Pharmacotherapy
-
Compared with parenteral nutrition, early administration of enteral nutrition (EN) to critically ill patients improves clinical outcomes and reduces infection rates. Intragastric EN often is complicated by intolerance, as indicated by elevated volumes of aspirated gastric residuals. Conflicting data are available for the volume of residual that represents intolerance, but most clinicians use 150-200 ml to signify gastrointestinal motility dysfunction. ⋯ Results of most studies are limited because patients did not receive or tolerated intragastric EN. Metoclopramide is the agent of choice for treating intolerance. Further studies are necessary before prokinetic drugs can be recommended for preventing intragastric EN-associated aspiration pneumonia.
-
Observational studies in patients have shown a dose-dependent enhancement of the anticoagulant effect of warfarin by acetaminophen whereas pharmacodynamic studies in healthy human volunteers have shown no such effect. This controversy is further intensified because any interaction between acetaminophen and racemic warfarin can involve only the weaker R-warfarin enantiomer. Certain drugs exclusively competing for the metabolism of R-warfarin enhance the anticoagulant effect of racemic warfarin and others do not. ⋯ Conditions such as aging and tissue hypoxia alter the relative activity of these enzymatic pathways in vitro and in small human studies. These phenomena may be manifested clinically when acetaminophen is administered to older anticoagulated patients and those with conditions that affect cardiac output such as atrial fibrillation and congestive heart failure. Verifying this hypothesis may provide insight into the clinically relevant interplay between common conditions as they affect oxidative and nonoxidative pathways of drug metabolism.