before surgery. Death is uncommon but does occur and is an unacceptable risk in an otherwise healthy, low-risk individual. Laparoscopic surgery may have some disadvantages compared with open surgery, including a higher rate of redo operations. Studies show that many children undergo surgery for unclear indications, often with few preoperative diagnostic studies. The availability of highly effective medical therapy, together with more careful selection of patients for surgery, may result in better patient outcomes, with much lower operative rates.

Concomitant dosing of famotidine with a triple therapy increases the cure rates of Helicobacter pylori infections in patients with the homozygous extensive metabolizer genotype of CYP2C19

BACKGROUND

Proton-pump inhibitors, such as lansoprazole, are metabolized in the liver by CYP2C19 and cannot inhibit acid sufficiently in homozygous extensive metabolizers of CYP2C19.

AIM

To examine whether famotidine would increase the cure rates of Helicobacter pylori infection by a standard triple therapy.

METHODS

A total of 177 H. pylori-positive patients were randomly assigned to either lansoprazole 30 mg b.d., clarithromycin 200 mg b.d. and amoxicillin 750 mg b.d. for 1 week (LCA group; n = 89) or famotidine 20 mg b.d., lansoprazole 30 mg b.d., clarithromycin 200 mg b.d. and amoxicillin 750 mg b.d. for 1 week (FLCA group; n = 88). Famotidine was administered after lunch and before sleep, and the others were after breakfast and dinner. CYP2C19 genotypes were determined by a polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) method.

RESULTS

In the LCA group, the eradication rates for homozygous extensive metabolizers, heterozygous extensive metabolizers, and poor metabolizers were 63%, 87%, and 100%, respectively (P = 0.014). Those in the FLCA group were 85%, 85%, and 100%, respectively (N.S.). The cure rate for homozygous extensive metabolizers in the FLCA group was significantly higher than that in the LCA group (P = 0.035).

CONCLUSION

Famotidine improves the cure rate of H. pylori infection by a triple therapy in CYP2C19 homozygous extensive metabolizers patients.

Variable omeprazole kinetics in healthy Jordanian adults

OBJECTIVES

The objective of this study was to examine the pharmacokinetics of orally administered omeprazole in healthy adult Jordanian men.

METHOD

Plasma concentrations of omeprazole were measured over a 12 h period after administration of a single oral dose of 40 mg omeprazole (Losec), AstraZeneca, UK). Subjects were healthy adult Jordanian men age 18-38 (24 +/- 4, mean +/- SD). The pharmacokinetic parameters were derived from the plasma concentration-time profiles for AUC(0-t), AUC(0-inf), C(max), t(max), t(1/2e) and K(e).

RESULTS

The pharmacokinetic of omeprazole were scattered over a wide range. The median AUC(0-inf) was 784.86 +/- 1182.88 (ng.h/ml), and the median C(max) was 521 +/- 354 (ng/ml) (median +/- SD). In general, most subjects showed normal distribution (approximately 90%). Some subjects (10%) did show very high AUC and C(max) compared with the reported AUC and C(max) levels. These subjects had higher half-lives and lower rates of elimination.

CONCLUSION

Significant difference in the pharmacokinetics of omeprazole after a single dose administration was noted. Approximately 10% of the study group showed very high omeprazole plasma levels and AUCs. Differences in the pharmacokinetics might be due to differences in the genetic make-up of subjects.