Side effects of ranitidine

Histamine H2-receptor antagonism improves conduit artery endothelial function and reduces plasma aldosterone level without lowering arterial blood pressure in angiotensin II-hypertensive mice

Aldosterone through the mineralocorticoid receptor MR has detrimental effects on cardiovascular disease. It reduces the bioavailability of nitric oxide and impairs endothelium-dependent vasodilatation. In resistance arteries, aldosterone impairs the sensitivity of vascular smooth muscle cells to nitric oxide by promoting the local secretion of histamine which activates H2 receptors. The present experiments tested in vivo and ex vivo the hypothesis that systemic H2-receptor antagonism reduces arterial blood pressure and improves vasodilatation in angiotensin II-induced chronic hypertension. Hypertension was induced by intravenous infusion of angiotensin II (60 ng kg-1 min-1) in conscious, unrestrained mice infused concomitantly with the H2-receptor antagonist ranitidine (27.8 µg kg-1 min-1) or vehicle for 24 days. Heart rate and arterial blood pressure were recorded by indwelling arterial catheter. Resistance (mesenteric) and conductance (aortae) arteries were harvested for perfusion myography and isometric tension recordings by wire myography, respectively. Plasma was analyzed for aldosterone concentration. ANGII infusion resulted in elevated arterial blood pressure and while in vivo treatment with ranitidine reduced plasma aldosterone concentration, it did not reduce blood pressure. Ranitidine improved ex vivo endothelial function (acetylcholine 10-9 to 10-6 mol L-1) in mesenteric resistance arteries. This was abolished by ex vivo treatment with aldosterone (10-9 mol L-1, 1 h). In aortic segments, in vivo ranitidine treatment impaired relaxation. Activation of histamine H2 receptors promotes aldosterone secretion, does not affect arterial blood pressure, and protects endothelial function in conduit arteries but promotes endothelial dysfunction in resistance arteries during angiotensin II-mediated hypertension. Aldosterone contributes little to angiotensin II-induced hypertension in mice.

Inhibitors of gastric acid secretion increase oxidative stress and matrix metalloproteinase-2 activity leading to vascular remodeling

The use of inhibitors of gastric acid secretion (IGAS), especially proton pump inhibitors (PPI), has been associated with increased cardiovascular risk. While the mechanisms involved are not known, there is evidence supporting increased oxidative stress, a major activator of matrix metalloproteinases (MMP), as an important player in such effect. However, there is no study showing whether other IGAS such as histamine H2-receptor blockers (H2RB) cause similar effects. This study aimed at examining whether treatment with the H2RB ranitidine promotes oxidative stress resulting in vascular MMP activation and corresponding functional and structural alterations in the vasculature, as compared with those found with the PPI omeprazole. Male Wistar rats were treated (4 weeks) with vehicle (2% tween 20), omeprazole (10 mg/Kg/day; i.p.) or ranitidine (100 mg/Kg/day; gavage). Then the aorta was collected to perform functional, biochemical, and morphometric analysis. Both ranitidine and omeprazole increased gastric pH and oxidative stress assessed in situ with the fluorescent dye dihydroethidium (DHE) and with lucigenin chemiluminescence assay. Both IGAS augmented vascular activated MMP-2. These findings were associated with aortic remodeling (increased media/lumen ratio and number of cells/μm2). Both IGAS also impaired the endothelium-dependent relaxation induced by acetylcholine (isolated aortic ring preparation). This study provides evidence that the H2RB ranitidine induces vascular dysfunction, redox alterations, and remodeling similar to those found with the PPI omeprazole. These findings strongly suggest that IGAS increase oxidative stress and matrix metalloproteinase-2 activity leading to vascular remodeling, which helps to explain the increased cardiovascular risk associated with the use of those drugs.

Renal histaminergic system and acute effects of histamine receptor 2 blockade on renal damage in the Dahl salt-sensitive rat

Histamine is involved in the regulation of immune response, vasodilation, neurotransmission, and gastric acid secretion. Although elevated histamine levels and increased expression of histamine metabolizing enzymes have been reported in renal disease, there is a gap in knowledge regarding the mechanisms of histamine-related pathways in the kidney. We report here that all four histamine receptors as well as enzymes responsible for the metabolism of histamine are expressed in human and rat kidney tissues. In this study, we hypothesized that the histaminergic system plays a role in salt-induced kidney damage in the Dahl salt-sensitive (DSS) rat, a model characterized with inflammation-driven renal lesions. To induce renal damage related to salt sensitivity, DSS rats were challenged with 21 days of a high-salt diet (4% NaCl); normal-salt diet (0.4% NaCl)-fed rats were used as a control. We observed lower histamine decarboxylase and higher histamine N-methyltransferase levels in high-salt diet-fed rats, indicative of a shift in histaminergic tone; metabolomics showed higher histamine and histidine levels in the kidneys of high-salt diet-fed rats, whereas plasma levels for both compounds were lower. Acute systemic inhibition of histamine receptor 2 in the DSS rat revealed that it lowered vasopressin receptor 2 in the kidney. In summary, we established here the existence of the local histaminergic system, revealed a shift in the renal histamine balance during salt-induced kidney damage, and provided evidence that blockage of histamine receptor 2 in the DSS rat affects water balance and urine concentrating mechanisms.NEW & NOTEWORTHY Histamine is a nitrogenous compound crucial for the inflammatory response. The knowledge regarding the renal effects of histamine is very limited. We showed that renal epithelia exhibit expression of the components of the histaminergic system. Furthermore, we revealed that there was a shift in the histaminergic tone in salt-sensitive rats when they were challenged with a high-salt diet. These data support the notion that histamine plays a role in renal epithelial physiological and pathophysiological functions.

Callerya atropurpurea suppresses inflammation in vitro and ameliorates gastric injury as well as septic shock in vivo via TLR4/MyD88-dependent cascade

BACKGROUND

Callerya atropurpurea is a traditional plant in a tropical zone discovered to have anti-inflammatory functions.

PURPOSE

we want to investigate the mechanism related to anti-inflammation of C. atropurpurea ethanol extract (Ca-EE) both in vitro and in vivo.

STUDY DESIGN

Murine macrophage cells and mouse models for gastritis and septic shock were conducted to evaluate the abilities of Ca-EE in anti-inflammation.

METHODS

Ca-EE was tested by HPLC and LC-MS/MS. NO outcome was checked by Griess reagent test. Cell viabilities were evaluated using MTT assay. Inflammatory cytokines were determined via RT-PCR and ELISA. The mechanism of Ca-EE in anti-inflammation was investigated by luciferase reporter gene assay and immunoblot in transcription level and protein level respectively. Gastric injury and septic shock administrated with Ca-EE were studied by H&E, PCR, and immunoblot.

RESULTS

Ca-EE significantly decreased LPS-induced NO production, but hardly stimulated the expression of NO itself. It not only showed no cytotoxicity, but also protected cells from LPS damage. Moreover, Ca-EE decreased TLR4 expression, altered MyD88 recruitment and TRAF6, and suppressed the phospho-Src/PI3K/AKT. Ca-EE inhibited downstream signaling P38, JNK and NF-κB. Finally, Ca-EE alleviated HCl/EtOH-induced gastritis and LPS/poly (I:C)-induced septic shock through the previously mentioned signaling cascades.

CONCLUSION

Ca-EE exhibited an integrated and promising mechanism against TLR4-related inflammation, which shows potential for treating gastritis, septic shock, and other inflammatory diseases.

Ranitidine decreases human sperm motility and vitality and increases the activity of seminal creatine kinase

Ranitidine (brand name: Zantac), an acid reducer, belongs to histamine-2 receptor antagonists. Since 1981, even though several adverse effects of this drug were reported in the body, still, its effects on human sperm parameters have yet to be confirmed. In this work, we attempted to measure sperm motility, sperm vitality and activity of seminal creatine kinase in the ejaculated human semen (n = 31) in the presence of ranitidine at a range of concentrations (0.1, 0.3, 0.6, 0.9 and 1.2 μg/ml) compared with control (without ranitidine). Sperm motility was measured using the Makler counter, whilst sperm vitality was assessed using the Eosin test. Creatine kinase activity was measured using the kinetic spectrophotometric method. Sperm motility (total and progressive) as well as sperm vitality was significantly (p < .05) reduced in the presence of ranitidine in human semen, particularly at the higher tested concentrations (0.6-1.2 μg/ml) compared with the control. On the other hand, creatine kinase activity was significantly increased (p < .05) in the presence of ranitidine at 0.6, 0.9 and 1.2 μg/ml. In conclusion, ranitidine at 0.6-1.2 μg/ml reduced sperm motility and vitality, but increased the activity of creatine kinase in ejaculated human semen.

The Roles of Cardiovascular H2-Histamine Receptors Under Normal and Pathophysiological Conditions

This review addresses pharmacological, structural and functional relationships among H₂-histamine receptors and H₁-histamine receptors in the mammalian heart. The role of both receptors in the regulation of force and rhythm, including their electrophysiological effects on the mammalian heart, will then be discussed in context. The potential clinical role of cardiac H₂-histamine-receptors in cardiac diseases will be examined. The use of H₂-histamine receptor agonists to acutely increase the force of contraction will be discussed. Special attention will be paid to the potential role of cardiac H₂-histamine receptors in the genesis of cardiac arrhythmias. Moreover, novel findings on the putative role of H₂-histamine receptor antagonists in treating chronic heart failure in animal models and patients will be reviewed. Some limitations in our biochemical understanding of the cardiac role of H₂-histamine receptors will be discussed. Recommendations for further basic and translational research on cardiac H₂-histamine receptors will be offered. We will speculate whether new knowledge might lead to novel roles of H₂-histamine receptors in cardiac disease and whether cardiomyocyte specific H₂-histamine receptor agonists and antagonists should be developed.

Common Antacid Medication-Ranitidine Causing a Rare Serious Adverse Effect

Ranitidine is a widely used over-the-counter antacid medication, and is generally very well tolerated. To our knowledge, anaphylaxis secondary to ranitidine is exceedingly rare, and has only been reported in a few case reports. We present a patient who developed an anaphylactic reaction after one tablespoon of ranitidine. The goal of this manuscript is to add to the paucity of literature of this rare but life-threatening adverse effect of a commonly used medication.

The gastrointestinal symptoms present in patients with postural tachycardia syndrome: A review of the literature and overview of treatment

Orthostatic intolerance, including postural tachycardia syndrome, is often associated with gastrointestinal symptoms. In the vast majority of the cases, the gastrointestinal symptoms are not secondary to the orthostatic disorder, but rather just a comorbid condition. This concept is critical, since treatment aimed at the orthostatic condition will not improve the gastrointestinal symptoms. Only when the gastrointestinal symptoms develop in the upright position and improve or resolve in the supine position, they may be related to the orthostatic stress. The most common symptoms associated with orthostatic intolerance include nausea, dyspepsia, bloating and constipation. The majority of subjects do not have gastroparesis. The chapter discusses available treatments of these conditions.

Utilization Pattern of Potentially Inappropriate Medications in Geriatric Patients in a Tertiary Care Hospital: A Retrospective Observational Study

INTRODUCTION

Geriatric population is on the rise throughout the world, hence the quality and the safety of prescribing in the elderly is a global healthcare concern. It is important for the healthcare providers to be aware of the limitations in prescribing certain drugs to the elderly. This study was an attempt to shed light on the utilization pattern of Potentially Inappropriate Medications (PIMs) in elderly patients admitted in the medicine wards in a tertiary care hospital in Goa.

AIM

To measure the percentage prevalence of PIMs prescribed in the admitted geriatric patients.

MATERIALS AND METHODS

In this retrospective observational study, 150 case records of patients aged 60 years or more were analysed. All the prescribed medications, for each case record, were then analysed by referring to the American Geriatrics Society (AGS) Beers Criteria 2015. Data was analysed using Statistical Package for Social Sciences (SPSS) software.

RESULTS

Of the 150 patients, 99 (66%) received at least one PIM according to the Beers Criteria 2015 (including drugs to be used with caution). However, after excluding the drugs to be used with caution, the prevalence of PIMs decreased to 44%. The most commonly prescribed PIMs were ranitidine (17.33%) and prazosin (8.66%) and the most commonly prescribed drug to be used with caution was furosemide (35.33%).

CONCLUSION

As the medication needs of the geriatric population are unique, it is essential that the healthcare professionals are aware of these needs and also follow the available guidelines and tools. Formulation of hospital policies and protocols in this regard would help to improve the scenario. Increased education, awareness and reporting of drug-related problems along with more doctor-patient interaction in these situations are some of the factors that could play an important role in promoting better and safer prescribing practices and a better quality of life to the older generations of our communities.

Mania associated with ranitidine: a case report and review of literature

H2 receptor antagonists can be associated with central adverse drug reactions (ADRs), like confusion, delirium, hallucinations, slurred speech or headaches. We report here a 'serious' case of severe mania leading to hospitalization in a 42-year-old alcohol-dependent man, 4 days after ranitidine introduction. Review of literature showed that this 'very rare' ADR occurs mainly in patients with predisposing factors: age, decrease in renal and/or hepatic function, polymedication, alcohol. Knowledge of this ADR can be particularly important for these drugs widely used as self-medication.

Safe prescribing of physical health medication in patients with dementia

OBJECTIVE

The prescription of multiple medications for older people is common, despite concerns over the dangers associated with this. Older adults are particularly vulnerable to adverse effects of medication, and this is an even greater risk in patients with dementia. Many drugs used for physical health conditions can negatively affect cognition. Our aim was to identify areas of concern and which drugs to avoid in patients with dementia.

DESIGN

A review of the literature was carried out using Pubmed, Medline and Embase.

RESULTS

Many drugs used for physical health conditions may worsen the symptoms of dementia. They do this either by negating the effects of cognitive enhancers or through direct adverse effects on cognition

CONCLUSIONS

Where evidence exists, we provide guidance as to the safest drugs to prescribe in particular clinical situations. Anticholinergic drugs should be avoided in dementia wherever possible. Effective pain management is important in older patients, but caution should be used when selecting an opioid analgesic because of their adverse central effects. Cardiac drugs have overall negligible effects on cognition, although some have been reported to cause delirium.

Comparison of the effect of a single dose of erythromycin with pantoprazole on gastric content volume and acidity in elective general surgery patients

INTRODUCTION

Pulmonary aspiration of gastric contents remains one of the most feared complications of anesthesia. A gastric pH of 2.5 or less and a volume of 25 ml (0.4 ml/kg body weight) or more in average adult patients are considered critical factors for the development of pulmonary damage in adults.

MATERIALS AND METHODS

This study compared the efficacy of a single oral dose of erythromycin (a macrolide antibiotic) with oral pantoprazole (a proton pump inhibitor) on pre-operative gastric fluid volume and pH in a prospective, randomized, double-blind controlled fashion in 80 adult patients (of ASA physical status I and II) planned for elective surgery under general anesthesia. Patients were divided into two groups of 40 patients each. The pantoprazole group (Group I) received oral pantoprazole 40 mg and the erythromycin group (Group II) received oral erythromycin 250 mg at least 1 h prior to the induction of anesthesia. After tracheal intubation, gastric fluid was aspirated via a Salem Sump tube and its volume and pH were measured.

RESULTS

Although both erythromycin and pantoprazole decreased the gastric fluid volume to a similar extent, the decrease in gastric fluid acidity by pantoprazole was significantly greater than that by erythromycin. The proportion of patients at risk of pulmonary aspiration according to traditional criteria, i.e. pH ≤2.5 and volume ≥25ml, was lower in the pantoprazole group.

CONCLUSION

Administration of pantoprazole was found to be more useful than a sub-therapeutic dose of erythromycin in decreasing both volume and acidity of gastric content.

Inflammatory stress and idiosyncratic hepatotoxicity: hints from animal models

Adverse drug reactions (ADRs) present a serious human health problem. They are major contributors to hospitalization and mortality throughout the world (Lazarou et al., 1998; Pirmohamed et al., 2004). A small fraction (less than 5%) of ADRs can be classified as "idiosyncratic." Idiosyncratic ADRs (IADRs) are caused by drugs with diverse pharmacological effects and occur at various times during drug therapy. Although IADRs affect a number of organs, liver toxicity occurs frequently and is the primary focus of this review. Because of the inconsistency of clinical data and the lack of experimental animal models, how IADRs arise is largely undefined. Generation of toxic drug metabolites and induction of specific immunity are frequently cited as causes of IADRs, but definitive evidence supporting either mechanism is lacking for most drugs. Among the more recent hypotheses for causation of IADRs is that inflammatory stress induced by exogenous or endogenous inflammagens is a susceptibility factor. In this review, we give a brief overview of idiosyncratic hepatotoxicity and the inflammatory response induced by bacterial lipopolysaccharide. We discuss the inflammatory stress hypothesis and use as examples two drugs that have caused IADRs in human patients: ranitidine and diclofenac. The review focuses on experimental animal models that support the inflammatory stress hypothesis and on the mechanisms of hepatotoxic response in these models. The need for design of epidemiological studies and the potential for implementation of inflammation interaction studies in preclinical toxicity screening are also discussed briefly.

p38 mitogen-activated protein kinase-dependent tumor necrosis factor-alpha-converting enzyme is important for liver injury in hepatotoxic interaction between lipopolysaccharide and ranitidine

Ranitidine (RAN) is one of the drugs associated with idiosyncratic adverse drug reactions (IADRs) in human patients. In rats, cotreatment with nontoxic doses of lipopolysaccharide (LPS) and RAN causes liver injury. This is a potential animal model for RAN-induced IADRs in humans. Previous studies showed that RAN augmented serum tumor necrosis factor (TNF)-alpha production and hepatic neutrophil activation after LPS treatment and that both TNF-alpha and neutrophils are crucial for the liver pathogenesis. We tested the hypothesis that p38 mitogen-activated protein kinase activation is necessary for TNF-alpha production, neutrophil activation, and subsequent liver injury. LPS/RAN cotreatment caused more p38 activation compared with LPS alone. The p38 inhibitor SB 239063 [trans-1-(4-hydroxycyclohexyl)-4-(4-fluorophenyl)-5-(2-methoxypyridimidin-4-yl) imidazole] reduced liver injury in rats cotreated with LPS/RAN. This inhibitor also reduced neutrophil activation and attenuated hemostatic system activation. SB 239063 decreased serum TNF-alpha concentration after LPS/RAN treatment to the same level as LPS treatment. However, the inhibitor did not reduce TNF-alpha mRNA in liver, suggesting a post-transcriptional mode of action. This might occur through TNF-alpha-converting enzyme (TACE), which cleaves pro-TNF-alpha into its active form. Indeed, a TACE inhibitor administered just before RAN treatment reduced serum TNF-alpha protein. The TACE inhibitor also reduced liver injury and serum plasminogen activator inhibitor (PAI)-1. Furthermore, a PAI-1 inhibitor reduced neutrophil activation and liver injury after LPS/RAN treatment. In summary, RAN enhanced TNF-alpha production after LPS treatment through augmented p38 activation, and this seems to occur through TACE. The prolonged TNF-alpha production enhanced PAI-1 production after RAN cotreatment, and this is important for the hepatotoxicity.

The Role of Tumor Necrosis Factor Alpha in Lipopolysaccharide/Ranitidine-Induced Inflammatory Liver Injury

Exposure to a nontoxic dose of bacterial lipopolysaccharide (LPS) increases the hepatotoxicity of the histamine-2 (H2) receptor antagonist, ranitidine (RAN). Because some of the pathophysiologic effects associated with LPS are mediated through the expression and release of inflammatory mediators such as tumor necrosis factor alpha (TNF), this study was designed to gain insights into the role of TNF in LPS/RAN hepatotoxicity. To determine whether RAN affects LPS-induced TNF release at a time near the onset of liver injury, male Sprague-Dawley rats were treated with 2.5 x 10(6) endotoxin units (EU)/kg LPS or its saline vehicle (iv) and 2 h later with either 30 mg/kg RAN or sterile phosphate-buffered saline vehicle (iv). LPS administration caused an increase in circulating TNF concentration. RAN cotreatment enhanced the LPS-induced TNF increase before the onset of hepatocellular injury, an effect that was not produced by famotidine, a H2-receptor antagonist without idiosyncrasy liability. Similar effects were observed for serum interleukin (IL)-1beta, IL-6, and IL-10. To determine if TNF plays a causal role in LPS/RAN-induced hepatotoxicity, rats were given either pentoxifylline (PTX; 100 mg/kg, iv) to inhibit the synthesis of TNF or etanercept (Etan; 8 mg/kg, sc) to impede the ability of TNF to reach cellular receptors, and then they were treated with LPS and RAN. Hepatocellular injury, the release of inflammatory mediators, hepatic neutrophil (PMN) accumulation, and biomarkers of coagulation and fibrinolysis were assessed. Pretreatment with either PTX or Etan resulted in the attenuation of liver injury and diminished circulating concentrations of TNF, IL-1beta, IL-6, macrophage inflammatory protein-2, and coagulation/fibrinolysis biomarkers in LPS/RAN-cotreated animals. Neither PTX nor Etan pretreatments altered hepatic PMN accumulation. These results suggest that TNF contributes to LPS/RAN-induced liver injury by enhancing inflammatory cytokine production and hemostasis.

Safety issues relating to long-term treatment with histamine H2-receptor antagonists

H2-receptor antagonist therapy is associated with a low incidence of adverse reactions. Adverse events reported in clinical trials of ranitidine in daily doses of up to 1200 mg include headache, tiredness and mild gastrointestinal disturbances, but the incidence is similar to or less than that for placebo. High doses of cimetidine (> 5 g/day) can cause reversible impotence or gynaecomastia. While ranitidine exhibits no clinically significant drug-drug interactions, cimetidine interacts with many drugs metabolized by cytochrome P450. In contrast to ranitidine and cimetidine, where safety data are available for up to 10 years of continuous therapy, experience with famotidine and nizatidine is limited. The safety of long-term H2-receptor antagonist therapy needs to be considered in relation to the potential consequences of prolonged acid suppression, including the risk of proliferation of gastric flora and the risk of developing enterochromaffin-like cell hyperplasia, which could in turn, theoretically, lead to gastric malignancy. Such problems have not been observed in patients during long-term therapy at low or full doses of H2-receptor antagonists. Standard doses of currently available H2-receptor antagonists permit acid secretion in response to food and other stimuli, and this daily acid tide prevents persistent bacterial colonization.

Investigations toward enhanced understanding of hepatic idiosyncratic drug reactions

Idiosyncratic drug reactions (IDRs) of a hepatic origin are a major health concern and a notoriously difficult challenge for the pharmaceutical industry. These types of adverse events are rare, with a typical occurrence of 1 in 100 to 1 in 100,000 patients. Typical adverse outcomes are most likely statistically impossible to predict in traditional preclinical safety studies or clinical trials. Unfortunately, these reactions can pose a significant risk to the public health, resulting in devastating consequences such as irreversible liver injury, liver transplantation and fatality. This review provides many examples of experimental efforts that are underway for a better understanding of molecular events that may be responsible for IDRs. A list of existing hypotheses for IDRs is also provided, each with current literature examples or supporting evidence. The possibilities for developing suitable animal models for the prediction and characterisation of IDRs are elaborated, especially for a drug-inflammation interaction rat model of hepatic IDR. The need for predictive biomarkers of IDR is addressed, with the exploration of some possible candidates. Finally, the use of primary human hepatocyte culture systems is explored as an in vitro system, with application for providing an increased mechanistic knowledge of IDR. Several examples of informative studies on the nature of IDRs that employ toxicogenomic and proteomic technologies are summarised.

Unique gene expression and hepatocellular injury in the lipopolysaccharide-ranitidine drug idiosyncrasy rat model: comparison with famotidine

Rats cotreated with lipopolysaccharide (LPS) and ranitidine (RAN) but not LPS and famotidine (FAM) develop hepatocellular injury in an animal model of idiosyncratic drug reactions. Evaluation of liver gene expression in rats given LPS and/or RAN led to confirmation that the hemostatic system, hypoxia, and neutrophils (PMNs) are critical mediators in LPS/RAN-induced liver injury. We tested the hypothesis that unique gene expression changes distinguish LPS/RAN-treated rats from rats given LPS or RAN alone and from those cotreated with LPS/FAM. Rats were treated with a nonhepatotoxic dose of LPS (44.4 x 10(6) endotoxin units/kg, iv) or its vehicle. Two hours thereafter they were given RAN (30 mg/kg, iv), FAM (either 6 mg/kg, a pharmacologically equi-efficacious dose, or 28.8 mg/kg, an equimolar dose, iv), or vehicle. They were killed 2 or 6 h after drug treatment for evaluation of hepatotoxicity (2 and 6 h) and liver gene expression (2 h only). At a time before the onset of hepatocellular injury, hierarchical clustering distinguished rats treated with LPS/RAN from those given LPS alone. 205 probesets were expressed differentially to a greater or lesser degree only in LPS/RAN-treated rats compared to LPS/FAM or LPS alone, which did not develop liver injury. These included VEGF, EGLN3, MAPKAPK-2, BNIP3, MIP-2, COX-2, EGR-1, PAI-1, IFN-gamma, and IL-6. Expression of these genes was confirmed by real-time PCR. Serum concentrations of MIP-2, PAI-1, IFN-gamma, and IL-6 correlated with their respective gene expression patterns. Overall, the expression of several gene products capable of controlling requisite mediators of injury (i.e., hemostasis, hypoxia, PMNs) in this model were enhanced in livers of LPS/RAN-treated rats. Furthermore, enhanced expression of MAPKAPK-2 in RAN-treated rats and its target genes in LPS/RAN-treated rats suggests that p38/MAPKAPK-2 signaling is a regulation point for enhancement of LPS-induced gene expression by RAN.

Coagulation-Mediated Hypoxia and Neutrophil-Dependent Hepatic Injury in Rats Given Lipopolysaccharide and Ranitidine

Idiosyncrasy-like liver injury occurs in rats cotreated with nonhepatotoxic doses of ranitidine (RAN) and bacterial lipopolysaccharide (LPS). Hepatocellular oncotic necrosis is accompanied by neutrophil (PMN) accumulation and fibrin deposition in LPS/RAN-treated rats, but the contribution of PMNs to injury has not been shown. We tested the hypothesis that PMNs are critical mediators of LPS/RAN-induced liver injury and explored the potential for interaction between PMNs and hemostasis-induced hypoxia. Rats were given either LPS (44.4 x 10(6) endotoxin units/kg) or its vehicle and then RAN (30 mg/kg) or its vehicle 2 h later. They were killed 3 or 6 h after RAN treatment, and hepatocellular injury was estimated from serum alanine aminotransferase activity and liver histopathology. Plasma PMN chemokine concentration and the number of PMNs in liver increased after LPS treatment at 3 h and were not markedly altered by RAN cotreatment. Depletion of circulating PMNs attenuated hepatic PMN accumulation and liver injury and had no effect on coagulation system activation. Anticoagulation with heparin attenuated liver fibrin deposition and injury in LPS/RAN-treated rats; however, heparin had little effect on liver PMN accumulation or plasma chemokine concentration. Liver hypoxia occurred in LPS/RAN-cotreated rats and was significantly reduced by heparin. In vitro, hypoxia enhanced the killing of rat hepatocytes by PMN elastase and shortened its onset, indicating a synergistic interaction between PMNs and hypoxia. The results suggest that PMNs are involved in the hepatocellular injury caused by LPS/RAN-cotreatment and that hemostasis increases sensitivity to PMN-induced hepatocellular injury by causing liver hypoxia.

Role of hepatic fibrin in idiosyncrasy-like liver injury from lipopolysaccharide-ranitidine coexposure in rats

Coadministration of nonhepatotoxic doses of the histamine 2-receptor antagonist ranitidine (RAN) and bacterial lipopolysaccharide (LPS) results in hepatocellular injury in rats, the onset of which occurs in 3 to 6 hours. This reaction resembles RAN idiosyncratic hepatotoxicity in humans. Early fibrin deposition occurs in livers of rats cotreated with LPS/RAN. Accordingly, we tested the hypothesis that the hemostatic system contributes to liver injury in LPS/RAN-treated rats. Rats were given either LPS (44.4 x 10(6) EU/kg) or its vehicle, then RAN (30 mg/kg) or its vehicle 2 hours later. They were killed 2, 3, 6, 12, or 24 hours after RAN treatment, and liver injury was estimated from serum alanine aminotransferase activity. A modest elevation in serum hyaluronic acid, which was most pronounced in LPS/RAN-cotreated rats, suggested altered sinusoidal endothelial cell function. A decrease in plasma fibrinogen and increases in thrombin-antithrombin dimers and in serum concentration of plasminogen activator inhibitor-1 occurred before the onset of liver injury. Hepatic fibrin deposition was observed in livers from LPS/RAN-cotreated rats 3 and 6 hours after RAN. Liver injury was abolished by the anticoagulant heparin and was significantly attenuated by the fibrinolytic agent streptokinase. Hypoxia, one potential consequence of sinusoidal fibrin deposition, was observed in livers of LPS/RAN-treated rats. In conclusion, the results suggest that the hemostatic system is activated after LPS/RAN cotreatment and that fibrin deposition in liver is important for the genesis of hepatic parenchymal cell injury in this model.

Application of high-throughput Fourier-transform infrared spectroscopy in toxicology studies: contribution to a study on the development of an animal model for idiosyncratic toxicity

An evaluation of high-throughput Fourier-transform infrared spectroscopy (FT-IR) as a technology that could support a "metabonomics" component in toxicological studies of drug candidates is presented. The hypothesis tested in this study was that FT-IR had sufficient resolving power to discriminate between urine collected from control rat populations and rats subjected to treatment with a potent inflammatory agent, bacterial lipopolysaccharide (LPS). It was also hypothesized that co-administration of LPS with ranitidine, a drug associated with reports of idiosyncratic susceptibility, would induce hepatotoxicity in rats and that this could be detected non-invasively by an FT-IR-based metabonomics approach. The co-administration of LPS with "idiosyncratic" drugs represents an attempt to develop a predictive model of idiosyncratic toxicity and FT-IR is used herein to support characterization of this model. FT-IR spectra are high dimensional and the use of genetic programming to identify spectral sub-regions that most contribute to discrimination is demonstrated. FT-IR is rapid, reagentless, highly reproducible and inexpensive. Results from this pilot study indicate it could be extended to routine applications in toxicology and to supporting characterization of a new animal model for idiosyncratic susceptibility.

Ranitidine treatment during a modest inflammatory response precipitates idiosyncrasy-like liver injury in rats

Drug idiosyncrasy is an adverse event of unknown etiology that occurs in a small fraction of people taking a drug. Some idiosyncratic drug reactions may occur from episodic decreases in the threshold for drug hepatotoxicity. Previous studies in rats have shown that modest underlying inflammation triggered by bacterial lipopolysaccharide (LPS) can decrease the threshold for xenobiotic hepatotoxicity. The histamine-2 (H2)-receptor antagonist ranitidine (RAN) causes idiosyncratic reactions in people, with liver as a usual target. We tested the hypothesis that RAN could be rendered hepatotoxic in animals undergoing a modest inflammatory response. Male rats were treated with a nonhepatotoxic dose of LPS (44 x 10(6) endotoxin units/kg i.v.) or its vehicle and then 2 h later with a nonhepatotoxic dose of RAN (30 mg/kg i.v.) or its vehicle. Liver injury was evident only in animals treated with both RAN and LPS as estimated by increases in serum alanine aminotransferase, aspartate aminotransferase, and gamma-glutamyl transferase activities within 6 h after RAN administration. LPS/RAN cotreatment resulted in midzonal liver lesions characterized by acute necrosuppurative hepatitis. Famotidine (FAM) is an H2-antagonist for which the propensity for idiosyncratic reactions is far less than RAN. Rats given LPS and FAM at a dose pharmacologically equipotent to that of RAN did not develop liver injury. In vitro, RAN sensitized hepatocytes to killing by cytotoxic products from activated neutrophils, whereas FAM lacked this ability. The results indicate that a response resembling human RAN idiosyncrasy can be reproduced in animals by RAN exposure during modest inflammation.

Cimetidine prevents suppression of delayed hypersensitivity in an animal model of haemorrhagic shock

BACKGROUND

Cimetidine reverses immunosuppression following trauma, however, its effect on pure haemorrhagic shock is unknown.

METHODS

Mice sensitized by injection of sheep red blood cells (SRBCs), were subjected to cardiac puncture and randomized to a control group-A (n=11) and three shock groups (35% of blood volume extracted): group-S had no treatment (n=16), group-CP received cimetidine 50mg/kg intraperitoneally (n=16), group-CW received oral cimetidine (200mg/kg per day, n=16). After 5 days, animals were challenged by injection of SRBCs into the foot-pad of the right hind paw (same volume of saline was injected into left paw). Foot-pad thickness ratios (FPTRs) were determined at 16 and 40 h, and inflammatory response was assessed histologically.

RESULTS

At 16 h, FPTRs were greater in group-CW than group-S (P=0.01). There were no differences at 40 h. More animals in groups-CP and -CW had grade 3/4 inflammation, whilst group-S had the least inflammatory response (NS).

CONCLUSIONS

Cimetidine prevents suppression of delayed hypersensitivity in this model.

Ranitidine-related Stevens-Johnson syndrome in patients with severe liver diseases: a report of two cases

Ranitidine is widely used and well tolerated. Ranitidine-related skin eruption is rare and usually mild. We presented two patients who developed Stevens-Johnson syndrome after ranitidine therapy. Before therapy, both patients had severe liver disease and jaundice. The first was a case of ketoconazole-induced hepatitis, and the second was a case of hepatitis C-related liver cirrhosis with hepatocellular carcinoma. Ranitidine was the most likely drug responsible for causing Stevens-Johnson syndrome in these two patients.

Nephrotoxicity and hepatotoxicity of histamine H2 receptor antagonists

The extensive use of selective histamine H2 receptor antagonists provides a unique opportunity to describe very rare adverse drug reactions. Although mild elevation of serum creatinine level following the administration of cimetidine is relatively common, acute interstitial nephritis (AIN) is a rare hypersensitivity reaction. There have been 25 published reports of AIN associated with H2 antagonist therapy and we also identified 16 cases from the Australian Adverse Drug Reaction Advisory Committee (ADRAC) database. AIN was reported most commonly following cimetidine administration. AIN was supported by renal biopsy in 28 patients and by rechallenge in 6. H2 antagonist-induced AIN was more commonly reported in men older than 50 years. In the majority of cases the onset was within 2 weeks of initiation of therapy (1 day to 11 months). The clinical manifestations were nonspecific including sterile pyuria, elevated erythrocyte sedimentation rate, fatigue, proteinuria and leucocytosis whereas rash, arthralgia and flank pain were rarely reported. There were 170 cases of hepatotoxicity following H2 antagonist administration reported to ADRAC. These were more common following ranitidine and included cholestatic, hepatocellular and mixed reactions. Hepatotoxicity was proven following liver biopsy in several cases published in the literature and in 15 cases reported to ADRAC. Hepatotoxicity recurred upon rechallenge in 6 cases. Generally, renal and hepatic adverse effects resolved quickly after cessation of H2 antagonist therapy and did not require specific treatment. Nephrotoxicity and hepatotoxicity following administration of an H2 antagonist is rare and a high index of suspicion is necessary for early detection. Now that many H2 antagonists are available over the counter, awareness of these conditions and early detection with cessation of H2 antagonist therapy would appear paramount.

Effects of liver disease on pharmacokinetics. An update

Liver disease can modify the kinetics of drugs biotransformed by the liver. This review updates recent developments in this field, with particular emphasis on cytochrome P450 (CYP). CYP is a rapidly expanding area in clinical pharmacology. The information currently available on specific isoforms involved in drug metabolism has increased tremendously over the latest years, but knowledge remains incomplete. Studies on the effects of liver disease on specific isoenzymes of CYP have shown that some isoforms are more susceptible than others to liver disease. A detailed knowledge of the particular isoenzyme involved in the metabolism of a drug and the impact of liver disease on that enzyme can provide a rational basis for dosage adjustment in patients with hepatic impairment. The capacity of the liver to metabolise drugs depends on hepatic blood flow and liver enzyme activity, both of which can be affected by liver disease. In addition, liver failure can influence the binding of a drug to plasma proteins. These changes can occur alone or in combination; when they coexist their effect on drug kinetics is synergistic, not simply additive. The kinetics of drugs with a low hepatic extraction are sensitive to hepatic failure rather than to liver blood flow changes, but drugs having a significant first-pass effect are sensitive to alterations in hepatic blood flow. The drugs examined in this review are: cardiovascular agents (angiotensin converting enzyme inhibitors, angiotensin II receptor antagonists, calcium antagonists, ketanserin, antiarrhythmics and hypolipidaemics), diuretics (torasemide), psychoactive and anticonvulsant agents (benzodiazepines, flumazenil, antidepressants and tiagabine), antiemetics (metoclopramide and serotonin antagonists), antiulcers (acid pump inhibitors), anti-infectives and antiretroviral agents (grepafloxacin, ornidazole, pefloxacin, stavudine and zidovudine), immunosuppressants (cyclosporin and tacrolimus), naltrexone, tolcapone and toremifene. According to the available data, the kinetics of many drugs are altered by liver disease to an extent that requires dosage adjustment; the problem is to quantify the required changes. Obviously, this requires the evaluation of the degree of hepatic impairment. At present there is no satisfactory test that gives a quantitative measure of liver function and its impairment. A critical evaluation of these methods is provided. Guidelines providing a rational basis for dosage adjustment are illustrated. Finally, it is important to consider that liver disease not only affects pharmacokinetics but also pharmacodynamics. This review also examines drugs with altered pharmacodynamics.

Hepatotoxicity possibly caused by amphotericin B

OBJECTIVE

To report a case of possible amphotericin B-induced hepatotoxicity in a patient with pulmonary blastomycosis.

SUMMARY

A 26-year-old white man with life-threatening pulmonary blastomycosis developed elevation of his liver enzymes after the addition of amphotericin B to his initial itraconazole therapy. The hepatotoxicity resolved rapidly with discontinuation of the amphotericin B, and the blastomycosis was successfully treated with itraconazole alone.

DISCUSSION

This case illustrates an unusual occurrence of hepatotoxicity associated with a short course of amphotericin B. Liver biopsy was compatible with drug-induced changes and showed no evidence of blastomycosis. Discontinuation of amphotericin B with no other therapeutic changes resulted in a rapid resolution of hepatotoxicity. A possible adverse drug interaction with itraconazole and amphotericin B is postulated based on the mechanism of action of each drug.

CONCLUSIONS

Amphotericin B therapy can be associated with many adverse effects, but reports of hepatotoxicity are rare. Closer monitoring of liver enzymes in patients receiving amphotericin B, especially in combination with potentially hepatotoxic agents, including azole antifungal drugs, would be prudent.

On-demand treatment of gastro-oesophageal reflux symptoms: a comparison of ranitidine 75 mg with cimetidine 200 mg or placebo

AIM

To compare the effects of ranitidine 75 mg with those of either cimetidine 200 mg or placebo given on demand for relief of typical symptoms of gastro-oesophageal reflux disease during a 15-day period.

METHODS

A total of 1336 patients (aged > or = 18 years) with heartburn episodes were recruited and randomly assigned to a ranitidine 75 mg, cimetidine 200 mg or placebo group. Depending on the occurrence or persistence of heartburn, treatment was administered as required up to three times daily, with at least 2 h between drug doses. Antacids were allowed as rescue medication if symptoms persisted for at least 2 h after the third medication on any given day. The primary end-point was defined as the proportion of patients with relief of at least 75% of heartburn episodes during the study period (i.e. relief occurring within 2 h after drug ingestion and lasting for at least 5 h).

RESULTS

Analysis was performed in an intention-to-treat population comprising 504 subjects in the ranitidine group, 515 in the cimetidine group and 270 in the placebo group. Primary end-point success rates were 41, 38 and 28%, respectively, for the three groups (P < 0.001 for ranitidine vs. placebo, P = 0.274 for ranitidine vs. cimetidine). Ranitidine 75 mg was significantly more effective than placebo in providing overall heartburn relief (P < 0.001). The differences between the ranitidine and cimetidine groups were not significant, except for a greater reduction in heartburn frequency in the ranitidine group at the end of the study period (P < 0.05). Drug dose was lower and less rescue medication was used in the ranitidine group than the placebo group. The three treatment groups did not differ in terms of tolerability.

CONCLUSION

On-demand ranitidine 75 mg or cimetidine 200 mg are safe and effective treatment for reflux-related symptoms.

A prospective study of omeprazole suspension to prevent clinically significant gastrointestinal bleeding from stress ulcers in mechanically ventilated trauma patients

OBJECTIVE

To prospectively evaluate the incidence of clinically significant bleeding, side effects, and cost of therapy in mechanically ventilated trauma patients at high risk for stress ulcers who received simplified omeprazole suspension (SOS).

METHODS

Prospective, evaluative study in a Level I trauma center. Mechanically ventilated trauma patients admitted with at least one additional risk factor for stress ulcer development received SOS for stress ulcer prophylaxis.

RESULTS

Sixty trauma patients were enrolled. The mean Injury Severity Score was 27.3. After starting SOS, there were no cases of clinically significant upper gastrointestinal bleeding related to stress ulceration. Baseline pH was 3.3, and mean gastric pH after SOS was increased to 6.7 (p < 0.005). There were no adverse effects thought to be related to omeprazole suspension. Incidence of nosocomial pneumonia after beginning SOS was 28.3%. The cost of acquisition plus administration of SOS was $13.13 per day, whereas the cost of drug acquisition alone was $3.83 per day.

CONCLUSION

In a prospective, evaluative study of 60 trauma patients who required mechanical ventilation and had at least one additional risk factor for stress ulcer development, omeprazole suspension prevented clinically significant gastrointestinal bleeding, maintained excellent control of gastric pH, produced no toxicity, and was the least costly medication alternative.

Ranitidine does not affect psoriasis: a multicenter, double-blind, placebo-controlled study

BACKGROUND

Data from open studies suggest that ranitidine has a beneficial effect on psoriasis and is well tolerated.

OBJECTIVE

Our purpose was to determine the effectiveness of ranitidine in a 24-week, multicenter, double-blind, placebo-controlled, dose-comparing study of 201 patients with psoriasis.

METHODS

Patients with moderate to severe psoriasis who had stopped systemic antipsoriatic therapy, including PUVA and UVB, for at least 10 weeks were included. After a washout period of 2 weeks, patients were randomly allocated to use either ranitidine, 150 mg twice a day; ranitidine, 300 mg twice a day; or placebo for up to 24 weeks. Assessment with the Psoriasis Area and Severity Index was performed at weeks 3, 6, 9, 12, 18, and 24 after randomization. Reduction of the Psoriasis Area and Severity Index score by 70% at the completion of the study was considered a treatment success.

RESULTS

The success rates at week 24 in the 300 mg, 600 mg, and placebo groups were 11%, 5%, and 12%, respectively. No significant differences were observed between the three treatment groups at any stage of the study.

CONCLUSION

This study provides strong evidence that ranitidine does not affect the skin disease in patients with psoriasis.

Policy analysis of the conversion of histamine2 antagonists to over-the-counter use

OBJECTIVES

The authors assess the costs associated with treatment of dyspepsia with histamine2 antagonists versus without availability of over-the-counter (OTC).

METHODS

A cost analysis was performed using a decision-analysis model. Patients with an initial episode of dyspepsia were studied. The model includes costs associated with consumption of OTC and prescription (Rx) medications for dyspepsia, physician visits and associated diagnostic testing, time spent for physician visits and diagnostic tests, and hospitalization costs.

RESULTS

The model is sensitive to the relative cost of histamine2 antagonists when purchased Rx or OTC, as well as to the efficacy of these drugs in relieving dyspeptic symptoms. For patients with nonulcer dyspepsia (the largest group of likely consumers), the model demonstrates a cost savings if the OTC cost of the medication is slightly less than one third the Rx cost. Costs are similar whether or not histamine2 antagonists are available OTC. If the symptom relief efficacies of histamine2 antagonists are equivalent whether purchased by prescription only or OTC, then the health-care expenditures for a typical patient with dyspepsia are $204 for OTC availability and $203 for Rx-only use. Viewing costs from the perspective of a managed-care organization, expenditures for an episode of dyspepsia are $149 regardless of whether or not histamine2 antagonists are available OTC. Restricting the analysis to patients with underlying nonulcer dyspepsia yields similar results. Variation of numerous assumptions and probabilities other than histamine antagonist cost and efficacy, including costs associated with physician visits and diagnostic tests, and the likelihood of seeking medical care, do not substantially affect the results of the model.

CONCLUSIONS

Health-care costs associated with initial treatment of dyspepsia are similar regardless of the availability of histamine2 antagonists OTC. This is due largely to the similar efficacy of these drugs compared with antacids and the predicted increase in diagnostic testing that may result if a patient visits a physician after failure to achieve symptom relief with OTC use of histamine2 antagonists.

A prospective study of simplified omeprazole suspension for the prophylaxis of stress-related mucosal damage

OBJECTIVES

To determine the efficacy, safety, and cost of simplified omeprazole suspension in mechanically ventilated critically ill patients who have at least one additional risk factor for stress-related mucosal damage.

DESIGN

Prospective, open-label study.

SETTING

Surgical intensive care and burn unit at a university tertiary care center.

PATIENTS

Seventy-five adult, mechanically ventilated patients with at least one additional risk factor for stress-related mucosal damage.

INTERVENTIONS

Patients received 20 mL of simplified omeprazole suspension (containing 40 mg of omeprazole) initially, followed by a second 20-mL dose 6 to 8 hrs later, then 10 mL (20 mg) daily. Simplified omeprazole suspension was administered through a nasogastric tube, followed by 5 to 10 mL of tap water. The nasogastric tube was clamped for 1 to 2 hrs after each administration.

MEASUREMENTS AND MAIN RESULTS

The primary outcome measure was clinically significant gastrointestinal bleeding determined by endoscopic evaluation, nasogastric aspirate examination, or heme-positive coffee ground material that did not clear with lavage, which was associated with at least a 5% decrease in hematocrit. Secondary efficacy measures were gastric pH measured 4 hrs after omeprazole was first administered, mean gastric pH after omeprazole was started, and the lowest gastric pH during omeprazole therapy. Safety-related outcomes included the occurrence rate of adverse events and pneumonia. No patient experienced clinically significant upper gastrointestinal bleeding after receiving omeprazole suspension. The 4-hr postomeprazole mean gastric pH was 7.1, the mean gastric pH after starting omeprazole was 6.8, and the mean lowest pH after starting omeprazole was 5.6. The occurrence rate of pneumonia was 12%. No patient in this high-risk population experienced an adverse event or a drug interaction that was attributable to omeprazole.

CONCLUSIONS

Simplified omeprazole suspension prevented clinically significant upper gastrointestinal bleeding and maintained gastric pH of > 5.5 in mechanically ventilated critical care patients without producing toxicity.

Gastric and extragastric actions of the histamine antagonist ranitidine during posttraumatic sepsis

BACKGROUND

Histamine H2 antagonists (e.g., ranitidine) are generally thought to specifically reduce gastric acid secretion and are commonly used for stress ulcer prophylaxis in critically ill patients because of their efficacy and safety profile. A few reports suggest that ranitidine might also bind to extragastric sites and/or act as an immunomodulator. The potential effects on posttraumatic sepsis are unknown.

METHODS

Mongrel pigs (n = 24) were anesthetized with fentanyl, injured by a 10 kg steel bar dropped from a height of 1 m onto the fleshy portion of the posterior thigh, and then 35% of their blood volume was drained through the arterial catheter. All the shed blood plus two times the hemorrhage volume as lactated Ringer's solution was infused after a 1-hour shock period. Either vehicle or ranitidine (1.5 mg/kg) was intravenously administered at the time of resuscitation and every 12 hours thereafter in a blinded fashion. After 72 hours a septic challenge was administered (15 micrograms/kg Escherichia coli lipopolysaccharide [LPS] x 30 min). Serial gastroscopy, gastric pH, hemodynamics, leukocyte counts, cortisol, and tumor necrosis factor were recorded for 180 minutes after LPS.

RESULTS

Immediately before LPS all hemodynamic variables were identical between treatments, but gastric pH was slightly higher and stress gastritis was marginally lower with ranitidine. LPS caused profound leukopenia and a hyperdynamic circulatory response (i.e., tachycardia, increased cardiac output, and decreased peripheral vascular resistance at relatively constant blood pressure); these changes were not altered by ranitidine. Gastric pH remained elevated after LPS with ranitidine, but LPS-induced gastritis was not modified. Ranitidine delayed the LPS-induced ventilation-perfusion imbalance and attenuated the peak increase in the proinflammatory cytokine, tumor necrosis factor, without altering its antiinflammatory opponent, cortisol. Similar changes were observed in four additional animals treated with cimetidine. The proportion of circulating neutrophils and lymphocytes was slightly altered 180 minutes after LPS, but there was no obvious effect on T lymphocytes in vivo, and no effect on the LPS-induced increase in neutrophil CD18 expression in vitro was seen.

CONCLUSIONS

(1) Ranitidine increased gastric pH, which blunted the stress gastritis caused by trauma but not that caused by LPS; (2) ranitidine delayed the early LPS-evoked pulmonary changes and reduced the tumor necrosis factor spike, which is consistent with a favorable immunomodulatory action that has been reported in patients who are critically ill or are undergoing an elective abdominal surgical procedure; (3) the mechanism is probably related to H2 receptor antagonism rather than to a nonspecific side effect of ranitidine, which suggests that histamine may have a previously unrecognized role in posttraumatic septic responses; and (4) the site of action is probably not in the heart or peripheral resistance vessels, but salutary effects on circulating lymphocytes or neutrophils cannot be excluded.

Ranitidine-induced bradycardia in a neonate--a first report

Bradycardia, an extremely rare side-effect of ranitidine therapy is described in a 4-day-old full-term male neonate, who was admitted because of massive gastro-intestinal bleeding. Two hours after the intravenous injection of 1 mg/kg body weight per day, ECG showed sinus bradycardia of 60 beats/min with normal axis and QRS complex. The bradycardia gradually resolved in the next 24 h.