lipid-a and Tachycardia

E5564 (alpha-D-glucopyranose) is a synthetic antagonist of bacterial endotoxin that has been shown to completely block human endotoxin response. Low doses of E5564 (0.35-3.5 mg) have a long pharmacokinetic half-life, but a surprisingly short ex vivo and in vivo pharmacodynamic half-life (generally less than several hours). To determine whether extended antagonistic activity can be achieved in vivo, this study assesses the pharmacodynamic activity of 4- and 72-h infusions of E5564 into normal volunteers. Administration of 3.5 mg of E5564/h x 72 h completely blocked effects of endotoxin challenge at the end of dosing (72 h), and at 48 and 72 h postdosing. Similarly, a 4-h infusion of E5564, 3 mg/h completely blocked endotoxin administered 8 h postdosing. A lower dose of E5564, 0.5 mg/h x 4 h, ameliorated but did not block most effects of endotoxin 8 h postdosing (p <0.05). Finally, the effect of varying plasma lipoprotein content on E5564 activity was studied in subjects having high or low cholesterol levels (>180 or <140 mg/dl) after 72-h infusion of 252 mg of E5564. No differences were observed. These results demonstrate that E5564 blocks the effects of endotoxin in a human model of clinical sepsis and indicate its potential in the treatment and/or prevention of clinical sepsis.

Topics: Adolescent; Adult; Blood Pressure; C-Reactive Protein; Cytokines; Endotoxemia; Endotoxins; Humans; Leukocytes; Lipid A; Lipopolysaccharides; Male; Middle Aged; Tachycardia

The present study was designed to assess whether a protective effect of the modified diphosphoryl lipid A (modLA) against myocardial ischemia-reperfusion injury (IRI) in rats can be related to the mechanism involving inducible nitric oxide synthase (iNOS). Pre-treatment with modLA significantly reduced the duration of both ventricular tachycardia (p < 0.01) and ventricular fibrillation (p < 0.001) compared to controls. Under these conditions the incidence of animal death was reduced (p < 0.05). The beneficial effect of modLA was markedly attenuated by the prior administration of selective iNOS inhibitor S-methylisothiourea (SMT). In this animal group, mortality was significantly increased (p < 0.01) partially in consequence of sustained ventricular arrhythmias. These results indicate that induction of iNOS can be responsible for cardioprotection of modLA.

Topics: Animals; Cardiotonic Agents; Enzyme Inhibitors; In Vitro Techniques; Isothiuronium; Lipid A; Male; Myocardial Reperfusion Injury; NG-Nitroarginine Methyl Ester; Nitric Oxide Synthase Type II; Rats; Rats, Wistar; Tachycardia