Changing patterns of gastrointestinal bleeding

This study, a retrospective analysis of 351 patients with acute gastrointestinal (GI) hemorrhage, was undertaken to define patterns of disease and age-related operative and mortality rates and to determine changes over time related to changes in management. One third (116 patients) of the admissions had bleeding esophageal varices. Upper GI hemorrhage accounted for 85% (N = 200) and lower GI hemorrhage for 15% (N = 35). Emergency surgical intervention was required in 90 patients (38%), 40% of the upper and 29% of the lower GI hemorrhage patients. Benign ulcer disease accounted for 86% of the cases requiring emergency surgery and was treated with vagotomy and drainage and/or oversewing. Lower GI bleeding is seen in older patients; it has a lower operative intervention rate and a higher mortality. Stress bleeding as a surgical lesion has disappeared since 1979. A more assertive policy for surgical intervention has decreased operative mortality for all age groups. Bleeding duodenal ulcers are decreasing in incidence while gastric lesions appear to be increasing. These population-specific patterns, different from earlier periods, may have implications for training and patient management decisions.     

Population pharmacokinetics of nevirapine in HIV-1-infected pregnant women and their neonates

The aim of the present study was to describe the nevirapine (NVP) pharmacokinetics (PK) in pregnant women and their neonates and to evaluate the transplacental drug transfer and administration scheme for the prevention of mother-to-child transmission. Thirty-eight HIV-1-infected pregnant women were administered one tablet of NVP (200 mg) and two tablets of tenofovir-emtricitabine (Truvada) at the initiation of labor. Children were given NVP syrup (2 mg/kg of body weight) as a single dose (sdNVP) on the first day of life. By pair, NVP concentrations were measured in 11 maternal, 1 cord blood, and 2 neonatal plasma samples and analyzed by a population approach. A one-compartment model was used for mothers and neonates; the absorption rate constants for mothers and neonates were 0.95 h(-1) (intersubject variability, 111%) and 0.39 h(-1), respectively; the apparent elimination clearances were 1.42 liter·h(-1) (intersubject variability, 22%) and 0.035 liter·h(-1), respectively; and apparent volumes of distribution were 87.3 liters (intersubject variability, 25%) and 5.65 liters, respectively. An effect compartment was linked to maternal circulation by mother-to-cord and cord-to-mother rate constants of 1.10 h(-1) and 1.43 h(-1), respectively. Placental transfer, expressed as the fetal-to-maternal area under the curve ratio, was 75%. Neonates had a very long half-lives (110 h) compared to adults. In the 38 mothers, the simulated median individual predicted time during which the NVP concentration remained above the half-maximal inhibitory concentration (IC(50)) was 13.2 days (range, 12 to 19.2 days). Thus, the administration of tenofovir-emtricitabine for at least 3 weeks after delivery should be considered to prevent the emergence of resistant viruses. The neonate must receive sdNVP immediately after birth when the infant is born less than 30 min after maternal drug intake to keep NVP concentrations above the IC(50).     

Independent-model diagnostics for a priori identification and interpretation of outliers from a full pharmacokinetic database: correspondence analysis,Mahalanobis distance and Andrews curves

Population pharmacokinetic (PK) (or pharmacodynamic (PD)) modelling aims to analyse the variability of drug kinetics (or dynamics) between numerous subjects belonging to a population. Such variability includes inter- and intra-individual sources leading to important differences between the variation ranges, the relative concentrations and the global shapes of PK profiles. These various sources of variability suggest that the distance metrics between the subjects can be examined under different aspects. Some subjects are so distant from the majority that they tend to be atypical or outliers. This paper presents three multivariate statistical methods to diagnose the outliers within a full population PK dataset, prior to any modelling step. Each method combined all the concentration-time variables to analyse the differences between patients by referring to a distance criterion: (a) Correspondence analysis (CA) used the chi-square distance to highlight the most atypical profiles in terms of relative concentrations; (b) Mahalanobis distance was calculated to extract PK profiles showing atypical shapes due to atypical variations in concentration; (c) Andrews method combined all the concentration variables into a Fourier transformation to give sine-cosine curves showing the clustering behaviours of subjects under the Euclidean distance criterion. After identification of outlier subjects, these methods can also be used to extract the concentration values which cause the atypical states of the patients. Therefore, the outliers will incorporate different variability sources of the PK dataset according to each method and independently of any PK modelling. Finally, a significant positive trend was found between the number of times outlier concentrations were detected (by one, two or three diagnostics) and the NPDE metrics of these concentrations (after a PK modelling): NPDE were highest when the corresponding concentration was detected by more diagnostics a priori. The application of a priori outlier diagnostics is illustrated here on two PK datasets: stimulated cortisol by synacthen and capecitabine administrated orally.     

Safety,pharmacokinetics, and activity of EZN‐2208, a novel conjugate of polyethylene glycol and SN38, in patients with advanced malignancies

BACKGROUND:

EZN‐2208 is a water‐soluble, polyethylene glycol drug conjugate of SN38, which is the active moiety of irinotecan. In this study, the authors evaluated the tolerability, pharmacokinetics (PK), and activity of EZN‐2208 in adult patients with advanced solid tumors.

METHODS:

Patients in sequential cohorts (3 + 3 design) received intravenous EZN‐2208 at doses between 1.25 mg/m² and 25 mg/m² once every 21 days.

RESULTS:

Thirty‐nine patients received EZN‐2208. The median number of prior therapies was 2 (range, 0‐10 prior therapies). Seventeen patients received prior irinotecan. Two maximum tolerated doses (MTDs) were defined: EZN‐2208 with (16.5 mg/m²) and without (10 mg/m²) granulocyte‐colony–stimulating factor (G‐CSF). The dose‐limiting toxicity (DLT) was febrile neutropenia. Two of 19 patients who were heterozygous for a polymorphism in the uridine diphosphate glucuronosyltransferase 1 family, polypeptide A1 (UGT1A1) gene (UGT1A1*28) developed DLTs (dose, 25 mg/m² with G‐CSF), and 2 patients who were homozygous for UGT1A1*28 were treated without DLTs (dose, 5 mg/m²). PK analysis indicated a mean terminal half‐life of 19.4 ± 3.4 hours. Sixteen patients (41%) achieved stable disease, including 6 of 39 patients (15%) who had stable disease that lasted ≥4 months. One patient with cholangiocarcinoma (no prior irinotecan) achieved a short‐lived 32% tumor regression. Among 6 patients who had stable disease that lasted for ≥4 months, 3 had received prior irinotecan, and 1 had KRAS‐positive colorectal cancer.

CONCLUSIONS:

EZN‐2208 was well tolerated and produced stable disease that lasted for ≥4 months/unconfirmed partial responses in 7 of 39 heavily pretreated patients (18%) with advanced solid tumors, including those who had failed prior irinotecan therapy. Cancer 2012. © 2012 American Cancer Society.     

Cystatin M loss is associated with the losses of estrogen receptor,progesterone receptor,and HER4 in invasive breast cancer

Introduction  

This study was aimed at understanding the clinicopathological significance of cystatin M loss, and investigating possible factors responsible for cystatin M loss in breast cancer.     

Serum free 5-methoxypsoralen fraction in health and psoriasis: relationship with human serum albumin concentration

Human serum albumin is known to be the main carrier of 5-methoxypsoralen (5-MOP) in serum. As hypoalbuminaemia may occur in psoriasis with inflammatory syndrome, variability of the free 5-MOP fraction in serum can be expected. The free 5-MOP fraction was determined by equilibrium dialysis in serum samples obtained from 18 psoriatic patients and 18 control subjects. The median free 5-MOP fraction was not significantly different in the psoriatic group (fu=4.75%) than in the control group (fu=5%). However, there was a significantly larger variability of the free fraction in the psoriatic group (2.7 to 8.6%) than in the healthy group (3.2 to 6.8%) (p=0.002). The binding index of 5-MOP (ratio of bound to free concentrations) was correlated with human serum albumin level (r=0.784). This work confirms that the 5-MOP fraction in human serum is principally serum albumin dependent, as has been described with in vitro models. Free drug monitoring of 5-MOP is discussed.     

Is the Recommended Dose of Efavirenz Optimal in Young West African Human Immunodeficiency Virus-Infected Children?

We aimed in this study to describe efavirenz concentration-time courses in treatment-naïve children after once-daily administration to study the effects of age and body weight on efavirenz pharmacokinetics and to test relationships between doses, plasma concentrations, and efficacy. For this purpose, efavirenz concentrations in 48 children were measured after 2 weeks of didanosine-lamivudine-efavirenz treatment, and samples were available for 9/48 children between months 2 and 5 of treatment. Efavirenz concentrations in 200 plasma specimens were measured using a validated high-performance liquid chromatography method. A population pharmacokinetic model was developed with NONMEM. The influence of individual characteristics was tested using a likelihood ratio test. The estimated minimal and maximal concentrations of efavirenz in plasma (C_min and C_max, respectively) and the area under the concentration-time curve (AUC) were correlated to the decrease in human immunodeficiency virus type 1 RNA levels after 3 months of treatment. The threshold C_min (and AUC) that improved efficacy was determined. The target minimal concentration of 4 mg/liter was considered for toxicity. An optimized dosing schedule that would place the highest percentage of children in the interval of effective and nontoxic concentrations was simulated. The pharmacokinetics of efavirenz was best described by a one-compartment model with first-order absorption and elimination. The mean apparent clearance and volume of distribution for efavirenz were 0.211 liter/h/kg and 4.48 liters/kg, respectively. Clearance decreased significantly with age. When the recommended doses were given to 46 of the 48 children, 19% (44% of children weighing less than 15 kg) had C_mins below 1 mg/liter. A significantly higher percentage of children with C_mins of >1.1 mg/liter or AUCs of >51 mg/liter·h than of children with lower values had viral load decreases greater than 2 log₁₀ copies/ml after 3 months of treatment. Therefore, to optimize the percentage of children with C_mins between 1.1 and 4 mg/liter, children should receive the following once-daily efavirenz doses: 25 mg/kg of body weight from 2 to 6 years, 15 mg/kg from 6 to 10 years, and 10 mg/kg from 10 to 15 years. These assumptions should be prospectively confirmed.The combination of didanosine (ddI), lamivudine (3TC), and efavirenz (EFV) once daily has improved compliance for adults and shown good antiretroviral efficacy (12); moreover, the treatment could be better tolerated in the long term (5, 6, 13). For children, the efficacy and tolerance of this ddI-3TC-EFV combination have not been investigated. The aims of the BURKINAM (ANRS 12103) study, then, were to investigate the pharmacokinetics of EFV, ddI, and 3TC given once daily in children 30 months to 15 years old and to evaluate the efficacy and tolerance of this combination.EFV is metabolized exclusively via CYP2B6 (cytochrome P450 isoenzyme) in the liver (20). Several factors (covariates), such as age (9), duration of treatment (7), or ethnicity (8), may affect EFV metabolism. In the present work, a population pharmacokinetic study was performed with African children in order to describe the concentration-time courses of EFV and to study the influence of covariates on EFV pharmacokinetics.Relationships between EFV antiretroviral efficacy/toxicity and plasma EFV concentrations have been established previously for adults (14). No or weak pharmacokinetic-pharmacodynamic relationships were reported in children. Moreover, pediatric studies suggested that the actual recommended EFV dosage produced insufficient concentrations of the drug in plasma (19, 21). In this study, the correlation between concentrations and efficacy was finally tested, the threshold area under the concentration-time curve (AUC) and minimum concentration of the drug in plasma (C_min) that improved efficacy were determined, and an optimized dosing scheme was simulated.