Smoking and pH response to H2-receptor antagonists

Smoking has been shown to impair the therapeutic effect of H2-receptor antagonists. To evaluate the acid-reducing capacity of H2-receptor antagonists in relation to smoking habits, we tested the effect of ranitidine (Ran) and famotidine (Fam) under physiologic conditions, using ambulatory pH-metry. Intragastric pH was measured over 20 h. Each of 18 healthy volunteers, 9 smokers and 9 nonsmokers, received 40 mg Fam, 300 mg Ran, or placebo in a double-blind, randomized study as a single evening dose. With both drugs 20-h acidity was markedly suppressed. After Fam treatment mean inhibition was 61% in smokers and 76% in nonsmokers and after Ran 51% and 67%, respectively. When areas under the pH curves for each individual were calculated and treatment compared with placebo (= 100%), the response was smaller in smokers than in nonsmokers with either drug (Fam, 153 +/- 21% versus 214 +/- 19%, p less than 0.01; Ran, 176 +/- 21% versus 232 +/- 29%, p less than 0.05) during the first 4 h after drug intake. A similar effect was observed in the morning period from 0600 to 1000 h (Fam, 118 +/- 19% versus 206 +/- 19%, p less than 0.001; Ran, 133 +/- 21% versus 207 +/- 31%, p less than 0.02). During the nighttime there were no significant differences. These findings indicate that smoking impairs the response to both drugs tested.

Enprostil reduces the increase of gastric corpus mucosal mass induced by the hydrogen-potassium-stimulated adenosine triphosphatase inhibitor BY 831-78 in the rat

We studied whether enprostil, a synthetic prostaglandin E2 derivative, might inhibit gastrin release and the trophic effects on gastric oxyntic mucosa induced by prolonged treatment with an inhibitor of hydrogen-potassium-stimulated adenosine triphosphatase, the substituted benzimidazole BY 831-78. Rats were treated intragastrically with enprostil (1 or 15 micrograms/kg b.i.d.), BY 831-78 (15 mumol/kg once daily), the combination of enprostil and BY 831-78, ranitidine (300 mumol/kg b.i.d.), and placebo. Plasma gastrin and somatostatin levels and gastric acid secretion were measured during a 1-day treatment in animals fitted with chronic gastric fistulas and repeatedly during 9 wk of treatment in intact rats. Despite inhibiting acid secretion, enprostil did not increase plasma gastrin. When combined with BY 831-78, enprostil transiently reduced the BY 831-78-induced increase of integrated plasma gastrin (1375 +/- 206 vs. 2137 +/- 256 pmol/L.12 h, p less than 0.05) in fasted rats with fistulas, but failed to prevent the marked hypergastrinemia following 9 wk of treatment with BY 831-78 (717 +/- 80 vs. 731 +/- 56 pmol/L) in intact rats. However, enprostil reduced the BY 831-78-induced increase of oxyntic mucosal volume (458 +/- 31 vs. 567 +/- 33 mm3, p less than 0.01), whereas BY 831-78 prevented the enprostil-induced increase of antral mucosal volume (42 +/- 3 vs. 56 +/- 3 mm3, p less than 0.01). These results demonstrate that some of the trophic effects induced by a hydrogen-potassium-stimulated adenosine triphosphatase inhibitor are not exclusively governed by gastrin.

Early dinner reduces nocturnal gastric acidity

This study examines whether eating food at different times has differential effects on intragastric pH. Experiments were done in 23 healthy volunteers (12 men). Intragastric acidity was monitored by ambulatory 22 hour pH-metry. Composition of meals was standardised: breakfast and lunch at 7 am and 12 noon respectively, and dinner at 6 or 9 pm, in random order. The time of going to bed and getting up was also standardised. With early dinner nocturnal pH was higher, than with late dinner (pH median: 1.67 and 1.39, p less than 0.001). During the remaining time periods, pH values were similar. Thus early dinner may be helpful in conditions where low intragastric acidity is desirable.

[Clozapine-induced cholestatic jaundice: a case report]

We report on a patient who became jaundiced during treatment with clozapine (Leponex). Histologically, cholestatic hepatitis with single-cell necroses of hepatocytes and infiltration of the portal zones with eosinophilic granulocytes were found. The patient recovered after discontinuation of clozapine, and liver function tests returned to normal within 4 weeks. This adverse effect of clozapine suggests that this "atypical" tricyclic neuroleptic resembles the phenothiazines both with regard to therapeutic spectrum and side effects.

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.

Influence of prostaglandins, omeprazole, and indomethacin on healing of experimental gastric ulcers in the rat

We investigated whether the trophic actions of prostaglandins, omeprazole, and indomethacin on gastric mucosa lead to accelerated healing of gastric ulcers in the rat. Cryoulcers were produced in the corpus area and treated with 16,16-dimethyl prostaglandin E2 (5 or 100 micrograms/kg b.i.d., intragastrically), omeprazole (40 mumol/kg once daily, subcutaneously), indomethacin (2 mg/kg b.i.d., subcutaneously), or placebo. At the end of the treatment, plasma gastrin, cell labeling index (autoradiography with [3H]thymidine), and the size and depth of mucosal defects were measured. Compared with placebo, omeprazole accelerated ulcer healing as indicated by a smaller ulcer area [1.1 +/- 0.2 vs. 4.8 +/- 1.2 mm2 (mean +/- SEM)] and smaller ulcer depth (383 +/- 31 vs. 488 +/- 41 microns) after 10 days of treatment. Prostaglandins did not affect ulcer healing despite thickening of gastric corpus mucosa. Indomethacin delayed ulcer healing and reduced the labeling index. Omeprazole induced a marked hypergastrinemia (208 +/- 12 vs. 66 +/- 12 pmol/L on day 5, and 469 +/- 23 vs. 58 +/- 16 pmol/L on day 10). The results indicate that abolishment of acid secretion by omeprazole accelerates healing. Trophic actions and "cytoprotective" effects by prostaglandins are not relevant for ulcer healing in this model.

Prophylactic treatment of acute gastroduodenal stress ulceration. Low-dose antacid treatment without and with additional ranitidine

Low-dose antacid treatment without and with additional ranitidine in the prevention of acute gastroduodenal stress ulceration in high-risk patients was compared in a randomized, double-blind clinical trial with endoscopic examination of the upper gastrointestinal tract before entry and after the 7-day study period. Of 67 patients who entered the study, 56 could be evaluated. Only one patient, allocated to antacid and placebo, had massive acute upper gastrointestinal bleeding, arising from a gastric ulcer. Although gastric intraluminal pH was better controlled with additional ranitidine treatment, the occurrence of mucosal lesions did not depend on the assigned treatment. We conclude that there is no significant difference between the two regimens in terms of endoscopically visible lesions and clinical outcome.

Effect of 16,16-dimethyl prostaglandin E2 on small intestinal mucosa in suckling rats

Suckling rats were treated every 8 h by intragastric instillation of 16,16-dimethyl prostaglandin E2 (PG) in a dose of 25 micrograms kg-1 (PG25), or 100 micrograms kg-1 (PG100), or saline from postnatal day 7-11. PG increased small intestinal villus length and crypt depth, most markedly in the duodenum, leading to a mucosal height of 543 +/- 24 microns after saline, 670 +/- 26 microns after PG25 and 823 +/- 40 microns after PG100. In the proximal small bowel, PG100 raised the mean activities of sucrase by 439%, maltase by 98%, trehalase by 584%, lactase by 58% and alkaline phosphatase by 76%. In the distal small intestine, only sucrase and trehalase activities were stimulated whereas other enzymes were depressed. PG25 caused similar but less pronounced changes of enzyme activities. Eight hours after both the last PG25 and the last PG100 dose, plasma gastrin and corticosterone levels were decreased while thyroxine remained unchanged. The effect of a single dose of 100 micrograms kg-1 PG or saline was also tested on 5- and 11-day-old rats; they were killed 16 h after PG administration. An increase in villus length occurred along the entire small intestine of rats treated on day 5, and also in the ileum of rats treated on day 11. In the proximal intestine, maltase and trehalase were stimulated after early and late treatment and, in addition, sucrase and lactase after late treatment. Serum corticosterone levels were found to be significantly higher 2-6 h after PG100 than in the controls and then decreased gradually.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of prostaglandins on the adult rat stomach and intestine

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It is wise to prescribe NSAIDs with modern gastroprotective agents?

The administration of non-steroidal anti-inflammatory drugs (NSAIDs) leads to mucosal lesions in the upper gastrointestinal tract. Furthermore, NSAIDs increase the risk of ulcer bleeding and perforation, but the overall risk of fatal complications is relatively small (about 21 per one million prescriptions). Therefore, in asymptomatic patients, it is not justified to prescribe NSAIDs together with gastroprotective agents. The following recommendations can be given with respect to the management of peptic lesions in patients taking NSAIDs: (i) Fibre endoscopy should be performed even when there are relatively mild symptoms since mucosal lesions in rheumatic patients under NSAIDs produce minor or no symptoms. (ii) "Modern" NSAIDs might produce less gastric lesions than aspirin. (iii) Rheumatic patients with peptic disorders should be treated with an H2-antagonist. (iv) After complications such as ulcer bleeding or after rapid recurrence of peptic lesions, maintenance treatment with an H2-antagonist is advisable.

Healing and relapse of reflux esophagitis during treatment with ranitidine

In 108 patients the healing and relapse of reflux esophagitis, defined endoscopically by the presence of epithelial defects (erosions and ulcerations) of the esophageal mucosa, were studied. In the first study, with open treatment of ranitidine, the healing rate after 6 wk was 50%. The most important factor that negatively influenced healing was the extent of esophageal erosions. Patients with isolated erosions had a 6-wk healing rate of 78%; the healing rate was 38% in patients with longitudinally confluent lesions and 23% in those with circumferential erosions of the distal esophagus. Smoking also had an unfavorable effect. Age, sex, duration of history, body weight, and alcohol consumption were not related to outcome. Symptoms improved during treatment with ranitidine, but the correlation between symptoms and endoscopic findings at 6 wk was weak. In the second study, relapse was investigated in 61 patients with healed esophagitis in a randomized, double-blind trial comparing placebo and ranitidine (150 mg at bedtime for 6 mo). In both groups, relapse occurred in more than one-third of the patients, with no significant difference between ranitidine and placebo treatment. Patients with worse daytime symptoms at the time of previous healing had a higher relapse rate. The initial severity of esophagitis and smoking did not influence recurrence. Thus, the initial endoscopic findings are of prognostic value in reflux esophagitis. Smoking retards healing. Low-dose maintenance treatment with ranitidine does not prevent relapse.

Indomethacin and turnover of gastric mucosal cells in the rat

Mucosal morphology and the balance between cell loss and cell renewal were analyzed during treatment with a non-ulcerative dose of indomethacin. All rats were treated twice daily by subcutaneous injection of 2 mg/kg indomethacin or the solvent. The following parameters were assessed: cell proliferation on day 3 (determination of in vitro [3H]thymidine incorporation), cell migration on days 1 and 3 (autoradiography), cell shedding on days 7 and 14 (measurement of the remaining DNA-bound mucosal radioactivity after in vivo labeling with [3H]thymidine prior to treatment), mucosal morphology on day 14 (light microscopy), ex vivo mucosal prostaglandin E2 on day 14, and serum gastrin on days 0, 7, and 14. Indomethacin treatment had no effect on serum gastrin levels but reduced mucosal prostaglandin E2. Indomethacin produced a significant increase of [3H]thymidine incorporation, cell migration, and loss of mucosal DNA-bound radioactivity in the corpus and, to a lesser degree, in the antrum. Morphologically, this led to a hyperplasia of parietal cells (+15%, P less than 0.05) and chief cells (+45%, P less than 0.01) in the corpus, but antral morphology remained unchanged. We conclude that indomethacin stimulates the turnover of gastric mucosal cells. In the corpus, but not in the antrum, proliferation exceeds shedding, thus leading to increased mucosal volume.

Effect of acid inhibition on the growth of parietal cells

Studies in the rat have shown that prolonged inhibition of acid secretion by high doses of a histamine H2 antagonist is followed by a 20-30% increase in the number of parietal cells, and that this is paralleled by an augmentation of the maximum acid output. A similar effect has been shown after prolonged acid neutralization with high doses of an antacid. These trophic effects are not unexpected. An increase in gastric pH is followed by gastrin release, and the parietal cell mass may be augmented by repeated exogenous administration of gastrin or by endogenous hypergastrinaemia following surgery. To further evaluate whether a direct correlation exists between the magnitude of drug-induced hypergastrinaemia and parietal cell hyperplasia, rats were treated for 24 days with two acid inhibitors which differ markedly in the degree of acid inhibition and acute or chronic gastrin release. Six animals each were treated with either omeprazole (40 mumol/kg once daily), or atropine (3 mg/kg twice daily), or omeprazole combined with atropine or with placebo. On day 24, plasma gastrin was elevated more than 10-fold in both groups of rats treated with omeprazole but not in animals given atropine alone. As compared to placebo treatment, total parietal cell volume was significantly higher in animals treated with atropine (102 +/- 9 mm3 versus 140 +/- 18 mm3), but was unchanged in the other two groups. These studies demonstrate that marked prolonged drug-induced hypergastrinaemia does not necessarily exert trophic effects on parietal cells. Furthermore, the finding that omeprazole abolishes the effect of atropine suggests that omeprazole interferes with trophic actions on parietal cells.

Protective drugs in the treatment of gastroduodenal ulcer disease

Reduction of gastric acidity by the inhibition of secretion or neutralization is the therapeutic principle most widely used in peptic ulcer disease. From a pathophysiological standpoint, this does not appear logical, because in a majority of patients gastric acid secretion is not increased. In addition, there is some concern about the consequences of a reduction in gastric acidity, especially in the long term. And finally, all available inhibitors of gastric acid secretion have a systemic action and may thus cause systemic side effects. Carbenoxolone, sucralfate, and tri-potassium dicitrato bismuthate have been shown to accelerate healing of ulcers without appreciable acid inhibition. Despite an apparently different mode of action, the healing rates are similar to those of commonly used acid inhibitors. Several possible mechanisms of action have been claimed for each of these agents, but none has been convincingly demonstrated to be essential in ulcer healing. This may reflect ignorance of the relevant events rather than an action by a combined principle.

Clinical relevance of mucosal protection

An inquiry was made among 70 of the 76 participants of an international symposium entitled 'Future Directions in Peptic Ulcer Research', held in Bellagio, Italy, in April 1986. There was almost unanimous agreement that research in the development of protective drugs should be intensified. The participants felt that in future studies the prevention of ulcer relapse, concomitant administration with potentially ulcerogenic drugs, prevention of stress ulceration, and treatment of ulcer hemorrhage should be emphasized rather than the healing of uncomplicated ulcers. They were not generally satisfied with the performance of available prostaglandin analogues in ulcer treatment. The moderate commercial success of sucralfate was attributed mainly to the complicated mode of intake, but also to the unknown mechanism of action of this substance. It was felt likely that antacids have a clinically relevant protective effect on gastroduodenal mucosa.

Structure and function of gastric corpus mucosa in suckling rats after treatment with 16,16-dimethyl prostaglandin E2

Suckling rats were treated every 8 h by intragastric instillation of 16,16-dimethyl prostaglandin E2 (PG) from postnatal day 7 to 11. As compared to saline control treatment, PG increased the thickness of antral and corpus mucosa, the volume density of parietal cells, the mean individual parietal cell volume and pentagastrin-stimulated acid secretion at the end of the treatment. Plasma gastrin and corticosterone levels were depressed by PG while plasma thyroxine levels were unchanged. These structural and functional changes suggest PG-induced accelerated maturation of gastric mucosa.

Influence of 16,16-dimethyl prostaglandin E2 on morphology and brush border enzymes of small-bowel mucosa. Differences in reactivity between adult and suckling rats

High doses of 16,16-dimethyl prostaglandin E2 (dmPGE) are trophic to the small bowel of adult and suckling rats. In suckling rats this effect is paralleled by an increase in brush border enzyme activities, possibly indicating accelerated mucosal maturation. To investigate the possible physiological significance of this phenomenon, we examined whether this induction of intestinal enzyme activities can be reproduced in adult rats and whether cell growth and enzyme activity might be suppressed by indomethacin. Treatment twice daily for 2 weeks with 100 micrograms/kg dmPGE by intragastric instillation increased villus length in the proximal and distal small bowel by 36% and 40%, respectively, while 2 mg/kg indomethacin by subcutaneous injection had no effect. Maltase, trehalase, lactase, and sucrase activities were unchanged after dmPGE or indomethacin. [3H]-thymidine incorporation into DNA was not significantly influenced for up to 24 h after a single dose of both 100 micrograms/kg PGE intragastrically or 10 mg/kg indomethacin subcutaneously. These studies confirm that in adult rats large doses of 16,16-dm PGE2 increase the volume of the small-bowel mucosa. In contrast to the situation in suckling rats, the activity of hydrolytic brush border enzymes is not increased. There is thus no evidence that endogenous prostaglandins are trophic or influence brush border enzymes in the adult rat.