Racecadotril demonstrates intestinal antisecretory activity in vivo

Efficacy of Racecadotril in a Patient Affected by a Therapy-Refractory VIPoma and Carcinoid Syndrome

Neuroendocrine neoplasms (NENs) encompass a heterogeneous spectrum of tumors originating from the diffuse neuroendocrine cell system. Approximately 30% of NEN exhibit functional activity with clinical syndromes through hormone-mediated effects. Synchronous and metachronous functioning syndromes, resulting from the simultaneous release of distinct hormones, are exceptionally rare. Of note, hormonal excess syndromes can have a greater effect on patients' morbidity and mortality than the tumor mass itself. We present the case of a 49-year-old male patient affected by an oligo-metastatic ileal NEN, concurrently demonstrating vasointestinal peptide (VIP) and serotonin excretion, complicated by pulmonary tuberculosis. After the first cycle of Lutetium-177-DOTATATE peptide-radio-receptor therapy, the patient developed a severe watery diarrhea, hypokalemia, and achlorhydria (WDHA) syndrome, despite receiving high-dose somatostatin analogues, everolimus, and telotristat ethyl, without any surgical options. The WDHA syndrome necessitated intensive-care-unit (ICU) admission with continual intravenous administration of electrolytes and fluids. With limited alternatives, an off-label intervention using the enkephalinase inhibitor racecadotril was initiated. After 5 days of treatment, the WDHA syndrome exhibited sufficient control, facilitating the patient's discharge from the ICU. This case report underscores racecadotril as an individualized, off-label treatment strategy for patients with severe VIPoma and serotonin-driven WDHA syndrome, where conventional therapeutic avenues have been exhausted.

Can diarrhea affect the pharmacokinetics of racecadotril in neonatal calves?

This study was aimed to determine the pharmacokinetics of antisecretory-acting racecadotril, used in the treatment of diarrhea in humans and dogs, following oral administration in both neonatal calves with healthy and neonatal calves with infectious diarrhea. The study was carried out on a total of 24 Holstein calves (2-20 days), of which 6 were healthy and 18 were infectious diarrhea. Calves with infectious diarrhea were divided into 3 groups according to the infectious agent (Escherichia coli, Cryptosporidium parvum, and rotavirus/coronavirus). Racecadotril was administered orally at 2.5 mg/kg dose to calves. The plasma concentrations of racecadotril and its main active metabolite (thiorphan) were determined using HPLC-UV. The pharmacokinetic parameters were analyzed using the non-compartmental method. In healthy calves, the t_1/2ʎz , C_max , T_max, and AUC_0-12 of racecadotril were determined 4.70 h, 377 ng/ml, 0.75 h, and 1674 h × ng/ml, respectively. In the plasma of calves with infectious diarrhea, racecadotril and thiorphan were only detected at the sampling time from 0.25 to 1.5 h. As in calves with infectious diarrhea, thiorphan in plasma was only detected in healthy calves from 0.25 to 1.5 h. Racecadotril showed a large distribution volume, rapid elimination, and low metabolism to thiorphan in healthy calves.

A comprehensive review of therapeutic approaches available for the treatment of cholera

Objectives

The oral rehydration solution is the most efficient method to treat cholera; however, it does not interfere in the action mechanism of the main virulence factor produced by Vibrio cholerae, the cholera toxin (CT), and this disease still stands out as a problem for human health worldwide. This review aimed to describe therapeutic alternatives available in the literature, especially those related to the search for molecules acting upon the physiopathology of cholera.

Key findings

New molecules have offered a protection effect against diarrhoea induced by CT or even by infection from V. cholerae. The receptor regulator cystic fibrosis channel transmembrane (CFTR), monosialoganglioside (GM1), enkephalinase, AMP-activated protein kinase (AMPK), inhibitors of expression of virulence factors and activators of ADP-ribosylarginine hydrolase are the main therapeutic targets studied. Many of these molecules or extracts still present unclear action mechanisms.

Conclusions

Knowing therapeutic alternatives and their molecular mechanisms for the treatment of cholera could guide us to develop a new drug that could be used in combination with the rehydration solution.

Racecadotril for acute diarrhoea in children

BACKGROUND

Acute diarrhoea is a leading cause of death for children under five years of age. Most deaths are caused by excessive fluid and electrolyte losses. Racecadotril is an anti-secretory drug that has been used for acute diarrhoea in children as an adjunct to oral rehydration therapy.

OBJECTIVES

To assess the efficacy and safety of racecadotril for treating acute diarrhoea in children under five years of age.

SEARCH METHODS

We searched the Cochrane Infectious Diseases Group Specialized Register; the Cochrane Central Register of Controlled Trials (CENTRAL, published in the Cochrane Library Issue 3, March 2019); MEDLINE; Embase; LILACS; ClinicalTrials.gov; and the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP), up to 4 March 2019, for clinical trials regardless of publication language or status.

SELECTION CRITERIA

Randomized controlled trials (RCTs) that compared racecadotril to placebo or no intervention in addition to standard care (oral rehydration therapy) in children under five with acute diarrhoea. The primary outcomes were failure of oral rehydration, duration of diarrhoea, and number of stools. The secondary outcomes were stool output, length of the hospital stay, and adverse events.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial eligibility, extracted the data and assessed risk of bias. We presented dichotomous data with risk ratios (RR) and continuous data with mean difference (MD) or standardized mean difference (SMD). Where appropriate, we combined trials with meta-analysis and used a random-effects model if there was significant heterogeneity (I² ≥ 50%). We assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

Seven RCTs with a total of 1140 participants met the inclusion criteria. The trials were carried out on children aged three months to five years, in outpatient and inpatient facilities from France, Spain, Peru, India, Kenya, and Ecuador. The efficacy and safety of racecadotril were compared to placebo or no treatment. Racecadotril may reduce the risk of rehydration failure (RR 0.41, 95% CI 0.13 to 1.23; 2 RCTs, 192 participants; low-certainty evidence). Data on duration of diarrhoea, number of stools in the first 48 hours are insufficient to reach a conclusion; stool output in the first 48 hours appears to be lower in the two trials measuring this, although the data is not combinable. Length of hospital stay was similar in two studies measuring this, and overall there was no evidence that racecadotril increased overall rate of adverse events (RR 0.90, 95% CI 0.66 to 1.22; 5 RCTs, 688 participants; low-certainty evidence). Most adverse events in the racecadotril group were mild or moderate.

AUTHORS' CONCLUSIONS

Racecadotril seems to be a safe drug but has little benefit in improving acute diarrhoea in children under five years of age. Current evidence does not support routine use of racecadotril in management of acute diarrhoea in children under five outside of the context of placebo controlled RCTs. 18 December 2019 Up to date All studies incorporated from most recent search All studies identified during the most recent search (4 Mar, 2019) have been incorporated in the review, and no ongoing studies identified.

Guideline for the Antibiotic Use in Acute Gastroenteritis

Acute gastroenteritis is common infectious disease in community in adults. This work represents an update of 'Clinical guideline for the diagnosis and treatment of gastrointestinal infections' that was developed domestically in 2010. The recommendation of this guideline was developed regarding the following; epidemiological factors, test for diagnosis, the indications of empirical antibiotics, and modification of antibiotics after confirming pathogen. Ultimately, it is expected to decrease antibiotic misuse and prevent antibiotic resistance.

Tackling Pseudomonas aeruginosa Virulence by a Hydroxamic Acid-Based LasB Inhibitor

In search of novel antibiotics to combat the challenging spread of resistant pathogens, bacterial proteases represent promising targets for pathoblocker development. A common motif for protease inhibitors is the hydroxamic acid function, yet this group has often been related to unspecific inhibition of various metalloproteases. In this work, the inhibition of LasB, a harmful zinc metalloprotease secreted by Pseudomonas aeruginosa, through a hydroxamate derivative is described. The present inhibitor was developed based on a recently reported, highly selective thiol scaffold. Using X-ray crystallography, the lack of inhibition of a range of human matrix metalloproteases could be attributed to a distinct binding mode sparing the S1' pocket. The inhibitor was shown to restore the effect of the antimicrobial peptide LL-37, decrease the formation of P. aeruginosa biofilm and, for the first time for a LasB inhibitor, reduce the release of extracellular DNA. Hence, it is capable of disrupting several important bacterial resistance mechanisms. These results highlight the potential of protease inhibitors to fight bacterial infections and point out the possibility to achieve selective inhibition even with a strong zinc anchor.

Racecadotril in the treatment of acute diarrhea in children: a systematic, comprehensive review and meta-analysis of randomized controlled trials

BACKGROUND

Racecadotril is a guideline-recommended option for the treatment of acute diarrhea in children but existing guidelines and previous reviews of the field are based on a small fraction of published evidence. Therefore, we have performed a systematic search for randomized controlled trials evaluating racecadotril as add-on or in comparison to other treatments.

METHODS

A search was performed in PubMed, Scopus and Google Scholar without limits about country of origin or reporting language. A meta-analysis was conducted for the five most frequently used efficacy parameters.

RESULTS

We have retrieved 58 trials, from nine countries including six in comparison to placebo, 15 in comparison to various active treatments and 41 as add-on to various standard treatments (some multi-armed studies allowing more than one comparison). Trials used 45 distinct efficacy parameters, most often time to cure, % of cured children after 3 days of treatment, global efficacy and number of stools on second day of treatment. Racecadotril was superior to comparator treatments in outpatients and hospitalized patients with a high degree of consistency as confirmed by meta-analysis for the five most frequently used outcome parameters. For instance, it reduced time to cure from 106.2 h to 78.2 h (mean reduction 28.0 h; P < 0.0001 in 24 studies reporting on this parameter). Tolerability of racecadotril was comparable to that of placebo (10.4% vs. 10.6% adverse events incidence) or that of active comparator treatments other than loperamide (2.4% in both groups).

CONCLUSIONS

Based on a comprehensive review of the existing evidence, we conclude that racecadotril is more efficacious than other treatments except for loperamide and has a tolerability similar to placebo and better than loperamide. These findings support the use of racecadotril in the treatment of acute diarrhea in children.

Rotavirus infection

Rotavirus infections are a leading cause of severe, dehydrating gastroenteritis in children <5 years of age. Despite the global introduction of vaccinations for rotavirus over a decade ago, rotavirus infections still result in >200,000 deaths annually, mostly in low-income countries. Rotavirus primarily infects enterocytes and induces diarrhoea through the destruction of absorptive enterocytes (leading to malabsorption), intestinal secretion stimulated by rotavirus non-structural protein 4 and activation of the enteric nervous system. In addition, rotavirus infections can lead to antigenaemia (which is associated with more severe manifestations of acute gastroenteritis) and viraemia, and rotavirus can replicate in systemic sites, although this is limited. Reinfections with rotavirus are common throughout life, although the disease severity is reduced with repeat infections. The immune correlates of protection against rotavirus reinfection and recovery from infection are poorly understood, although rotavirus-specific immunoglobulin A has a role in both aspects. The management of rotavirus infection focuses on the prevention and treatment of dehydration, although the use of antiviral and anti-emetic drugs can be indicated in some cases.

Racecadotril in the Management of Rotavirus and Non-rotavirus Diarrhea in Under-five Children: Two Randomized, Double-blind, Placebo-controlled Trials

OBJECTIVE

To study the effect of racecadotril on reduction in the duration of acute rotavirus and non-rotavirus diarrhea.

DESIGN

Two randomized double-blind placebo-controlled trials.

SETTING

Community-based trial in an urban area in Vellore, hospital-based trial at a secondary hospital in Vellore.

PARTICIPANTS

199 and 130 3-59 month old children in the community- and hospital-based trials, respectively.

METHODS

Racecadotril (1.5 mg/kg/dose, thrice a day for three days) or placebo were given to manage acute diarrhea in both trials.

MAIN OUTCOME MEASURE

Median duration of diarrhea.

RESULTS

Among 124 children completing the hospital trial, the median duration of diarrhea was 25 h in both arms (P=0.5); median total stool weight was 74 g/kg and 53.5 g/kg in racecadotril group and placebo group, respectively (P=0.4); and average fluid intake per day was 3.6 mL/kg/h and 3mL/kg/h in racecadotril and placebo arms, respectively (P=0.3). Among rotavirus-positive children, median duration of diarrhea was 26.9 h and 30.2 h in racecadotril and placebo arms, respectively (P=0.7). In the community, 196 completed the trial, the median duration of diarrhea was 2 days for both arms (P=0.8) and rotavirus positive children had similar outcomes with median diarrheal duration of 3 d in both arms (P=0.4).

CONCLUSIONS

Treatment with racecadotril did not reduce diarrheal duration, stool volume or the requirement for fluid replacement in children with acute gastroenteritis, both with and without rotavirus infection.

A Comprehensive Comparison of the Efficacy and Tolerability of Racecadotril with Other Treatments of Acute Diarrhea in Adults

Racecadotril is a guideline-recommended treatment to alleviate symptoms of acute diarrhea. A systematic review of randomized studies was performed comparing efficacy and safety of treatment with racecadotril to that with placebo or active treatments in adults. In five double-blind studies, racecadotril and placebo had comparable tolerability, but racecadotril was more effective. This was consistent across multiple efficacy parameters including duration of diarrhea, number of diarrheic stools, abdominal pain, and meteorism; it was also consistent across countries in Africa, Asia, and Europe. In six randomized studies in outpatients comparing racecadotril to loperamide, resolution of symptoms occurred with similar speed and efficacy; however, racecadotril treatment was associated with less rebound constipation and less abdominal discomfort. The seventh comparative study performed in geriatric nursing home residents reported a superior efficacy of racecadotril. In direct comparison with Saccharomyces boulardii treatment, racecadotril exhibited similar tolerability but was more efficacious. One study compared racecadotril to octreotide in patients with acute diarrhea requiring hospitalization, rehydration, and antibiotic treatment; in this cohort, octreotide was more efficacious than racecadotril. In conclusion, in adults with acute diarrhea, racecadotril is more efficacious than placebo or S. boulardii, similarly efficacious as loperamide and, in patients with moderate to severe disease as add-on to antibiotics, less than octreotide. The tolerability of racecadotril is similar to that of placebo or S. boulardii and better than that of loperamide, particularly with regard to risk of rebound constipation. Taken together, these data demonstrate that racecadotril is a suitable treatment to alleviate symptoms of acute diarrhea in adults.

Opioid Facilitation of β-Adrenergic Blockade: A New Pharmacological Condition?

Recently, propranolol was suggested to prevent hyperlactatemia in a child with hypovolemic shock through β-adrenergic blockade. Though it is a known inhibitor of glycolysis, propranolol, outside this observation, has never been reported to fully protect against lactate overproduction. On the other hand, literature evidence exists for a cross-talk between β-adrenergic receptors (protein targets of propranolol) and δ-opioid receptor. In this literature context, it is hypothesized here that anti-diarrheic racecadotril (a pro-drug of thiorphan, an inhibitor of enkephalinases), which, in the cited observation, was co-administered with propranolol, might have facilitated the β-blocker-driven inhibition of glycolysis and resulting lactate production. The opioid-facilitated β-adrenergic blockade would be essentially additivity or even synergism putatively existing between antagonism of β-adrenergic receptors and agonism of δ-opioid receptor in lowering cellular cAMP and dependent functions.

Physiology, signaling, and pharmacology of opioid receptors and their ligands in the gastrointestinal tract: current concepts and future perspectives

Opioid receptors are widely distributed in the human body and are crucially involved in numerous physiological processes. These include pain signaling in the central and the peripheral nervous system, reproduction, growth, respiration, and immunological response. Opioid receptors additionally play a major role in the gastrointestinal (GI) tract in physiological and pathophysiological conditions. This review discusses the physiology and pharmacology of the opioid system in the GI tract. We additionally focus on GI disorders and malfunctions, where pathophysiology involves the endogenous opioid system, such as opioid-induced bowel dysfunction, opioid-induced constipation or abdominal pain. Based on recent reports in the field of pharmacology and medicinal chemistry, we will also discuss the opportunities of targeting the opioid system, suggesting future treatment options for functional disorders and inflammatory states of the GI tract.

Crofelemer for the treatment of chronic diarrhea in patients living with HIV/AIDS

Diarrhea is a common comorbidity present in patients with human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS) who are treated with highly active antiretroviral therapy. With a multifactorial etiology, this diarrhea often becomes difficult to manage. In addition, some antiretrovirals are associated with chronic diarrhea, which potentially creates an adherence barrier to antiretrovirals and may ultimately affect treatment outcomes and future therapeutic options for HIV. A predominant type of diarrhea that develops in HIV patients has secretory characteristics, including increased secretion of chloride ions and water into the intestinal lumen. One proposed mechanism that may lead to this type of secretory diarrhea is explained by the activation of the cystic fibrosis transmembrane conductance regulator and calcium-activated chloride channels. Crofelemer is a novel antidiarrheal agent that works by inhibiting both of these channels. The efficacy and safety of crofelemer has been evaluated in clinical trials for various types of secretory diarrhea, including cholera-related and acute infectious diarrhea. More recently, crofelemer was approved by the US Food and Drug Administration for the symptomatic relief of noninfectious diarrhea in adult patients with HIV/AIDS on antiretroviral therapy. Results from the ADVENT trial showed that crofelemer reduced symptoms of secretory diarrhea in HIV/AIDS patients. Because crofelemer is not systemically absorbed, this agent is well tolerated by patients, and in clinical trials it has been associated with minimal adverse events. Crofelemer has a unique mechanism of action, which may offer a more reliable treatment option for HIV patients who experience chronic secretory diarrhea from antiretroviral therapy.

Towards a human rotavirus disease model

While the clinical importance of human rotavirus (RV) disease is well recognized and potent vaccines have been developed, our understanding of how human RV causes diarrhoea, vomiting and death remains unresolved. The fact that oral rehydration corrects electrolyte and water loss, indicates that enterocytes in the small intestine have a functional sodium-glucose co-transporter. Moreover, RV infection delays gastric emptying and loperamide appears to attenuate RV diarrhoea, thereby suggesting activation of the enteric nervous system. Serotonin (5-HT) receptor antagonists attenuate vomiting in young children with gastroenteritis while zinc and enkephalinase inhibitors attenuate RV-induced diarrhoea. In this review we discuss clinical symptoms, pathology, histology and treatment practices for human RV infections and compile the data into a simplified disease model.

A comprehensive review of the pharmacodynamics, pharmacokinetics, and clinical effects of the neutral endopeptidase inhibitor racecadotril

Racecadotril, via its active metabolite thiorphan, is an inhibitor of the enzyme neutral endopeptidase (NEP, EC 3.4.24.11), thereby increasing exposure to NEP substrates including enkephalins and atrial natriuretic peptide (ANP). Upon oral administration racecadotril is rapidly and effectively converted into the active metabolite thiorphan, which does not cross the blood–brain-barrier. Racecadotril has mainly been tested in animal models and patients of three therapeutic areas. As an analgesic the effects of racecadotril across animal models were inconsistent. In cardiovascular diseases such as hypertension or congestive heart failure results from animal studies were promising, probably related to increased exposure to ANP, but clinical results have not shown substantial therapeutic benefit over existing treatment options in cardiovascular disease. In contrast, racecadotril was consistently effective in animal models and patients with various forms of acute diarrhea by inhibiting pathologic (but not basal) secretion from the gut without changing gastro-intestinal transit time or motility. This included studies in both adults and children. In direct comparative studies with loperamide in adults and children, racecadotril was at least as effective but exhibited fewer adverse events in most studies, particularly less rebound constipation. Several guidelines recommend the use of racecadotril as addition to oral rehydration treatment in children with acute diarrhea.

Crofelemer for the treatment of secretory diarrhea

Secretory diarrhea is a leading cause of morbidity and mortality worldwide. Crofelemer is a first-in-class antidiarrheal agent that simultaneously targets two distinct channels, the cystic fibrosis conductance regulator and calcium-activated chloride channel, responsible for chloride and fluid secretion in the GI tract. Crofelemer is a novel compound extracted from the stem bark latex of the Croton lechleri tree found in the western Amazonian region of South America. There is little to no systemic absorption of crofelemer when given orally and studies have shown minimal toxicity beyond mild gastrointestinal effects. In studies in diarrheal illness associated with primarily a secretory component, such as cholera, travelers' diarrhea and acute infectious diarrhea, crofelemer has shown improvements in stool consistency and duration of symptoms. Less clear, but interesting, results have been observed in other diarrheal diseases associated with a mixed pathology, including diarrhea in patients with HIV and diarrhea-predominant irritable bowel syndrome.

An update on management of severe acute infectious gastroenteritis in children

This article focuses on clinical and diagnostic aspects relevant to severe acute infectious gastroenteritis in children and will update treatment strategies focused on, although not limited to, anti-infective therapy. For the purposes of this article we will consider severe acute infectious gastroenteritis as follows: watery diarrhea accompanied by, or at high risk for, moderate to severe dehydration due to abrupt onset of vomiting that reduces oral intake, and/or frequent emission of liquid stools, or moderate to severe dysenteric/bloody diarrhea with moderate to high-grade fever. The article will not include food poisoning associated with bacterial toxins and will only briefly discuss oral rehydration strategies and intravenous solutions. The article will also briefly discuss current preventive measures against rotavirus gastroenteritis through vaccination, a topic that has been extensively discussed elsewhere.

[An evidence based Iberic-Latin American guideline for acute gastroenteritis management in infants and prescholars]

Acute gastroenteritis (AG) morbidity and mortality rates in infants and prescholars continue to be high in developing countries. Authors want to develop an evidence-based document that supports decision making regarding AG therapy in infants and children younger than 5 y/o. A systematic review of the literature was performed (May, 2008). Evidence grading was established according to Oxford guidelines and Latin American experts submitted their opinions on the recommendations generated. Oral rehydration solutions are the threatment's keystone for children with AG, showing lesser complications due to therapy than IV fluids. AG is no contraindication of a normal diet. Racecadotril, zinc and smectite can contribute to AG treatment, as well as Lactobacillus GG and Saccharomycces boulardii. No other drugs are recommended. It is recommended to treat children presenting AG with oral rehydration solutions among racecadotril, zinc or smectite as well as some probiotics.

Use of racecadotril as outpatient treatment for acute gastroenteritis: a prospective, randomized, parallel study

OBJECTIVE

To compare the efficacy of therapy with racecadotril plus oral rehydration versus oral rehydration alone in children with gastroenteritis in an outpatient setting care.

STUDY DESIGN

Prospective, randomized, open and parallel study performed in a Pediatric Emergency Service of a tertiary care hospital. The study included 189 patients, ages 3 to 36 months, with acute gastroenteritis: 94 were administered an oral rehydration solution (OR), 94 received oral rehydration solution plus racecadotril (OR + R). The principal variable studied was the number of bowel movements in 48 hours after initiating treatment.

RESULTS

The groups were comparable clinically and epidemiologically at enrollment. No significant differences were found in the number of bowel movements between the 2 groups 48 hours after initiating treatment (4.1 +/- 2.7 bowel movements in the OR group vs 3.8 +/- 2.4 bowel movements in the OR + R group). No differences were found in the average duration of gastroenteritis (4.7 +/- 2.2 days in the OR group, 4.0 +/- 2.1 days in the OR + R group; P = .15). The incidence of adverse events was similar in both groups (19 patients [20.2%] in the OR group, 18 patients [19.1%] in the OR + R group).

CONCLUSIONS

In our study group, the use of racecadotril did not improve the symptoms of diarrhea compared with standard rehydration therapy.

[Systematic review of the efficacy of racecadotril in the treatment of acute diarrhoea]

OBJECTIVE

To estimate, through a systematic review of the literature, the efficacy of racecadotril in the treatment of acute diarrhoea.

MATERIAL AND METHODS

Randomised trials carried out in children comparing racecadotril with placebo in terms of diarrhoea recovery, stools output and adverse effects were selected. Electronic databases (Medline, EMBASE, CENTRAL, CINAHL, mRCT, Pascal) and bibliographies of retrieved articles were searched, and the drug developer was contacted. Two authors independently assessed the quality of the retrieved articles and extracted the data.

RESULTS

Two small sample size randomised trials (135 and 172 children) of moderate quality were selected. They included children with less than five days diarrhoea and aged between 3 months and 4 years. There was no difference in the proportion of children who recovered by day 5 (RR=0.73, CI 95% 0.29 to 1.81), although the stools volume during the first 48 hours was less in the racecadotril group (SMD=-0.65, CI 95% -0.88 to -0.52). There is no difference in the risk of vomiting (RR=1.16, CI 95% 0.64 to 2.12).

CONCLUSION

The proportion of recoveries by the 5th day is the same, although the stool volumes during the first 48 hours are less in the racecadotril treated children. It would be interesting to study the efficacy in a primary care setting assessing the cure rate, the stool volumes and the admission rate to elucidate if there is room for this drug.

Systematic review: racecadotril in the treatment of acute diarrhoea in children

BACKGROUND

Racecadotril (acetorphan) is an antisecretory drug that exerts its antidiarrhoeal effects by inhibiting intestinal enkephalinase.

AIM

To summarize studies testing the efficacy and safety of racecadotril for treating children with acute gastroenteritis.

METHODS

Reports were gathered by searching electronic databases MEDLINE, EMBASE, the Cochrane Library (all up to April 2007), relevant journals, and bibliographies of reviewed articles. Only randomized-controlled trials were included.

RESULTS

Three randomized-controlled trials (471 participants) met the inclusion criteria. Two trials reported stool output, and data suggested less stool output in the racecadotril group than in the control group. The duration of diarrhoea was significantly reduced in the three trials reporting this outcome. Achievement of a cure by day 5 was similar in both groups. Adverse effects were similar in both groups.

CONCLUSIONS

The small number of included trials provided some evidence in favour of the use of racecadotril over placebo or no intervention, to reduce the stool output and duration of diarrhoea in children with acute gastroenteritis. However, more data in out-patients are needed. The safety as well as the cost-effectiveness of the therapy should be explored, before routine therapy with racecadotril is recommended.

Acute infectious pediatric gastroenteritis: beyond oral rehydration therapy

Worldwide diarrheal diseases are a leading cause of childhood morbidity and mortality. Improvements in gastroenteritis management have reduced the annual number of pediatric deaths attributable to gastroenteritis from 5 million in 1982 to 2 million over 20 years. Recent advances are likely to contribute further to a reduction in morbidity and mortality secondary to acute infectious gastroenteritis. A new generation of vaccines against rotavirus is entering into routine use. Research into antisecretory agents has demonstrated that this class of medications may play a significant role in the future management of acute infectious gastroenteritis. A significant body of literature has recently emerged supporting the use of the antiemetic agent ondansetron. In developing countries, the routine use of zinc is now recommended by many experts, while, in developed countries, the use of probiotic agents has been associated with significant benefits in acute infectious gastroenteritis. Finally, more aggressive intravenous rehydration strategies are being employed; however, at present, limited data from randomized clinical trials are available to support its routine use.

Quantitative analysis of racecadotril metabolite in human plasma using a liquid chromatography/tandem mass spectrometry

Orally administered racecadotril is rapidly hydrolyzed to the more potent enkephalinase inhibitor thiorphan in vivo. A sensitive and specific liquid chromatography/tandem mass spectrometry method was developed and validated to quantify thiorphan in human plasma using lisinopril as the internal standard. After a simple protein precipitation with methanol, the post-treatment samples were analyzed on a CN column interfaced with a triple-quadruple tandem mass spectrometer using negative electrospray ionization. The method was validated to demonstrate the specificity, lower limit of quantification, accuracy, and precision of measurements. The assay was linear over the concentration range 9.38-600 ng/mL using a 5 microL aliquot of plasma. The correlation coefficients for the calibration curves ranged from 0.9985 to 0.9995. The intra- and inter-day precisions over the entire concentration were not more than 6.33%. Methanol and water (35:65, v/v) is used as the isocratic mobile phase, with 0.1% of formic acid in water. The method was successfully applied for pharmacokinetic study after a single oral administration of 200 mg racecadotril to 20 healthy volunteers.

A blind, randomized comparison of racecadotril and loperamide for stopping acute diarrhea in adults

AIM

Racecadotril is a specific enkephalinase inhibitor that exhibits intestinal antisecretory activity without affecting intestinal transit. Loperamide is an effective anti-diarrheal agent, but it usually induces constipation. This study is to compare the efficacy, safety, and tolerability of racecadotril versus loperamide in the outpatient treatment of acute diarrhea in adults.

METHODS

A two-center, randomized, parallel-group, single-blind study was carried out to compare the efficacy, tolerability, and safety of racecadotril (100 mg thrice daily) and loperamide (2.0 mg 2 twice daily) in 62 adult patients suffering from acute diarrhea. The main efficacy criterion used was the duration of diarrhea after beginning the treatment (in hours). Other signs and symptoms were also evaluated.

RESULTS

The clinical success rates for these anti-diarrheal treatments were 95.7% and 92.0% for racecadotril and loperamide respectively. Patients on racecadotril had a median duration of diarrhea of 19.5 h compared with a median of 13 h for patients on loperamide. Rapid improvement in anal burn and nausea was found for each drug. However, more patients on loperamide suffered from reactive constipation (29.0% vs 12.9%). Itching, another adverse event was notably higher in the racecadotril group (28.6% vs 0%). With regard to other adverse events, the two medications showed similar occurrence rates and similar concomitant medication usage rates.

CONCLUSION

Racecadotril and loperamide are rapid, equally effective treatments for acute diarrhea in adults, but loperamide treatment is associated with a higher incidence of treatment-related constipation.

Animal and human models for studying effects of drugs on intestinal fluid transport in vivo

The understanding of the physiology and pathophysiology of intestinal fluid transport has been derived from animal and human models of normal and perturbed intestines. This understanding helped in designing drugs and changing the composition of oral rehydration solutions in a targeted manner to affect intestinal fluid absorption/secretion that was tested both in vitro and in vivo before embarking on clinical trials. In this review, in vivo techniques used to study water transport in both animal and human models are described. In particular, steady state intestinal perfusion techniques, closed segment techniques, fistulous animal models, balance study models, enteropooling models, and isotope tracer models are reviewed. Advantages and drawbacks of each technique and examples where drug effects have been studied in a particular model are provided.

Treatment of infectious diarrhea in children

Diarrheal diseases remain an important cause of childhood morbidity and death in developing countries, although diarrheal deaths have significantly declined in recent years, mostly due to successes in the implementation of oral rehydration therapy (ORT), which is the principal treatment modality. Diarrhea may occur for varied reasons; however, most episodes of diarrhea in developing countries are infectious in origin. Three clinical forms of diarrhea (acute watery diarrhea, invasive diarrhea, and persistent diarrhea) have been identified to formulate a management plan. Acute diarrhea may be watery (where features of dehydration are prominent) or dysenteric (where stools contain blood and mucus). Rehydration therapy is the key to management of acute watery diarrhea, whereas antimicrobial agents play a vital role in the management of acute invasive diarrhea, particularly shigellosis and amebiasis. In persistent diarrhea, nutritional therapy, including dietary manipulations, is a very important aspect in its management, in addition to rehydration therapy. Rehydration may be carried out either by the oral or intravenous route, depending upon the degree of dehydration. Oral rehydration salts (ORS) solution (World Health Organization formula) is recommended for ORT. Intravenous fluid is recommended for initial management of severe dehydration due to diarrhea, followed by ORT with ORS solution for correction of ongoing fluid losses. Antimicrobial therapy is beneficial for cholera and shigellosis. Antiparasitic agents are indicated only if amebiasis and giardiasis are present. Appropriate feeding during diarrhea is recommended for nutritional recovery and to prevent bodyweight loss. Antidiarrheal agents do not provide additional benefit in the management of infectious diarrhea. Although some probiotics have been shown to be beneficial in the treatment of acute diarrhea due to rotavirus, their use in the treatment of diarrhea is yet to be recommended, even in developed countries. The children of developing countries might benefit from zinc supplementation during the diarrheal illness, but its mode of delivery and cost effectiveness are yet to be decided.

The historiography of psychology in Italy

The article outlines the studies conducted in Italy on the history of psychology since the 1970s, with particular attention to those elaborated in the 1990s. Reference is made to the institutions, authors, congresses, and other initiatives that in the course of 3 decades have promoted the growth of the history of psychology, and a review is presented of the principal research themes undertaken by scholars. An attempt has been made to identify the principal historiographic tendencies and to illustrate the passage from a sort of "positivistic" historiography to an orientation that could be considered multifactorial or one of complexity, attentive to both the internal and the external components of the scientific enterprise, although with a propensity for the history of ideas.

Getting control of intestinal secretion: thoughts for 2003

There has been a search for more than 20 years for agents that will directly inhibit intestinal secretory mechanisms and thereby reduce stool volume in patients with high volume watery diarrhoea. Recent work has highlighted the importance of neurohumoral mechanisms in the pathogenesis of diarrhoea, notably the role of 5-hydroxytryptamine, substance P, vasoactive intestinal polypeptide and neural reflexes within the enteric nervous system. Cholera toxin and Escherichia coli enterotoxins are known to invoke these mechanisms in some diarrhoeal states. This new dimension of intestinal pathophysiology has suggested possible novel targets for anti-secretory therapy including, 5-hydroxytryptamine receptor antagonists, substance P antagonists, vasoactive intestinal polypeptide antagonists and the possibility for potentiating the pro-absorptive effects of endogenous enkephalins by use of enkephalinase inhibitors. There now seems to be a real possibility that anti-secretory therapy will become more widely available in the future.

[Effect of racecadotril in the management of acute diarrhea in infants and children]

BACKGROUND

The treatment of diarrhoea relies on the maintenance or restoration of hydration with maintenance of an adequate nutritional intake. Racecadotril has been shown to reduce the stools output during acute diarrhoea. The present work was aimed at measuring the number of emergency department visits for acute diarrhoea either the children received racecadotril or not.

METHOD

Racecadotril and rehydration were compared with rehydration alone in children aged three months to three years who had acute diarrhoea and were evaluated in the emergency department (ED). The primary end point was the number of medical exams during the week after starting treatment. Secondary end points were the number of stools during the first 48 hours, the duration of the diarrhoea and the weight on day 7.

RESULTS

One hundred and sixty-six children were alternatively randomized to the treated and the control groups. There was no difference for age, degree of dehydration and length of illness before the first visit between the groups. Whatever type of rehydration (oral or i.v.), the treated group had a significant lower number of stools (p < 0.001) and a faster recovery (p < 10(-9)). The children receiving racecadotril needed less additional ED visits for the same episode (p < 0.05). There was no difference for the weight-gain on day 7.

CONCLUSIONS

This study demonstrates the efficacy of racecadotril as adjuvant therapy to oral and i.v. rehydration in the treatment of acute diarrhoea and a fewer emergency department second visit before recovery.

Efficacy and tolerability of racecadotril in acute diarrhea in children

BACKGROUND & AIMS

Oral rehydration therapy is the only treatment recommended by the World Health Organization in acute diarrhea in children. Antisecretory drugs available could not be used because of their side effects, except for racecadotril, which is efficient in acute diarrhea in adults.

METHODS

The efficacy and tolerability of racecadotril (1.5 mg/kg administered orally 3 times daily) as adjuvant therapy to oral rehydration were compared with those of placebo in 172 infants aged 3 months to 4 years (mean age, 12.8 months) who had acute diarrhea. The treatment groups were comparable in terms of age, duration of diarrhea, number of stools, and causative microorganism at inclusion.

RESULTS

During the first 48 hours of treatment, patients receiving racecadotril had a significantly lower stool output (grams per hour) than those receiving placebo. The 95% confidence interval was 43%-88% for the full data set (n = 166; P = 0.009) and 33%-75% for the per-protocol population (n = 116; P = 0.001). There was no difference between treatments depending on rotavirus status. Significant differences between treatment groups were also found after 24 hours of treatment: full data set (n = 167; P = 0.026) and per-protocol population (n = 121; P = 0.015). Tolerability was good in both groups of patients.

CONCLUSIONS

This study demonstrates the efficacy (up to 50% reduction in stool output) and tolerability of racecadotril as adjuvant therapy to oral rehydration solution in the treatment of severe diarrhea in infants and children.

Endogenous opiates: 1999

This paper is the twenty-second installment of the annual review of research concerning the opiate system. It summarizes papers published during 1999 that studied the behavioral effects of the opiate peptides and antagonists, excluding the purely analgesic effects, although stress-induced analgesia is included. The specific topics covered this year include stress; tolerance and dependence; learning, memory, and reward; eating and drinking; alcohol and other drugs of abuse; sexual activity, pregnancy, and development; mental illness and mood; seizures and other neurologic disorders; electrical-related activity; general activity and locomotion; gastrointestinal, renal, and hepatic function; cardiovascular responses; respiration and thermoregulation; and immunologic responses.

Role of the neuroendocrine system in pathogenesis of gastroenteritis

The concept of neuroendocrine modulation of infectious gastroenteritis adds another dimension to the pathophysiology of diarrhoeal diseases. Furthermore it opens up new avenues for therapeutic intervention. Until now, most interest has been directed at enterotoxin-producing bacteria, notably Vibrio cholerae and the enterotoxigenic Escherichia coli. However, more recently neuroendocrine recruitment has been implicated by other pathogens. The roles of vasoactive intestinal peptide, 5-hydroxytryptamine, tachykinins, nitric oxide and opioids are explored in this review. In addition new insights in the contradictory galanin story are discussed.

Novel targets for the pharmacotherapy of diarrhoea: a view for the millennium

Acute diarrhoea continues to carry a high morbidity and mortality worldwide. Intestinal infection is the major cause of acute diarrhoea although the prevalence of individual pathogens varies according to geographic location. In many countries in the industrialized world, reports of intestinal infections continue to increase; these are largely related to waterborne and foodborne outbreaks. Acute diarrhoea may be due to increased intestinal secretion, commonly as a result of infection with enterotoxin-producing organisms (enterotoxigenic Escherichia coli, Vibrio cholerae) or to decreased intestinal absorption from infection with organisms that damage the intestinal epithelium (enteropathogenic E. coli, Shigella sp., Salmonella sp.). Although oral rehydration therapy has reduced the mortality associated with acute diarrhoea, the diarrhoea attack rate remains unchanged and stool volume often increases during the rehydration process. The search for agents that will directly inhibit intestinal secretory mechanisms and thereby reduce stool volume has been going on for more than 20 years. Research during the past decade has highlighted the importance of neurohumoral mechanisms in the pathogenesis of diarrhoea, notably the role of 5-hydroxytryptamine, substance P, vasoactive intestinal polypeptide and neural reflexes within the enteric nervous system. Cholera toxin, E. coli enterotoxins and Clostridium difficile toxin A are known to invoke these mechanisms in diarrhoea pathogenesis. This new dimension of intestinal pathophysiology has already exposed possible novel targets for anti-secretory therapy, namely, 5-HT receptor antagonists, substance P antagonists and the possibility for potentiating the proabsorptive effects of endogenous enkephalins by use of enkephalinase inhibitors. There now seems to be a real possibility that anti-secretory therapy will become more widely available in the future.

Racecadotril in the treatment of acute watery diarrhea in children

BACKGROUND

Racecadotril (acetorphan), an enkephalinase inhibitor with antisecretory and antidiarrheal actions, is an effective and safe treatment for acute diarrhea in adults and children. Whether treatment with racecadotril and oral rehydration therapy is more effective than treatment with oral rehydration alone in hospitalized children with acute watery diarrhea is not known.

METHODS

We treated 135 boys 3 to 35 months of age who had watery diarrhea of five days' duration or less with racecadotril (1.5 mg per kilogram of body weight orally every eight hours) or placebo, in addition to oral rehydration solution. The primary end point was the 48-hour stool output (measured in grams); the total stool output, duration of diarrhea, and total intake of oral rehydration solution were also measured.

RESULTS

The mean (+/-SE) 48-hour stool output was 92+/-12 g per kilogram in the racecadotril group and 170+/-15 g per kilogram in the placebo group (P<0.001), a 46 percent reduction with racecadotril. The results were similar among the 73 boys with rotavirus infections. The total stool output was 157+/-27 g per kilogram in the racecadotril group and 331+/-39 g per kilogram in the placebo group (P<0.001). The median duration of diarrhea was significantly less (P<0.001) in the racecadotril group (28 hours regardless of rotavirus status) than in the placebo group (72 and 52 hours, respectively, for rotavirus-positive and rotavirus-negative patients). The intake of oral rehydration solution was significantly lower in the racecadotril group than in the placebo group (P<0.001). Racecadotril was well tolerated; only seven patients taking racecadotril had adverse effects, which were all mild and transient.

CONCLUSIONS

In young boys with acute watery diarrhea, racecadotril is an effective and safe treatment.

Racecadotril

Racecadotril is an oral enkephalinase inhibitor used in the treatment of acute diarrhoea. It prevents the degradation of endogenous opioids (enkephalins), thereby reducing hypersecretion of water and electrolytes into the intestinal lumen. In a randomised double-blind study in 6 adult volunteers with castor oil-induced diarrhoea, racecadotril significantly reduced stool weight and stool number in comparison with placebo. Similar results have been obtained in treating castor oil-induced diarrhoea in rats. Racecadotril was significantly more effective than placebo in randomised double-blind studies in adults or children with diarrhoea (of infectious origin or in adults with HIV infection). In well controlled trials, racecadotril had efficacy similar to that of loperamide and was generally as effective as loperamide-oxide. Racecadotril had a similar tolerability profile to placebo, and was better tolerated than loperamide, in adults and children with diarrhoea. It caused significantly less constipation after resolution of diarrhoea than loperamide.

An overview of clinical studies with racecadotril in adults

Since preclinical studies had indicated the potential efficacy and tolerability of racecadotril for the treatment of diarrhoea in man, a series of studies was carried out to assess the clinical effects of racecadotril. These studies were also designed to evaluate whether racecadotril possessed the clinical properties that had been previously identified for an ideal agent to treat infectious diarrhoea. The pure antisecretory action of racecadotril was confirmed in these clinical studies, as was the drug's rapid onset of action. The high therapeutic index of racecadotril was combined with a lack of effect on the central nervous system. Finally, racecadotril was found to be effective in treating acute diarrhoea in double-blind studies against both placebo and the mu opiate receptor agonist, loperamide. The efficacy of racecadotril in acute diarrhoea was not associated with adverse gastrointestinal effects, and its adverse events profile was similar to that of placebo. It was concluded that racecadotril offers a new approach to the treatment of diarrhoea via its mechanism of action as a true antisecretory agent.

Racecadotril: a new approach to the treatment of diarrhoea

Since enkephalins were discovered in 1975, it has become clear that they play an antisecretory role in the gastrointestinal tract. Hence a rational research programme was directed at the development of a drug that would preserve these neurotransmitter peptides in the gut by preventing their inactivation. This research programme has resulted in the development of the enkephalinase inhibitor, racecadotril. Preclinical studies have demonstrated the efficacy of racecadotril in two models of hypersecretory diarrhoea: infusion of cholera toxin and castor oil-induced diarrhoea. Moreover, unlike loperamide, racecadotril did not prolong transit time in the small intestine or colon. Further experiments have shown that racecadotril does not promote bacterial overgrowth in the small intestine. Racecadotril lacks any potential for neurotoxicity, and radiolabelled studies have demonstrated that the drug does not enter the brain after oral administration. No potential for abuse or physical dependence has been seen. It is concluded that racecadotril demonstrates specificity of antisecretory action on the gastrointestinal tract without any adverse effect on gastrointestinal motility, and that the results of the preclinical studies indicate the potential usefulness in the treatment of hypersecretory diarrhoea in man.

Racecadotril versus placebo in the treatment of acute diarrhoea in adults

METHODS

A two-centre, double-blind, parallel-group, randomized study was carried out to compare the efficacy and tolerability of racecadotril (100 mg three times daily) and placebo in 70 adult patients with acute diarrhoea. An objective criterion of antisecretory activity, stool weight, was used.

RESULTS

Racecadotril produced a significant (P = 0.025) decrease in stool weight during the first day of treatment compared with placebo, and was also associated with significantly fewer diarrhoeic stools than placebo after 1 day of treatment (p = 0.027). Racecadotril and placebo were equally well tolerated, and the frequency of symptoms and signs was similar in both groups after 4 days of treatment. Fewer patients on racecadotril suffered from abdominal distension following treatment (5.6% vs. 18.2% on placebo).

CONCLUSIONS

Racecadotril acts rapidly to resolve acute diarrhoea and has an incidence of adverse events similar to that of placebo.

Comparison of racecadotril and loperamide in children with acute diarrhoea

METHODS

A multicentre, parallel-group, double-blind, double-placebo study was carried out to compare the efficacy, tolerability, and safety of racecadotril and loperamide in children aged 2 to 10 years who were suffering from acute diarrhoea. Patients received racecadotril (1.5 mg/kg) or loperamide (0.03 mg/kg) three times daily plus matching placebo until recovery. Fifty-two children received racecadotril and 50 loperamide.

RESULTS

Patients on racecadotril passed a mean (+/- S.E.M.) of 2.7 +/- 0.4 stools before recovery compared with 2.1 +/- 0.4 stools for loperamide. The duration of diarrhoea was similar with both treatments. The incidence of adverse events was lower with racecadotril than with loperamide (11.5% vs. 22%), and significantly more patients on loperamide suffered from constipation (58% vs. 36.5%; P = 0.03). Moreover, significantly more children receiving loperamide required concomitant medication during the study (38% v 19.2%; P = 0.047). Measurement of abdominal circumference at the final consultation, 6 days after entry to the study, revealed no significant differences between treatments.

CONCLUSIONS

Racecadotril and loperamide were equally effective in treating acute diarrhoea in these children, and racecadotril had a superior tolerability and safety profile.

Comparison of racecadotril and loperamide in adults with acute diarrhoea

METHODS

A multicentre, randomized, double-blind, double-placebo, parallel-group study was carried out to compare the efficacy, tolerability, and safety of racecadotril (100 mg three times daily) and loperamide (2 mg after each diarrhoeic stool) in 157 adults with acute diarrhoea. Patients were treated for 7 days or until recovery, if this took place earlier.

RESULTS

Both groups of patients passed similar numbers (mean +/- S.E.M.) of stools before recovery (3.5 +/- 0.5 for racecadotril vs. 2.9 +/- 0.4 for loperamide), and the duration of diarrhoea (mean +/- S.E.M.) was similar in both groups (14.9 +/- 2.0 h for racecadotril and 13.7 +/- 2.2 h for loperamide). Both treatments reduced the incidence of associated symptoms and signs during the study, and both were similarly well tolerated. However, more patients on loperamide reported rebound constipation during treatment (18.7% vs. 9.8% with racecadotril).

CONCLUSIONS

The enkephalinase inhibitor, racecadotril, and the intestinal transit inhibitor, loperamide, were similarly and rapidly effective in resolving the symptoms and associated signs of diarrhoea.