Identification of rhein as the metabolite responsible for toxicity of rhubarb anthraquinones.

Rhubarb is a popular food in Europe with laxative properties attributed to anthraquinones. Long term usage of rhubarb anthraquinones has been linked to colonic toxicity, including the formation of melanosis coli, which is associated with increased risk of colon cancer. The major purgative anthraquinone in rhubarb is thought to be sennoside A, which is metabolised by colonic microflora. Here, we sought to identify the toxic metabolite responsible for melanosis coli in rats dosed with rhubarb anthraquinones for up to 90 days. Three metabolites were detected in rat faeces using HPLC. Of these, rhein was identified as the metabolite that accumulated most over time. Fecal flora from treated rats were capable of greater biotransformation of sennoside A to rhein compared to that from control rats. Cell culture experiments suggested that apoptosis and autophagy induced by rhein is the likely mechanism of chronic toxicity of rhubarb anthraquinones.

Laxative effects of wheat bran and psyllium: Resolving enduring misconceptions about fiber in treatment guidelines for chronic idiopathic constipation.

BACKGROUND: Treatment guidelines for chronic idiopathic constipation (CIC) recommend an "increase in fiber intake" as a first-line therapy, but most epidemiologic studies fail to support an association between a high-fiber diet and a reduced risk of constipation. Furthermore, randomized controlled clinical studies show that most isolated fibers (e.g., supplements) are not different from placebo for a laxative effect, and several may be constipating. OBJECTIVES: The objective of this review was to compare the effects of two isolated fibers, coarse wheat bran and psyllium, on stool output and stool water content in patients with CIC. This review will also address misconceptions about fiber that are perpetuated by treatment guidelines. DATA SOURCES: A comprehensive literature review was conducted with the use of the Scopus, SciFinder, and PubMed scientific databases, limited to the previous 50 years (1968-2018; latest date included, December 31, 2018). CONCLUSIONS: In patients with CIC, nonfermented gel-forming psyllium was 3.4 times more effective than insoluble wheat bran for increasing stool output. Both psyllium and coarse wheat bran increased stool water content, a stool-softening effect, but finely ground wheat bran decreased stool water content, a stool-hardening effect. IMPLICATIONS FOR PRACTICE: It is a misconception that dietary fiber and all isolated fibers provide a laxative effect in patients with CIC. Our analysis suggests that treatment guidelines for CIC should make specific evidence-based recommendations as it pertains to fiber. To do otherwise takes the risk of perpetuating myth and misunderstanding and depriving patients of an effective therapy for CIC. A generic recommendation to "increase fiber intake" is akin to a recommendation to "increase pill intake" without regard to therapeutic or adverse effects.

An overview of the efficacy and safety of prucalopride for the treatment of chronic idiopathic constipation.

Introduction: Chronic idiopathic constipation (CIC) is a kind of constipation in which the patient experiences constipation more than 3 months without any identifiable cause. Prucalopride is one such treatment considered for relieving symptoms of CIC regarding due to its selectivity for the 5HT4 receptor.Areas covered: This article is based on a PubMed and clinicaltrials.gov search for studies undertaken over the past 19 years (2000-2019) using the following keywords either alone or in combination: Prucalopride, chronic idiopathic constipation, chronic constipation, 5HT4 receptor, Resolor and Motegrity.Expert opinion: Prucalopride should be considered as one of the safe options for the treatment of CIC especially when previous treatments have failed. It can be helpful in the treatment of constipation caused by irritable bowel syndrome or spinal cord injury, opioid-induced constipation, post-operative ileus, and intestinal/colonic pseudo-obstruction. The major drawback of prucalopride is its high cost, which makes it less accessible to all patients.

Naloxegol: A Review of Clinical Trials and Applications to Practice.

Opioid-induced constipation is a known side effect of long-term opioid therapy and may contribute to increased healthcare utilization. Common laxatives such as polyethylene glycol and bisacodyl are often selected as first-line agents. However, refractory constipation may persist despite the addition of a second agent. In such situations, alternate agents may be considered. The peripherally acting mu-opioid receptor antagonist naloxegol was approved in 2014 for management of opioid-induced constipation in adult patients with chronic noncancer pain. This agent is similar to the mu-opioid antagonist naloxone but selectively blocks opioid receptors in the periphery, thereby preventing constipation while avoiding any worsening of pain scores. Given that the medication undergoes hepatic metabolism, it is important to monitor liver function prior to initiation and assess for other medications, which may increase or decrease the levels of naloxegol, to determine whether adjustment in therapy may be required.

Pharmacodynamics, Safety, and Tolerability of the NHE3 Inhibitor Tenapanor: Two Trials in Healthy Volunteers.

BACKGROUND: Tenapanor, a small molecule with minimal systemic availability, is a first-in-class sodium/hydrogen exchanger 3 (NHE3) inhibitor that acts in the gut. Here, we evaluate the pharmacodynamics and safety of tenapanor in healthy adults. METHODS: Two phase I, single-center, randomized, double-blind, placebo-controlled studies were performed. The first study assessed single-ascending oral tenapanor doses of 10, 50, 150, 450, and 900 mg (n = 8 per group; six tenapanor, two placebo) and multiple ascending doses over 7 days of 3, 10, 30, and 100 mg q.d. (n = 10 per group; eight tenapanor, two placebo). In the second study, different tenapanor regimens were evaluated over 7 days (n = 15 per group; 12 tenapanor, three placebo): 15 mg twice daily (b.i.d.), 30 mg once daily (q.d.), 30 mg b.i.d., 30 mg three times daily (t.i.d.), 60 mg b.i.d., escalating b.i.d. dose (daily total 30-90 mg), 30 mg b.i.d. with psyllium. RESULTS: Tenapanor produced generally dose-dependent increases in stool sodium excretion and decreases in urinary sodium excretion versus placebo; in addition, twice-daily dosing appeared to have a greater effect on sodium absorption than once-daily dosing with an equivalent daily dose. Tenapanor softened stool consistency and increased stool frequency and weight from baseline versus placebo. Tenapanor concentrations were below the quantification limit (0.5 ng/ml) in 98.5% of 895 plasma samples. Adverse events were mild or moderate in severity, and were typically gastrointestinal in nature. There were no clinically relevant changes in serum electrolytes. CONCLUSIONS: Tenapanor was well tolerated and resulted in reduced intestinal sodium absorption and softer stool consistency versus placebo. Systemic exposure to tenapanor was minimal. These results support potential use of tenapanor in patients who could benefit from modification of gastrointestinal sodium balance. CLINICALTRIALS. GOV IDENTIFIERS: NCT02819687, NCT02796131.

Evaluation of diuretic and laxative activity of aqueous extract of Argemone mexicana leaves in rats / Evaluación de la actividad diurética y laxante del extracto acuoso de hojas de Argemone mexicana en ratas

Objectives: Argemone mexicana have been widely studied for its several pharmacological benefits and has been used in traditional medicine to treat constipation like symptoms. The present study carried out to evaluate the extract for its diuretic and laxative potential. Method: The aqueous extract of Argemone mexicana prepared using percolation method and subjected to phytochemical analysis. Evaluation of diuretic and laxative activity was carried out using metabolic cage apparatus and flame photometer as per the standard method reported earlier. Frusemide (20 mg/ kg) and sodium picosulate (5 mg/kg) were served as positive control for diuretic activity and laxative activity respectively. Result: The extract showed significant diuretic activity at 250 mg/kg dose when compared to standard frusemide. Even this extract also effective in increasing electrolyte concentration. Whereas the extract at 250 mg/kg showed significantly increasing in fecal output, and also significantly increased the weight of feces at 100 mg/kg and 200 mg/kg dose. Conclusion: The previous significant finding supports the traditional use of Argemone mexicana for its diuretic and laxative potential

Objetivos: Argemone mexicana ha sido ampliamente estudiada por sus diversos beneficios farmacológicos y se ha utilizado en la medicina tradicional para tratar síntomas de estreñimiento. El presente estudio evaluó el extracto por su potencial diurético y laxante. Método: El extracto acuoso de Argemone mexicana se preparó utilizando el método de percolación y se sometió a análisis fitoquímico. La evaluación de la actividad diurética y laxante se llevó a cabo utilizando unas jaulas metabólicas y un fotómetro de llama según el método estándar descrito con anterioridad. Se administró frusemida (20 mg / kg) y picosulato de sodio (5 mg / kg) como control positivo de la actividad diurética y actividad laxante respectivamente. Resultado: El extracto mostró una actividad diurética significativa a una dosis de 250 mg / kg en comparación con la frusemida estándar. Incluso, este extracto también es efectivo para aumentar la concentración de electrolitos. Mientras que el extracto a 250 mg/kg mostró un aumento significativo en la producción fecal, y también aumentó significativamente el peso de las heces en ambas dosis. Conclusión: El hallazgo significativo anterior apoya el uso tradicional de Argemone mexicana por sus potencialidades diurética y laxante

Naldemedine: First Global Approval.

Naldemedine (Symproic®) is an orally active µ-opioid receptor antagonist being developed by Shionogi & Co., Ltd. that has been approved in the USA and Japan for the treatment of opioid-induced constipation. The drug inhibits peripheral µ-opioid receptors such as those present in the gastrointestinal tract and has minimal or no effect on central opioid activity. This article summarizes the milestones in the development of naldemedine leading to its first global approval in the USA for the treatment of opioid-induced constipation in patients with chronic non-cancer pain.

Preparation, characterization, and in vivo study of rhein solid lipid nanoparticles for oral delivery.

In this study, rhein-SLNs were successfully produced by hot homogenization followed by ultrasonication. Precirol ATO5 in which rhein exhibited higher partition coefficient was selected for preparation of SLNs. In the dynamic light scattering, the rhein-SLNs showed a smaller size with a mean value of 120.8 ± 7.9 nm and with zeta potential of -16.9 ± 2.3 mV. SLNs exhibited a good stability during the period of 2 months. The SLNs indicated faster drug release with a burst release within 2 hr and followed by a sustained release with a biphasic drug-release pattern. Comparing with the same concentration (free drug), the cellular cytotoxicity of rhein-loaded SLNs increased significantly at the same incubation condition. In vivo, the AUC0-t of rhein in the form of SLNs was significantly increased and was 2.06-fold that of suspensions group. The results showed an increased oral absorption and improved the oral bioavailability of rhein by the formulation of SLNs.

Colon-targeted delivery of solubilized bisacodyl by doubly enteric-coated multiple-unit tablet.

A doubly enteric-coated multiple-unit tablet (DET) of bisacodyl (BD) was formulated to selectively deliver the stimulant laxative to the large intestine. Solubilized BD in surfactants was adsorbed into the porous carrier and primarily coated with different combinations of pH-sensitive polymers (Eudragit S and Eudragit L) and time-dependent release polymer (Eudragit RS). BD-loaded granules were compressed into tablets and coated again with pH-sensitive polymers (Eudragit S:Eudragit L=1:1). The multiple-unit tablet was optimized with respect to the granular coating compositions (Eudragit S:Eudragit L:Eudragit RS=5:1:4) and coating level (12.5%), and coating level on the tablet (25%), by evaluating in vitro release profile in continuous dissolution medium. Drug release from the optimized tablet was effectively retarded in the simulated gastric and small intestinal fluids (below 7%), but profound drug liberation was attained in the colonic fluid (over 50%). On the other hand, drug release from the marketed product (Dulcolax®, Boehringer Ingelheim Pharma), a reference drug, in the gastric and small intestinal fluids was reached to 30%, while that in the colonic fluid was only 7%. In an in vivo efficacy study in loperamide-induced constipated rabbits, a remarkable recovery in fecal secretion was observed in the DET-treated group 24h post-dosing, compared to vehicle-treated (p<0.05) and the marketed product-treated groups (p<0.05). Moreover, pharmacokinetic evaluation in the constipated rabbits revealed that the DET system significantly lowered the systemic exposure compared with the marketed product (p<0.05), by hindering drug release in the upper intestine, a preferential absorption site. Therefore, the novel colon-targeted delivery system may be an alternative for boosting pharmacological responses in the colon, while diminishing the intestinal irritation and/or systemic adverse effect of the stimulant laxative.

Pharmacokinetic Studies of Orally Administered Magnesium Oxide in Rats.

Magnesium oxide (MgO) tablets are widely used as laxatives in patients with constipation. Recently, the "Revision of Precautions on the Use of Magnesium Oxide" has been issued by the Japanese Pharmaceuticals and Medical Devices Agency, warning against the risk of hypermagnesemia with the use of MgO. However, the majority of physicians continue to administer MgO for constipation without adequately considering its safe use. In the present study, we performed two analyses using an identical lot of MgO tablets and evaluated the risk of hypermagnesemia. Approximately 90% of the MgO tablets dissolved within 120 min in dissolution testing; it was believed to form an absorbable state for magnesium. With orally administered MgO, 15% is absorbed in the body and 85% is excreted via the feces without being detected in pharmacokinetic analysis. Magnesium absorbed into the plasma demonstrated peak concentration 3 h after administration and was excreted via the urine within 48 h.

A Phase I Study to Investigate the Absorption, Pharmacokinetics, and Excretion of [(14)C]Prucalopride After a Single Oral Dose in Healthy Volunteers.

PURPOSE: Chronic constipation is a prevalent gastrointestinal disorder globally. It is often treated with medications such as laxatives. Newer therapies to improve gastric motility include the selective 5-hydroxytryptamine receptor-4 agonist prucalopride, which is licensed for the treatment of chronic constipation in adults. The aim of this study was to investigate the pharmacokinetic properties and excretion of prucalopride in healthy individuals, using a microtracer approach with (14)C radioactivity detection using liquid scintillation counting and accelerator mass spectrometry. METHODS: This was a single-period, open-label, nonrandomized absorption, metabolism, and excretion study of [(14)C]prucalopride. Participants were 6 healthy men aged 18 to 50 years. After screening, participants were administered a single dose of [(14)C]prucalopride succinate 2 mg (~200 nCi). Postadministration, urine, feces, and blood samples were collected over a 10-day period. Safety and adverse event data were also collected. FINDINGS: Almost 100% of the administered dose of radioactivity was recovered, with a mean (SD) of 84.2% (8.88%) recovered in urine and 13.3% (1.73%) recovered in feces. The mean blood-to-plasma concentration ratio of 1.9 indicated uptake of prucalopride into blood cells. The renal clearance of prucalopride was 17.0 (2.5) L/h, which is higher than the glomerular filtration rate in healthy individuals, suggesting active renal transport of prucalopride. Prucalopride was well tolerated, with no serious adverse events reported. IMPLICATIONS: Prucalopride was well absorbed and excreted mainly by the kidneys, including both passive and active transporter mechanisms. Quantitative recovery of the radioactive dose was achieved. Consistent with previous studies, prucalopride was generally well tolerated. ClinicalTrials.gov identifier: NCT01807000.

Comparación sobre la efectividad y seguridad del polietilenglicol con y sin electrolitos en el tratamiento del estreñimiento funcional / Comparison of the effectiveness and safety of polyethylene glycol with and without electrolytes in the treatment of chronic constipation

INTRODUCCIÓN: El objetivo del estudio fue comparar la efectividad y seguridad del polietilenglicol con y sin electrolitos (EL) en el estreñimiento funcional pediátrico a lo largo de 12 semanas. MATERIAL Y MÉTODOS: Estudio observacional, prospectivo, longitudinal, de grupos paralelos, que incluye a 62 niños diagnosticados de estreñimiento funcional según los criterios de ROMA III con antecedente de impactación fecal. De ellos, 30 niños recibieron polietilenglicol sin EL (PEG) y 32 PEG con EL (PEG+EL) durante al menos 12 semanas. Los resultados principales fueron determinar el número de deposiciones por semana a las 6 y 12 semanas de tratamiento y la presencia de alteraciones hidroelectrolíticas a las 6 semanas. RESULTADOS: La media de deposiciones por semana fue similar en ambos grupos a las 6 y a las 12 semanas, siendo en la semana 12 de 5,4 y 4,6 deposiciones por semana en los grupos PEG+EL y PEG respectivamente. Después de 6 semanas de tratamiento, el 83% (25 de 30) del grupo PEG tuvo al menos un parámetro alterado en la analítica, comparado con el 56% (18 de 32) en el grupo PEG + EL (p = 0,02). Se reportó una hiponatremia hasta en un 15% (5 de 32) y un 36% (11 de 30) del grupo PEG + EL y el grupo PEG (p = 0,05). Ninguna de las alteraciones analíticas fue clínicamente relevante. CONCLUSIONES: Las formulaciones PEG con o sin EL tienen una efectividad, seguridad y aceptabilidad similar. PEG sin EL presentó un mayor número de alteraciones electrolíticas, pero ninguna fue sintomática

INTRODUCTION: To compare the effectiveness and safety of polyethylene glycol with and without electrolytes (EL) over a 12 week period in treatment of chronic constipation in paediatrics. MATERIAL AND METHODS: This was an observational, prospective, longitudinal, parallel group study, including 62 children with chronic constipation according to ROME III criteria and a history of faecal impaction. The children were divided into groups, one group of 30 received polyethylene glycol without EL (PEG) and 32 PEG with EL (PEG+EL) for at least 12 weeks. The main outcomes were the number of bowel movements at 6 and 12 weeks, and the presence of electrolyte disturbances at 6 weeks. RESULTS: The mean weekly stool frequencies were similar in both groups at 6 and 12 weeks, with 5.4 and 4.6 stools per week in the PEG+EL and PEG groups, respectively at 12 weeks. After 6 weeks of treatment, 83% (25 of 30) of the PEG group had at least one electrolyte disturbance compared with 56% (18 of 32) in the PEG+EL group (P=.02). Hyponatraemia was found in 15% (5 of 32) vs. 36% (11 of 30) of PEG+EL and PEG groups, respectively (P=.05). None of the laboratory abnormalities were clinically relevant. CONCLUSIONS: PEG formulations with or without EL have a quite similar effectiveness, safety and acceptability. PEG without EL produced more electrolyte abnormalities, but none of them were symptomatic

Prucalopride succinate for the treatment of constipation: an update.

Constipation is a disorder frequently complained about by patients in daily clinical practice. However, to date, its treatment is still commonly unsatisfactory, especially concerning patients' quality of life, when using conventional measures. Prucalopride, a selective 5-hydroxytryptamine receptor 4 agonist, was introduced to the market in 2009 and has been commercially available in Europe since 2010. The main effect of prucalopride is to stimulate colonic motility, which explains its efficacy to treat constipated patients unresponsive to other regimens. Literature search was carried out to look for effects of prucalopride on constipated patients. Several papers were found demonstrating that prucalopride is effective in treatment of constipated patients. Due to its few side effects, the lack of cardiovascular effects and interactions with other drugs, prucalopride may be safely used in elderly people as well.

Prucalopride: A Review in Chronic Idiopathic Constipation.

Prucalopride (Resolor®), a highly selective serotonin 5-HT4 receptor agonist, is indicated in the European Economic Area for the treatment of adults with chronic idiopathic constipation (CIC) in whom laxatives have failed to provide adequate relief. This article reviews the pharmacological properties of prucalopride and its clinical efficacy and tolerability in patients with CIC. In five well-designed, 12-week trials in patients with CIC, oral prucalopride 2 mg/day was significantly more effective than placebo at improving bowel function, including the number of bowel movements and a range of other constipation symptoms, as well as health-related quality of life and patient satisfaction; however, no significant differences in bowel function measures were observed between prucalopride and placebo in a 24-week trial. Oral PEG-3350 + electrolytes reconstituted powder was found to be noninferior but not superior to prucalopride according to primary endpoint data from a 4-week, controlled-environment trial. Prucalopride was generally well tolerated in clinical trials; the most common adverse events were headache, diarrhoea, nausea and abdominal pain. No cardiovascular safety issues have arisen with prucalopride treatment. Although further long-term and comparative data would be beneficial, prucalopride provides an additional treatment option for patients with CIC.

Investigations of bisacodyl with modified ß-cyclodextrins: Characterization, molecular modeling, and effect of PEG.

Bisacodyl inclusion into hydroxypropyl-ß-cyclodextrin and 2,6-di-O-methyl-ß-cyclodextrin cavities was experimentally and theoretically investigated, and the effect of PEG 4000 on these inclusions was studied. Isothermal calorimetry titration curves indicated that the binary inclusion processes are enthalpy- and entropy-driven. The solid-state complexes were fully characterized by FT-IR, XRPD, DSC and SEM analyses. FT-IR, (1)H NMR, and ROESY studies provided the most favorable encapsulation modes of binary complexes, and results were further confirmed by molecular docking and molecular dynamics studies. The presence of PEG 4000 slightly enhanced encapsulation efficiency, solubility and dissolution rates of the binary complexes. In vivo studies showed that complexes with CDs markedly accelerated gastrointestinal transit time compared with pure bisacodyl, whereas addition of PEG 4000 showed no further significant improvement of the bioavailability.

Comparative pharmacokinetics of rhein in normal and loperamide-induced constipated rats and microarray analysis of drug-metabolizing genes.

ETHNOPHARMACOLOGICAL RELEVANCE: Rhein is a pharmacological active component found in Rheum palmatum L. that is the major herb of the San-Huang-Xie-Xin-Tang (SHXXT), a medicinal herbal product used as a remedy for constipation. Here we have investigated the comparative pharmacokinetics of rhein in normal and constipated rats. Microarray analysis was used to explore whether drug-metabolizing genes will be altered after SHXXT treatment. MATERIALS AND METHODS: The comparative pharmacokinetics of rhein in normal and loperamide-induced constipated rats was studied by liquid chromatography with electrospray ionization tandem mass spectrometry (LC-MS/MS). Gene expression profiling in drug-metabolizing genes after SHXXT treatment was investigated by microarray analysis and real-time polymerase chain reaction (RT-PCR). RESULTS: A validated LC-MS/MS method was applied to investigate the comparative pharmacokinetics of rhein in normal and loperamide-induced constipated rats. The pharmacokinetic results demonstrate that the loperamide-induced constipation reduced the absorption of rhein. Cmax significantly reduced by 2.5-fold, the AUC decreased by 27.8%; however, the elimination half-life (t1/2) was prolonged by 1.6-fold. Tmax and mean residence time (MRT) were significantly prolonged by 2.8-fold, and 1.7-fold, respectively. The volume of distribution (Vss) increased by 2.2-fold. The data of microarray analysis on gene expression indicate that five drug-metabolizing genes, including Cyp7a1, Cyp2c6, Ces2e, Atp1b1, and Slc7a2 were significantly altered by the SHXXT (0.5 g/kg) treatment. CONCLUSION: The loperamide-induced constipation reduced the absorption of rhein. Since among the 25,338 genes analyzed, there were five genes significantly altered by SHXXT treatment. Thus, information on minor drug-metabolizing genes altered by SHXXT treatment indicates that SHXXT is relatively safe for clinical application.

Determination of bioactive components in Chinese herbal formulae and pharmacokinetics of rhein in rats by UPLC-MS/MS.

Rhein (4,5-dihydroxy-9,10-dioxoanthracene-2-carboxylic acid, cassic acid) is a pharmacological active component found in Rheum palmatum L. the major herb of San-Huang-Xie-Xin-Tang (SHXXT), a medicinal herbal product used as a remedy for constipation. Here we have determined multiple bioactive components in SHXXT and investigated the comparative pharmacokinetics of rhein in rats. A sensitive and specific method combining liquid chromatography with electrospray ionization tandem mass spectrometry has been developed and validated to simultaneously quantify six active compounds in the pharmaceutical herbal product SHXXT to further study their pharmacokinetics in rats. Multiple reaction monitoring (MRM) was employed for quantification with switching electrospray ion source polarity between positive and negative modes in a single run. There were no significant matrix effects in the quantitative analysis and the mean recovery for rhein in rat plasma was 91.6%±3.4%. The pharmacokinetic data of rhein demonstrate that the herbal formulae or the single herbal extract provide significantly higher absorption rate than the pure compound. This phenomenon suggests that the other herbal ingredients of SHXXT and rhubarb extract significantly enhance the absorption of rhein in rats. In conclusion, the herbal formulae (SHXXT) are more efficient than the single herb (rhubarb) or the pure compound (rhein) in rhein absorption.

Oral prucalopride in children with functional constipation.

BACKGROUND AND OBJECTIVES: Prucalopride is a selective, high-affinity 5-HT4 receptor agonist with gastrointestinal prokinetic activities. The aim of this study was to evaluate the pharmacokinetics, efficacy, safety, and tolerability of prucalopride oral solution in children, ages 4 years or older to 12 years or younger, with functional constipation. METHODS: A single oral dose of 0.03 mg/kg prucalopride was administered to 38 children to characterize prucalopride pharmacokinetics (NCT01674166). Thereafter, 37 children entered an open-label extension period in which 0.01 to 0.03 mg/kg of prucalopride was administered once per day for 8 weeks to investigate efficacy, safety, and tolerability (NCT01670669). RESULTS: Mean (standard deviation [SD]) Cmax, tmax, and AUC∞ (area under the plasma concentration-time curve from time 0 to infinity) were 3.8 (0.6) ng/mL, 1.8 (0.9) hour, and 65.3 (10.6) ng · h · mL, respectively, with limited (16%) variability in Cmax and AUC∞. Mean (SD) t1/2 was 19.0 (3.1) hours. On average, mean (SD) renal clearance (0.25 [0.08] L · h · kg) accounted for 54% of the apparent total plasma clearance (0.46 [0.07] L · h · kg). The apparent volume of distribution was 12.6 (2.6) L/kg. Prucalopride treatment resulted in a mean bowel movement frequency of 6.8/week, normal stool consistency, and reduced frequency of fecal incontinence. During the 8-week extension, 70% of study participants had at least 1 adverse event (all but 1 of mild/moderate intensity, 19% considered related to prucalopride). No children discontinued prucalopride because of adverse events. CONCLUSIONS: The pharmacokinetic profile of a single dose of prucalopride oral solution (0.03 mg · kg · day) generally resembled the profile in adults (2-mg tablet) but reflected lower systemic exposure in children. Prucalopride treatment for 8 weeks demonstrated an apparent favorable efficacy and tolerability profile in children with functional constipation.

Pharmacokinetic and pharmacodynamic considerations for the current chronic constipation treatments.

INTRODUCTION: Chronic constipation is a frequent condition often treated pharmacologically. The laxatives available belong to very different pharmacologic groups. AREAS COVERED: This is a short but comprehensive review of the pharmacology, efficacy and safety of currently available laxatives for chronic constipation. Pertinent publications were retrieved from reference lists of publications and by literature searches via PubMed, lastly performed in November 2012. EXPERT OPINION: The most relevant laxative groups are the older representatives osmotic salts, sugars and sugar alcohols, macrogol, anthraquinones, diphenolic laxatives or diphenyl methanes (bisacodyl and sodium picosulfate) and the newer compounds prucalopride, lubiprostone and linaclotide. For all of these laxatives efficacy has been shown in controlled trials. Electrolyte losses do not occur when laxatives are given in therapeutic doses (rare exceptions with phosphate salts and salinic laxatives). The older laxatives are also safe regarding teratogenicity, abortion and lactation. For the newer compounds no respective data are available as yet. It is questionable whether the newer compounds offer advantages over the older ones. Unfortunately, comparative trials are lacking.

Safety evaluation of lubiprostone in the treatment of constipation and irritable bowel syndrome.

INTRODUCTION: Lubiprostone is approved in the United States for the treatment of chronic idiopathic constipation and constipation predominant irritable bowel syndrome (IBS-C). Lubiprostone causes secretion of fluid and electrolytes in the small bowel, through the activation of chloride channels, and thereby induces laxation and improvement of bowel functions. It is generally considered to be safe and effective. Common side effects of lubiprostone include nausea, diarrhea, abdominal pain and bloating, and the rare side effect dyspnea. Likely mechanisms for these side effects may be related to lubiprostone's primary action on small bowel secretion and the associated intestinal distension, as well as smooth muscle contraction. AREAS COVERED: This article reviews the pharmacokinetic and safety profile of lubiprostone, with particular relevance to the two FDA-approved dosages. EXPERT OPINION: Lubiprostone acts topically in the gut lumen and is almost completely metabolized in the gut lumen. Lubiprostone's M3 metabolite can be detected in low concentrations in the serum and may be responsible for some of its side effects. However, the exact mechanisms by which the side effects are produced are currently unknown.