Adverse reactions and interactions with H2-receptor antagonists

Plants with potential anti-ulcerogenic activity and possible mechanism of actions based on their phyto-constitutional profile

Gastric ulcer, the most common disorder of the digestive tract is formed due to an imbalance between acid and mucus content of the stomach. However, the currently used western therapeutic regimens have many drawbacks like adverse effects, recurrence of gastric ulcers, are expensive, and also, may have interactions with other drugs. Hence, there is a need for effective alternative therapy. Medicinal herbs have been used since ancient times to treat several diseases and are also evidenced to be effective against gastric ulcers. It is also evident that medicinal herbs have been proved to be equally effective or superior as compared to the existing synthetic medicines. In this review, five herbs have been taken into consideration and assumed to be effective against gastric ulcers. Abrus mollis, Korean Thistle (Cirsium japonicum var. maackii), Astralagus complanatus Bunge, Bauhinia monandra, and Embelia ribes Burm f. are the herbs whose data is been collected and reviewed for their potential gastro-protective action. Although, their side effects and toxicity profile need to be further evaluated. Hence, the purpose of this review is to gather evidence of these five medicinal herbs and their probable mechanism of action against gastric ulcers based on their phyto-constitutional profile.

International consensus statement on allergy and rhinology: Allergic rhinitis - 2023

BACKGROUND

In the 5 years that have passed since the publication of the 2018 International Consensus Statement on Allergy and Rhinology: Allergic Rhinitis (ICAR-Allergic Rhinitis 2018), the literature has expanded substantially. The ICAR-Allergic Rhinitis 2023 update presents 144 individual topics on allergic rhinitis (AR), expanded by over 40 topics from the 2018 document. Originally presented topics from 2018 have also been reviewed and updated. The executive summary highlights key evidence-based findings and recommendation from the full document.

METHODS

ICAR-Allergic Rhinitis 2023 employed established evidence-based review with recommendation (EBRR) methodology to individually evaluate each topic. Stepwise iterative peer review and consensus was performed for each topic. The final document was then collated and includes the results of this work.

RESULTS

ICAR-Allergic Rhinitis 2023 includes 10 major content areas and 144 individual topics related to AR. For a substantial proportion of topics included, an aggregate grade of evidence is presented, which is determined by collating the levels of evidence for each available study identified in the literature. For topics in which a diagnostic or therapeutic intervention is considered, a recommendation summary is presented, which considers the aggregate grade of evidence, benefit, harm, and cost.

CONCLUSION

The ICAR-Allergic Rhinitis 2023 update provides a comprehensive evaluation of AR and the currently available evidence. It is this evidence that contributes to our current knowledge base and recommendations for patient evaluation and treatment.

Metabolic Profiling of Heliotropium crispum Aerial Parts Using HPLC and FTIR and In Vivo Evaluation of Its Anti-Ulcer Activity Using an Ethanol Induced Acute Gastric Ulcer Model

This study explored the antiulcer potential of methanol extract and fractions of Heliotropium crispum roots against the ethanol-induced gastric ulcer model in rats. Metabolic profiling of H. crispum aerial parts using Fourier-transform infrared spectroscopy (FTIR) revealed the presence of different metabolites with various functional groups. Meanwhile, High Performance Liquid Chromatography (HPLC) revealed the presence of three main peaks assigned to myricetin, quercetin, and kaempferol. In vivo, antiulcer activity results showed that the disease control group displayed five tiny ulcers less than 2 mm in diameter in addition to two hemorrhagic streaks. However, in the standard control group, only one small ulcer was visible for the total methanol extract. Gastric tissues and contents were evaluated to determine many parameters such as ulcer score, ulcer index, percentage inhibition of ulcer, gastric pH, gastric juice volume, and acidity. Results were endorsed by histopathological evaluation; gastric pH and mucus content were significantly increased, but gastric juice volume was significantly decreased. All fractions showed a significant decrease in ulcer index and % inhibition except the n-hexane fraction, whose results were insignificant compared to the disease control group. Thus, it was concluded that H. crispum shows an antiulcer effect by decreasing gastric juice volume and acidity, whereas gastric pH and mucus contents were increased that is attributed to the synergistic action of its detected polyphenolic compounds.

Peptic Ulcer Disease: A Brief Review of Conventional Therapy and Herbal Treatment Options

Peptic ulcer is a chronic disease affecting up to 10% of the world's population. The formation of peptic ulcers depends on the presence of gastric juice pH and the decrease in mucosal defenses. Non-steroidal anti-inflammatory drugs (NSAIDs) and Helicobacter pylori (H. pylori) infection are the two major factors disrupting the mucosal resistance to injury. Conventional treatments of peptic ulcers, such as proton pump inhibitors (PPIs) and histamine-2 (H2) receptor antagonists, have demonstrated adverse effects, relapses, and various drug interactions. On the other hand, medicinal plants and their chemical compounds are useful in the prevention and treatment of numerous diseases. Hence, this review presents common medicinal plants that may be used for the treatment or prevention of peptic ulcers.

International Consensus Statement on Allergy and Rhinology: Allergic Rhinitis

BACKGROUND

Critical examination of the quality and validity of available allergic rhinitis (AR) literature is necessary to improve understanding and to appropriately translate this knowledge to clinical care of the AR patient. To evaluate the existing AR literature, international multidisciplinary experts with an interest in AR have produced the International Consensus statement on Allergy and Rhinology: Allergic Rhinitis (ICAR:AR).

METHODS

Using previously described methodology, specific topics were developed relating to AR. Each topic was assigned a literature review, evidence-based review (EBR), or evidence-based review with recommendations (EBRR) format as dictated by available evidence and purpose within the ICAR:AR document. Following iterative reviews of each topic, the ICAR:AR document was synthesized and reviewed by all authors for consensus.

RESULTS

The ICAR:AR document addresses over 100 individual topics related to AR, including diagnosis, pathophysiology, epidemiology, disease burden, risk factors for the development of AR, allergy testing modalities, treatment, and other conditions/comorbidities associated with AR.

CONCLUSION

This critical review of the AR literature has identified several strengths; providers can be confident that treatment decisions are supported by rigorous studies. However, there are also substantial gaps in the AR literature. These knowledge gaps should be viewed as opportunities for improvement, as often the things that we teach and the medicine that we practice are not based on the best quality evidence. This document aims to highlight the strengths and weaknesses of the AR literature to identify areas for future AR research and improved understanding.

Acid-Suppressive Therapy and Risk of Infections: Pros and Cons

This narrative review summarises the benefits, risks and appropriate use of acid-suppressing drugs (ASDs), proton pump inhibitors and histamine-2 receptor antagonists, advocating a rationale balanced and individualised approach aimed to minimise any serious adverse consequences. It focuses on current controversies on the potential of ASDs to contribute to infections-bacterial, parasitic, fungal, protozoan and viral, particularly in the elderly, comprehensively and critically discusses the growing body of observational literature linking ASD use to a variety of enteric, respiratory, skin and systemic infectious diseases and complications (Clostridium difficile diarrhoea, pneumonia, spontaneous bacterial peritonitis, septicaemia and other). The proposed pathogenic mechanisms of ASD-associated infections (related and unrelated to the inhibition of gastric acid secretion, alterations of the gut microbiome and immunity), and drug-drug interactions are also described. Both probiotics use and correcting vitamin D status may have a significant protective effect decreasing the incidence of ASD-associated infections, especially in the elderly. Despite the limitations of the existing data, the importance of individualised therapy and caution in long-term ASD use considering the balance of benefits and potential harms, factors that may predispose to and actions that may prevent/attenuate adverse effects is evident. A six-step practical algorithm for ASD therapy based on the best available evidence is presented.

Protective effects of garlic extract, PMK-S005, against nonsteroidal anti-inflammatory drugs-induced acute gastric damage in rats

BACKGROUND

PMK-S005 is synthetic s-allyl-L-cysteine (SAC), a sulfur-containing amino acid, which was initially isolated from garlic. The antioxidant and anti-inflammation activities of SAC have been demonstrated in diverse experimental animal models.

AIMS

The purpose of this study was to investigate the gastroprotective effects of PMK-S005 against NSAIDs-induced acute gastric damage in rats.

METHODS

Eight-week SD rats were pretreated with PMK-S005 (1, 5, or 10 mg/kg) or rebamipide (50 mg/kg) 1 h before administration of NSAIDs including aspirin (200 mg/kg), diclofenac (80 mg/kg), and indomethacin (40 mg/kg). After 4 h, the gross ulcer index, histological index, and gastric mucus level were determined. Myeloperoxidase (MPO), TNF-α, IL-1β, PGE2, and LTB4 levels were estimated in the gastric mucosal tissue by ELISA. Protein expressions of cPLA2, COX-1, and COX-2 were assessed by Western blot analysis.

RESULTS

Pretreatment with PMK-S005 significantly attenuated the NSAIDs-induced gastric damage and increased the gastric mucus level. In addition, PMK-S005 attenuated increases in MPO, TNF-α, and IL-1β production. The expressions of cPLA2 and COX-2 induced by NSAIDs were decreased by PMK-S005 pretreatment. PMK-S005 did not cause suppression of PGE2 synthesis induced by NSAIDs, but LTB4 production was significantly suppressed by PMK-S005. The effects of PMK-S005 were consistently maximized at a concentration of 5 mg/kg, which were frequently superior to those of rebamipide.

CONCLUSIONS

These results strongly suggest that PMK-S005 can be a useful gastroprotective agent against acute gastric mucosal damage by suppressing proinflammatory cytokines, down-regulating cPLA2, COX-2 and LTB4 expression, and increasing the synthesis of mucus.

Antiulcer and gastric antisecretory effects of dichloromethane fraction and piplartine obtained from fruits of Piper tuberculatum Jacq. in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Piper tuberculatum Jacq. (Piperaceae) is medicinally used as an analgesic and as a treatment for gastric complaints. Thus, the current study aimed to investigate the gastroprotective and antisecretory properties of the dichloromethane fraction of the fruit of Piper tuberculatum (DFPT) and piplartine, a compound isolated from the DFPT, in rats.

MATERIALS AND METHODS

Gastric ulcers were induced in fasted rats by oral administration of absolute ethanol and then mucus content and glutathione (GSH) levels were measured. Mechanisms underlying the antisecretory action were studied through gastric H(+),K(+)-ATPase activity of highly purified rabbit gastric microsomes and pylorus ligature method in rats.

RESULTS

In the acute toxicity test the values of estimated LD50 for oral and intraperitoneal administration of DFPT were 1.6266 and 0.2684g/kg, respectively. The DFPT (ED50=29mg/kg, p.o.) and piplartine (4.5mg/kg, p.o.) promoted gastroprotection against acute lesions induced by ethanol, effect that could be related with the maintenance of GSH levels in the gastric mucosa. However, only DFPT stimulated gastric mucus secretion. In vitro, the DFPT and piplartine inhibited the H(+),K(+)-ATPase activity and, in vivo DFPT and piplartine also reduced basal gastric acid secretion, as well as that stimulated by pentagastrin.

CONCLUSIONS

These results demonstrate that DFPT and piplatine cause marked gastroprotective effects accompanied by the increase and maintenance of gastric mucus and GSH levels, as well as a reduction in gastric acid secretion through the gastrinergic pathway.

Variables associated with stress ulcer prophylaxis misuse: a retrospective analysis

BACKGROUND

Stress ulcer prophylaxis (SUP) is commonly used in hospitals. Although its indications are better delineated for intensive care unit (ICU) patients, its use in non-ICU settings is somewhat arbitrary and based on judgment.

OBJECTIVE

We attempted to assess the extent of SUP overuse in our hospital. We also carefully collected and analyzed several variables to detect associations governing this flawed behavior and its financial burden on the hospital's budget.

MATERIALS AND METHODS

We retrospectively analyzed charts of patients admitted to the medical floor of a tertiary referral university hospital over a 1 year period. All adult patients admitted to the medical ward who received at least one dose of SUP were included and reviewed for a multitude of variables in addition to the appropriateness of acid suppression therapy (AST).

RESULTS

We included 320 charts and found that 92% of patients admitted during that period were not eligible for SUP. The total inappropriateness of SUP was noted to be 58% (p = 0.015). Increasing age and male gender were found to be significant variables in AST misuse (p = 0.045 and p = 0.010), much like duration of hospital stay (p = 0.008). Comorbidities was also found to be a defining variable for AST overuse (odds ratio [OR] = 3.27). Patients with two or more minor risk factors were also subjected more to SUP inappropriately (OR = 3.53), in addition to patients of certain specialties (Neurology, Infectious Diseases, etc.). Our calculated financial burden was more than $23,000 per year for the medical floor.

CONCLUSION

This retrospective study confirmed the growing suspicion that SUP misuse is evident on the medical floors. We also delineated several factors and variables associated with and affecting SUP overuse.

The place of famotidine in anti-ulcer therapy

Famotidine now presents physicians in the USA and many European countries with a third option when considering H2-antagonist therapy. A dose of 40 mg in the evening decreases nocturnal gastric acidity for 10-12 hours, leaving daytime-stimulated acidity virtually unaffected. This single evening dosage regimen produces effective healing of gastric and duodenal ulceration; maintenance of healing can then be achieved satisfactorily with 20 mg in the evening. In extensive clinical studies, the adverse effect profile of famotidine is similar to placebo. Famotidine has no known drug interactions and there are no identified mechanisms by which it might be expected to produce them. Circulating plasma hormone concentrations in man are not affected by famotidine and no antiandrogenic properties have been observed in animal studies. Future potential uses of famotidine may include the treatment of haemorrhage from peptic ulcers and the healing of oesophageal ulceration.

Maintenance therapy for peptic ulcer disease

Peptic ulcers tend to recur; recurrence may be associated with an increased risk of potentially lethal complications, such as haemorrhage or perforation. Therapy aims to keep ulcers in remission. Currently, the optimal maintenance therapy is long-term, continuous administration of antisecretory drugs. More than 80% of patients remain in remission during maintenance therapy. Maintenance therapy may be required for the life of the patient, but it is acceptable to patients and is safe.

Safety profile of long-term H2-antagonist therapy

The safety profile of low-dose maintenance therapy with H2-antagonists for duodenal ulcer disease suggests that these agents can be given safely for several years and probably much longer. Because information regarding the use of these compounds for more than 10 years in large numbers of patients is lacking, the safety of these drugs should continue to be monitored. The safety profiles of famotidine and nizatidine will require several additional years of postmarking surveillance data to match the depth of our knowledge regarding cimetidine and ranitidine. Compared to a surgical approach to ulcer disease, continuous H2-blocker maintenance therapy is cost-effective and is associated with significantly less morbidity. Patients with a history of bleeding or other ulcer complication should be encouraged to remain on maintenance therapy if they do not undergo surgery. The need for extended maintenance therapy also applied to individuals with frequent symptomatic ulcer relapses, reflux oesophagitis, and a range of less common disorders. Currently, H2-blockers and sucralfate are the only agents approved by the Food and Drug Administration for maintenance therapy of duodenal ulcer disease. Experience with omeprazole is still limited, and its long-term safety profile must await the completion of controlled trials of maintenance therapy. Given the apparent long-term safety of the H2-blockers for maintenance therapy, any new agent must prove to be equally safe in the clinical arena, a task that may be indeed formidable.

The influence of commonly prescribed synthetic drugs for peptic ulcer on the pharmacokinetic fate of glycyrrhizin from Shaoyao-Gancao-tang

The influence of synthetic drugs prescribed for peptic ulcer on the pharmacokinetic fate of glycyrrhizin (GL) from Shaoyao-Gancao-tang (SGT, a traditional Chinese formulation, Shakuyaku-Kanzo-to in Japanese) was investigated in rats. Co-administration of histamine H2-receptor antagonist (cimetidine) and anticholinergic drug (scopolamine butyl bromide) with SGT didn't influence the area under the plasma concentration-time curves (AUC) of glycyrrhetic acid (GA), an active metabolite derived from GL in SGT. The AUC of GA from SGT were significantly reduced by co-administration of synthetic drugs commonly used for peptic ulcer in a triple therapy (OAM), a combination of a proton pump inhibitor (omeprazole) and two antibiotics (amoxicillin and metronidazole). We found that the reduction of AUC in OAM treatment was due to the antibacterial effect of amoxicillin and metronidazole on intestinal bacteria in rat which lead to the decrease of GL-hydrolysis activity. The present study suggests that it may not be a proper way to use triple therapy containing antibiotics simultaneously with SGT for healing of chronic ulcers.

The use of intravenous H2-receptor antagonists in a tertiary care hospital

OBJECTIVE

The rationale for the widespread use of intravenous H2 receptor antagonists(IVH2 RA) in hospitalized patients is not clear. We therefore examined prescribing patterns and, using strict criteria, determined whether use was appropriate. Cost of administration and potential savings were also determined.

METHODS

Data were obtained prospectively on 100 consecutive patients prescribed intravenous ranitidine and retrospectively on patients admitted with gastrointestinal (GI) bleeding.

RESULTS

For the prospective study, various indications for prescribing intravenous ranitidine were given, including postoperative patients and patients treated with steroids. Using criteria from published literature 80% of the use was considered inappropriate. Nearly 40% of the doses were given while the patient was tolerating oral intake. Creatinine clearance was impaired in 26% of patients, though only one had dosage reduction. Estimated annual cost of intravenous ranitidine was $317,000. The retrospective study of 86 consecutive patients admitted with GI bleeding revealed that all patients received intravenous ranitidine on admission, none of which was considered appropriate. The final diagnoses were peptic ulcer (49), colonic process (11), esophagitis (seven), gastric erosions (five), esophageal varices (five), Mallory-Weiss tears (four), duodenitis (two), no diagnosis (three), and jejunal ulcer (one).

CONCLUSIONS

Inappropriate use of intravenous ranitidine is common. This includes inappropriate indication, dosage, and duration of use. Large financial benefits could have been obtained if close attention was given to prescribing patterns.

Safety of acid-suppressing drugs

There is an extensive literature on the adverse effects of drugs that inhibit gastric acid secretion. This study presents a critical examination of interactions between antisecretory drugs and other compounds, the frequency of serious adverse effects relating to various body systems, the safety of antisecretory drugs in pregnancy, and longer-term safety data from postmarketing surveillance studies. While interactions with some other drugs, alcohol, and certain carcinogens are of potential concern, in practice clinically significant reactions appear to be rare if they occur at all. A small number of major side-effects have been documented, but they occur rarely, and postmarketing surveillance has not detected other longer-term sequelae. Safety of these drugs in pregnancy is not established, as data are so few. It is concluded that antisecretory agents, by comparison with most other classes of drugs, are remarkably well tolerated.

The safety assessment of over-the-counter (OTC) products

In recent years many compounds have become available as Over-The-Counter (OTC) medicine, for self-medication, which were originally marketed as prescription medicines only. This has been coupled with changes in the consumers' behaviour to self treatment and the governments commitment to restrict rising health costs. The safety and safe use of OTC products are important considerations for their wide distribution which is paralleled by diminishing medical supervision. OTC products were generally registered when toxicological requirements differed from the stringent guidelines of today, and their safety assessment thus often involves ongoing evaluation as new data become available. For this, human data must also be integrated for these assessments. However, in some areas, such as mutagenicity and carcinogenicity testing, human data are hardly obtainable and testing in animals or cells, is ultimately the only reliable source for extrapolation to man. Routine toxicological methods have mainly been developed for the assessment of new pharmaceutical entities and often provide 'yes/no' answers only. Data of such tests are, therefore, not directly applicable to the safety assessment of OTC products. Additional information on the kinetics in animal and man are indispensable for such extrapolation. On the other hand, modifications of original test protocols for the assessment of new formulations are indispensable. It was the aim of this workshop to discuss general approaches of safety assessments within the important new area of OTC products, as well as to present specific cases of recently arisen safety issues.

Comparative effects of H2-receptor antagonists on subjective and objective assessments of sleep

BACKGROUND

Clinically, it is common for patients to experience drowsiness in association with consumption of H1-receptor antagonists. Reported side-effects with H2-receptor antagonists include insomnia and somnolence. The present study was designed to assess and compare the effects of three H2-receptor antagonists (cimetidine, famotidine, and ranitidine) on nocturnal and daytime sleepiness.

METHODS

This is a double-blind crossover study on 12 normal volunteers. Subjects were studied under conditions of placebo, cimetidine (400 mg b.d.), famotidine (20 mg b.d.), and ranitidine (150 mg b.d.) for one week. Sleep was assessed at the end of each one-week interval via polysomnographic evaluation conducted on nights 6 and 7 of drug administration. On the day between the two nights in the sleep laboratory, a multiple sleep latency test was conducted.

RESULTS

The results revealed a significant reduction in the sleep onset latency with famotidine administration, but since there were no effects of any of the medications in the multiple sleep latency test, this finding is of dubious clinical significance. Cimetidine revealed a small increase in subjective estimates of sleepiness. No effects on sleep-related respiratory parameters were noted.

CONCLUSIONS

This study demonstrates the lack of effect of peripheral administration of H2-receptor antagonists on sleep stages, while subjective or objective assessment of daytime alertness revealed small effects of famotidine and cimetidine.

Risk for adverse events among patients receiving intravenous histamine2-receptor antagonists

OBJECTIVE

To identify risk factors for adverse drug reactions (ADRs) in patients receiving intravenous histamine2-receptor antagonists (H2-RAs).

DESIGN

The study hypothesis was evaluated by performing a logistic regression procedure with a backward elimination of the explanatory variables associated with ADRs.

MAIN OUTCOME MEASURES

ADRs temporally associated with the use of intravenous H2-RAs served as the dependent variable. Background information about the patients and drug use evaluation criteria in three general areas were entered into the regression analysis.

SETTING

Hospitals were selected from the southeastern US, based on their willingness to participate and their characteristics. Participating hospitals exhibited a variety of sizes and ownership arrangements.

PATIENTS

1200 adult patients who were receiving intravenous H2-RAs.

RESULTS

Seven percent of patients experienced a presumed ADR (PADR) to intravenous H2-RAs. The only risk factor for ranitidine was for patients who did not have their dosage corrected for renal function ("overdose"); these patients were twice as likely to experience a PADR compared with patients who received the correct dosage as determined by their renal function. Two risk factors for cimetidine were identified: (1) patients taking cimetidine with another medication known to cause a drug interaction; and (2) patient age. No risk factors were identified for famotidine.

CONCLUSIONS

The two risk factors for ADRs identified in this study are preventable. Healthcare providers should strive to prevent ADRs by adjusting patients' dosages based on their renal function and by monitoring patients receiving cimetidine with another medication known to interact with cimetidine.

Review article: maintenance treatment with H2-receptor antagonists for peptic ulcer disease

In recent years a number of different strategies for managing patients with peptic ulcer disease have become available. The present review discusses the relative merits of each form of treatment. Intermittent treatment (whether given in response to symptoms or as a prophylactic regimen prescribed seasonally or at weekends) fails to prevent ulcer recurrence and leaves patients at risk of haemorrhage and perforation. Anti-Helicobacter pylori therapy, although useful in certain circumstances, cannot be recommended for all patients with ulcer disease because of side effects and, in any case, requires further assessment of efficacy. Gastric surgery reduces ulcer recurrence and complications, but operations which have a low incidence of side effects are associated with higher rates of ulcer recurrence, particularly when patients are followed up for more than 10 years. Long-term continuous maintenance treatment with H2-receptor antagonists for 5 or more years effectively prevents ulcer recurrence in the majority of patients and significantly reduces the risk of ulcer complications. In addition, maintenance treatment has proved to be safe and is well tolerated by patients. Maintenance treatment with H2-receptor antagonists is the preferred option for the management of patients with peptic ulcer disease.

Adverse reactions to H2-receptor antagonists in Denmark before and after transfer of cimetidine and ranitidine to over-the-counter status

The H2-receptor antagonists cimetidine and ranitidine were transferred from prescription only to over-the-counter (OTC) status in Denmark on March 27, 1989. Reports to the Danish Committee on Adverse Drug Reactions, a voluntary reporting system, have been evaluated to detect possible changes in frequency and pattern of adverse drug reactions (ADRs) caused by the altered delivery status. From the introduction of cimetidine in 1977 and until March 31, 1990, the Committee received 494 reports of 612 suspected adverse reactions to anti-ulcer drugs. The H2-receptor antagonists (mainly cimetidine and ranitidine) were responsible for 548 (90%) of the ADRs. The study, which presents experience with these drugs from more than a decade and a total consumption corresponding to 65 million treatment days, confirms their excellent safety record. Serious reactions were rare, and when they occurred, reversible. During the first year with cimetidine and ranitidine available OTC no changes were seen in reporting frequency or ADR pattern which could be ascribed to OTC transfer. Only one ADR report concerning OTC cimetidine was received. This may be caused by several factors: the safety of these drugs, the fact that only very little was actually sold OTC, and a relatively low sensitivity of the voluntary reporting system.

Side effects of ranitidine

Ranitidine was first marketed in 1981; since then many patients have been treated such that much experience has been accumulated on the safety of this histamine H2-receptor antagonist in the treatment of gastroduodenal disease. A wide array of ranitidine-associated side effects has been described, but infrequently. As so much information is now available, the aim of this review is to assess the weight of evidence for a causal link between ranitidine and the reported side effects. Overall, ranitidine is well tolerated. The incidence of general side effects at less than 2% is very similar to placebo. Headaches, tiredness, dizziness and mild gastrointestinal disturbance (e.g. diarrhoea, constipation and nausea) are among the most frequent complaints, but have very seldom resulted in stopping treatment. Cardiovascular side effects are extremely rare and unpredictable with the usual doses of oral ranitidine (at most 1 in 1 million patients). They mostly comprise sinusal bradycardia and atrioventricular blockade, especially after rapid intravenous administration, receding after cessation of the drug. Clinical studies, however, have not shown a significant pharmacological effect of ranitidine on the cardiovascular system via H2-receptors, even though individual sensitivities cannot be ruled out in a few isolated reports. Ranitidine is unlikely to be directly hepatotoxic: a transient change in liver function tests has been noted in only 1 in 100 to 1 in 1000 patients. Several cases of mixed hepatitis have been reported, but very few were fully documented. The incidence of ranitidine-associated acute hepatitis has been estimated to be less than 1 in 100,000 patients. Neuropsychiatric complications may be less common and clinically quite similar to those reported with cimetidine, i.e. confusion, disorientation, hallucinations, delirium. These side effects have occurred especially in critically ill and multiple-therapy patients, or patients with chronic renal or hepatic failure, so that the direct causal link with ranitidine treatment was often difficult to ascertain. Even though an H2-receptor-mediated effect is an attractive hypothesis (since similar complications were noted with other H2-receptor antagonists), other mechanisms have been suggested to play a role, e.g. cholinergic or histaminic effects. The overall incidence of neuropsychiatric complications is probably markedly less than 1%. White cell injury (i.e. agranulocytosis) appears to be the most frequent haematological complication, even though case reports are very few and poorly documented.(ABSTRACT TRUNCATED AT 400 WORDS)

Ranitidine in the treatment of non-steroidal anti-inflammatory drug associated gastric and duodenal ulcers

In a multicentre study the effect of ranitidine on healing non-steroidal anti-inflammatory drug (NSAID) associated peptic ulcers was compared in a group of patients who had stopped NSAID treatment with another group who continued with NSAID treatment. A total of 190 patients with confirmed ulcers were randomised to continue or stop NSAID treatment. All patients in addition received ranitidine 150 mg twice daily. Patients were endoscopically monitored at four, eight, and 12 weeks. Gastric ulcers at eight weeks had healed in 63% of those taking NSAIDs compared with 95% of those who had stopped NSAID treatment. For duodenal ulcer the healing rates at eight weeks were 84% in the group continuing NSAIDs compared with 100% in those who stopped NSAIDs. The differences in healing rates were statistically significant for both gastric ulcer (p = 0.001) and for duodenal ulcer (p = 0.006). At 12 weeks, 79% of gastric ulcers and 92% of duodenal ulcers were healed in the group continuing with NSAIDs. All patients with gastric and duodenal ulcers who stopped taking NSAIDs were healed at 12 weeks. The study shows that ranitidine 150 mg twice daily effectively heals NSAID associated peptic ulcers. Healing is more successful when NSAID treatment stops but even if these drugs are continued, substantial healing rates are achievable.

Gastric histology and plasma gastrin response to a meal in patients with duodenal ulcer disease after five years treatment with ranitidine

Fifty asymptomatic patients with duodenal ulcer disease, aged 31-82 years, who had received ranitidine maintenance therapy continuously for five or more years without a symptomatic recurrence, were studied. Fasting plasma gastrin concentrations were normal (mean 24 pmol/L, S.D. +/- 22) while the post-prandial gastrin response was variable with maximum plasma concentrations ranging from 16 to 309 pmol/L. Endoscopy revealed six asymptomatic peptic ulcers. Histological examination of gastric biopsies showed mild, superficial inflammatory cell infiltration of the fundic mucosa, but more extensive inflammatory cell infiltration with some atrophy of the mucosal glands in the antral mucosa. Patchy intestinal metaplasia was evident in the antral mucosa of 18 patients. No fundic ECL cell hyperplasia was seen. Helicobacter pylori were detected in the corpus and antrum of most patients. These results suggest that maintenance treatment with ranitidine for 5 years is not associated with either significant hypergastrinaemia or with changes in the fundic mucosa which could be interpreted as pre-malignant.

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.

Maintenance treatment with H2 receptor antagonists in patients with peptic ulcer disease: rarely justified in terms of cost or patient benefit

Maintenance treatment reduces the frequency of ulcer relapse. Its routine use is unnecessary because the condition is benign and most patients do not relapse frequently. Routine maintenance treatment does not reduce the incidence of complications of ulcers overall, although it may do so in specific groups mentioned above. Routine maintenance treatment for all patients with ulcers would be expensive as well as largely unnecessary.

First-degree atrioventricular block in a young duodenal ulcer patient treated with a standard oral dose of ranitidine

A 20-year-old male patient on oral treatment with ranitidine 300 mg/day in a single bedtime dose was admitted to hospital for a brief episode of syncope which had occurred 20 min earlier. All clinical, laboratory and instrumental examinations yielded negative findings, except for electrocardiographic evidence of first-degree atrioventricular block. Administration of atropine produced transient disappearance of the block, which disappeared altogether after discontinuing ranitidine treatment. Two separate rechallenges with ranitidine each produced recurrence of (asymptomatic) first-degree atrioventricular block at electrocardiographic examination, but oral treatment with cimetidine (400-800 mg/day) and famotidine (40-80 mg/day) induced no electrocardiographic abnormalities. The hypothesis that this patient may be abnormally susceptible to the cholinergic or cholinergic-like effect of ranitidine, a side effect unrelated to the drug's primary H2-blocking action, would appear to be consistent with evidence of an increased vagal tone of the atrioventricular node as revealed by atrial pacing. However, the ability of ranitidine to release histamine in man and the potential dysrhythmia-inducing effect of histamine should also be taken into consideration.