Effects of Posture and Meal Volume on Gastric Emptying, Intestinal Transit, Oral Glucose Tolerance, Blood Pressure and Gastrointestinal Symptoms After Roux-en-Y Gastric Bypass

Gut motility and hormone changes after bariatric procedures

PURPOSE OF REVIEW

Metabolic and bariatric surgery (MBS) and endoscopic bariatric therapies (EBT) are being increasingly utilized for the management of obesity. They work through multiple mechanisms, including restriction, malabsorption, and changes in the gastrointestinal hormonal and motility.

RECENT FINDINGS

Roux-en-Y gastric bypass (RYGB) and laparoscopic sleeve gastrectomy (LSG) cause decrease in leptin, increase in GLP-1 and PYY, and variable changes in ghrelin (generally thought to decrease). RYGB and LSG lead to rapid gastric emptying, increase in small bowel motility, and possible decrease in colonic motility. Endoscopic sleeve gastroplasty (ESG) causes decrease in leptin and increase in GLP-1, ghrelin, and PYY; and delayed gastric motility.

SUMMARY

Understanding mechanisms of action for MBS and EBT is critical for optimal care of patients and will help in further refinement of these interventions.

Gastrointestinal Permeability After Bariatric Surgery: A Systematic Review

Gastrointestinal permeability refers to the movement of substances across the gut wall. This is mediated by endotoxemia (bacterial products entering the systemic circulation), and is associated with metabolic disease. The effect of bariatric surgery on permeability remains uncertain; the associated dietary, metabolic and weight changes are suggested to influence, or trigger, altered permeability. The primary aim of this study is to synthesize evidence and analyze the effect of bariatric surgery on permeability. A systematic review was performed, searching MEDLINE, EMBASE, and Scopus until February 2023, using MESH terms "intestinal permeability", "bariatric", for studies reporting in vivo assessment of permeability. Three cohort studies and two case series were identified (n=96). Data was heterogeneous; methodology and controls preclude meta-analysis. Gastroduodenal permeability reduced post-sleeve gastrectomy (SG). Two studies showed an increase in small intestinal permeability after biliopancreatic diversion. Two studies revealed a decrease in post-Roux-en-Y gastric bypass. One study identified increased colonic permeability six months post-SG. Evidence regarding permeability change after bariatric surgery is conflicting, notably for the small intestine. Impaired colonic permeability post-SG raises concerns regarding colonic protein fermentation and harmful dietary sequelae. There are multiple interacting variables confounding gastrointestinal permeability change; procedure type, altered microbiota and metabolic response to surgery. Further understanding of this important aspect of obesity is required, both before and after bariatric surgery.

Obesity and hypertension: Obesity medicine association (OMA) clinical practice statement (CPS) 2023

Background

This Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) provides an overview of the mechanisms and treatment of obesity and hypertension.

Methods

The scientific support for this CPS is based upon published citations, clinical perspectives of OMA authors, and peer review by the Obesity Medicine Association leadership.

Results

Mechanisms contributing to obesity-related hypertension include unhealthful nutrition, physical inactivity, insulin resistance, increased sympathetic nervous system activity, renal dysfunction, vascular dysfunction, heart dysfunction, increased pancreatic insulin secretion, sleep apnea, and psychosocial stress. Adiposopathic factors that may contribute to hypertension include increased release of free fatty acids, increased leptin, decreased adiponectin, increased renin-angiotensin-aldosterone system activation, increased 11 beta-hydroxysteroid dehydrogenase type 1, reduced nitric oxide activity, and increased inflammation.

Conclusions

Increase in body fat is the most common cause of hypertension. Among patients with obesity and hypertension, weight reduction via healthful nutrition, physical activity, behavior modification, bariatric surgery, and anti-obesity medications mostly decrease blood pressure, with the greatest degree of weight reduction generally correlated with the greatest degree of blood pressure reduction.

PBPK Modeling of Azithromycin Systemic Exposure in a Roux-en-Y Gastric Bypass Surgery Patient Population

In this investigation, PBPK modeling using the Simcyp® Simulator was performed to evaluate whether Roux-en-Y gastric bypass (RYGB) surgery impacts the oral absorption and bioavailability of azithromycin. An RYGB surgery patient population was adapted from the published literature and verified using the same probe medications, atorvastatin and midazolam. Next, a PBPK model of azithromycin was constructed to simulate changes in systemic drug exposure after the administration of different oral formulations (tablet, suspension) to patients pre- and post-RYGB surgery using the developed and verified population model. Clinically observed changes in azithromycin systemic exposure post-surgery following oral administration (single-dose tablet formulation) were captured using PBPK modeling based on the comparison of model-predicted exposure metrics (Cmax, AUC) to published clinical data. Model simulations predicted a 30% reduction in steady-state AUC after surgery for three- and five-day multiple dose regimens of an azithromycin tablet formulation. The relative bioavailability of a suspension formulation was 1.5-fold higher than the tablet formulation after multiple dosing. The changes in systemic exposure observed after surgery were used to evaluate the clinical efficacy of azithromycin against two of the most common pathogens causing community acquired pneumonia based on the corresponding AUC24/MIC pharmacodynamic endpoint. The results suggest lower bioavailability of the tablet formulation post-surgery may impact clinical efficacy. Overall, the research demonstrates the potential of a PBPK modeling approach as a framework to optimize oral drug therapy in patients post-RYGB surgery.

Bariatric Bypass Surgery Is a Risk Factor for Incomplete Colonoscopy Preparation

OBJECTIVES

Effective colon cancer screening requires adequate bowel preparation. Anecdotal evidence has suggested that patients with a history of bariatric surgery are more likely to have inadequate preparation. This study aims to evaluate the role of bariatric surgery as a predictive risk factor for inadequate bowel preparation.

METHODS

Data were collected retrospectively for consecutive colonoscopies between March 1, 2013, and November 15, 2017. Only the index colonoscopy for each patient within the review period, and those scored using the Boston Bowel Preparation Scale (BBPS) were included. Inadequate preparation was defined as any one or more colon segments with a BBPS score of less than two, and patients with a history of bariatric surgery were identified using ICD 9/10 codes. Multivariate logistic regression and propensity score matching was used to assess for independent factors predictive of inadequate bowel preparation.

RESULTS

A total of 25,318 colonoscopies were included in the analysis. Two hundred 278 (1.1%) patients had a history of bariatric surgery, among which 171 (61.5%) had a history of bypass surgery and 107 (38.5%) had a history of restrictive surgical procedure. A history of bariatric surgery was predictive of inadequate bowel preparation in both univariate (OR: 2.87, 95% CI: 1.92-4.29, P = 0.0003) and multivariate analysis (OR: 2.16, 95% CI: 1.43-3.27, P = 0.0003) after controlling for differences in baseline characteristics. When evaluated separately, a history of bypass surgery was associated with inadequate bowel preparation (aOR: 2.96, 95% CI: 1.86-4.72, P < 0.0001), whereas a history of a restrictive bariatric surgery was not associated with inadequate bowel preparation in multivariate analysis (aOR: 0.98, 95% CI: 0.4-2.45, P = 0.971).

CONCLUSIONS

A history of bariatric surgery is an independent risk factor for inadequate bowel preparation. Furthermore, bypass bariatric surgeries had higher rates of inadequate preparation when compared to restrictive bariatric surgeries. Further quality improvement initiatives should be directed at identifying the appropriate bowel preparation regimen in this population.

Orthostatic intolerance after bariatric surgery: A systematic review and meta-analysis

There have been increased reports of orthostatic intolerance post-bariatric surgery. However, the prevalence, pathophysiology and long-term outcomes have not been well described. Therefore, we sought to summarize evidence of orthostatic intolerance after bariatric surgery. We conducted a systematic review using PubMed, Scopus, CINAHL, Cochrane Database of Systematic Reviews and the Cochrane Central Register of Controlled Trials (CENTRAL) to identify relevant articles from the date of inception until 1st April 2020. Study selection, data extraction and quality assessment of the included studies were performed independently by two reviewers. The findings of the included studies were narratively reported. When feasible, a meta-analysis was done to summarize the relevant results. We included 20 studies (n = 19 843 participants) reporting findings of 12 prospective cohort studies, 5 retrospective cohort studies, 2 cross-sectional studies and one randomized controlled trial. The 5-year cumulative incidence of orthostatic intolerance was 4.2% (one study). Common clinical presentations of orthostatic intolerance were lightheadedness, dizziness, syncope and palpitation. The pooled data suggested improvement in overall cardiac autonomic function (sympathetic and parasympathetic) post-bariatric surgery. In addition, a significant systolic blood pressure drop may reflect a reset of the balance between the sympathetic and parasympathetic nervous systems after weight loss in the pooled analysis. Existing literature on orthostatic intolerance post-bariatric surgeries was limited or of low quality, and larger studies are needed to know the true incidence of orthostatic intolerance post-bariatric surgeries and the pathophysiology. We found one study reporting the 5-years cumulative incidence of orthostatic intolerance post-bariatric surgeries as only 4.2%. This could challenge the idea of increased orthostatic intolerance prevalence post-bariatric surgeries. Registration The review protocol was registered at the International Prospective Register of Systemic Reviews PROSPERO (CRD42020170877).

Gastroretentive Technologies in Tandem with Controlled-Release Strategies: A Potent Answer to Oral Drug Bioavailability and Patient Compliance Implications

There have been many efforts to improve oral drug bioavailability and therapeutic efficacy and patient compliance. A variety of controlled-release oral delivery systems have been developed to meet these needs. Gastroretentive drug delivery technologies have the potential to achieve retention of the dosage form in the upper gastrointestinal tract (GIT) that can be sufficient to ensure complete solubilisation of the drugs in the stomach fluids, followed by subsequent absorption in the stomach or proximal small intestine. This can be beneficial for drugs that have an “absorption window” or are absorbed to a different extent in various segments of the GIT. Therefore, gastroretentive technologies in tandem with controlled-release strategies could enhance both the therapeutic efficacy of many drugs and improve patient compliance through a reduction in dosing frequency. The paper reviews different gastroretentive drug delivery technologies and controlled-release strategies that can be combined and summarises examples of formulations currently in clinical development and commercially available gastroretentive controlled-release products. The different parameters that need to be considered and monitored during formulation development for these pharmaceutical applications are highlighted.

Effect of Roux-en-Y gastric bypass on the pharmacokinetic-pharmacodynamic relationships of liquid and controlled-release formulations of oxycodone

The physiological changes following Roux-en-Y gastric bypass (RYGB) surgery may impact drug release from mechanistically different controlled-release tablets, making generic substitution inappropriate. This study aimed to characterise the pharmacokinetic-pharmacodynamic relationships of oxycodone from a lipid-based and water-swellable controlled-release tablet in RYGB patients. Twenty RYGB patients received 10-mg oral solution oxycodone or 20-mg controlled-release (water-swellable or lipid-based) oxycodone in a three-way, randomised, semiblinded and cross-over study. Blood sampling and pupillary recordings were conducted over a 24-h period. A previously established pharmacokinetic-pharmacodynamic model of these three formulations in healthy volunteers was used in the analysis as a reference model. No differences in absorption kinetics were seen between controlled-release formulations in patients. However, the absorption lag time was 11.5 min in patients vs 14 min in healthy volunteers for controlled-release tablets (P < 0.001). Furthermore, oral bioavailability was 14.4% higher in patients compared to healthy volunteers regardless of formulation type (P < 0.001). Oxycodone pharmacodynamics were not significantly affected by formulation or patient status. However, baseline pupil diameter was inversely correlated with age (P < 0.001) and plasma concentrations of oxycodone at half-maximum effect were 31% lower in males compared to females (P < 0.05). Generic substitution of monophasic lipid-based and water-swellable controlled-release oxycodone tablets may be considered safe in RYGB patients.

Exaggerated postprandial GLP-1 secretion following esophagectomy is not associated with gastric emptying and intestinal transit

Esophagectomy causes postprandial symptoms associated with an exaggerated postprandial gut hormone response. This study aimed to compare the gastrointestinal transit time of patients 1 year after esophagectomy with unoperated controls, including its relation to satiety gut hormone release. In this cross-sectional study, consecutive, disease-free patients after esophagectomy with pyloroplasty were compared with unoperated control subjects to assess gastric emptying (GE) and cecal arrival time (CAT). Serial plasma samples were collected before, and for 300 minutes after, a mixed-meal challenge. Body composition was assessed, and symptom scores were calculated. Eleven patients 1 year post-esophagectomy (age: 62.6 ± 9.8, male: 82%) did not show a significantly different GE pattern compared with 10 control subjects (P = 0.245). Rather, patients could be categorized bimodally as exhibiting either rapid or slow GE relative to controls. Those with rapid GE trended toward a higher postprandial symptom burden (P = 0.084) without higher postprandial glucagon-like peptide-1 (GLP-1) secretion (P = 0.931). CAT was significantly shorter after esophagectomy (P = 0.043) but was not significantly associated with GE, GLP-1 secretion, or symptom burden. Neither early nutrient delivery to the proximal small intestine nor to the colon explains the exaggerated postprandial GLP-1 response after esophagectomy. GE varies significantly in these patients despite consistent pyloric management.

Oral drug dosing following bariatric surgery: General concepts and specific dosing advice

Bariatric or weight‐loss surgery is a popular option for weight reduction. Depending on the surgical procedure, gastric changes like decreased transit time and volume and increased pH, decreased absorption surface in the small intestine, decreased exposure to bile acids and enterohepatic circulation, and decreased gastrointestinal transit time may be expected. In the years after bariatric surgery, patients will also substantially lose weight. As a result of these changes, the absorption, distribution, metabolism and/or elimination of drugs may be altered. The purpose of this article is to report the general influence of bariatric surgery on oral drug absorption, and to provide guidance for dosing of commonly used drugs in this special population. Upon oral drug administration, the time to maximum concentration is often earlier and this concentration may be higher with less consistent effects on trough concentrations and exposure. Additionally, prescription of liquid formulations to bariatric patients is supported by some reports, even though the high sugar load of these suspensions may be of concern. Studies on extended‐release medications result in an unaltered exposure for a substantial number of drugs. Also, studies evaluating the influence of timing after surgery show dynamic absorption profiles. Although for this group specific advice can be proposed for many drugs, we conclude that there is insufficient evidence for general advice for oral drug therapy after bariatric surgery, implying that a risk assessment on a case‐by‐case basis is required for each drug.

Gastric Sensory and Motor Functions and Energy Intake in Health and Obesity-Therapeutic Implications

Sensory and motor functions of the stomach, including gastric emptying and accommodation, have significant effects on energy consumption and appetite. Obesity is characterized by energy imbalance; altered gastric functions, such as rapid gastric emptying and large fasting gastric volume in obesity, may result in increased food intake prior to reaching usual fullness and increased appetite. Thus, many different interventions for obesity, including different diets, anti-obesity medications, bariatric endoscopy, and surgery, alter gastric functions and gastrointestinal motility. In this review, we focus on the role of the gastric and intestinal functions in food intake, pathophysiology of obesity, and obesity management.

Impact of drinking Chinese green tea on postoperative short outcomes for gastric cancer: a randomized controlled trial

Background

Early intake after surgery can decrease postoperative ileus. Several studies show coffee can stimulate bowel activity and be safe in patients after elective colectomy, mainly due to caffeine. It was postulated that drinking Chinese green tea as rich caffeine beverage after subtotal distal gastrectomy accelerates postoperative recovery in patients.

Method

This was a single-centre parallel open-label randomized trial. Patients with gastric cancer undergoing robotic or laparoscopic subtotal gastrectomy were randomly allocated to receive drinking Chinese green tea (GT group) or potable water (PW group) after surgery. The primary endpoint was the time to gastrointestinal function recovery and tolerance of solid food, and the secondary endpoints included the incidence of postoperative complications, symptoms of postoperative adverse reaction, length of stay, pain as assessed by analgesic consumption and a visual analogue scale, and fatigue as assessed by a fatigue score model.

Results

A total of 80 patients were recruited, 40 to each group. Patient characteristics were similar in both groups. The GT group showed significantly shorter time to gastrointestinal function recovery compared with PW group to first flatus (47.23 ± 13.46 vs. 76.96 ± 20.35, P < 0.001), first bowel motion (78.70 ± 25.77 vs. 125.76 ± 36.25, P < 0.001) and tolerance of solid food (62.20 ± 16.15 vs. 98.66 ± 20.15, P < 0.001).

Conclusion

Drinking Chinese green tea after robotic or laparoscopic subtotal gastrectomy is safe and promotes postoperative recovery of gastrointestinal function, also was an add method with strengthening analgesia and anti-inflammatory effect in the presence of the Enhance Recovery After Surgery (ERAS) program. Registration number: ChiCTR1800018294 (http://www.chictr.org.cn).

Gastrointestinal pH, Motility Patterns, and Transit Times After Roux-en-Y Gastric Bypass

BACKGROUND

Studies investigating the underlying pathophysiology are needed to help explain and understand the postoperative complications following Roux-en-Y gastric bypass (RYGB) surgery. This study aimed to characterize segmental gastrointestinal pH profiles, motility measures, and transit times in patients with RYGB.

MATERIALS AND METHODS

Nineteen patients with RYGB underwent a standardized wireless motility capsule assessment. The oro-cecal segment was defined from capsule ingestion until the passage of the ileocecal junction. Segmental median pH, motility index, and transit time were determined for the oro-cecal and colonic segment as well as for the first and last hour of both these segments. For comparison to reference values, data from 17 healthy age- and gender-matched controls was used. A mixed effect model was used to describe differences between groups.

RESULTS

Median pH was high in patients with RYGB during the first hour of the oro-cecal segment (6.45 ± 0.4 vs 3.65 ± 1.55 pH units for healthy controls; P < 0.001), as well as during the entire oro-cecal segment (6.97 ± 0.4 vs 5.51 ± 1.1 pH units; P < 0.001). The same was evident for the median motility index (152 ± 64 vs 35.8 ± 31.1 mmHg*sec/min; P < 0.001 and 130 ± 65.9 vs 89.1 ± 20 mmHg*sec/min; P < 0.012, respectively). Median motility index was low the first hour of the colon (55.2 ± 45.7 vs 122 ± 77.9 mmHg*sec/min; P < 0.002). Additionally, patients had short oro-cecal transit time (5.8 ± 1.6 vs 7.6 ± 1.4 h; P < 0.001) and long colonic transit time (29.4 ± 17.5 vs 19.6 ± 12.2 h; P = 0.048).

CONCLUSIONS

In patients with RYGB, the oro-cecal segment was characterized by an alkaline intraluminal environment, high motility activity, and short transit time. In contrast, colonic transit time was long.

Adaptations in gastrointestinal physiology after sleeve gastrectomy and Roux-en-Y gastric bypass

Linked to the growing obesity epidemic, demand for bariatric and metabolic surgery has increased, the most common procedures being sleeve gastrectomy and Roux-en-Y gastric bypass. Originally, bariatric procedures were described as purely restrictive, malabsorptive, or combined restrictive-malabsorptive procedures limiting food intake, nutrient absorption, or both. Nowadays, anatomical alterations are known to affect gastrointestinal physiology, which in turn affects the digestion and absorption of nutrients and drugs. Therefore, understanding gastrointestinal physiology is crucial to prevent postoperative nutritional deficiencies and to optimise postoperative drug therapy. Preclinical and clinical research indicates that sleeve gastrectomy accelerates liquid and solid gastric emptying and small intestinal transit, and increases bile acid serum levels, whereas its effects on gastrointestinal acidity, gastric and pancreatic secretions, surface area, and colonic transit remain largely unknown. Roux-en-Y gastric bypass diminishes gastric acid secretion, accelerates liquid gastric emptying, and increases bile acid serum levels, but its effects on intestinal pH, solid gastric emptying, intestinal transit time, gastric enzyme secretions, and surface area remain largely unknown. In this Review, we summarise current knowledge of the effects of these two procedures on gastrointestinal physiology and assess the knowledge gaps.

Postprandial Changes in Gastrointestinal Hormones and Hemodynamics after Gastrectomy in Terms of Early Dumping Syndrome

Purpose

This study aimed to examine the early postprandial changes in gastrointestinal (GI) hormones and hemodynamics in terms of early dumping syndrome after gastrectomy for gastric cancer.

Materials and Methods

Forty patients who underwent gastrectomy for gastric cancer and 18 controls without previous abdominal surgery were enrolled. Before and 20 minutes after liquid meal ingestion, blood glucose, glucagon-like peptide-1 (GLP-1), and GLP-2 concentrations and superior mesenteric artery (SMA) and renal blood flow were measured. The patients' heart rates were recorded at 5-minute intervals. All subjects were examined for dumping syndrome using a questionnaire based on Sigstad's clinical diagnostic index.

Results

The postprandial increases in blood glucose, GLP-1, and GLP-2 levels as well as SMA blood flow and heart rate were greater in patients who underwent gastrectomy than in controls (all P<0.010). Patients who underwent gastrectomy showed a significantly decreased renal blood flow (P<0.001). Among patients who underwent gastrectomy, distal gastrectomy was a significant clinical factor associated with a lower risk of early dumping syndrome than total gastrectomy (hazard ratio, 0.092; 95% confidence interval, 0.013–0.649; P=0.017). Patients who underwent total gastrectomy showed a greater postprandial increase in blood glucose (P<0.001), GLP-1 (P=0.030), and GLP-2 (P=0.002) levels as well as and heart rate (P=0.013) compared to those who underwent distal gastrectomy.

Conclusions

Early postprandial changes in GI hormones and hemodynamics were greater in patients who underwent gastrectomy than in controls, especially after total gastrectomy, suggesting that these changes play a crucial role in the pathophysiology of early dumping syndrome.

The effect of acute dual SGLT1/SGLT2 inhibition on incretin release and glucose metabolism after gastric bypass surgery

Enhanced meal-related enteroendocrine secretion, particularly of glucagon-like peptide-1 (GLP-1), contributes to weight-loss and improved glycemia after Roux-en-Y gastric bypass (RYGB). Dietary glucose drives GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) secretion postoperatively. Understanding how glucose triggers incretin secretion following RYGB could lead to new treatments of diabetes and obesity. In vitro, incretin release depends on glucose absorption via sodium-glucose cotransporter 1 (SGLT1). We investigated the importance of SGLT1/SGLT2 for enteropancreatic hormone concentrations and glucose metabolism after RYGB in a randomized, controlled, crossover study. Ten RYGB-operated patients ingested 50 g of oral glucose with and without acute pretreatment with 600 mg of the SGLT1/SGLT2-inhibitor canagliflozin. Paracetamol and 3-O-methyl-d-glucopyranose (3-OMG) were added to the glucose drink to evaluate rates of intestinal entry and absorption of glucose, respectively. Blood samples were collected for 4 h. The primary outcome was 4-h plasma GLP-1 (incremental area-under the curve, iAUC). Secondary outcomes included glucose, GIP, insulin, and glucagon. Canagliflozin delayed glucose absorption (time-to-peak 3-OMG: 50 vs. 132 min, P < 0.01) but did not reduce iAUC GLP-1 (6,067 vs. 7,273·min·pmol^-1·L^-1, P = 0.23), although peak GLP-1 concentrations were lowered (-28%, P = 0.03). Canagliflozin reduced GIP (iAUC -28%, P = 0.01; peak concentrations -57%, P < 0.01), insulin, and glucose excursions, whereas plasma glucagon (AUC 3,216 vs. 4,160 min·pmol·L^-1, P = 0.02) and amino acids were increased. In conclusion, acute SGLT1/SGLT2-inhibition during glucose ingestion did not reduce 4-h plasma GLP-1 responses in RYGB-patients but attenuated the early rise in GLP-1, GIP, and insulin, whereas late glucagon concentrations were increased. The results suggest that SGLT1-mediated glucose absorption contributes to incretin hormone secretion after RYGB.

Effect of Roux-en-Y gastric bypass on the bioavailability of metoprolol from immediate and controlled release tablets: a single oral dose study before and after surgery

Objective

Roux-en-Y gastric bypass (RYGB) surgery induces major changes in the gastrointestinal tract that may alter the pharmacokinetics of orally administered drugs. Results from pharmacokinetic studies are sparse. This study aimed to investigate the effect of RYGB on the bioavailability of metoprolol from immediate release (IR) and controlled release (CR) tablets in female patient volunteers before and after surgery.

Methods

An explorative, two-phase, single oral dose pharmacokinetic study of metoprolol in female patients undergoing RYGB was carried out. The dose was administered twice in each patient, 1 month before and 6 months after surgery. After intake of either 100 mg of metoprolol IR or CR tablet serum concentration-time profiles of metoprolol were determined. The endpoint was the ratio of AUC_after/AUC_before of metoprolol.

Results

Twelve patients were included in the study (metoprolol IR: 7; metoprolol CR: 5). After intake of a metoprolol IR tablet major intraindividual and interindividual differences for area under the serum concentration versus time curve (AUC) of metoprolol before and after surgery were observed (range ratio AUC_{0-10 hours after}/AUC_{0-10 hours before}: 0.74-1.98). For metoprolol CR tablets a significant reduction in bioavailability of metoprolol was observed after surgery (range ratio AUC_{0-24 hours after}/AUC_{0-24 hours before}: 0.43-0.77).

Conclusion

RYGB may influence the bioavailability of metoprolol from an IR tablet. The magnitude of changes in bioavailability after RYGB requires close monitoring of patients using metoprolol IR tablets and dose adjustment if deemed necessary. RYGB clearly reduces the bioavailability of metoprolol from a CR tablet. After RYGB clinicians may consider to increase the dose according to clinical response.

Reduced bioavailability of oral amoxicillin tablets compared to suspensions in Roux-en-Y gastric bypass bariatric subjects

AIMS

To evaluate the relative bioavailability of oral amoxicillin (AMX) tablets in comparison to AMX suspension in Roux-en-Y gastric bypass bariatric subjects.

METHODS

A randomized, double-blind, cross-over study was performed on the bioavailability of oral AMX tablets and suspension in Roux-en-Y gastric bypass subjects operated at least 3 months previously . Doses of 875 mg of the AMX tablet or 800 mg of the AMX suspension were given to all the subjects, allowing a washout of 7 days between the periods. Blood samples were collected at 0, 0.25, 0.5, 1, 1.5, 2, 4, 6 and 8 hours after drug administration and the AMX levels were quantified by liquid chromatography coupled with triple quadrupole tandem mass spectrometry. The pharmacokinetic parameters were calculated by noncompartmental analysis, normalized to an 875 mg dose and the bioavailability of the AMX from the tablets was compared to that from the suspension formulation.

RESULTS

Twenty subjects aged 42.65 ± 7.21 years and with a body mass index of 29.88 ± 4.36 kg/m² were enrolled in the study. The maximum AMX plasma concentration of the tablets and the suspension (normalized to 875 mg) were 7.42 ± 2.99 mg/L and 8.73 ± 3.26 mg/L (90% confidence interval of 70.71-99.11), and the total area under the curve from time zero to infinity were 23.10 ± 7.41 mg.h/L and 27.59 ± 8.32 mg.h/L (90% confidence interval of 71.25-97.32), respectively.

CONCLUSION

The tablets presented a lower bioavailability than the suspension formulation and the total absorbed amount of AMX in these subjects was lower in comparison to the standard AMX absorption rates in nonbariatric subjects, regardless of the formulation.

Current State and Future Perspectives on Gastroretentive Drug Delivery Systems

In recent years, many attempts have been made to enhance the drug bioavailability and therapeutic effectiveness of oral dosage forms. In this context, various gastroretentive drug delivery systems (GRDDS) have been used to improve the therapeutic efficacy of drugs that have a narrow absorption window, are unstable at alkaline pH, are soluble in acidic conditions, and are active locally in the stomach. In this review, we discuss the physiological state of the stomach and various factors that affect GRDDS. Recently applied gastrointestinal technologies such as expandable, superporous hydrogel; bio/mucoadhesive, magnetic, ion-exchange resin; and low- and high-density-systems have also been examined along with their merits and demerits. The significance of in vitro and in vivo evaluation parameters of various GRDDS is summarized along with their applications. Moreover, future perspectives on this technology are discussed to minimize the gastric emptying rate in both the fasted and fed states. Overall, this review may inform and guide formulation scientists in designing the GRDDS.

Importance of the gastrointestinal tract in type 2 diabetes. Metabolic surgery is more than just incretin effect

Bariatric and metabolic surgery is creating new concepts about how the intestine assimilates food. Recent studies highlight the role of the gastrointestinal tract in the genesis and evolution of type 2 diabetes. This article has been written to answer frequent questions about metabolic surgery results and the mechanisms of action. For this purpose, a non-systematic search of different databases was carried out, identifying articles published in the last decade referring to the mechanisms of action of metabolic techniques. Understanding these mechanisms will help grasp why some surgeries are more effective than others and why the results can be so disparate among patients undergoing the same surgical approach.

Impact of gastric emptying and small intestinal transit on blood glucose, intestinal hormones, glucose absorption in the morbidly obese

This study evaluated gastric emptying (GE) and small intestinal (SI) transit in people with morbid obesity and their relationships to glycaemia, incretin hormones, and glucose absorption METHODS: GE and caecal arrival time (CAT) of a mixed meal were assessed in 22 morbidly obese (50.2 ± 2.5 years; 13 F:9 M; BMI: 48.6 ± 1.8 kg/m²) and 10 lean (38.6 ± 8.4 years; 5 F:5 M; BMI: 23.9 ± 0.7 kg/m²) subjects, using scintigraphy. Blood glucose, plasma 3-O-methylglucose, insulin, glucagon, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) were measured. Insulin sensitivity and resistance were also quantified RESULTS: When compared with lean subjects, GE (t50: 60.7 ± 6.5 vs. 41.1 ± 7.3 min; P  = 0.04) and CAT (221.5 ± 9.8 vs. 148.0 ± 7.1 min; P =  0.001) of solids were prolonged in morbid obesity. Postprandial rises in GIP (P = 0.001), insulin (P  = 0.02), glucose (P = 0.03) and 3-O-methylglucose (P = 0.001) were less. Whereas GLP-1 increased at 45 mins post-prandially in lean subjects, there was no increase in the obese (P  = 0.04). Both fasting (P = 0.045) and postprandial (P = 0.012) plasma glucagon concentrations were higher in the obese CONCLUSIONS: GE and SI transit are slower in the morbidly obese, and associated with reductions in postprandial glucose absorption, and glycaemic excursions, as well as plasma GIP and GLP-1.

Intraabdominal Pressure and Postoperative Discomfort in Laparoscopic Roux-en-Y Gastric Bypass (RYGB) Surgery: a Randomized Study

BACKGROUND

High intraabdominal pressure (IAP) during laparoscopic surgery has been associated with postoperative discomfort. Effects on nausea and access have not been subjected to randomized studies. In cholecystectomy, lower IAP may cause less pain, but nausea and surgical access in RYGB surgery have not been investigated. We studied the influence of two IAP levels on surgical access, operation time, postoperative pain, and nausea.

METHODS

Fifty consecutive female gastric bypass patients were randomized to intraabdominal pressure of 12 (IAP12) or 18 (IAP18) mm Hg. Surgeons and personnel were blinded to randomization; study groups were well matched for age and BMI. Operative time was noted in minutes. Visual analogue scales were used for assessing access and for patients assessing pain (abdomen-shoulder) and nausea (supine-standing) at six time points during the first 16 postoperative hours. Rescue medication was recorded.

RESULTS

In 3/25 patients in the IAP12 group, the code was broken due to access problems vs. 0/25 in the IAP18 group (p = 0.1398). Operative time did not differ. Access was significantly better for IAP18 (92.2 ± 2.3 vs. 69.3 ± 4.2; p = 0.0001). Postoperative shoulder pain was maximal after 6 h but throughout less than in the abdomen (p < 0.0001); there were no differences in pain between IAP18 and IAP12 (p = 0.7408). Postoperative nausea was significantly greater standing than supine but without differences between groups.

CONCLUSION

Higher IAP gives better surgical access in laparoscopic Roux-en-Y gastric bypass with no negative effect on pain or nausea.

Effect of meal size and texture on gastric pouch emptying and glucagon-like peptide 1 after gastric bypass surgery

BACKGROUND

Roux-en-Y gastric bypass (RYGB) accelerates gastric pouch emptying, enhances postprandial glucagon-like peptide 1 (GLP-1) and insulin, and lowers glucose concentrations. To prevent discomfort and reactive hypoglycemia, it is recommended that post-RYGB patients eat small, frequent meals and avoid caloric drinks. However, the effect of meal size and texture on GLP-1 and metabolic response has not been studied.

OBJECTIVES

To demonstrate that frequent minimeals and solid meals (S) elicit less GLP-1 and insulin release and less reactive hypoglycemia and are better tolerated compared with a single isocaloric liquid meal (L).

SETTING

A university hospital.

METHODS

In this prospective study, 32 RYGB candidates were enrolled and randomized to L or S groups before gastric bypass. Each subject received an L or S 600-kcal single meal (SM) administered at hour 0 or three 200-kcal minimeals administered at hours 0, 2, and 4 on 2 separate days. Twenty-one patients were retested 1 year after RYGB. Blood and visual analogue scale measurements were collected up to 6 hours postprandially. Outcome measures included gastric pouch emptying, glucose, insulin, and GLP-1; hunger, fullness, and stomach discomfort were measured by visual analogue scale.

RESULTS

Twenty-one were patients retested after RYGB (L: n = 12; S: n = 9). Meal texture had a significant effect on peak GLP-1 (L-SM: 106.1 ± 67.2 versus S-SM: 45.3 ± 25.2 pM, P = .004), peak insulin, and postprandial glucose. Hypoglycemia was more frequent after the L-SM meal compared with the S-SM. Gastric pouch emptying was 2.4 times faster after RYGB but was not affected by texture.

CONCLUSIONS

Meal texture and size have significant impact on tolerance and metabolic response after RYGB.

Gastric pouch emptying of solid food in patients with successful and unsuccessful weight loss after Roux-en-Y gastric bypass surgery

BACKGROUND

After Roux-en-Y gastric bypass (RYGB), approximately 10% of patients have insufficient weight loss (excess body mass index loss<50%). Gastric pouch emptying may have a role in weight loss.

OBJECTIVES

To compare pouch emptying of patients with poor weight loss and patients with successful weight loss after RYGB.

SETTING

A research-intensive nonacademic hospital and center of expertise in bariatric surgery in the Netherlands METHODS: Female patients were included from among patients with the least (poor weight loss group [P-WL]) and the most weight loss (successful weight loss group [S-WL]) in our center 2 years after RYGB. Pouch emptying scintigraphy was performed after ingestion of a radiolabeled solid meal. Emptying curves, intestinal content (IC) at meal completion and after 15, 30, 45, and 60 minutes, half emptying time, and maximal pouch emptying rate were compared.

RESULTS

Five individuals were included in P-WL and 5 in S-WL, on average 2.5 ± .3 years after RYGB. Total weight loss was 18 ± 4.1% in P-WL and 44 ± 5.7% in S-WL (P<.001). In P-WL, a fast initial pouch emptying and exponential emptying curve was observed, compared with a slower initial emptying and more linear curve in S-WL. Faster emptying in P-WL was also shown by a larger IC_meal (42 ± 18% versus 4.0 ± 3.3%,), IC₁₅ (76 ± 15% versus 35 ± 22%), and IC₃₀ (85 ± 12% versus 54 ± 25%), and a greater maximal pouch emptying rate (17 ± 4.7 versus 5.6 ± 3.4%/min) compared with S-WL (P<.05). A linear correlation was found between total weight loss and maximal pouch emptying rate (Pearson R = .82, P = .004).

CONCLUSIONS

Pouch emptying for solid food was faster in patients with the least weight loss compared with patients with the most weight loss after RYGB. If pouch emptying is an important mechanism in weight loss, altering the pouch outlet may improve poor weight loss management.

Overview on gastroretentive drug delivery systems for improving drug bioavailability

In recent decades, many efforts have been made in order to improve drug bioavailability after oral administration. Gastroretentive drug delivery systems are a good example; they emerged to enhance the bioavailability and effectiveness of drugs with a narrow absorption window in the upper gastrointestinal tract and/or to promote local activity in the stomach and duodenum. Several strategies are used to increase the gastric residence time, namely bioadhesive or mucoadhesive systems, expandable systems, high-density systems, floating systems, superporous hydrogels and magnetic systems. The present review highlights some of the drugs that can benefit from gastroretentive strategies, such as the factors that influence gastric retention time and the mechanism of action of gastroretentive systems, as well as their classification into single and multiple unit systems.

Effects of Fat and Protein Preloads on Pouch Emptying, Intestinal Transit, Glycaemia, Gut Hormones, Glucose Absorption, Blood Pressure and Gastrointestinal Symptoms After Roux-en-Y Gastric Bypass

BACKGROUND

The aim was to determine the effects of fat and protein preloads on pouch emptying (PE), caecal arrival time (CAT), glucose absorption, blood glucose (BSL), gut hormones, haemodynamics and gastrointestinal (GI) symptoms in subjects who had undergone Roux-en-Y gastric bypass (RYGB) >12 months previously.

METHODS

Ten RYGB subjects were studied on three occasions, in randomised order, receiving 200-ml preloads of either water, fat (30 ml olive oil) or whey protein (55 g), 30 min before a mixed meal. PE, CAT, BSL, plasma 3-O-methyl-D-glucopyranose (3-OMG), insulin, glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide 1 (GLP-1) and glucagon, blood pressure (BP), heart rate (HR) and GI symptoms were assessed over 270 min.

RESULTS

Although fat and protein preloads did not alter PE of either solids or liquids, the CAT of solids, but not liquids, was longer than that after the water preload (fat 68 ± 5 min and protein 71 ± 6 min vs. water 46 ± 5 min; P = 0.02). BSL elevated promptly after the meal on all days (P < 0.001), but after protein, the magnitude and integrated increases in the first 75 min were less than fat and water preloads (area under the curve (AUC(0-75 min)), 18.7 ± 18.2 vs. 107.2 ± 30.4 and 76.1 ± 19.3 mmol/L/min; P < 0.05). Compared to water preload, the protein and fat preloads were associated with greater increases in plasma insulin, GLP-1 and glucagon concentrations, a reduction in BP, and greater increases in HR, fullness, bloating and nausea. Plasma 3-OMG levels were lower after the protein than after the water and fat preloads (P < 0.001).

CONCLUSIONS

Given its effects to attenuate post-prandial glycaemia, reduce intestinal glucose absorption and potentiate the "incretin response", without inducing more adverse post-prandial GI symptom, protein preload may prove clinically useful in RYGB patients and warrant further evaluation, particularly in those with type 2 diabetes (T2DM) and/or dumping syndrome.