Omeprazole reduces preoperative gastric fluid acidity and volume in children

Review of paediatric gastrointestinal physiology relevant to the absorption of orally administered medicines

Despite much progress in regulations to improve paediatric drug development, there remains a significant need to develop better medications for children. For the design of oral dosage forms, a detailed understanding of the specific gastrointestinal (GI) conditions in children of different age categories and how they differ from GI conditions in adults is essential. Several review articles have been published addressing the ontogeny of GI characteristics, including luminal conditions in the GI tract of children. However, the data reported in most of these reviews are of limited quality because (1) information was cited from very old publications and sometimes low quality sources, (2) data gaps in the original data were filled with textbook knowledge, (3) data obtained on healthy and sick children were mixed, (4) average data obtained on groups of patients were mixed with data obtained on individual patients, and (5) results obtained using investigative techniques that may have altered the outcome of the respective studies were considered. Consequently, many of these reviews draw conclusions that may be incorrect. The aim of the present review was to provide a comprehensive and updated overview of the available original data on the ontogeny of GI luminal conditions relevant to oral drug absorption in the paediatric population. To this end, the PubMed and Web of Science metadatabases were searched for appropriate studies that examined age-related conditions in the oral cavity, esophagus, stomach, small intestine, and colon. Maturation was observed for several GI parameters, and corresponding data sets were identified for each paediatric age group. However, it also became clear that the ontogeny of several GI traits in the paediatric population is not yet known. The review article provides a robust and valuable data set for the development of paediatric in vitro and in silico biopharmaceutical tools to support the development of age-appropriate dosage forms. In addition, it provides important information on existing data gaps and should provide impetus for further systematic and well-designed in vivo studies on GI physiology in children of specific age groups in order to close existing knowledge gaps and to sustainably improve oral drug therapy in children.

Practice Guidelines for Preoperative Fasting and the Use of Pharmacologic Agents to Reduce the Risk of Pulmonary Aspiration: Application to Healthy Patients Undergoing Elective Procedures

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Gastric Volume and Its Relationship to Underlying Pathology or Acid-suppressing Medication

Background

Pulmonary aspiration during sedation is a major concern for sedation providers, making identifying high-risk patients a priority. Gastric fluid volume (GFV), an accepted risk factor for aspiration, has not been well characterized in fasting children. We hypothesized that GFV would increase with gastrointestinal (GI) pathology and decrease with regular acid-suppressor use.

Aims

The primary objective was to determine baseline GFV in fasting children. The secondary objectives were to evaluate the effect of GI pathology and regular use of acid-suppressing medications on GFV.

Settings and Study Design

This was prospective, observational study.

Materials and Methods

We endoscopically aspirated and measured GFV of 212 children fasting for >6 h who were sedated for esophagogastroduodenoscopy (EGD). Inclusion criteria were children up to 21 years of age, with the American Society of Anesthesiologists physical Status I and II presenting for elective EGD. After determining baseline GFV, the effect of GI pathology and effect of regular acid-suppressing medication use on GFV was analyzed.

Statistical Analysis

Analysis of variance was used to compare the GFV among ages and pathology and medication groups. Student's t-test was used to compare GFV between genders and also to compare GFV in confounder analyses.

Results

For the studied 212 children, average GFV was 0.469 ± 0.448 mL/kg (0-2.663 mL/kg). We found no association between GI pathology and GFV (P = 0.147), or acid-suppressor use and GFV (P = 0.360).

Conclusions

Average GFV in this study falls within the range of prior EGD-measured GFV in fasting children. Contrary to our hypothesis, we found no association between pathologies or regular acid-suppressor use on GFV. On the basis of GFV, children with GI disorders or those using acid-suppressors do not appear to pose an increased risk of aspiration. Future studies should discern differences in effects on GFV of immediate preprocedural versus the regular use of acid-suppressing medications.

Ontogeny of oral drug absorption processes in children

INTRODUCTION

A large proportion of prescribed drugs to children are administered orally. Age-related change in factors affecting oral absorption can have consequences for drug dosing.

AREAS COVERED

For each process affecting oral drug absorption, a systematic search has been performed using Medline to identify relevant articles (from inception till February 2012) in humans. This review presents the findings on age-related changes of the following processes affecting oral drug absorption: gastric pH, gastrointestinal motility, bile salts, pancreatic function, intestinal pH, intestinal drug-metabolizing enzymes and transporter proteins.

EXPERT OPINION

Clinicians should bear in mind the ontogeny of oral drug absorption processes when prescribing oral drugs to children. The authors' review shows large information gaps on almost all drug absorption processes. It is important that more knowledge is acquired on intestinal transit time, intestinal pH and the ontogeny of intestinal drug-metabolizing enzymes and drug transporter proteins. Furthermore, the ultimate goal in this field should be to predict more precisely the oral disposition of drugs in children across the entire pediatric age range.

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.

Double-blind placebo-controlled trial of omeprazole in irritable infants with gastroesophageal reflux

OBJECTIVE

To assess the efficacy of omeprazole in treating irritable infants with gastroesophageal reflux and/or esophagitis.

STUDY DESIGN

Irritable infants (n=30) 3 to 12 months of age met the entry criteria of esophageal acid exposure >5% (n=22) and/or abnormal esophageal histology (n=15). They completed a 4-week, randomized, double-blind, placebo-controlled crossover trial of omeprazole. Cry/fuss diary (minutes/24 hours) and a visual analogue scale of infant irritability as judged by parental impression were obtained at baseline and the end of each 2-week treatment period.

RESULTS

The reflux index fell significantly during omeprazole treatment compared with placebo (-8.9%+/-5.6%, -1.9%+/-2.0%, P<.001). Cry/fuss time decreased from baseline (267+/-119), regardless of treatment sequence (period 1, 203+/-99, P<.04; period 2, 188+/-121, P<.008). Visual analogue score decreased from baseline to period 2 (6.8+/-1.6, 4.8+/-2.9, P=.008). There was no significant difference for both outcome measures while taking either omeprazole or placebo.

CONCLUSIONS

Compared with placebo, omeprazole significantly reduced esophageal acid exposure but not irritability. Irritability improved with time, regardless of treatment.

The use of proton pump inhibitors in children: a comprehensive review

Proton pump inhibitors (PPIs) belong to a group of chemically related compounds whose primary function is the inhibition of acid production in the final common metabolic pathway of gastric parietal cells. PPIs are highly selective and effective in their action and have few short- or long-term adverse effects. These pharmacologic features have made the development of PPIs the most significant advancement in the management of acid peptic related disorders in the last two decades. There are numerous published adult studies that describe the pharmacology, efficacy and safety of these anti-secretory agents; however, in the pediatric population, there are very few comparable studies, particularly multicenter studies with significant patient enrollment. In preparing this article, our aim was to perform a comprehensive review of the literature on the clinical pharmacology and use of PPIs in the pediatric population, and to briefly review some recent articles. Relevant literature was identified by performing MEDLINE/Pubmed searches from January 1990 to December 2001. Combinations of the following search terms were use to analyze these databases: proton pump inhibitor, children, pediatrics, gastroesophageal reflux disease (GERD), esophagitis, intestinal metaplasia, Helicobacter pylori, omeprazole, lansoprazole, pantoprazole, rabeprazole, esomeprazole, and safety. Abstracts from the 14th annual conference of the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition (NASPGHAN) 2001, and the Disease and Digestive Week 2001, were also included in the review. All pediatric studies reviewed were limited to either omeprazole or lansoprazole. The dosage range used for the management of GERD and related disorders with lansoprazole was 0.73-1.66 mg/kg/day (maximum 30 mg/day). The dosage range for GERD management using omeprazole was 0.3-3.5 mg/kg (maximum 80 mg/day). The dosage range for omeprazole used for H. pylori was 0.5-1.5 mg/kg/day, with a maximum dosage of 40 mg/day, and lansoprazole-containing regimens for H. pylori eradication used dosages ranging from 0.6-1.2 mg/kg/day, with a maximum dosage of 30 mg/day. Few severe adverse events were reported with the use of either drug. Eradication rates for H. pylori were 56-87% for lansoprazole-based triple therapy, and 75-94% for omeprazole-based eradication regimens. To date, there are no published controlled trials of sufficient power comparing the efficacy of the five commercially available PPIs in children, for a variety of acid peptic diseases. Studies suggest that PPIs are highly effective for the management of GERD and related disorders, and are a critically needed component of triple therapy to eradicate H. pylori. PPIs have a very good tolerability profile in adults and children, but long-term tolerability studies are needed, particularly in the pediatric population. Multicenter studies are critically needed to evaluate the second-generation PPIs, to compare PPI efficacy to each other, and to assess the importance of developmental and genetic pharmacology of these drugs in children with acid-peptic disease.

The efficacy of lafutidine in improving preoperative gastric fluid property: a comparison with ranitidine and rabeprazole

IMPLICATIONS

Acid aspiration syndrome remains a potentially critical perioperative complication. We compared lafutidine, ranitidine, and rabeprazole for reduction of preoperative gastric fluid acidity and volume in elective surgery and found that these variables were minimized with a single morning dose of lafutidine 20 mg compared with ranitidine or rabeprazole. Preoperative oral lafutidine may be an alternative to ranitidine as a prophylaxis against aspiration pneumonia.

Omeprazole pharmacodynamics and gastric acid suppression in critically ill pediatric transplant patients

OBJECTIVE: To characterize the pharmacodynamics and pharmacokinetics of omeprazole suspension in critically ill pediatric liver/intestinal transplant patients. DESIGN: Open-label pharmacodynamic and pharmacokinetic study. SETTING: Pediatric intensive care unit of an academic medical center. PATIENTS: Eleven pediatric liver and/or intestinal transplant patients. INTERVENTIONS: Extemporaneously prepared 0.5 mg/kg omeprazole suspension every 12 hrs via nasogastric tube before sequential measurements of omeprazole serum concentration and gastric pH monitoring. Gastric pH was monitored continuously for 48 hrs and plasma omeprazole concentrations were determined upon first and multiple dosing. MEASUREMENTS AND MAIN RESULTS: Mean onset of action of omeprazole in a sodium bicarbonate vehicle was 62 +/- 82 mins (range, 2-226 mins). Subjects <4 yrs of age exhibited a more variable onset of omeprazole action (range, 3-226 mins) when compared with older subjects (onset of action, 2-40 min). Omeprazole maximum concentration and area under the concentration-time curve for the dosage interval were significantly greater upon multiple dosing when compared with the first dose. Mean baseline gastric pH in this study population was 1.0 +/- 0.8. Gastric pH remained >4.0 for 78.8% +/- 18.9% of the first dosage interval and 97.8% +/- 5.4% of multiple dosage intervals regardless of age when administered twice daily as a suspension. CONCLUSION: These results support the use of omeprazole administered twice daily as a suspension to maintain gastric pH of >4.0 and to achieve maximal pharmacodynamic effect in pediatric liver and/or intestinal transplant patients.

Preoperative anxiety and volume and acidity of gastric fluid in children

Forty-three patients aged 3-6 years, undergoing minor surgery were studied. Parents staying with their children were asked to evaluate the anxiety of their children and themselves by a visual-analogue scale the night before surgery (VAS-N) and just before premedication in the morning (VAS-M). After induction, gastric fluid was collected and the volume and pH were measured. Patients with a VAS-M lower than 5 were considered the low-anxiety group (L-group; n=24) and the remainder comprised the high-anxiety group (H-group; n=19). The gastric volume of the H-group was significantly lower than that of the L-group. No difference was found in pH. A significant overall correlation of VAS-N was found between patients and their parents. These results suggest that the low level anxiety of children and their parents could not reduce the volume and acidity of gastric fluid and consequently the risk of aspiration pneumonia.

Upper gastrointestinal tract bleeding in critically ill pediatric patients

Similar to adults, children under physiologic stress can develop an imbalance in defensive (mucosal layer, motility) and aggressive (gastric acid, bile salts, enzymes) factors responsible for maintaining a healthy gastrointestinal tract. Hypoxia in the gastrointestinal tract likely disrupts the defensive factors, thereby permitting damage by aggressive factors to upper gastrointestinal epithelium that may progress to stress ulceration and acute upper gastrointestinal tract bleeding (UGIB). The basic pathophysiology may be similar in children and adults; however, differences in the time to developing ulceration, ulcer location, and number of ulcers have been reported. Functional development of the gastrointestinal tract is influenced by disease, gestational and postnatal age, and exposure to and type of enteral feedings, thereby confounding the development and prophylaxis of UGIB in neonates and infants. In addition, pharmacotherapy decisions are often complicated by drug administration issues and adverse effects.

A comparison of lansoprazole, omeprazole, and ranitidine for reducing preoperative gastric secretion in adult patients undergoing elective surgery

Acid aspiration syndrome of induction of anesthesia is a life-threatening complication whose severity is affected by both pH and volume of the aspirated gastric juice. We compared the effects of two proton pump inhibitors (PPIs), lansoprazole and omeprazole, and an H2 blocker, ranitidine, on gastric secretion in a prospective, randomized, double-blind fashion in 200 adult patients of ASA physical status I undergoing elective surgery. The patients were divided into eight groups (n = 25 each) according to their premedication. The patients received lansoprazole-lansoprazole (Group L-L), lansoprazole-placebo (Group L-P), placebo-lansoprazole (Group P-L), omeprazole-omeprazole (Group O-O), omeprazole-placebo (Group O-P), placebo-omeprazole (Group P-O), placebo-ranitidine (Group P-R), or placebo-placebo (Group P-P), as the first and second medications. The dose of the study drug was 30 mg for lansoprazole, 150 mg for ranitidine, and 80 mg for omeprazole. The first medication was administered orally at 9:00 PM on the night before surgery and the second at 5:30 AM in the morning on the day of the surgery. Each patient fasted overnight and took the drug with 20 mL of water. After tracheal intubation, gastric fluid was aspirated via an orogastric tube and the volume and pH of the aspirate were measured. The pH of the aspirated gastric fluid was higher in Groups P-R, L-L, P-L, O-O, and O-P than in Group P-P (P < 0.05). The volume of the gastric contents was similar in Groups P-0 and P-P, and the other groups had smaller gastric volume than Group P-P (P < 0.05). Gastric fluid from patients in Group P-R was the least acidic (pH 6.1 +/- 1.2) and had the least volume (0.09 +/- 0.06 mL/kg). Group L-L was comparable with Group P-R in both pH and volume, whereas Groups P-L and O-O were similar to Group P-R only in volume. The proportion of patients at risk according to the traditional criteria (pH < 2.5 and volume 0.4 mL/kg) was significantly lower in Groups L-L (0%), P-L (4%), O-O (4%), and P-R (0%) than in Group P-P (48%) (P < 0.05). We concluded that two consecutive doses of lansoprazole or a morning dose of ranitidine seemed to be the most effective preanesthetic medication for reducing gastric acidity and volume.

Lansoprazole reduces preoperative gastric fluid acidity and volume in children

The purpose of this study was to explore the efficacy of lansoprazole, a proton pump inhibitor, in reducing the acidity and volume of gastric aspirate in children immediately following the induction of anaesthesia. One hundred healthy in-patients aged 3-11 yr undergoing elective surgery were randomly allocated to four groups (n = 25 each): lansoprazole-lansoprazole, placebo-placebo, placebo-lansoprazole, and lansoprazole-placebo. For each treatment regimen, the first medication was administered at 9:00 pm on the night before surgery and the second at 5:30 am on the morning of the day of surgery (three hours preoperatively). The dose of lansoprazole was 30 mg (approximately 1.4 mg.kg-1 mean). Children were offered 10 ml.kg-1 apple juice three hours before induction of anaesthesia. After induction of anaesthesia and tracheal intubation, gastric fluid was aspirated through a large-bore, multiorifice orogastric tube and analyzed for pH and total fluid volume. Lansoprazole increased gastric fluid pH and decreased gastric fluid volume regardless of whether it was administered before or after placebo. Two consecutive doses of lansoprazole was the most effective means of increasing the pH and reducing the volume of gastric aspirate; in this group, there were no subjects with gastric aspirate volume > 0.4 ml.kg-1 and pH < 2.5. Oral lansoprazole, at least 30 mg, given on the night before surgery or on the morning of surgery will improve the gastric environment at the time of induction of paediatric anaesthesia. The most effective regimen was two doses (at bedtime and on the morning) of lansoprazole.