Low-dose famotidine and ranitidine as single post-prandial doses: a three-period placebo-controlled comparative trial

Acid peptic diseases: pharmacological approach to treatment

Acid peptic disorders are the result of distinctive, but overlapping pathogenic mechanisms leading to either excessive acid secretion or diminished mucosal defense. They are common entities present in daily clinical practice that, owing to their chronicity, represent a significant cost to healthcare. Key elements in the success of controlling these entities have been the development of potent and safe drugs based on physiological targets. The histamine-2 receptor antagonists revolutionized the treatment of acid peptic disorders owing to their safety and efficacy profile. The proton-pump inhibitors (PPIs) represent a further therapeutic advance due to more potent inhibition of acid secretion. Ample data from clinical trials and observational experience have confirmed the utility of these agents in the treatment of acid peptic diseases, with differential efficacy and safety characteristics between and within drug classes. Paradigms in their speed and duration of action have underscored the need for new chemical entities that, from a single dose, would provide reliable duration of acid control, particularly at night. Moreover, PPIs reduce, but do not eliminate, the risk of ulcers in patients taking NSAIDs, reflecting untargeted physiopathologic pathways and a breach in the ability to sustain an intragastric pH of more than 4. This review provides an assessment of the current understanding of the physiology of acid production, a discussion of medications targeting gastric acid production and a review of efficacy in specific acid peptic diseases, as well as current challenges and future directions in the treatment of acid-mediated diseases.

Management of gastroesophageal reflux disease

Gastroesophageal reflux disease (GERD) is a chronic condition requiring long-term treatment. Simple lifestyle modifications are the first methods employed by patients and, because of their low cost and simplicity, should be continued even when more potent therapies are initiated. Potent acid-suppressive therapy is currently the most important and successful medical therapy. Whereas healing of the esophageal mucosa is achieved with a single dose of any proton pump inhibitor (PPI) in more than 80% of cases, symptoms are more difficult to control. Patients with persistent symptoms on therapy should be tested (preferably with combined multichannel intraluminal impedance and pH) for association of symptoms with acid, nonacid, or no GER. Long-term follow-up studies indicate that PPIs are efficacious, tolerable, and safe medication. So far, promotility agents have shown limited efficacy, and their side-effect profile outweighs their benefits. Antireflux surgery in carefully selected patients (ie, young, typical GERD symptoms, abnormal pH study, and good response to PPI) is as effective as PPI therapy and should be offered to these patients as an alternative to medication. Still, patients should be informed about the risks of antireflux surgery (ie, risk of postoperative dysphagia; decreased ability to belch, possibly leading to bloating; increased flatulence). Endoscopic antireflux procedures are recommended only in selected patients and given the relative short experience with these techniques, patients treated with endoscopic procedures should be enrolled in a rigorous follow-up program.

Tolerance to famotidine and ranitidine treatment after 14 days of administration in healthy subjects without Helicobacter pylori infection

BACKGROUND AND AIM

The attenuated antisecretory activity observed during continuous administration of ranitidine has been described as tolerance. However, it remains unclear whether a similar phenomenon occurs with other histamine H2 receptor antagonists (H2RA). We investigated whether tolerance to famotidine, a stronger H2RA than ranitidine, occurs during long-term administration.

METHODS

Seven healthy male Japanese subjects without Helicobacter pylori infection participated in a randomized cross-over study in which ranitidine and famotidine were administered for 14 days with a 4-week wash-out period. We performed 24-h intragastric pH monitoring on the first and 14th days of administration of each drug, and measured serum gastrin and plasma drug concentrations on the first, seventh and 14th days.

RESULTS

The acid-inhibiting activity of ranitidine and famotidine declined during continuous administration. In particular, the potent nocturnal pH-increasing effect of the H2RA, which was observed on day 1, declined on day 14. Serum gastrin concentrations on day 14 were significantly lower than those on day 7, although plasma drug concentrations remained unchanged.

CONCLUSION

Tolerance to famotidine occurs during continuous administration for 14 days, as previously shown in ranitidine studies.

Control of intragastric acidity with over-the-counter doses of ranitidine or famotidine

BACKGROUND

Histamine H2-receptor antagonists are available over the counter for the treatment of heartburn.

AIM

To compare the effects of low doses of ranitidine and famotidine on intragastric acidity in a three-way crossover study.

METHODS

Healthy subjects (12 male, 12 female) were dosed on three occasions with single oral doses of placebo, ranitidine, 75 mg, and famotidine, 10 mg, 1 h after lunch. The pH of gastric aspirates was then measured for 20 h. Subjects ate standard meals and snacks. Analysis of variance was used to determine the statistical significance of differences in acidity (mmol/L) during the day (12.30-22.30 hours) and night (22.30-08.30 hours).

RESULTS

Ranitidine and famotidine were superior (P < 0.05) to placebo in decreasing acidity for daytime and night-time intervals. There were no significant differences in mean gastric acidity between ranitidine and famotidine during the daytime (11.37 mmol/L vs. 13.42 mmol/L, respectively) and night-time (23.57 mmol/L vs. 24.74 mmol/L, respectively). Intragastric acidity after ranitidine was significantly lower than that after famotidine in the first 2.5-h period following dosing (4.32 mmol/L vs. 9.28 mmol/L; P < 0.05).

CONCLUSIONS

Lunchtime doses of ranitidine and famotidine decreased acidity during day- and night-time periods. The effect of ranitidine was significantly greater for the first 2.5 h after dosing.

Review article: over-the-counter drugs and the gastrointestinal tract

An increasing number of drugs are becoming available over-the-counter, empowering patients to treat them- selves. Although drugs presently available over-the-counter are generally safe, there are issues of safety and possible delays in diagnosis of serious conditions. Therefore it is vital that patients are made aware of the indications and limitations of over-the-counter drugs through improved communication and education. Pharmacists and drug companies will have an increasingly important role in giving information and advice to patients. This review looks at the present and future of over-the-counter medication, highlighting the safety aspects.

H2-receptor antagonists in the treatment of functional (nonulcer) dyspepsia: a meta-analysis of randomized controlled clinical trials

AIM

To perform a meta-analysis evaluating the efficacy of H2-receptor antagonists in functional (nonulcer) dyspepsia.

SELECTION OF STUDIES

A Medline search was used to identify placebo controlled randomized clinical trials, using the subject headings dyspepsia and H2-receptor antagonist.

OUTCOME MEASURES

Global assessment by the patient of dyspepsia symptoms, improvement of epigastric pain and complete relief of epigastric pain.

RESULTS

Twenty-two studies met the inclusion criteria, 15 of which reported the active drug to be superior to placebo. Many studies suffered from suboptimal study design. The odds ratio in favour of active drug was 1.48 (95% confidence interval: 0.9-2.3) for global assessment of dyspepsia symptoms, 2.3 (95% CI: 1.6-3.3) for improvement of epigastric pain, and 1.8 (95% CI: 1.2-2.8) for complete relief of epigastric pain.

CONCLUSION

There is some evidence that H2-receptor antagonists are superior to placebo in functional dyspepsia, but larger studies evaluating higher doses of H2-receptor antagonists and of longer duration are necessary to determine the exact effect size.

Gastroesophageal reflux disease and Barrett's esophagus

GERD has emerged as an important medical issue by virtue not only of its high prevalence, but also by the concern that it may predispose to adenocarcinoma of the esophagus. It generally is classified into erosive and nonerosive forms. Nonerosive GERD tends to remain as such in most patients, and treatment is based on symptom relief. In contrast, erosive GERD mandates aggressive lifelong treatment based on its inevitable relapse without appropriate treatment. Two excellent therapies are available for GERD. Proton-pump inhibitors are highly efficacious and have an excellent long-term (> 10 years) safety profile. Laparoscopic fundoplication offers a new and easier method of delivering a standard reliable procedure also with excellent long-term efficacy. The occurrence of Barrett's esophagus among reflux patients has emerged as an important problem mostly because of the rapidly rising incidence of adenocarcinoma of the esophagus in the population. All patients with long-standing reflux symptoms should be screened for Barrett's and subsequently followed regularly with surveillance endoscopy if Barrett's is detected. Although there are no data to show that aggressive medical or surgical treatment alters the malignant potential of this disease, patients need lifelong therapy.

Impact of food intake on the antisecretory effect of low-dose ranitidine and famotidine

BACKGROUND

Over-the-counter status has recently been approved for low-dose H2-antagonists in several countries. Insufficient information is currently available on the effect of food in low-dose H2-antagonist therapy.

AIM

Compare the antisecretory efficacy of low-dose ranitidine and famotidine in fasting and non-fasting volunteers.

METHODS

Twenty volunteers were randomized into a double-blind, placebo-controlled, multiple-step crossover study comparing the antisecretory efficacy of 75 mg ranitidine, 10 mg famotidine and placebo over 12 h using intragastric pH-metry. Two standard meals were given after 4 h and 8 h of medication. Fifteen volunteers also participated in a second study comparing the antisecretory effect of both drugs, both with and without meals.

RESULTS

In non-fasting subjects, the percentage of time with pH > 4 was similarly elevated for both drugs compared with placebo over the first 8 h: ranitidine 39.3%, famotidine 29.5%, placebo 9.5% (P < 0. 001); but not for the last 4 h after the second meal (P > 0.05). Comparing the first 4-h period with the second, the percentage of pH > 4 was significantly reduced for both drugs in the second period in the subjects given food at the end of the initial 4-h period (ranitidine 56.9% vs. 26.6%, P = 0.005; famotidine 46.6% vs. 13.3%, P < 0.001). It remained more or less constant, however, for the second 4-h period in fasting subjects (ranitidine 41% vs. 28.1%, P = 0.46; famotidine 52.7% vs. 52.2%, P = 0.12).

CONCLUSION

In non-fasting volunteers both low-dose H2-antagonists had comparable antisecretory effects and were superior to placebo over the first 8 h of therapy. Both drugs achieved a slightly higher antisecretory effect without food intake compared to with food intake.

Effects of tablet and effervescent formulations of ranitidine 75 mg and cimetidine 200 mg on gastric acidity and oesophageal acid exposure in healthy humans

BACKGROUND

Because of their tolerance and safety, low doses of H2-receptor antagonists are now increasingly used in some countries for self-care medication of gastro-oesophageal reflux symptoms.

AIM

The purpose of this randomized, double-blind, placebo-controlled, five-way crossover study was to determine and to compare the effects of low doses of ranitidine and cimetidine both on gastric pH and on oesophageal acid exposure.

METHODS

Gastric and oesophageal pH were simultaneously monitored in 20 healthy subjects using two glass pH electrodes, after placebo and single doses of ranitidine 75 mg and cimetidine 200 mg (effervescent and tablet forms), for 4 h before and after a meal.

RESULTS

During the fasting period, median gastric pH rose significantly with both drugs, but more rapidly with the effervescent forms; the oesophageal acid exposure was significantly decreased by all drug regimens. After the meal, although there was no significant difference in gastric pH values, oesophageal acid exposure was significantly decreased in comparison with placebo with both forms of ranitidine (P < 0.05), and also for ranitidine tablets in comparison with cimetidine tablets (P < 0.05).

CONCLUSIONS

Low doses of ranitidine and cimetidine increase gastric pH, with a more pronounced effect for ranitidine. Effervescent formulations of both drugs induce a slightly more rapid initial increase in pH than tablets. Ranitidine demonstrates a more prolonged effect than cimetidine and decreases oesophageal acid exposure monitored after a meal ingested 4 h after the drug intake.