Direct Oral Anticoagulants in Special Patient Populations

Anticoagulants are a cornerstone of treatment in atrial fibrillation. Nowadays, direct oral anticoagulants (DOACs) are extensively used for this condition in developed countries. However, DOAC treatment may be inappropriate in certain patient populations, such as: patients with chronic kidney disease in whom DOAC concentrations may be dangerously elevated; frail elderly patients with an increased risk of falls; patients with significant drug–drug interactions (DDI) affecting either DOAC concentration or effect; patients at the extremes of body mass in whom an “abnormal” volume of distribution may result in inappropriate drug concentrations; patients with recurrent stroke reflecting an unusually high thromboembolic tendency; and, lastly, patients who experience major hemorrhage on an anticoagulant and in whom continued anticoagulation is deemed necessary. Herein we provide a fictional case-based approach to review the recommendations for the use of DOACs in these special patient populations

QSAR models for tyrosinase inhibitory activity description applying modern statistical classification techniques: A comparative study

Cluster analysis (CA). Linear and Quadratic Discriminant Analysis (L(Q)DA), Binary Logistic Regression (BLR) and Classification Tree (CT) are applied on two datasets for description of tyrosinase inhibitory activity from molecular structures. The first set included 701 tyrosinase inhibitors (TI) that are used for performance of inhibitory and non-inhibitory activity and the second one is for potency estimation of active compounds. 2D TOMOCOMD-CARDD atom-based quadratic indices are computed as molecular descriptors. CA is used to "rational" design of training (TS) and prediction set (PS) but it shows of not being adequate as classification technique. On the first data, the overall accuracies (Q) are 91.42%, 92.35% 91.88%, 91.79% for TS, and 91.04%, 92.43%, 88.24%, 89.36% for PS in LDA, QDA BLR and CT-based model, respectively, while the corresponding values obtained on the second one are 89.95%, 90.70%, 90.20%, 89.20% for TS and 83.71%, 84.44%, 82.96%, 82.22% for PS. A comparative analysis of used statistical techniques is held out taking into consideration generated posterior probability, accuracy, required assumptions and the form of predictor variables used. On the two datasets, results depicted by Receiver Operating Characteristic (ROC) curves together with Multiple Comparison Procedures (MCP) show that QDA has in general the best behavior as classification algorithm. The results suggest that it will be possible to produce a better description of tyrosinase activity applying the statistical techniques presented in this report, which could increase the practicality of the in silico data mining for the discovery of novel Tls. (C) 2010 Elsevier B.V. All rights reserved