Rebound hypersecretion after H2-antagonist withdrawal--a comparative study with nizatidine, ranitidine and famotidine

Rebound Acid Hypersecretion after Withdrawal of Long-Term Proton Pump Inhibitor (PPI) Treatment-Are PPIs Addictive?

Proton pump inhibitors (PPIs) are widely used in the long-term treatment of gastroesophageal reflux disease (GERD) and other upper gastrointestinal disorders, such as the healing of peptic ulcers and/or prophylactic treatment of peptic ulcers. PPIs are also widely used as symptomatic treatment in patients with functional dyspepsia. One of the adverse effects of the long-term use of PPI is rebound acid hypersecretion (RAHS), which can occur after the withdrawal of PPI therapy due to a compensatory increase in gastric acid production. Mechanisms of the RAHS have been well established. Studies have shown that pentagastrin-stimulated acid secretion after the discontinuation of PPIs increased significantly compared to that before treatment. In healthy volunteers treated with PPIs, the latter induced gastrointestinal symptoms in 40-50% of subjects after the discontinuation of PPI therapy but after stopping the placebo. It is important for practicing physicians to be aware and understand the underlying mechanisms and inform patients about potential RAHS before discontinuing PPIs in order to avoid continuing unnecessary PPI therapy. This is important because RAHS may lead patients to reuptake PPIs as symptoms are incorrectly thought to originate from the recurrence of underlying conditions, such as GERD. Mechanisms of RAHS have been well established; however, clinical implications and the risk factors for RAHS are not fully understood. Further research is needed to facilitate appropriate management of RAHS in the future.

Can H2 -receptor upregulation and raised histamine explain an anaphylactoid reaction on cessation of ranitidine in a 19-year-old female? A case report

The anaphylactoid reaction described follows cessation of ranitidine in a 19-year-old female with the disease cluster: mast cell activation syndrome, hypermobile Ehlers-Danlos syndrome and postural tachycardia syndrome. Anaphylaxis can give wide-ranging symptoms from rhinorrhoea and urticaria to tachycardia and system-wide, life-threatening, anaphylactic shock. Individuals with a disorder of mast cell activation can experience many such symptoms. H2 receptor antagonists, such as ranitidine, are commonly prescribed in this population. A mechanism for the reaction is proposed in the context of ranitidine, as an inverse agonist, causing upregulation of H2 histamine receptors and raised histamine levels due to enzyme induction. This effect, following extended and/or high antihistamine dosing, may have implications for other individuals with a disorder of mast cell activation, such as mastocytosis or mast cell activation syndrome. There are potential policy and patient guidance implications for primary and secondary care with respect to cessation of H2 antagonists.

Rebound acid hypersecretion after withdrawal of gastric acid suppressing drugs: new evidence of similitude

BACKGROUND

Homeopathy is based on the principle of similitude (similia similibus curentur) using medicines that cause effects similar to the symptoms of disease in order to stimulate the reaction of the organism. Such vital, homeostatic or paradoxical reaction of the organism is closely related to rebound effect of drugs.

METHOD

Review of the literature concerning the rebound effects of drugs used to suppress gastric acidity, particularly proton pump inhibitors (PPIs).

RESULTS

The mechanism of action of these effects is discussed. Rebound in terms of clinical symptoms and physiological effects occur in about 40% of people taking PPIs, their timing depends on the half-life of the drug and the adaptation period of the physiological mechanisms involved. The wide use of PPIs may be linked to the rising incidence of carcinoid tumours.

CONCLUSIONS

These findings support Hahnemann's concept of secondary action of drugs. We are developing a homeopathic materia medica and repertory of modern drugs on the basis of reported rebound effects.

Dyspeptic symptom development after discontinuation of a proton pump inhibitor: a double-blind placebo-controlled trial

OBJECTIVES

Conflicting data exist on whether discontinuation of proton pump inhibitors (PPIs) is associated with rebound secretion of gastric acid.

METHODS

A total of 48 healthy Helicobacter pylori-negative volunteers (24 females) were randomized in a double-blinded manner to treatment with either pantoprazole 40 mg or placebo once daily for 28 days. Dyspeptic symptoms were registered daily using the Glasgow dyspepsia score (GDS) 2 weeks before, during, and 6 weeks after treatment. Plasma levels of gastrin and serum levels of chromogranin-A levels were measured before, during, and after treatment.

RESULTS

During the 2 weeks before treatment, the placebo group had a mean GDS of 0.20 + or - 0.7 compared with the pantoprazole group score of 0.54 + or - 1.3 (NS). No significant differences between the symptom severity scores of the two groups were shown during the treatment period. During the first week after discontinuation of treatment, the pantoprazole group had a mean symptom score of 5.7 + or - 11.7 vs. 0.74 + or - 2.6 in the placebo group (P<0.01). A total of 11 out of 25 (44%) subjects in the pantoprazole group developed dyspepsia compared with 2 out of 23 (9%) in the placebo group (P<0.01). During the second week of follow-up, the pantoprazole group had a mean symptom score of 1.6 + or - 3.4 compared with 0 + or - 0 in the placebo group (P<0.05). There were no significant differences in the mean symptom score for the pantoprazole group (1.1 + or - 0.6) compared with the placebo group (0.4 + or - 0.3) during the third week of follow-up. Symptom scores during the first week after treatment correlated with basal (P<0.01) and meal-stimulated (P<0.01) gastrin levels at the end of treatment.

CONCLUSIONS

A 4-week course of pantoprazole seems to induce dyspeptic symptoms in previously asymptomatic healthy H. pylori-negative subjects. The correlation between symptom score and gastrin levels suggests that these symptoms are due to acid rebound hypersecretion and seem to be related to the degree of acid inhibition.

Systematic review: Rebound acid hypersecretion after therapy with proton pump inhibitors

BACKGROUND

The occurrence and the clinical relevance of rebound acid hypersecretion after discontinuation of proton pump inhibitors is unclear.

AIM

To perform a systematic review of rebound acid hypersecretion after discontinuation of proton pump inhibitors.

METHODS

PubMed, Embase and Central were searched up to October 2005 with indexed terms.

RESULTS

Eight studies were included, sample size was 6-32. The studies used both basal and stimulated acid output as parameters to study rebound acid hypersecretion and assessed these at different time points and with variable methods. Five studies (including four randomized studies) did not find any evidence for rebound acid hypersecretion after proton pump inhibitor therapy. Of the remaining three studies, the duration of proton pump inhibitor therapy was the longest and two of these studies were the only to assess Helicobacter pylori status of their study subjects. These two studies suggested that rebound acid hypersecretion may occur in H. pylori-negatives after 8 weeks of proton pump inhibitors.

CONCLUSIONS

Studies that have investigated rebound acid hypersecretion after cessation of proton pump inhibitor treatment are heterogenic in design, methods and outcome. There is some evidence from uncontrolled trials for an increased capacity to secrete acid in H. pylori-negative subjects after 8 weeks of treatment. There is no strong evidence for a clinically relevant increased acid production after withdrawal of proton pump inhibitor therapy.

Problems related to acid rebound and tachyphylaxis

Rebound acid hypersecretion after taking histamine H(2)-receptor antagonists is a now well-established class phenomenon. It has been demonstrated both basally and in response to meal and gastrin-releasing peptide stimulation, but not in response to peak pentagastrin stimulation. It is present by 3 days after treatment but has resolved by 10 days. A recent study in previously asymptomatic healthy volunteers has suggested that this phenomenon may be clinically relevant. Tachyphylaxis/tolerance after the use of H(2)-receptor antagonists is also now well established. It manifests as a loss of acid inhibitory efficacy and is also a class effect. It is present within a few doses but is not progressive after 29 days. Rebound acid hypersecretion after proton pump inhibitors has been shown for both basal and maximal acid output by 14 days after treatment. It is found in Helicobacter pylori -negative, but not positive, subjects, probably owing to the influence of the enhanced oxyntic gastritis that occurs during proton pump inhibitor therapy. It is a prolonged phenomenon, lasting for at least 2 months after a 2-month treatment course. This duration is likely to reflect its development as a result of trophic effects on the oxyntic mucosa. This trophism is caused by the marked hypergastrinaemia that occurs secondary to the profound acid suppression during proton pump inhibitor treatment. The clinical relevance of this phenomenon remains at present unknown. Tachyphylaxis/tolerance has not yet been shown in several short-term studies after taking proton pump inhibitors. A recent clinical study has, however, suggested that this phenomenon may merit longer-term evaluation.

Pharmacological and pharmacodynamic essentials of H(2)-receptor antagonists and proton pump inhibitors for the practising physician

The suppression of gastric acid secretion with anti-secretory agents has been the mainstay of medical treatment for patients with acid-related disorders. Although the majority of Helicobacter pylori -related peptic ulcers can be healed with antibiotics, ulcer healing and symptom control can be significantly improved when antibiotics are given with anti-secretory agents, especially with a proton pump inhibitor. There is a dynamic relationship between the suppression of intragastric acidity and the healing of peptic ulcer and erosive oesophagitis and control of acid-related symptoms. The suppression of gastric acid secretion achieved with H(2)-receptor antagonists has, however, proved to be suboptimal for effectively controlling acid-related disorders, especially for healing erosive oesophagitis and for the relief of reflux symptoms. H(2)-receptor antagonists are also not effective in inhibiting meal-stimulated acid secretion, which is required for managing patients with erosive oesophagitis. Furthermore, the rapid development of tolerance to H(2)-receptor antagonists and the rebound acid hypersecretion after the withdrawal of an H(2)-receptor antagonist further limit their clinical use. Although low-dose H(2)-receptor antagonists are currently available as over-the-counter medications for self-controlling acid-related symptoms, their pharmacology and pharmacodynamics have not been well studied, especially in the self-medicating population. Proton pump inhibitors have been proved to be very effective for suppressing intragastric acidity to all known stimuli, although variations exist in the rapidity of onset of action and the potency of acid inhibition after oral administration at the approved therapeutic doses, which may have important clinical implications for the treatment of gastro-oesophageal reflux disease and perhaps for eradicating H. pylori infection when a proton pump inhibitor is given with antibiotics. Once-daily dosing in the morning is more effective than dosing in the evening for all proton pump inhibitors with respect to the suppression of intragastric acidity and daytime gastric acid secretion in particular, which may result from a better bio-availability being achieved with the morning dose. When higher doses are needed, these drugs must be given twice daily to achieve the optimal suppression of 24 hour intragastric acidity. Preliminary results have shown that esomeprazole, the optical isomer of omeprazole, given at 40 mg, is significantly more effective than omeprazole 40 mg, lansoprazole 30 mg or pantoprazole 40 mg for suppressing gastric acid secretion. However, more studies in different patient populations are needed to compare esomeprazole with the existing proton pump inhibitors with regard to their efficacy, cost-effectiveness and long-term safety for the management of acid-related disorders.

Bicarbonate stimulatory action of nizatidine, a histamine H(2)-receptor antagonist, in rat duodenums

Nizatidine, a histamine H(2)-antagonist, is known to inhibit acetylcholinesterase (AChE) activity and is used clinically as a gastroprokinetic agent as well as the anti-ulcer agent. We examined whether or not nizatidine stimulates duodenal HCO(3)(-) secretion in rats through vagal-cholinergic mechanisms by inhibiting AChE activity. Under pentobarbital anesthesia, a proximal duodenal loop was perfused with saline, and the HCO(3)(-) secretion was measured at pH 7.0 using a pH-stat method and by adding 10 mM HCl. Nizatidine, neostigmine, carbachol, famotidine or ranitidine was administered i.v. as a single injection. Intravenous administration of nizatidine (3-30 mg/kg) dose-dependently increased the HCO(3)(-) secretion, and the effect at 10 mg/kg was equivalent to that obtained by carbachol at 0.01 mg/kg. The HCO(3)(-) stimulatory action of nizatidine was observed at the doses that inhibited the histamine-induced acid secretion and enhanced gastric motility. This effect was mimicked by neostigmine (0.03 mg/kg) and significantly attenuated by bilateral vagotomy and pretreatment with atropine but not indomethacin. The IC(50) of nizatidine for AChE of rat erythrocytes was 1.4 x 10(-6) M, about 12 times higher than that of neostigmine. Ranitidine showed the anti-AchE activity and increased duodenal HCO(3)(-) secretion, similar to nizatidine, whereas famotidine had any influence on neither AChE activity nor the HCO(3)(-) secretion. On the other hand, duodenal damage induced by acid perfusion (100 mM HCl for 4 h) in the presence of indomethacin was significantly prevented by nizatidine and neostigmine, at the doses that increased the HCO(3)(-) secretion. These results suggest that nizatidine increases HCO(3)(-) secretion in the rat duodenum, mediated by vagal-cholinergic mechanism, the action being associated with the anti-AChE activity of this agent.

Stimulation by nizatidine, a histamine H2-receptor antagonist, of duodenal HCO3- secretion in rats: relation to anti-cholinesterase activity

AIM: To examine whether nizatidine stimulates duodenal HCO₃^- secretion in rats by inhibiting AChE activity.

METHODS: Under pentobarbital anesthesia, a proximal duodenal loop was perfused with saline, and the HCO₃^- secretion was measured at pH7.0 using a pH-stat method and by adding 10 mM HCl. Nizatidine, neostigmine, carbachol or famotidine was administered i.v. as a single injection.

RESULTS: Intravenous administration of nizatidine (3-30 mg/kg) dose-dependently increased duodenal HCO₃^- secretion, and the effect at 10 mg/kg was equivalent to that obtained by carbachol at 0.01 mg/kg. This nizatidine action was observed at the same dose range that inhibited acid secretion and enhanced gastric motility, mimicked by i.v. injection of neostigmine (0.03 mg/kg), and significantly attenuated by bilateral vagotomy and prior s.c. administration of atropine but not by indomethacin, a cyclooxygenase inhibitor, or N^G-nitro-L-arginine methyl ester, a NO synthase inhibitor. The HCO₃^- secretory response to acetylcholine (0.001 mg/kg) was significantly potentiated by the concurrent administration of nizatidine (3 mg/kg, i.v.). The IC₅₀ of nizatidine for AChE of rat erythrocytes was 1.4 × 10^-6 M, about 12 times higher than that of neostigmine. Neither famotidine (> 10^-3 M, 30 mg/kg, i.v.) nor cisapride (> 10^-3 M, 3 mg/kg, i.v.) had any influence on AChE activity or duodenal HCO₃^- secretion. Duodenal damage induced by acid perfusion (100 mM HCl for 4 h) in the presence of indomethacin was significantly prevented by nizatidine and neostigmine, at the doses that increased the HCO₃^- secretion.

CONCLUSION: Nizatidine stimulates duodenal HCO₃^- secretion, in both vagal-dependent and atropine-sensitive manners, and the action is associated with the anti-AChE activity of this agent.

Dyspepsia on withdrawal of ranitidine in previously asymptomatic volunteers

OBJECTIVE

H2 receptor antagonist therapy has been shown to produce rebound acid hypersecretion. The clinical significance of this phenomenon is not known. We performed this study to determine whether withdrawal of H2 receptor antagonist therapy results in dyspepsia in previously asymptomatic volunteers.

METHODS

Thirty-five Helicobacter pylori-positive asymptomatic volunteers were randomized in double-blind fashion to receive 2 months' treatment with either ranitidine 300 mg nocte or placebo. Dyspeptic symptoms were measured before starting treatment and over the course of 10 days after stopping treatment by means of a validated questionnaire.

RESULTS

Thirty-one subjects completed the study; 17 were randomized to ranitidine. The pretreatment median aggregate dyspepsia score of the placebo group was 0 (0-4), as was that of the ranitidine group (0-8) (N.S.). During the 10 days after completion of ranitidine, the median aggregate dyspepsia score was 1.4 (0-30), compared with 0 (0-6.3) after placebo (p < 0.01). Of those given ranitidine, 59% experienced dyspepsia after treatment, compared with only 14% who took placebo. In the subgroup that developed dyspepsia after active therapy, the median duration of symptoms was 2 days, symptom severity being maximal on the second day after completion of the tablets. On the days when dyspepsia was experienced, the median daily dyspepsia score was 5 (range, 2-10), which was similar to that of a control group with active duodenal ulcer disease (5; range, 0-11).

CONCLUSIONS

Withdrawal of a 2-month course of ranitidine 300 mg nocte results in the development of dyspeptic symptoms in a proportion of previously asymptomatic subjects. Patients receiving ranitidine should be warned about this rebound dyspepsia and advised not to immediately resume treatment, as rebound symptoms are likely to improve within a few days.

Rebound hypersecretion after omeprazole and its relation to on-treatment acid suppression and Helicobacter pylori status

BACKGROUND & AIMS

There have been conflicting reports regarding acid secretion after treatment with omeprazole. This study examined acid secretion after treatment with omeprazole and its relation to Helicobacter pylori status and on-treatment gastric function.

METHODS

Twelve H. pylori-negative and 9 H. pylori-positive subjects were examined before, on, and at day 15 after an 8-week course of 40 mg/day omeprazole. On each occasion, plasma gastrin, intragastric pH, and acid output were measured basally and in response to increasing doses of gastrin 17.

RESULTS

In the H. pylori-negative subjects at day 15 after omeprazole treatment, basal acid output was 82% higher (P < 0.007) and maximal acid output 28% higher (P < 0.003) than before omeprazole. The degree of increase in maximal acid output was related to both on-treatment pH and on-treatment fasting gastrin levels, being 48.0% in subjects with an on-treatment pH of >4 vs. 21. 0% in those with a pH of <4 (P < 0.02) and 49.2% in subjects with an on-treatment gastrin of >25 ng. L-1 vs. 19.8% in those with a fasting gastrin of <25 ng. L-1 (P < 0.006). At day 15 after omeprazole treatment, the H. pylori-positive subjects showed a heterogeneous response with some having increased acid output and others persisting suppression.

CONCLUSIONS

Rebound acid hypersecretion occurs in H. pylori-negative subjects after omeprazole treatment. Its severity is related to the degree of elevation of pH on treatment. Persisting suppression of acid secretion masks the phenomenon in H. pylori-positive subjects.

Effects of S-0509, a novel CCKB/gastrin receptor antagonist, on acid secretion and experimental duodenal ulcers in rats

BACKGROUND

S-0509, 2-[(tert-butoxycarbonylmethyl) [(m-(carboxy-phenyl)-ureidomethyl-carbonyl]] aminobenzo phenone, was developed as a potent and selective CCKB/gastrin receptor antagonist that does not affect the central nervous system.

METHODS

We evaluated the effects of S-0509 on gastric acid secretion and duodenal ulcerogenic and healing responses in rats comparing it with L-365,260, another CCKB/gastrin receptor antagonist.

RESULTS

S-0509 (0.1 approximately 10 mg/kg, i.d.) was able to dose-dependently decrease basal acid secretion and inhibit the acid secretory responses induced by both pentagastrin (60 microg/kg/h, i.v.) and peptone (10%, i.g.) but not histamine (4 mg/kg/hr, i.v.) or carbachol (60 microg/kg/h, i.v.). L-365,260 (10 and 30 mg/kg, i.d.) caused only partial a suppression of the acid secretory response to pentagastrin but not to other stimuli, including peptone treatment. On the other hand, a duodenal ulcerogen, mepirizole (200 mg/kg, s.c. ) caused an increase in acid secretion and resulted in penetrating ulcers in the proximal duodenum, and these ulcers gradually healed over 3 weeks. S-0509 significantly inhibited both the acid secretory (> 1.0 mg/kg, i.d.) and ulcerogenic (> 3 mg/kg, p.o.) responses induced by mepirizole when it was given as a pre-treatment. It also promoted significantly the healing of these ulcers (> 3 x 2 mg/kg, p. o.) when it was given twice daily for 14 days. In contrast, L-365, 260 (30 mg/kg) tended to reduce the severity of mepirizole-induced duodenal ulcers, with a slight inhibition of acid secretion, but it caused no influence on the healing response of these ulcers.

CONCLUSION

These results confirmed that S-0509 is a selective CCKB/gastrin receptor antagonist with potent antisecretory action in vivo conditions, and further demonstrated that this agent not only prevents the development of duodenal ulcers but also shows healing promoting action on duodenal ulcers, probably through the blockade of CCKB/gastrin receptors.

Role of gastric acid in the aetiology of dyspeptic disease and dyspepsia

The main diseases associated with dyspepsia are peptic ulcer disease, gastro-oesophageal reflux disease and non-ulcer dyspepsia. Increased gastric acid secretion is a characteristic of most duodenal ulcer patients and of a small minority of non-ulcer dyspepsia and gastro-oesophageal reflux disease patients. Although acid secretion is normal in most gastro-oesophageal reflux disease patients, the condition is mainly the result of excess exposure of the distal oesophagus to acid refluxing from the stomach. Increased mucosal sensitivity to acid is involved in the aetiology of dyspeptic symptoms in the majority of patients with peptic ulcer disease and gastro-oesophageal reflux disease, and in a minority of non-ulcer dyspepsia subjects. Gastric acid, therefore, plays an important role in both the aetiology of dyspeptic diseases and in the aetiology of dyspeptic symptoms.

Gastric fluid volume and pH after nizatidine in adults undergoing elective surgery: influence of timing and dose

We conducted a prospective, randomized, double-blind study to investigate the effect of oral nizatidine (150-600 mg), a new potent H2 antagonist, on preoperative gastric fluid pH and volume in adults undergoing elective surgery. One hundred and seventy-five healthy adults (21-68 yr) were randomly allocated to seven treatment groups (n = 25); Placebo was administered at 21:00 and 06:30 the night before and on the day of surgery, respectively (0/0: control); nizatidine 150 mg at 21:00 and placebo at 06:30 (150/0); placebo at 21:00 and nizatidine 150 mg at 06:30 (0/150); nizatidine 150 mg at 21:00 and 06:30 (150/150); nizatidine 300 mg at 21:00 and placebo at 06:30 (300/0); placebo at 21:00 and nizatidine 300 mg at 06:30 (0/300); and nizatidine 300 mg at 21:00 and 06:30 (300/300). Each patient fasted overnight and took the drug and/or placebo with 20 ml water. After induction of anaesthesia, the pH and volume of gastric fluid obtained through an orogastric tube were measured. The mean pH of 0/150, 150/150, 300/0, 0/300, and 300/300 groups was higher than that of the control group (P < 0.05). Gastric volume in these groups was smaller than in the control (P < 0.05). The 150/0 group failed to decrease gastric fluid volume and increase pH. In the 300/0 group, the gastric pH was lower than other regimens which effectively decreased gastric acidity (P < 0.05). The number of patients with a pH < 2.5 and a volume > 0.4 ml.kg-1 in the 0/150, 150/150, 0/300, and 300/300 groups (0%) was less than in the control group (16%) (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Acid inhibitory characteristics of nizatidine in man: an overview

The antisecretory activity of nizatidine, an H2-receptor antagonist, has been extensively investigated in man both by quantitative acid secretory tests and by means of 24-h continuous ambulatory pH monitoring. Studies have shown that nizatidine is a potent inhibitor of basal, nocturnal and stimulated acid secretion. Particular modalities of nizatidine administration, such as early evening intake with supper or morning dosing, have been recently defined. Further studies are needed to clarify if rebound nocturnal acid hypersecretion may develop after abrupt withdrawal of nizatidine or if tolerance may develop during prolonged administration.