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Background The clearance of cytochrome P450 (CYP) 3A substrates is reported to be reduced with lower age, inflammation and obesity. As it is unknown what the overall influence is of these factors in the case of obese adolescents vs. morbidly obese adults, we studied covariates influencing the clearance of the CYP3A substrate midazolam in a combined analysis of data from obese adolescents and morbidly obese adults. Methods Data from 19 obese adolescents [102.7 kg (62–149.5 kg)] and 20 morbidly obese adults [144 kg (112–186 kg)] receiving intravenous midazolam were analysed, using population pharmacokinetic modelling (NONMEM 7.2). In the covariate analysis, the influence of study group, age, total body weight (TBW), developmental weight (WTfor age and length) and excess body weight (WTexcess = TBW − WTfor age and length) was evaluated. Results The population mean midazolam clearance was significantly higher in obese adolescents than in morbidly obese adults [0.71 (7%) vs. 0.44 (11%) L/min; p < 0.01]. Moreover, clearance in obese adolescents increased with TBW (p < 0.01), which seemed mainly explained by WTexcess, and for which a so-called ‘excess weight’ model scaling WTfor age and length to the power of 0.75 and a separate function for WTexcess was proposed. Discussion We hypothesise that higher midazolam clearance in obese adolescents is explained by less obesity-induced suppression of CYP3A activity, while the increase with WTexcess is explained by increased liver blood flow. The approach characterising the influence of obesity in the paediatric population we propose here may be of value for use in future studies in obese adolescents.

Introduction: Acetaminophen (paracetamol) is mainly metabolized via glucuronidation and sulphation, while the minor pathway through cytochrome P450 (CYP) 2E1 is held responsible for hepatotoxicity. In obese patients, CYP2E1 activity is reported to be induced, thereby potentially worsening the safety profile of acetaminophen. The aim of this study was to determine the pharmacokinetics of acetaminophen and its metabolites (glucuronide, sulphate, cysteine and mercapturate) in morbidly obese and non-obese patients. Methods: Twenty morbidly obese patients (with a median total body weight [TBW] of 140.1 kg [range 106–193.1 kg] and body mass index [BMI] of 45.1 kg/m2 [40–55.2 kg/m2]) and eight non-obese patients (with a TBW of 69.4 kg [53.4–91.7] and BMI of 21.8 kg/m2 [19.4–27.4]) received 2 g of intravenous acetaminophen. Fifteen blood samples were collected per patient. Population pharmacokinetic modelling was performed using NONMEM. Results: In morbidly obese patients, the median area under the plasma concentration–time curve from 0 to 8 h (AUC0–8h) of acetaminophen was significantly smaller (P = 0.009), while the AUC0–8h ratios of the glucuronide, sulphate and cysteine metabolites to acetaminophen were significantly higher (P = 0.043, 0.004 and 0.010, respectively). In the model, acetaminophen CYP2E1-mediated clearance (cysteine and mercapturate) increased with lean body weight [LBW] (population mean [relative standard error] 0.0185 L/min [15 %], P < 0.01). Moreover, accelerated formation of the cysteine and mercapturate metabolites was found with increasing LBW (P < 0.001). Glucuronidation clearance (0.219 L/min [5 %]) and sulphation clearance (0.0646 L/min [6 %]) also increased with LBW (P < 0.001). Conclusion: Obesity leads to lower acetaminophen concentrations and earlier and higher peak concentrations of acetaminophen cysteine and mercapturate. While a higher dose may be anticipated to achieve adequate acetaminophen concentrations, the increased CYP2E1-mediated pa

Background: The peritoneum is the second most common site of recurrence in colorectal cancer. Early detection of peritoneal carcinomatosis (PC) by imaging is difficult. Patients eventually presenting with clinically apparent PC have a poor prognosis. Median survival is only about five months if untreated and the benefit of palliative systemic chemotherapy is limited. Only a quarter of patients are eligible for curative treatment, consisting of cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CR/HIPEC). However, the effectiveness depends highly on the extent of disease and the treatment is associated with a considerable complication rate. Methods/Design: The aim of this study is to determine the effectiveness of adjuvant HIPEC in preventing the development of PC in patients with colon cancer at high risk of peritoneal recurrence. This study will be performed in the nine Dutch HIPEC centres, starting in April 2015. Eligible for inclusion are patients who underwent curative resection for T4 or intra-abdominally perforated cM0 stage colon cancer. After resection of the primary tumour, 176 patients will be randomized to adjuvant HIPEC followed by routine adjuvant systemic chemotherapy in the experimental arm, or to systemic chemotherapy only in the control arm. Adjuvant HIPEC will be performed simultaneously or shortly after the primary resection. Oxaliplatin will be used as chemotherapeutic agent, for 30 min at 42-43 °C. Just before HIPEC, 5-fluorouracil and leucovorin will be administered intravenously. Primary endpoint is peritoneal disease-free survival at 18 months. Diagnostic laparoscopy will be performed routinely after 18 months postoperatively in both arms of the study in patients without evidence of disease based on routine follow-up using CT imaging and CEA. Discussion: Adjuvant HIPEC is assumed to reduce the expected 25 % absolute risk of PC in patients with T4 or perforated colon cancer to a risk of 10 %. This reduction is likely to trans

Context: Most patients with infected necrotizing pancreatitis require necrosectomy. Surgical necrosectomy induces a proinflammatory response and is associated with a high complication rate. Endoscopic transgastric necrosectomy, a form of natural orifice transluminal endoscopic surgery, may reduce the proinflammatory response and reduce complications. Objective: To compare the proinflammatory response and clinical outcome of endoscopic transgastric and surgical necrosectomy. Design, Setting, and Patients: Randomized controlled a

Background: After an initial attack of biliary pancreatitis, cholecystectomy minimizes the risk of recurrent biliary pancreatitis and other gallstone-related complications. Guidelines advocate performing cholecystectomy within 2 to 4 weeks after discharge for mild biliary pancreatitis. During this waiting period, the patient is at risk of recurrent biliary events. In current clinical practice, surgeons usually postpone cholecystectomy for 6 weeks due to a perceived risk of a more difficult dissection in the early days following pancreatitis and for logistical reasons. We hypothesize that early laparoscopic cholecystectomy minimizes the risk of recurrent biliary pancreatitis or other complications of gallstone disease in patients with mild biliary pancreatitis without increasing the difficulty of dissection and the surgical complication rate compared with interval laparoscopic cholecystectomy.Methods/Design: PONCHO is a randomized controlled, parallel-group, assessor-blinded, superiority multicenter trial. Patients are randomly allocated to undergo early laparoscopic cholecystectomy, within 72 hours after randomization, or interval laparoscopic cholecystectomy, 25 to 30 days after randomization. During a 30-month period, 266 patients will be enrolled from 18 hospitals of the Dutch Pancreatitis Study Group. The primary endpoint is a composite endpoint of mortality and acute re-admissions for biliary events (that is, recurrent biliary pancreatitis, acute cholecystitis, symptomatic/obstructive choledocholithiasis requiring endoscopic retrograde cholangiopancreaticography including cholangitis (with/without endoscopic sphincterotomy), and uncomplicated biliary colics) occurring within 6 months following randomization. Secondary endpoints include the individual endpoints of the composite endpoint, surgical and other complications, technical difficulty of cholecystectomy and costs.Discussion: The PONCHO trial is designed to show that early laparoscopic cholecystectomy (wit

Background: Necrotizing pancreatitis with infected necrotic tissue is associated with a high rate of complications and death. Standard treatment is open necrosectomy. The outcome may be improved by a minimally invasive step-up approach. Methods: In this multicenter study, we randomly assigned 88 patients with necrotizing pancreatitis and suspected or confirmed infected necrotic tissue to undergo primary open necrosectomy or a step-up approach to treatment. The step-up approach consisted of percutaneous drainage followed, if necessary, by minimally invasive retroperitoneal necrosectomy. The primary end point was a composite of major complications (new-onset multiple-organ failure or multiple systemic complications, perforation of a visceral organ or enterocutaneous fistula, or bleeding) or death. Results: The primary end point occurred in 31 of 45 patients (69%) assigned to open necrosectomy and in 17 of 43 patients (40%) assigned to the step-up approach (risk ratio with the step-up approach, 0.57; 95% confidence interval, 0.38 to 0.87; P = 0.006). Of the patients assigned to the step-up approach, 35% were treated with percutaneous drainage only. New-onset multiple-organ failure occurred less often in patients assigned to the step-up approach than in those assigned to open necrosectomy (12% vs. 40%, P = 0.002). The rate of death did not differ significantly between groups (19% vs. 16%, P = 0.70). Patients assigned to the step-up approach had a lower rate of incisional hernias (7% vs. 24%, P = 0.03) and new-onset diabetes (16% vs. 38%, P = 0.02). Conclusions: A minimally invasive step-up approach, as compared with open necrosectomy, reduced the rate of the composite end point of major complications or death among patients with necrotizing pancreatitis and infected necrotic tissue. (Current Controlled Trials number, ISRCTN13975868.). Copyright

Background: The initial treatment of acute necrotizing pancreatitis is conservative. Intervention is indicated in patients with (suspected) infected necrotizing pancreatitis. In the Netherlands, the standard intervention is necrosectomy by laparotomy followed by continuous postoperative lavage (CPL). In recent years several minimally invasive strategies have been introduced. So far, these strategies have never been compared in a randomised controlled trial. The PANTER study (PAncreatitis, Necrosectomy versus sTEp up appRoach) was conceived to yield the evidence needed for a considered policy decision. Methods/design: 88 patients with (suspected) infected necrotizing pancreatitis will be randomly allocated to either group A) minimally invasive 'step-up approach' starting with drainage followed, if necessary, by videoscopic assisted retroperitoneal debridement (VARD) or group B) maximal necrosectomy by laparotomy. Both procedures are followed by CPL. Patients will be recruited from 20 hospitals, including all Dutch university medical centres, over a 3-year period. The primary endpoint is the proportion of patients suffering from postoperative major morbidity and mortality. Secondary endpoints are complications, new onset sepsis, length of hospital and intensive care stay, quality of life and total (direct and indirect) costs. To demonstrate that the 'step-up approach' can reduce the major morbidity and mortality rate from 45 to 16%, with 80% power at 5% alpha, a total sample size of 88 patients was calculated. Discussion: The PANTER-study is a randomised controlled trial that will provide evidence on the merits of a minimally invasive 'step-up approach' in patients with (suspected) infected necrotizing pancreatitis.