Identification of a novel adjuvant loperamide that enhances the antibacterial activity of colistin against MCR-1-positive pathogens in vitro/vivo.

Severe infection with multidrug-resistant Enterobacterales caused by the plasmid-induced colistin resistance gene MCR-1 is a serious public health challenge. In this case, it is necessary and pressing to find a treatment to overcome antibiotic resistance. Here, we investigated the synergistic effect and mechanism of loperamide combined with colistin against MCR-1-positive pathogens. We evaluated the combined effect of loperamide and colistin using the checkerboard method and the time-kill experiment. The results showed that loperamide could enhance the bactericidal ability of colistin, and this combination regimen could completely kill the tested bacteria within 4 h. Subsequently, spectrofluorimetric methods were used to explore the mechanism of loperamide combined with colistin. The results indicated that the mode of action of loperamide combined with colistin was found to involve mechanical disruption of the membrane. Furthermore, molecular simulation and microscale thermophoresis results revealed that loperamide reduced the impact of MCR-1 protein by directly binding to its active site. In addition, the combined regimen of loperamide and colistin effectively reduced the bacterial load in the thighs of mice while increasing the protection rate by 70%. In short, as a potential lead compound, loperamide can enhance the killing effect of colistin on pathogenic Enterobacterales carrying MCR-1 by causing membrane damage and inhibiting MCR-1 protein activity.

Clinical Characteristics and Treatment Response in Microscopic Colitis Based on Age at Diagnosis: A Multicenter Retrospective Study.

BACKGROUND: Microscopic colitis (MC) primarily affects older adults; thus, data in younger patients are scarce. AIMS: To compare clinical characteristics and treatment response by age at diagnosis. METHODS: This retrospective cohort study was performed at Mayo Clinic and Massachusetts General Hospital. Patients were chosen consecutively using established databases. Patients were 'younger' if age at diagnosis was ≤ 50 years and 'older' if age > 50 years. Treatment outcomes were captured for induction (12 ± 4 weeks), based on the total number of daily stools, and defined as remission (complete resolution), response (≥ 50% improvement), non-response (< 50% improvement), and intolerance. Patients were considered 'responders' if they had remission or response and 'non-responders' if they had non-response or intolerance. RESULTS: We included 295 patients (52 younger, 243 older). There were no differences in sex, race, MC subtype, and diarrhea severity between groups (all P > 0.05). Younger patients were more likely to have celiac disease (17.3% vs. 5.8%, P = 0.01), while older patients had higher BMI (mean 25.0 vs. 23.8 kg/m2, P = 0.04) were more likely smokers (53.9% vs. 34.6%, P = 0.01) and use NSAIDs (48.6% vs. 15.4%, P < 0.01) and statins (22.6% vs. 3.8%, P < 0.01). Overall treatment response was highest for budesonide (88.3%) and did not differ when comparing older to younger patients (90.6% vs. 77.8%, P = 0.12) or by MC subtype (LC, 81.5% vs. CC, 92.9%, P = 0.07). CONCLUSIONS: There are no significant differences in MC treatment response based on age or disease subtype. These findings support treating patients with MC based on symptom severity rather than age.

Cardiac Electropharmacological Effects of Antidiarrheal Drug Loperamide and Its Antidote Naloxone in Anesthetized Guinea Pigs.

Cardiac electropharmacological effects of an antidiarrheal drug loperamide and its antidote naloxone were assessed in isoflurane-anesthetized guinea pigs. Intravenous administration of loperamide at 0.01-0.1 mg/kg did not affect parameters of electrocardiogram (ECG) or monophasic action potential (MAP) of the right ventricle. Additional administration of loperamide at 1 mg/kg prolonged the QT interval and MAP duration of the ventricle accompanied with increments of the PQ interval and QRS width. The potency of loperamide for QT-interval prolongation was about 100-times lower than that of dofetilide, in spite that similar inhibitory effects on the human Ether-a-go-go Related Gene (hERG) K+ channels have been reported between loperamide and dofetilide, implying lower accessibility of loperamide to the K+ channels. Intravenous administration of naloxone at 0.003-0.3 mg/kg, which effectively inhibits µ-opioid receptors, did not affect ECG parameters including QT interval or MAP duration. Furthermore, the loperamide-induced cardiac electrophysiological changes were not modified in the presence of naloxone at 0.3 mg/kg. These results suggest that loperamide has a potential to delay cardiac conduction and repolarization in the in vivo condition. Since naloxone did not modify ECG parameters and loperamide-induced ECG changes, naloxone is confirmed to possess acceptable cardiac safety when used as an antidote.

A Case Report of Torsade de Pointes and Brugada Pattern Associated with Loperamide Misuse and Supratherapeutic Loperamide Concentrations.

BACKGROUND: Loperamide, commonly sold under the brand name Imodium® (Johnson & Johnson, Fort Washington, PA), is a widely available, over-the-counter antidiarrheal medication that possesses µ-opioid agonist properties and can have catastrophic cardiac events when misused or abused. Since the start of the opioid epidemic in the United States, there has been an increasing number of case reports and deaths linking loperamide abuse with cardiac events such as torsades de pointes (TdP) and Brugada syndrome. CASE REPORT: This case report presents a 22-year-old man who presented in cardiac arrest from polymorphic ventricular tachycardia consistent with TdP and a Type 1 Brugada pattern after intentional loperamide abuse. We discuss this patient's management and the proposed pathophysiology of these two cardiotoxicities, of which, to our knowledge, no previously published case report has displayed both in the same patient after a supratherapeutic loperamide ingestion. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: As the prevalence of opioid dependency and misuse has increased, so, too, has the misuse of un-scheduled medications such as loperamide to achieve central nervous system opioid effects. It is important for the emergency physician to know about and understand loperamide-associated cardiotoxicities such as prolongation of the QRS, unmasking of Brugada patterns, QT prolongation, or ventricular dysrhythmias such as TdP to be able to recognize and treat it.

Cucumis sativus extract elicits chloride secretion by stimulation of the intestinal TMEM16A ion channel.

CONTEXT: Cucumber (Cucumis sativus Linn. [Cucurbitaceae]) is widely known for its purgative, antidiabetic, antioxidant, and anticancer therapeutic potential. However, its effect on gastrointestinal (GI) disease is unrecognised. OBJECTIVE: This study investigated the effect of C. sativus fruit extract (CCE) on intestinal chloride secretion, motility, and motor function, and the role of TMEM16A chloride channels. MATERIALS AND METHODS: CCE extracts were obtained from commercially available cucumber. Active fractions were then purified by HPLC and analysed by high resolution mass spectrometry. The effect of CCE on intestinal chloride secretion was investigated in human colonic T84 cells, ex vivo mouse intestinal tissue using an Ussing chamber, and the two-electrode voltage-clamp technique to record calcium sensitive TMEM16A chloride currents in Xenopus laevis oocytes. In vivo, intestinal motility was investigated using the loperamide-induced C57BL/6 constipation mouse model. Ex vivo contractility of mouse colonic smooth muscles was assessed by isometric force measurements. RESULTS: CCE increased the short-circuit current (ΔIsc 34.47 ± µA/cm2) and apical membrane chloride conductance (ΔICl 95 ± 8.1 µA/cm2) in intestinal epithelial cells. The effect was dose-dependent, with an EC50 value of 0.06 µg/mL. CCE stimulated the endogenous TMEM16A-induced Cl- current in Xenopus laevis oocytes. Moreover, CCE increased the contractility of smooth muscle in mouse colonic tissue and enhanced small bowel transit in CCE treated mice compared to loperamide controls. Mass spectrometry suggested a cucurbitacin-like analogue with a mass of 512.07 g/mol underlying the bioactivity of CCE. CONCLUSION: A cucurbitacin-like analog present in CCE activates TMEM16A channels, which may have therapeutic potential in cystic fibrosis and intestinal hypodynamic disorders.

Laxative Effects of a Standardized Extract of Dendropanax morbiferus H. Léveille Leaves on Experimental Constipation in Rats.

Background and Objectives: This study aimed at investigating the laxative effects of a standardized aqueous extract of Dendropanax morbiferus H. Lév. on two different constipation rat models. Materials and Methods: Animal studies were conducted with low-fiber diet-induced and loperamide-induced constipation animal models, and isolated colons were used in ex vivo analysis to determine the changes in colonic motility caused by D. morbiferus H. Lév. leaf extract (DPL). Results: The results showed that DPL administration significantly improved certain reduced fecal parameters (number, weight, and water content of the stools) in a both low-fiber diet and loperamide-induced constipation models without adverse effects of diarrhea. The laxative effect of DPL was confirmed to improve the charcoal excretion time upon DPL treatment in a low-fiber diet or loperamide-induced constipation model through gastrointestinal (GI) motility evaluation using the charcoal meal test. In addition, when DPL was administered to RAW264.7 cells and loperamide-induced constipation model rats, the production of prostaglandin E2 (PGE2) increased significantly in cells and tissue. Furthermore, DPL dose-dependently stimulated the spontaneous contractile amplitude and frequency of the isolated rat colon. Conclusion: Although our study did not provide information on the acute or chronic toxicity of DPL, our results demonstrated that DPL can effectively promote defecation frequency and rat colon contraction, providing scientific evidence to support the use of DPL as a therapeutic application. However, further toxicity studies of DPL are needed prior to the initiation of clinical trials and clinical applications.

Impact of treatment for fecal incontinence on constipation symptoms.

OBJECTIVE: Defecatory symptoms, such as a sense of incomplete emptying and straining with bowel movements, are paradoxically present in women with fecal incontinence. Treatments for fecal incontinence, such as loperamide and biofeedback, can worsen or improve defecatory symptoms, respectively. The primary aim of this study was to compare changes in constipation symptoms in women undergoing treatment for fecal incontinence with education only, loperamide, anal muscle exercises with biofeedback or both loperamide and biofeedback. Our secondary aim was to compare changes in constipation symptoms among responders and nonresponders to fecal incontinence treatment. STUDY DESIGN: This was a planned secondary analysis of a randomized controlled trial comparing 2 first-line therapies for fecal incontinence in a 2 × 2 factorial design. Women with at least monthly fecal incontinence and normal stool consistency were randomized to 4 groups: (1) oral placebo plus education only, (2) oral loperamide plus education only, (3) placebo plus anorectal manometry-assisted biofeedback, and (4) loperamide plus biofeedback. Defecatory symptoms were measured using the Patient Assessment of Constipation Symptoms questionnaire at baseline, 12 weeks, and 24 weeks. The Patient Assessment of Constipation Symptoms consists of 12 items that contribute to a global score and 3 subscales: stool characteristics/symptoms (hardness of stool, size of stool, straining, inability to pass stool), rectal symptoms (burning, pain, bleeding, incomplete bowel movement), and abdominal symptoms (discomfort, pain, bloating, cramps). Scores for each subscale as well as the global score range from 0 (no symptoms) to 4 (maximum score), with negative change scores representing improvement in defecatory symptoms. Responders to fecal incontinence treatment were defined as women with a minimally important clinical improvement of ≥5 points on the St Mark's (Vaizey) scale between baseline and 24 weeks. Intent-to-treat analysis was performed using a longitudinal mixed model, controlling for baseline scores, to estimate changes in Patient Assessment of Constipation Symptoms scores from baseline through 24 weeks. RESULTS: At 24 weeks, there were small changes in Patient Assessment of Constipation Symptoms global scores in all 4 groups: oral placebo plus education (-0.3; 95% confidence interval, -0.5 to -0.1), loperamide plus education (-0.1, 95% confidence interval, -0.3 to0.0), oral placebo plus biofeedback (-0.3, 95% confidence interval, -0.4 to -0.2), and loperamide plus biofeedback (-0.3, 95% confidence interval, -0.4 to -0.2). No differences were observed in change in Patient Assessment of Constipation Symptoms scores between women randomized to placebo plus education and those randomized to loperamide plus education (P = .17) or placebo plus biofeedback (P = .82). Change in Patient Assessment of Constipation Symptoms scores in women randomized to combination loperamide plus biofeedback therapy was not different from that of women randomized to treatment with loperamide or biofeedback alone. Responders had greater improvement in Patient Assessment of Constipation Symptoms scores than nonresponders (-0.4; 95% confidence interval, -0.5 to -0.3 vs -0.2; 95% confidence interval, -0.3 to -0.0, P < .01, mean difference, 0.2, 95% confidence interval, 0.1-0.4). CONCLUSION: Change in constipation symptoms following treatment of fecal incontinence in women are small and are not significantly different between groups. Loperamide treatment for fecal incontinence does not worsen constipation symptoms among women with normal consistency stool. Women with clinically significant improvement in fecal incontinence symptoms report greater improvement in constipation symptoms.

Ileocecal Valve Removal Reverses the Constipating Effects of Loperamide in Rats.

BACKGROUND: Previous evidence associating ileocecal valve removal (ICVR) with a reduced risk of fecal impaction of the ileocecum in cystic fibrosis indicated possible benefits from ileocecal valve loss in disorders with inhibited proximal colon transit caused by fecal dehydration and hypoperistalsis. We aimed to investigate the ability of ICVR in reversing fecal impaction in a loperamide-induced model of a similar pattern of inhibited proximal colon transit in rats. MATERIALS AND METHODS: Thirty pubertal Sprague-Dawley rats were rendered constipated with subcutaneous loperamide treatment (1 mg/kg/d) for 7 d. On day four, rats were allocated to groups: ICVR (n = 12), total colectomy (TC, n = 9), and sham operation (SO, n = 9). Fecal pellet number and consistency were assessed daily. On day seven, all rats were gavaged with barium. Two hours later, intestinal transit ratio (distance of barium head from the pylorus adjusted for small intestine length) and adjusted (for total intestine length) barium-to-anus distance were assessed. RESULTS: ICVR showed higher transit ratio and shorter barium-to-anus distance, that is, faster transit, than SO (P < 0.0001); differences between ICVR and TC were not significant (P > 0.06). Furthermore, ICVR and TC showed similar reduction in hard feces, compared with SO (P < 0.0001). TC showed higher diarrhea rate than ICVR (P < 0.0001). CONCLUSIONS: ICVR led to an effective, similar to TC, reversal of the constipating effects of loperamide and, unlike TC, was not associated with diarrhea. Our findings support the idea that ICVR might be beneficial in disorders with inhibited proximal colon transit resulting from fecal dehydration and hypoperistalsis, such as refractory cystic fibrosis-related intestinal obstruction. Potential clinical implications merit further study.

In Silico Food-Drug Interaction: A Case Study of Eluxadoline and Fatty Meal.

Food-drug interaction is an infrequently considered aspect in clinical practice. Usually, drugs are taken together with meals and what follows may adversely affect pharmacokinetic and pharmacodynamic properties, and hence, the therapeutic effects. In this study, a computational protocol was proposed to explain the different assimilations of two µ-receptors agonists, eluxadoline and loperamide, with a peculiar pharmacokinetic profile. Compared to loperamide, eluxadoline is absorbed less after the intake of a fatty meal, and the LogP values do not explain this event. Firstly, keeping in mind the different pH in the intestinal tract, the protonation states of both compounds were calculated. Then, all structures were subjected to a conformational search by using MonteCarlo and Molecular Dynamics methods, with solvation terms mimicking the water and weak polar solvent (octanol). Both computational results showed that eluxadoline has less conformational freedom in octanol, unlike loperamide, which exhibits constant behavior in both solvents. Therefore, we hypothesize that fatty meal causes the "closure" of the eluxadoline molecule to prevent the exposure of the polar groups and their interaction with water, necessary for the drug absorption. Based on our results, this work could be a reasonable "case study", useful for future investigation of the drug pharmacokinetic profile.

Pharmacological Aspects of Over-the-Counter Opioid Drugs Misuse.

Several over-the-counter (OTC) drugs are known to be misused. Among them are opioids such as codeine, dihydrocodeine, and loperamide. This work elucidates their pharmacology, interactions, safety profiles, and how pharmacology is being manipulated to misuse these common medications, with the aim to expand on the subject outlined by the authors focusing on abuse prevention and prevalence rates. The reviewed literature was identified in several online databases through searches conducted with phrases created by combining the international non-proprietary names of the drugs with terms related to drug misuse. The results show that OTC opioids are misused as an alternative for illicit narcotics, or prescription-only opioids. The potency of codeine and loperamide is strongly dependent on the individual enzymatic activity of CYP2D6 and CYP3A4, as well as P-glycoprotein function. Codeine can also be utilized as a substrate for clandestine syntheses of more potent drugs of abuse, namely desomorphine ("Krokodil"), and morphine. The dangerous methods used to prepare these substances can result in poisoning from toxic chemicals and impurities originating from the synthesis procedure. OTC opioids are generally safe when consumed in accordance with medical guidelines. However, the intake of supratherapeutic amounts of these substances may reveal surprising traits of common medications.

Electrocardiographic changes in loperamide toxicity: Case report and review of literature.

INTRODUCTION: Loperamide, an antidiarrheal agent, is a µ-opioid receptor agonist increasingly abused to prevent opioid withdrawal or to produce euphoric effects. At supra-therapeutic doses, loperamide can cause cardiac toxicity due to blockade of Na and IKr channels, resulting in wide QRS rhythms, severe bradycardia, prolonged QTc, polymorphic ventricular tachycardia, cardiac arrest, and death. There are limited data on the cardiotoxic effects of high dose loperamide. METHODS AND RESULTS: A case report of loperamide toxicity is presented and then added to a contemporary review of the literature. In total, the presentation and management of 36 cases of loperamide cardiotoxicity are summarized. The overall median daily dose (interquartile range) of loperamide was 200 (134-400) mg. The median QRS duration was 160 (125-170) ms. The median QTc duration was 620 (565-701) ms. Ventricular tachycardia was experienced by 24/36 (67%) of patients, 20 of which were specified to be polymorphic. Treatment was supportive, providing advanced cardiopulmonary life support and aggressive electrolyte repletion. Isoproterenol infusion or overdrive pacing was employed in 19/36 (53%) of cases. The median time to electrocardiogram normalization or hospital discharge, whichever came first, was 5 (3.5-10) days. CONCLUSION: Loperamide overdose is a toxidrome that remains underrecognized, and in patients with unexplained cardiac arrhythmias, loperamide toxicity should be suspected. Prompt recognition is critical due to the delayed recovery and high risk for life-threatening arrhythmias.

Loperamide-induced cardiotoxicity in rats: Evidence from cardiac and oxidative stress biomarkers.

At therapeutic dose, loperamide is a safe over-the-counter antidiarrheal drug but could induce cardiotoxic effect at a supratherapeutic dose. In this study, we use cardiac and oxidative biomarkers to evaluate loperamide-induced cardiotoxicity in rats. Rats were orally gavaged with 1.5, 3, or 6 mg/kg body weight (BW) of loperamide hydrochloride for 7 days. The results after 7 days administration of loperamide, revealed dose-dependent increase (P < 0.05) in aspartate aminotransferase, lactate dehydrogenase, creatine kinase-MB, and serum concentration of cardiac troponin I, total homocysteine, and nitric oxide. A 50% decrease in antioxidant enzymes activity was observed at 6 mg/kg BW. Furthermore, malondialdehyde and fragmented DNA also increased significantly in the heart of the treatment groups. Loperamide provoked cardiotoxicity through oxidative stress, lipid peroxidation, and DNA fragmentation in rats. This study has provided a possible biochemical explanation for the reported cardiotoxicity induced by loperamide overdose.

Laxative Effects of Taurine on Loperamide-Induced Constipation in Rats.

In the present study, we investigated the laxative effects of taurine in a rat model of loperamide-induced constipation. Rats were divided into six groups of six animals each: normal (NOR), control (CON), loperamide + Dulcolax (5.5 mg/kg, p.o.), and loperamide + various doses of taurine (7.5, 15, and 30 mg/kg, p.o.). Laxative activity was determined based on body weight, feeding characteristics, fecal properties, gastrointestinal transit (GIT) ratio, and the levels of serum gastrointestinal hormones. Taurine supplementation significantly increased the number, wet weight, and water content of fecal pellets in rats with loperamide-induced constipation. GIT ratio and loperamide-induced serum metabolic parameters, such as gastrin (GAS), motilin (MTL), and somatostatin (SS) significantly changed after supplementation with taurine in loperamide-induced constipated rats. We suggest that taurine had a potent effect against loperamide-induced constipation in part by increasing gastrointestinal motility.

Laxative effects of triple fermented barley extracts (FBe) on loperamide (LP)-induced constipation in rats.

BACKGROUND: Constipation, a common health problem, causes discomfort and affects the quality of life. This study intended to evaluate the potential laxative effect of triple fermented barley (Hordeum vulgare L.) extract (FBe), produced by saccharification, Saccharomyces cerevisiae, and Weissella cibaria, on loperamide (LP)-induced constipation in Sprague-Dawley (SD) rats, a well-established animal model of spastic constipation. METHODS: Spastic constipation was induced via oral treatment with LP (3 mg/kg) for 6 days 1 h before the administration of each test compound. Similarly, FBe (100, 200 and 300 mg/kg) was orally administered to rats once a day for 6 days. The changes in number, weight, and water content of fecal, motility ratio, colonic mucosa histology, and fecal mucous contents were recorded. The laxative properties of FBe were compared with those of a cathartic stimulant, sodium picosulfate. A total of 48 (8 rats in 6 groups) healthy male rats were selected and following 10 days of acclimatization. Fecal pellets were collected one day before administration of the first dose and starting from immediately after the fourth administration for a duration of 24 h. Charcoal transfer was conducted after the sixth and final administration of the test compounds. RESULTS: In the present study, oral administration of 100-300 mg/kg of FBe exhibited promising laxative properties including intestinal charcoal transit ratio, thicknesses and mucous producing goblet cells of colonic mucosa with decreases of fecal pellet numbers and mean diameters remained in the lumen of colon, mediated by increases in gastrointestinal motility. CONCLUSION: Therefore, FBe might act as a promising laxative agent and functional food ingredient to cure spastic constipation, with less toxicity observed at a dose of 100 mg/kg.

The unsuspected threat of three opioid-like substitutes.

The opioid epidemic has left its toll on the United States with millions suffering from an opioid use disorder and tens of thousands dying from overdoses each year. With intentions to combat the crisis, health providers have been prescribing less opioids, which resulted in an unintentional increase in the abuse of other opioid-like substances. Three emerging drugs of abuse have been noted in the literature as having increased abuse potential in light of recent trends. Kratom, an herbal supplement, gabapentin, a prescription nerve pain and anticonvulsant medication, and loperamide, an over-the-counter antidiarrheal medication. These have all displayed opioid-like properties at high doses and used to alleviate opioid withdrawal. Healthcare clinicians and patients might not be aware of the potential risks involved with misusing or abusing these opioid substitutes. This article discusses the increased usage of kratom, gabapentin, and loperamide, the abuse potential, adverse effects and withdrawal symptoms of each drug, and nursing implications that impact inpatient safety and management.

A mass spectrometry imaging approach for investigating how drug-drug interactions influence drug blood-brain barrier permeability.

There is a high need to develop quantitative imaging methods capable of providing detailed brain localization information of several molecular species simultaneously. In addition, extensive information on the effect of the blood-brain barrier on the penetration, distribution and efficacy of neuroactive compounds is required. Thus, we have developed a mass spectrometry imaging method to visualize and quantify the brain distribution of drugs with varying blood-brain barrier permeability. With this approach, we were able to determine blood-brain barrier transport of different drugs and define the drug distribution in very small brain structures (e.g., choroid plexus) due to the high spatial resolution provided. Simultaneously, we investigated the effect of drug-drug interactions by inhibiting the membrane transporter multidrug resistance 1 protein. We propose that the described approach can serve as a valuable analytical tool during the development of neuroactive drugs, as it can provide physiologically relevant information often neglected by traditional imaging technologies.

Molecular determinants of loperamide and N-desmethyl loperamide binding in the hERG cardiac K+ channel.

Abuse of the common anti-diarrheal loperamide is associated with QT interval prolongation as well as development of the potentially fatal arrhythmia torsades de pointes. The mechanism underlying this cardiotoxicity is high affinity inhibition of the human ether-a-go-go-related gene (hERG) cardiac K+ channel. N-Desmethyl loperamide is the major metabolite of loperamide and is a close structural relative of the parent molecule. To date no information is available regarding the affinity of N-desmethyl loperamide for human cardiac ion channels. The effects of N-desmethyl loperamide on various cloned human cardiac ion channels including hERG, KvLQT1/mink and Nav1.5 were studied and compared to that of the parent. N-Desmethyl loperamide was a much weaker (7.5-fold) inhibitor of hERG compared to loperamide. However, given the higher plasma levels of the metabolite relative to the parent, it is likely that N-desmethyl loperamide can contribute, at least secondarily, to the cardiotoxicity observed with loperamide abuse. We used the recently solved cryo-EM structure of the hERG channel together with previously published inhibitors, to understand the basis of the interactions as well as the difference that a single methyl plays in the hERG channel blocking affinities of these two compounds.

Enhanced intestinal 2-deoxy-2-[18F]fluoro-D-glucose uptake under metformin is not fully suppressed by loperamide.

OBJECTIVE: This study investigated whether the metformin (Met)-induced enhanced intestinal uptake of 2-deoxy-2-[18F]fluoro-D-glucose (18F-FDG) is reduced by loperamide, a long-acting anti-diarrheal agent. METHODS: Mean 18F-FDG uptake in the mouse small intestine and colon with Met exposure was compared with that in control mice. In the Met group, high-dose (1.0 mg/kg body weight) and low-dose (0.1 mg/kg body weight) loperamide were introduced, and 18F-FDG uptake in the small intestine and colon was compared with that of control mice administered high-dose loperamide. The percent injected dose of 18F-FDG per gram of tissue (%ID/g) in the extracted tissues was then determined. RESULTS: 18F-FDG uptake increased significantly in the small intestine (0.64±0.06 vs. 1.01±0.15, p=0.040) and, especially, the colon (0.46±0.13 vs. 2.16±0.51, p<0.001) after Met exposure. Neither high-dose nor low-dose loperamide significantly reduced 18F-FDG uptake in the small intestine (0.82±0.31 vs. 0.84±0.22, p=0.93 and 0.78±0.25 vs. 0.70±0.15, p=0.13, respectively) or colon (2.13±0.41 vs. 1.67±0.55, p=0.063 and 1.77±0.39 vs. 1.80±0.25, p=0.56, respectively). The colonic %ID/g was significantly higher in Met groups irrespective of loperamide introduction than in control group, whereas the significant difference in the small intestine was observed only between Met and control groups. CONCLUSION: Metformin increased 18F-FDG uptake in intestines especially in colon. Loperamide administration partially, but not sufficiently, suppresses the Met-induced increased colonic uptake of 18F-FDG.

Loperamide abuse cardiotoxicity. Should loperamide still be an over the counter medication?

Loperamide is an over-the-counter anti-diarrheal medication that is inexpensive, easily accessible, and widely used. It is generally thought to be safe and effective without the potential for abuse. However, recent discovery of its ability to treat opioid withdrawal symptoms at high doses has led to not only its abuse, but also the need to recognize its cardiotoxicity due to the ability to prolong the QTc interval. We report a case of a 33 year old female with a history of opioid dependence who presented to the emergency department with acute onset shortness of breath and generalized weakness who was subsequently found to be in ventricular tachycardia. Electrocardiogram showed prolongation of the QTc and the patient later admitted to ingestion of 70 loperamide pills daily for the past year in order to alleviate her opioid withdrawal symptoms. Due to increased loperamide abuse and toxicity displayed within the last several years, public and health provider awareness should be optimized to fully understand its lethality, and stricter regulations on its availability to the general population should be considered. Even in asymptomatic patients with ECG abnormalities, emergency medicine physicians should admit them for further monitoring and aggressive medical therapy.

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.