Site-protective agents

Influence of colloidal bismuth subcitrate on enzyme secretion from isolated rat pancreatic acinar cells

Bismuth salts are currently used as monotherapy or in combination with antibiotics for the treatment of Helicobacter pylori-associated peptic ulcer disease. Besides encouraging clinical results with colloidal bismuth subcitrate (CBS), there is an ongoing fear of organ toxicity with the use of bismuth salts. To study potential toxic effects of CBS under short-term exposure, we tested the influence of CBS on amylase secretion from isolated rat pancreatic acinar cells under basal conditions and following carbachol (CCh) and ceruletide (CRT) stimulation. Basal secretion was reduced by 8.9 +/- 9.6% (n = 10) (mean +/- SEM) (P < 0.05), 5.2 +/- 9.2% (P < 0.05), 9.4 +/- 6.4% (P < 0.01), and 6.2 +/- 12.2% (P < 0.05) with 0.001, 0.01, 0.1, and 1 micrograms/ml CBS, respectively. With 10 micrograms/ml and 100 micrograms/ml CBS, basal amylase secretion was increased in a dose-dependent manner, by 13.7 +/- 11.7% (P < 0.05) and 24.5 +/- 12.8% (P < 0.01). CCh (10(-5) M)- and CRT (3 x 10(-10) M)-stimulated secretory responses were not altered significantly by any of the CBS doses used. In concentrations above 1 microgram/ml, CBS increased pancreatic amylase secretion. Amylase secretion in response to secretagogues was not affected by CBS. These findings are unlikely to be associated with a toxic effect of CBS on exocrine pancreatic acinar cell function.

Does a previous course of tripotassium dicitrato bismuthate affect the subsequent chances of successful Helicobacter pylori eradication?

We have performed a retrospective study of 103 patients with either peptic ulcer or non-ulcer dyspepsia, infected with metronidazole-sensitive strains of Helicobacter pylori (H. pylori), who were treated with a combination of tripotassium dicitrato bismuthate and metronidazole for a period of at least two weeks. Dual therapy with tripotassium dicitrato bismuthate plus metronidazole showed similarly high eradication rates (greater than or equal to 80%) of H. pylori from patients irrespective of age, gender or clinical diagnosis. Most importantly, dual therapy achieved a similar eradication rate of H. pylori infection in 41 patients who had previously been treated with tripotassium dicitrato bismuthate alone or in combination with an antibiotic other than metronidazole. It therefore appears that H. pylori does not become resistant to treatment with tripotassium dicitrato bismuthate.

Acid secretory changes and early relapse following duodenal ulcer healing with ranitidine or sucralfate

Controversial aspects relating to acid secretory changes following duodenal ulcer healing, and the effect of histamine-2 (H2)-receptor blockers on such changes are discussed. Recent studies comparing the effects of ranitidine or sucralfate on changes in the acid secretory responses in the healing of duodenal ulcers are described, and the relevance of these changes to early relapse considered. The duration of therapy and timing of acid-secretory studies and endoscopies are standardized in all studies, but the acid-secretory parameters vary. These comprised acid secretory responses to graded doses of an intravenous infusion of pentagastrin or histamine, sham-feeding responses, and basal and nocturnal acid secretion. In all studies, healing with sucralfate was associated with a significant decrease in the various parameters of acid secretion. In the ranitidine-healed groups, no appreciable decrease was noted and there was, indeed, a significant increase in nocturnal acid secretion. Routine endoscopies performed 4-6 weeks after documented ulcer healing showed a recurrence of 3 of the 32 (9%) sucralfate-healed and in 14 of the 35 (40%) ranitidine-healed ulcers. Increased acid secretory responsiveness following duodenal ulcer healing was strongly correlated with subsequent early relapse.

Treatment of peptic ulcer disease in the arthritic patient

Dyspepsia associated with arthritis and non-steroidal anti-inflammatory drugs (NSAIDs) is a common clinical problem. Up to 80% of deaths attributable to peptic ulceration may be associated with NSAID usage. The problem is foremost in the elderly population, in which there has been an increase both in the incidence of peptic ulcers and in the use of NSAIDs. Although the development of duodenal ulceration is not clearly associated with NSAIDs, it is accepted that these drugs increase the risk of gastric ulceration and the occurrence of peptic ulcer complications. Asymptomatic peptic ulceration is common, and patients taking NSAIDs are often asymptomatic prior to presentation with life-threatening complications. The key principle in management of this problem is prevention through careful selection of patients for NSAID use, adequate treatment of peptic ulceration and maintenance of remission. A variety of effective drugs are available for the treatment of peptic ulcers, including H2-receptor antagonists, pirenzepine, sucralfate and colloidal bismuth subcitrate. However, it is recognised that peptic ulceration is a chronic disease with a relapsing-remitting course, often with asymptomatic ulcer episodes. The knowledge that current ulcer-healing strategies do not significantly alter this natural history has lead to increasing efforts to prevent relapse with effective 'maintenance' therapy.

Sucralfate and ranitidine in the treatment of acute duodenal ulcer. Healing and relapse. Ulcer Study Group

Healing and relapse of acute duodenal ulcer were investigated in an endoscopically controlled multicenter study using a double-blind design. Patients with acute uncomplicated duodenal ulcer were randomly assigned to treatment with sucralfate (1 g four times per day) or ranitidine (150 mg twice per day) for four to eight weeks. After healing, all anti-ulcer treatment was discontinued except for low-dose antacids needed for occasional upper abdominal pain, and the patients were observed for up to one year. Endoscopy was repeated after one year or at any time earlier if symptoms suggested ulcer relapse. Of the 83 patients who entered the study, 75 (sucralfate 40, ranitidine 35) underwent endoscopy after four weeks and could be fully evaluated. Healing rates after four and eight weeks were similar in the two groups (four- and eight-week healing rates after sucralfate and ranitidine: 78 and 74 percent, and 95 and 94 percent, respectively). Fifty-three patients with healed ulcers (sucralfate 29, ranitidine 24) were observed for up to one year. Duodenal ulcers occurred somewhat later after sucralfate than after ranitidine treatment, but life table analysis showed no significant difference. Thus, this study confirms a similar efficacy of sucralfate and ranitidine in healing of duodenal ulcer. A tendency to delayed relapse early after discontinuation of sucralfate failed to reach statistical significance.

The absorption of bismuth from oral doses of tripotassium dicitrato bismuthate

Two studies measured plasma concentrations of bismuth during dosing with tripotassium dicitrato bismuthate (De-Noltab). The first study compared 24 h plasma bismuth concentration and urinary bismuth excretion in six patients who had already received 29-131 days (median 47 days) of treatment with De-Noltab 2 b.d., and six healthy subjects who only received De-Noltab 2 b.d. on the day of study. There was a prompt rise in plasma bismuth concentration after each dose of De-Noltabs. The median 24 h integrated plasma bismuth concentration was similar in both groups, but the median 24 h urinary bismuth excretion was 5.4-fold higher in the patients. The second study compared the plasma bismuth concentrations after the first and third doses of De-Noltab 2 b.d. in 16 healthy subjects. The median peak bismuth concentration occurred 30 min (range 15-105 min) post-dosing. The peak plasma bismuth concentration was greater than 50 ng/ml in 14 of the 16 subjects, and greater than 100 ng/ml in nine of the subjects. There was no significant difference in the median integrated 10-h plasma bismuth concentration after the first or third dose of De-Noltabs. The results of these studies confirm that bismuth is absorbed and sequestrated during dosing with De-Noltabs. Bismuth is absorbed rapidly after oral dosing with De-Noltabs, to produce peak plasma bismuth concentrations hitherto considered to be in the range associated with bismuth neurotoxicity.