Continuous Infusion Of Ranitidine Research Articles

Effect of Intravenous Infusion of Omeprazole and Ranitidine on Twenty-Four-Hour Intragastric pH in Patients with a History of Duodenal Ulcer

The effect on intragastric pH of two different dose regimens of continuous intravenous infusion of omeprazole (4 or 8 mg/h after a bolus of 80 mg), and ranitidine (0.25 mg/kg/h after a bolus of 50 mg) was studied in 10 patients with duodenal ulcer disease in symptomatic remission. The pH was monitored over 24-hour periods during fasting in a cross-over, randomised design including a baseline period. With the high omeprazole dose it was possible to maintain a pH > or = 4 in all patients but 1 and 6 of the patients also maintained a pH > or = 6. The lower dose of omeprazole seemed to be somewhat less effective. Continuous infusion of ranitidine was as efficient as the higher omeprazole infusion although with a tendency to decreased pH levels towards the end of the 24-hour period. Thus, in order to obtain consistently high pH levels of 4-6 over a prolonged period a continuous infusion of omeprazole, an 80-mg bolus plus a continuous infusion of 8 mg/h seem to be needed.

Effects of two dosing regimens of intravenous ranitidine on gastric pH in critically ill children

Gastric bleeding in children is associated with critical illness, shock, and physical trauma. Histamine-2 receptor antagonist therapy is used prophylactically to treat gastric bleeding, but it is not known whether bolus dosing or continuous infusion dosing is more effective. To compare the effects of continuous infusion intravenous ranitidine and intravenous bolus dosing of ranitidine on gastric pH in critically ill children and to look for correlation between illness severity scores and gastric pH. Sixteen critically ill children were randomized into two groups. Children in group 1 received bolus dosing on day 1 and continuous infusion of ranitidine on day 2. Group 2 received the continuous infusion on day 1 and bolus dosing on day 2. Equivalent doses of ranitidine were based on weight. Continuous infusion regimen: ranitidine bolus of 0.15 mg/kg followed by continuous infusion at 0.15 mg/kg per hour for 12 hours. Bolus regimen: 1 mg/kg, two doses 6 hours apart. Pediatric risk of mortality scores were recorded upon admission to the study. There was no statistically significant difference between regimens. Both raised gastric pH values above 4.0 during the treatment phase. There was no correlation between illness severity scores and gastric pH values. Both bolus dosing and continuous infusion dosing of 4 mg/kg per day of intravenous ranitidine were effective at raising and maintaining gastric pH in critically ill children.

PH‐feedback controlled infusions of ranitidine are no more effective than fixed‐dose infusions in reducing gastric acidity and variability in antisecretory responses.

1. The antisecretory responses to pH-feedback controlled (maximum dose 800 mg 24 h-1) and fixed-dose (0.25 mg kg-1 h-1) continuous infusions of ranitidine were compared in a randomised, placebo-controlled, cross-over study in 10 healthy male volunteers. 2. To assess tolerance during repeated dosing with ranitidine, the same infusion regimens were given before and after 6 days oral dosing with ranitidine 300 mg four times daily. 3. With the pH-feedback controlled infusion of ranitidine the median % time (interquartile range) with pH greater than 4 in the 24 h period was 57% (45-76) before and 23% (17-34) after 6 days oral dosing (P less than 0.001). The respective values with fixed-dose infusion were 51% (38-63) and 26% (15-32) (P less than 0.002). 4. The median 24 h doses (interquartile range) of ranitidine given by feedback-controlled infusion before and after 6 days oral dosing were 675 mg (542-728) and 749 mg (709-760), respectively (P less than 0.01). The dose of ranitidine given by fixed-rate infusion was 423 mg (393-502) on both study days (P less than 0.001 vs feedback infusion). 5. Plasma gastrin concentrations remained slightly elevated after 6 days of oral ranitidine dosing, whereas pancreatic polypeptide plasma levels remained unchanged. 6. The antisecretory efficacy of infusions of ranitidine is significantly decreased by circadian stimuli and tolerance. Individually-adapted infusions of high doses of ranitidine were not superior to fixed-dose infusion of 0.25 mg kg-1 h-1 in overcoming this variability.

Control of gastric pH with ranitidine in critically Ill patients

The effects of continuous versus bolus administration of ranitidine on gastric pH were compared in critically ill patients admitted to our intensive care unit. Patients were randomized to receive 0.2 mg/kg/hr ranitidine in continuous infusion or 50 mg in bolus every 4 hr. The pH was monitored throughout a 24-hr period, 2 hr in basal conditions and 22 hr during treatment, with a gastric probe. Basal gastric pH was 2.1 +/- 0.2 in the infused and 2.4 +/- 0.2 in the bolus group (P greater than 0.05). The hydrogen ion concentrations were 25.1 +/- 8 and 20.0 +/- 7 mmol/liter, respectively (P greater than 0.05). After ranitidine administration, mean pH was 6.3 +/- 0.6 in patients treated by infusion and 4.5 +/- 0.5 (P less than 0.001) in those who received the drug in bolus; hydrogen ion concentration was 2.5 +/- 2 and 6.9 +/- 6, respectively, (P less than 0.001). Percent of inhibition of acid secretion was 90% in the infused and 68% in the bolus group. Infusion raised pH to values constantly above 4, whereas bolus administration resulted in wide fluctuations. These data indicate that continuous infusion of ranitidine is superior to bolus administration in controlling gastric acidity in critically ill patients.

Comparative efficacy of parenteral histamine (H 2)-antagonists in acid suppression for the prevention of stress ulceration

Stress-related mucosal damage is related to a high intraluminal hydrogen ion concentration, a low intramural pH value, and a breakdown of the gastric mucosal barrier. Because the presence of gastric acid is required for stress-related mucosal damage to occur, therapy aimed at increasing intraluminal pH values has often been used as prophylaxis against complications. The amount of acid suppression required for adequate prophylaxis of gastrointestinal bleeding from stress-related mucosal damage has not been determined, but many investigators use a target gastric pH level of 3.5 to 4.0. When intravenous histamine (H 2)-receptor antagonists are given in bolus dosing regimens to critically ill patients, fluctuations in gastric pH values are often observed, as might be expected. However, recent studies with primed continuous infusion of cimetidine in critically ill patients have demonstrated that consistent elevation of gastric pH to 4.0 may be attained with this regimen. Studies with continuous infusions of ranitidine are less conclusive; little information is available on famotidine.

Continuous intragastric pH measurement in the critically ill and treatment with parenteral ranitidine.

Continuous measurement of gastric pH using a flexible pH electrode attached to a NG tube was performed in nineteen critically ill patients. The gastric pH readings correlated well with hourly intermittent pH values using indicator strips. Hypotension, physiotherapy and septicaemia was consistently associated with falls in gastric pH. A continuous infusion of Ranitidine, a H2-receptor antagonist, was titrated against the continuously measured gastric pH in an attempt to keep it above a pH of 4. This was successfully achieved in sixteen of the nineteen patients using widely variable doses of Ranitidine. The three patients whose gastric pH remained low all had severe septicaemia.