Gastric acid secretion and emptying rates in children with duodenal ulcer

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.

Gastric acid secretion and gastrin release in the baboon

Significant species differences have been demonstrated in gastric physiology, a factor that limits extrapolation of animal data to man. Primate physiology is thought to be similar to that of man; however, gastric function has not been adequately documented in the primate. In the present study six baboons (body weight 25.5 +/- 1.8 kg) were trained to sit in a chair and gastric acid secretion and gastrin release was studied in conscious animals. Mean basal acid secretion was 1.3 +/- 0.1 mmol (H+)/hr. Maximum output after pentagastrin (12 micrograms/kg/hr) was 9.5 +/- 0.9 mmol (H+)/hr and 11.0 +/- 0.4 mmol (H+)/hr after histamine (40 micrograms/kg/hr). A statistically significant (by cosinor analysis) circadian rhythm was demonstrated for intragastric pH over 24 hr in fasted baboons (P less than 0.001). Mean basal serum gastrin level was 37.7 +/- 8.3 pg/ml. The integrated gastrin response after administration of a protein rich meal was 2.52 +/- 0.07 ng x min/ml and this increased to 5.17 +/- 0.18 ng x min/ml (P less than 0.05) following simultaneous administration of a meal with atropine (0.2 mg/kg) (P less than 0.05). Our results suggest that there is significant basal and stimulated acid secretion in the baboon; the amount of acid secreted is similar to that reported in man. Gastric pH demonstrated a circadian rhythm. Postprandial gastrin release was significantly enhanced by cotreatment with atropine. As the present findings are similar to those previously reported in man, the baboon may be a useful model for further studies in gastric physiology and experimental peptic ulceration.

Peptic ulcer disease in children

Primary duodenal ulcer disease occurs in children of all ages, but is most often seen in those over 10 years. As in the adult, it often pursues a chronic course. Primary gastric ulcer is seen in children under 6 years, is more unusual, and does not tend to recur. Stress ulcers are seen most often in infants and in critically ill children and are asymptomatic until the complications of hemorrhage or perforation appear. Drug-related ulcers are being seen more frequently as the use of nonsteroidal anti-inflammatory agents increases. With the use of new therapeutic agents, management has been simplified and surgical intervention has become a rarity. Helicobacter pylori is now a recognized cause of antral gastritis and ulceration in the child.

Peptic ulcer in children

From January 1983 to April 1989, 39 children were diagnosed as suffering from primary peptic ulcer. Of these ulcers, 30 were duodenal, seven prepyloric, and two patients had a combination of both. Among 36 patients with H2-blocker therapy, 33 had treatment completed with ulcer healing assessed by endoscopic examinations. Sixteen patients (49%) had ulcer healing within a single 6-week course of treatment, whereas 17 patients (51%) required multiple 6-week courses. The latter group had a mean basal acid output (BAO) of 0.13 +/- 0.06 mmol/kg/h and a mean maximal acid output (MAO) of 0.48 +/- 0.12 mmol/kg/h, which is significantly higher (P less than .05 and P less than .005, respectively) than the mean BAO (0.08 +/- 0.06 mmol/kg/h) and mean MAO (0.31 +/- 0.11 mmol/kg/h) in patients whose ulcers healed within 6 weeks of treatment. Subsequent follow-up with endoscopy over a mean period of 1.8 years (range, 3 months to 6 years) showed 10 patients with recurrent ulcers. Life-table analysis showed a recurrence rate of 35% within 1 year after ulcer healing. Five patients required surgery for ulcer complications--obstruction (2), perforation (2), and bleeding (1). In two of these patients initial H2-blocker therapy was unsuccessful.

Hypergastrinemia in children with duodenal ulcer

Serum gastrin concentrations were determined in 25 children with duodenal ulcer (DU) and 25 normal children. Fasting values were significantly higher in DU children (mean +/- SE = 60.4 +/- 9.7 pg/mL) than in controls (mean +/- SE = 38.0 +/- 4.2 pg/mL; P less than .05). Integrated gastrin response to meal stimulation was also significantly higher in DU children (mean +/- SE = 140.5 +/- 32.4%) than in controls (mean +/- SE = 62.3 +/- 12.2%; P less than .05). Excessive gastrin activity (greater than normal mean + 2 SD), either fasting or meal-stimulated, occurred in 11 of 17 normal acid secretors and in two of eight hypersecretors in the DU group. The present findings suggest that excessive gastrin activity is a major factor in the pathogenesis of childhood DU. Unlike adult DU, which is associated with normal fasting gastrin concentrations, childhood DU manifests exaggerated gastrin activity both in the fasting and postprandial states.

Peptic ulcer disease in the pediatric population

Peptic ulcer disease occurs in infants, children, and adolescents. Primary and stress ulcers pose a challenge to the pediatrician, who needs to arrange for appropriate diagnostic and therapeutic services. Highlights of our understanding of the pathophysiology, genetics, natural history, diagnosis, and therapy of peptic ulcer disease are presented.