Current trends in the treatment of upper gastrointestinal disease

Demographic factors associated with dietary supplement prescriptions filled by United States Military Service Members 2005-2013

BACKGROUND

Dietary supplements (DSs) can be purchased over-the-counter but may also be prescribed by medical personnel for specific therapeutic reasons. Few studies have examined this latter source of DSs despite the fact that 79% of physicians and 82% of nurses have recommended DSs to their patients. This investigation examined demographic factors associated with temporal trends in oral DS prescriptions filled by all United States (US) service members (SMs) from 2005 to 2013 (n = 1,427,080 ± 22,139, mean ± standard deviation per year).

METHODS

The Food and Drug Administration National Drug Code database and the formularies of the US Defense Health Agency's Pharmacoeconomic Center were queried to identify DSs available to SMs. The number of these DS prescriptions filled by all SMs from 2005 through 2013 was then obtained from the US Department of Defense Pharmacy Data Transaction System. Data were grouped by American Hospital Formulary System (AHFS) pharmacologic-therapeutic classifications and examined over time. Denominators (number of SMs each year) were obtained from the Defense Health Agency.

RESULTS

Major findings included 1) generally greater prevalence of prescriptions filled by women and older SMs for most AHFS categories; 2) a temporal decline in total prescriptions filled by Marine Corps personnel accounted for by a decline in the prevalence of zinc preparations filled by younger male Marines; 3) a temporal decline in the prevalence of iron preparations filled by women; 4) a temporal increase in the prevalence of prescriptions for replacement preparations filled by women accounted for largely by more prescriptions for calcium compounds; and 5) a temporal decline in the prevalence of prescriptions filled for cathartics/laxatives in older SMs accounted for largely by a decline in prescriptions for sodium/potassium compounds.

CONCLUSIONS

These temporal trends may be associated with the greater health care utilization of women and older SMs as well as the perceptions of prescribers and/or patients on appropriate roles of these substances in medicine and public health.

Temporal trends in dietary supplement prescriptions of United States military service members suggest a decrease in pyridoxine and increase in vitamin D supplements from 2005 to 2013

Dietary supplements (DSs) can be obtained over-the-counter but can also be prescribed by health-care providers for therapeutic reasons. Few studies have documented this later source despite the fact that 79% of physicians and 82% of nurses have recommended DSs to patients. This investigation assessed prevalence and temporal trends in oral DS prescriptions filled by all United States service members (SMs) from 2005 to 2013 (n = 1 427 080 ± 22 139, mean ± standard deviation (SD)/y). We hypothesize that there would be temporal variations in specific types of DSs. Data obtained from Department of Defense Pharmacy Data Transaction System were grouped by American Hospital Formulary System pharmacologic-therapeutic classifications and prevalence examined over time. About 11% of SMs filled one or more DS prescriptions of 235 180 ± 4926 (mean ± SD) prescriptions/y over the 9-year period. Curve-fitting techniques indicated significant linear declines over time for multivitamins (P = .004), iron preparations (P < .001), antacids (P < .001), and vitamin B and B complex vitamins (P < .001). There were significant quadratic trends indicating a rise in early years followed by a leveling off in later years for replacement preparations (P < .001) and vitamin C (P < .001). There were significant quadratic trends (P < .001) for vitamin E indicating a decline in early years and leveling off in later years, and vitamin D indicating little change in early years followed by a large rise subsequently (P < .001). This study identified temporal trends in specific DS categories that may be associated with changing perceptions of prescribers and/or patients of the appropriate roles of DSs in medicine and public health.

Antiulcer, wound healing and hepatoprotective activities of the seaweeds Gracilaria crassa, Turbinaria ornata and Laurencia papillosa from the southeast coast of India

Seaweeds have bioactive compounds of interest in the pharmaceutical industry. In India, seaweeds are used exclusively for phycocolloids production and have not yet received consideration as a dietary supplement. So, it has become imperative to explore the biomedical potential of seaweeds and promote their utilization as a functional food. The seaweeds Turbinaria ornata, Gracillaria crassa and Laurencia papillosa, collected from the Tuticorin coast of the Southeast coast of India and selected based on preliminary screening, were extracted with acetone and evaluated for antiulcer, wound healing and hepatoprotective activities. L. papillosa showed the highest level of gastric protection activity (81%) at 200 mg/kg, comparable to the standard drug ranitidine (90%). G. crassa followed with 76%. G. crassa and L. papillosa, showed marked wound-healing activity. G. crassa at 200 mg/kg, showed a marked effect on the serum marker enzymes indicating prominent hepatoprotective activity. The noteworthy wound-healing and hepato-protective properties of G. crassa besides anti-ulcer activity next to L. papillosa were indicative of its potential for further consideration.

PREDICTING EFFICACY OF PROTON PUMP INHIBITORS IN REGULATING GASTRIC ACID SECRETION

Developing drugs to treat gastric acid related illnesses such as ulcers and acid reflux disease is the leading focus of pharmaceutical companies. In fact, expenditure for treating these disorders is highest among all illnesses in the US. Over the last few decades, a class of drugs known as a proton pump inhibitors (PPIs) appeared on the market and are highly effective at abating gastric illnesses by raising stomach pH (reducing gastric acid levels). While much is known about the action of PPIs , there are still open questions regarding their efficacy, dosing and long-term effects. Here we extend a previous gastric acid secretion model developed by our group to incorporate a pharmacodynamic/pharmacokinetic model to study proton pump inhibitor (PPI) action. Model-relevant parameters for specific drugs such as omeprazole (OPZ) , lansoprazole (LPZ) and pantoprazole (PPZ) were used from published data, and we conducted simulations to study various aspects of PPI treatment. Clinical data suggests that duration of acid suppression is dependent on proton pump turnover rates and this is supported by our model. We found the order of efficacy of the different PPIs to be OPZ>PPZ>LPZ for clinically recommended dose values, and OPZ>PPZ=LPZ for equal doses. Our results indicate that a breakfast dose for once-daily dosing regimens and a breakfast-lunch dose for twice-daily dosing regimens is recommended. Simulation of other gastric disorders using our model provides atypical applications for the study of drug treatment on homeostatic systems and identification of potential side-effects.

Roles of phosphorylation-dependent and -independent mechanisms in the regulation of histamine H2 receptor by G protein-coupled receptor kinase 2

It is widely assumed that G protein-coupled receptor kinase 2 (GRK2)-mediated specific inhibition of G protein-coupled receptors (GPCRs) response involves GRK-mediated receptor phosphorylation followed by β-arrestin binding and subsequent uncoupling from the heterotrimeric G protein. It has recently become evident that GRK2-mediated GPCRs regulation also involves phosphorylation-independent mechanisms. In the present study we investigated whether the histamine H2 receptor (H2R), a Gα(s)-coupled GPCR known to be desensitized by GRK2, needs to be phosphorylated for its desensitization and/or internalization and resensitization. For this purpose we evaluated the effect of the phosphorylating-deficient GRK2K220R mutant on H2R signaling in U937, COS7, and HEK293T cells. We found that although this mutant functioned as dominant negative concerning receptor internalization and resensitization, it desensitized H2R signaling in the same degree as the GRK2 wild type. To identify the domains responsible for the kinase-independent receptor desensitization, we co-transfected the receptor with constructions encoding the GRK2 RGS-homology domain (RH) and the RH or the kinase domain fused to the pleckstrin-homology domain. Results demonstrated that the RH domain of GRK2 was sufficient to desensitize the H2R. Moreover, disruption of RGS functions by the use of GRK2D110A/K220R double mutant, although coimmunoprecipitating with the H2R, reversed GRK2K220R-mediated H2R desensitization. Overall, these results indicate that GRK2 induces desensitization of H2R through a phosphorylation-independent and RGS-dependent mechanism and extends the GRK2 RH domain-mediated regulation of GPCRs beyond Gα(q)-coupled receptors. On the other hand, GRK2 kinase activity proved to be necessary for receptor internalization and the resulting resensitization.

Histamine H2 receptor trafficking: role of arrestin, dynamin, and clathrin in histamine H2 receptor internalization

Agonist-induced internalization of G protein-coupled receptors (GPCRs) has been implicated in receptor desensitization, resensitization, and down-regulation. In the present study, we sought to establish whether the histamine H2 receptor (H2r) agonist amthamine, besides promoting receptor desensitization, induced H2r internalization. We further studied the mechanisms involved and its potential role in receptor resensitization. In COS7 transfected cells, amthamine induced H2r time-dependent internalization, showing 70% of receptor endocytosis after 60-min exposure to amthamine. Agonist removal led to the rapid recovery of resensitized receptors to the cell surface. Similar results were obtained in the presence of cycloheximide, an inhibitor of protein synthesis. Treatment with okadaic acid, an inhibitor of the protein phosphatase 2A (PP2A) family of phosphatases, reduced the recovery of both H2r membrane sites and cAMP response. Arrestin 3 but not arrestin 2 overexpression reduced both H2r membrane sites and H2r-evoked cAMP response. Receptor cotransfection with dominant-negative mutants for arrestin, dynamin, Eps15 (a component of the clathrin-mediated endocytosis machinery), or RNA interference against arrestin 3 abolished both H2r internalization and resensitization. Similar results were obtained in U937 cells endogenously expressing H2r. Our findings suggest that amthamine-induced H2r internalization is crucial for H2r resensitization, processes independent of H2r de novo synthesis but dependent on PP2A-mediated dephosphorylation. Although we do not provide direct evidence for H2r interaction with beta-arrestin, dynamin, and/or clathrin, our results support their involvement in H2r endocytosis. The rapid receptor recycling to the cell surface and the specific involvement of arrestin 3 in receptor internalization further suggest that the H2r belongs to class A GPCRs.

Upper gastrointestinal bleeding in patients with acute coronary syndromes: clinical predictors and prophylactic role of proton pump inhibitors

OBJECTIVES

To determine the risk and the clinical predictors of in-hospital upper gastrointestinal (UGI) bleeding in patients with acute coronary syndromes (ACS), and to study the prophylactic role of proton pump inhibitors (PPI) in this setting.

BACKGROUND

Patients with ACS are usually treated by a combination of antiplatelet, antithrombotic and thrombolytic medications, thereby increasing the risk of bleeding.

STUDY

A retrospective study of 1023 patients hospitalized with ACS at the American University of Beirut Medical Center from September 2001 to November 2005. The main outcome measurements were the incidence of in-hospital UGI bleeding and its predictors; the utilization rate of PPI and its determinants.

RESULTS

Seven patients developed in-hospital UGI bleeding (0.7%) and 2 had major bleeding (0.2%). All required blood transfusion and none died in the hospital. Significant predictors of UGI bleeding were prior history of UGI bleeding or peptic ulcer disease (P<0.01), creatinine > 2 mg/dL (P=0.01), and home intake of aspirin, clopidogrel (P<0.05), or nonsteroidal anti-inflammatory drugs (P<0.05). Sixty-nine percent of patients received PPI during their hospital stay. There was no significant difference in the incidence of UGI bleeding between patients receiving and those not receiving PPI (0.7% vs. 0.6%, P= 0.88).

CONCLUSIONS

The risk of UGI bleeding is relatively low in patients hospitalized with ACS and does not appear to be significantly reduced by the use of PPI. The utilization rate of PPI was relatively high. Better patient selection and risk stratification for the prophylactic use of PPI are warranted.

Systematic expression profiling of the gastric H+/K+ ATPase in human tissue

OBJECTIVE

The potassium-competitive acid blockers (P-CABs), comprise a new, innovative group of competitive and reversible inhibitors of the gastric H+/K+ ATPase. Our aim was to identify sites of expression of the H+/K+ ATPase that are potential targets of these compounds by examining the expression profile of the gastric H+/K+ ATPase in the human body from a broad range of tissues.

MATERIAL AND METHODS

Expression profiling was done by quantitative mRNA analysis (TaqMan PCR). Tissues that were mRNA-positive for the alpha subunit were investigated further by Western blot and immunohistochemistry (IHC) for the presence of gastric H+/K+ ATPase protein.

RESULTS

In addition to the very high expression levels in the stomach, the adrenal gland, cerebellum and pancreas gave unexpectedly positive mRNA signals for the alpha subunit of gastric H +/K+ ATPase. However, they were negative for mRNA of the beta subunit, and Western blot and IHC were negative for alpha and beta subunit protein. Another group of tissues with low alpha subunit mRNA expression including the frontal cortex, cortex grey matter, testis, thymus and larynx submucosa were also found negative for both alpha and beta subunit protein. In contrast to mouse kidney, no gastric H+/K+ ATPase could be detected in human kidney.

CONCLUSIONS

We therefore conclude that the only organ in humans expressing significant levels of the P-CAB target gastric H+/K+ ATPase is the stomach.

Soraprazan: setting new standards in inhibition of gastric acid secretion

After treatment of millions of patients suffering from gastroesophageal reflux disease (GERD) and other acid-related ailments with proton pump inhibitors, there are still unmet medical needs such as rapid and reliable pain relief, especially for nocturnal acid breakthrough. In this work, we introduce and characterize the biochemistry and pharmacology of the potassium-competitive acid blocker (P-CAB) soraprazan, a novel, reversible, and fast-acting inhibitor of gastric H,K-ATPase. Inhibitory and binding properties of soraprazan were analyzed together with its mode of action, its selectivity, and its in vivo potency. This P-CAB has an IC(50) of 0.1 microM if measured with ion leaky vesicles and of 0.19 microM in isolated gastric glands. With a K(i) of 6.4 nM, a K(d) of 26.4 nM, and a B(max) of 2.89 nmol/mg, this compound is a highly potent and reversible inhibitor of the H,K-ATPase. Soraprazan shows immediate inhibition of acid secretion in various in vitro models and in vivo and was found to be more than 2000-fold selective for H,K-ATPase over Na,K- and Ca-ATPases. Soraprazan is superior to esomeprazole in terms of onset of action and the extent and duration of pH elevation in vivo in the dog. Rapid and consistent inhibition of acid secretion by soraprazan renders the P-CABs a promising group of compounds for therapy of GERD.

Advances in gastrointestinal pharmacotherapy

The medical management of patients with gastrointestinal diseases is advancing rapidly. At a recent symposium held during Digestive Disease Week in Chicago in May of 2005, specific attention was given to the future prospects for medical management of 3 common gastrointestinal disease areas: antisecretory therapy, chronic hepatitis C, and inflammatory bowel disease. Antisecretory approaches include drug combinations including a proton pump inhibitor, potassium competitive acid blockers, and antigastrin agents. The latter two classes are still experimental, but the former combinations have potential to enhance the highly effective agents currently available. The focus of treatment advances in chronic hepatitis C in the immediate future is the discovery of more effective treatment regimens for nonresponders to prior therapy, who are becoming the largest group of patients seeking treatment of hepatitis C. The combination of peginterferon with ribavirin results in 6%-15% sustained virologic response rates in patients who were prior nonresponders to standard interferon plus ribavirin. Newer strategies to eradicate hepatitis C virus infection using different interferons, such as interferon alfacon-1 or higher doses of peginterferon, or long-term maintenance peginterferon, are undergoing study and show promise based on data from preliminary studies. Several immunomodulators have promise in inflammatory bowel disease, although the risk-benefit ratio and costs of therapy require evaluation. Nevertheless, the success of new biologics such as anti-TNFalpha agents augurs well for effective future therapies.

Effect of different organic acids (citric, malic and ascorbic) on intragastric urease activity

BACKGROUND

The mechanism of citric acid-enhanced Helicobacter pylori urease activity remains unclear.

AIM

To compare ascorbic, citric and malic acid given at the same concentration and pH on intragastric urease activity.

METHODS

Volunteers received 40 mg of famotidine the evening prior to breath testing. After an overnight fast volunteers were randomized to receive 100 mL of water or 100 mm citric, malic, or ascorbic acid, pH 2.3 containing 75 mg of 13C-urea. At 15 min a second 100 mL solution of one of the test solutions was taken without added urea.

RESULTS

Twelve volunteers were studied (eight men, four women, age 19-57, median 50.7) in a randomized-crossover study. The mean breath test result at 30 min with ascorbic (17.5 +/- 5), malic (25.8 +/- 5) and citric acid (29.5 +/- 5) were all significantly greater than with water (9.5 +/- 3). Citric and malic acid were similar (P = 0.699) and significantly greater than ascorbic acid (P < 0.02). When the ascorbic acid was followed by citric acid, the result was similar to that with citrate alone (25.8 +/- 4) and greater than with ascorbic then ascorbic (P = 0.026).

CONCLUSIONS

Enhancement of H. pylori urease activity is not strictly a function of the pH. We propose the effect is related to differential effects of the availability of nickel, which is required for urease activity. Citric acid and malic acid were essentially equivalent such that malic acid could substitute for citric acid in the UBT; ascorbic acid would be a poor choice.

H. pylori infection: bacterial virulence factors and cytokine gene polymorphisms as determinants of infection outcome

The gram negative bacterium H. pylori infects the human stomach worldwide, invariably causing mucosal inflammation. In the majority of cases, H. pylori-associated gastritis remains the only clinical manifestation of the infection, which might cause, otherwise, peptic ulcer, gastric adenocarcinoma. or MALToma. The balance between the bacterial virulence machinery and the host response to the infection determines the different clinical outcomes. The main bacterial virulence factors comprise adhesins (BabA, SabA), the vacuolating cytotoxin VacA, and the products of cag pathogenicity island. The pattern of cytokine production in response to the infection is one of the main host determinants involved in limiting the infection outcome to gastritis or in favoring peptic ulcer or cancer onset. The polymorphisms of some cytokine genes (IL-1beta IL-1RN, TNF-alpha, IFN-gamma) have been correlated with H. pylori-associated gastric adenocarcinoma or peptic ulcer, possibly because they influence the amount of cytokine production in response to H. pylori infection. This review focuses on the role of H. pylori virulence genes and on host cytokines' genes polymorphisms in determining clinical outcome to H. pylori infection.

Review article: new pharmacological agents for the treatment of gastro-oesophageal reflux disease

Proton pump inhibitors, which act at the terminal point of acid secretion--the H+, K+-ATPase--are currently the most effective pharmacological treatments available for reflux disease. Despite the efficacy of the proton pump inhibitors, there is still potential for clinical improvement in gastro-oesophageal reflux disease pharmacotherapy. Faster onset of complete acid inhibition and improved duration of efficacy are two potential areas for improvement A number of novel pharmaceutical agents are currently undergoing clinical evaluation for the treatment of gastro-oesophageal reflux disease. These include transient lower oesophageal sphincter relaxation-reducing agents, serotonergic agents/prokinetics, potassium-competitive acid blockers, mucosal protectants, histamine H3 agonists and anti-gastrin agents. One or more of these drug groups may represent the future medical therapy for gastro-oesophageal reflux disease, should they prove effective in the clinical setting. This review summarizes the state of the art with these agents.

False negative urea breath tests with H2-receptor antagonists: interactions between Helicobacter pylori density and pH

BACKGROUND

We studied the effects of famotidine, sodium bicarbonate, and citric acid on the 13C-urea breath test (UBT).

METHODS

Helicobacter pylori-infected volunteers received a UBT, 40 mg of famotidine at bedtime, and a second UBT (pudding test meal, 648 mg NaHCO3 tablet then 125 mg of urea in 200 ml of water containing 650 mg of NaHCO3). Experiment 2 consisted of four UBTs. Two were standard citric acid UBTs with 75 mg of urea and 2 g citric acid and two were sequential bicarbonate-citric acid UBTs. Sequential UBTs consisted of administration of a 648 mg bicarbonate tablet with 50 g of Polycose in 200 ml of water. Five minutes later, 125 mg of 13C-urea was given in 75 ml of water containing 650 mg of NaHCO3. Breath samples were collected after 15 minutes. Then, to acutely acidify the stomach, 4 g of citric acid was given in 200 ml of water. A second breath sample was collected 15 minutes after the citric acid. The standard UBTs were done before and after 6 days of famotidine (40 mg b.i.d.). Sequential UBTs were done after 1 and 6 days of famotidine therapy. Gastric biopsies for histology, culture, and mucosal cytokines were assessed before and after 6 days of famotidine.

RESULTS

Eighteen subjects participated, 10 in each experiment; seven had endoscopy with biopsy. Famotidine/ bicarbonate resulted an approximately 50% fall in UBT values (p = .021) with 10% becoming negative. The gastric pH increased from 5.1 +/- 0.5 to 6.7 +/- 0.2 (p = .03) although no pH value predicted the occurrence of false negative results. Under famotidine acid suppression, NaHCO3 reduced the delta over baseline (DOB) by 63% (p = .021). This was reversed with citric acid. Histology showed a H2-receptor antagonist-associated increase in the depth of gastric corpus inflammation.

CONCLUSIONS

H2-receptor antagonists differ from proton pump inhibitors as high intragastric pH may cause a reduction in urease activity, unrelated to a reduced bacterial load and reversed by citric acid.