Gastric lesions in neonates: effects of stress?

Pharmacokinetics and pharmacodynamics of ranitidine in neonates treated with extracorporeal membrane oxygenation

The pharmacokinetics and pharmacodynamics of ranitidine were studied in 13 term neonates with stable renal and hepatic function who were treated with extracorporeal membrane oxygenation (ECMO). Ranitidine was initially administered as a single 2 mg/kg dose over 10 minutes and intragastric pH was monitored to determine response. Within 90 minutes after administration of ranitidine, intragastric pH for all of the patients whose initial reading was < or = 4 had increased to > 5. Intragastric pH remained > 4 for a minimum of 15 hours. Mean +/- 1 standard deviation elimination half-life was 6.61 +/- 2.75 hours, and 41.5 +/- 22.2% of the single dose was eliminated in urine within 24 hours. Total plasma clearance of ranitidine correlated well with estimated glomerular filtration rate. Twenty-four hours after the initial dose, a continuous infusion of ranitidine (2 mg/kg/24 hr) was started and continued for 72 hours or until ECMO was discontinued. Eleven patients completed 48 hours of continuous infusion and seven completed all 72 hours. Plasma clearance and elimination half-life were determined from steady-state plasma ranitidine concentrations 24, 48, and 72 hours after the start of the infusion. There were no significant differences in clearance between these intervals. These data suggest that for term neonates with stable renal and hepatic function, ranitidine does not need to be administered more frequently than every 12 hours. A continuous infusion of 2 mg/kg/24 hours maintained intragastric pH above 4 in more than 90% of our patients, and in our opinion is the preferred method for delivering ranitidine to term neonates undergoing ECMO who require H2 antagonists. Response to therapy should be monitored by repeated measurement of gastric pH and the dose should be adjusted accordingly.

A randomized, controlled study of prophylactic ranitidine in preventing stress-induced gastric mucosal lesions in neonatal intensive care unit patients

OBJECTIVE

To assess endoscopically the effect of prophylactic short-term ranitidine treatment in the prevention of stress-induced gastric lesions in neonatal intensive care unit (ICU) patients.

DESIGN

Prospective, randomized study.

SETTING

Department of Neonatal Intensive Care, University Hospital of Tampere.

PATIENTS

Fifty-three infants were enrolled in a randomized, controlled study. Forty-eight (90%) of these patients underwent endoscopic examination and were evaluated.

INTERVENTIONS

A histamine-2-receptor blocker, ranitidine, was given prophylactically after birth for 4 days to infants mechanically ventilated and treated in the neonatal ICU. The gastric mucosa was both visually and histologically evaluated after 3 to 6 days, and the outcome of the infants was registered.

MEASUREMENTS AND MAIN RESULTS

In the 23 infants prophylactically treated with ranitidine, the gastric mucosa was visually classified as normal in 14 (61%) infants as compared with five (20%) of 25 controls (p < .004). Histologic lesions showed parallel results (57% vs. 16%, p < .004). Eight gastric ulcers were diagnosed endoscopically in the control group vs. none in the treatment group. The ulcers were all clinically "silent" at the time of endoscopy. According to logistic regression modeling, the decreased risk for gastric mucosal lesions in infants receiving prophylactic ranitidine was 0.03 (95% confidence interval 0.003 to 0.178). Surfactant treatment for infant respiratory distress syndrome also decreased the risk for stress-induced gastric mucosal lesions (odds ratio 0.083; 95% confidence interval 0.009 to 0.788), whereas other variables (birth weight, gestational age, Apgar scores, cord blood pH, and duration of intubation) had no significant effect. No side effects could be attributed to the ranitidine treatment.

CONCLUSION

We conclude that short-term prophylactic ranitidine treatment prevents gastric mucosal lesions in newborn infants under stress.