Attenuation of Tissue Thrombosis and Hemorrhage by ala-TFPI Does not Account for Its Protection against E. coli

This study was designed to determine the effect of a delayed infusion (T+120 min) of alanyl tissue factor pathway inhibitor (ala-TFPI) on the response to LD100 E. coli. We hypothesized that baboons treated with a low dose of TFPI (5 mg/kg) which did not survive would exhibit thrombosis, infarction and hemorrhage of target tissues such as that seen in untreated animals infused with LD100 E. coli. Eight baboons were infused with 5 mg/kg of ala-TFPI over a 10 h period beginning immediately after a 2 h infusion of LD100 E. coli (experimental group). Four baboons were infused with E. coli followed by a 10 h infusion of saline (control group). Of the 12 baboons, the 11 non-survivors (TFPI = 7 out of 8; controls = 4 out of 4) were evaluated for the extent of thrombosis, necrosis, hemorrhage, and congestion of target tissues and for changes in clinical chemical parameters. We expected that failure to protect would correlate with failure to inhibit thrombosis of target tissue (8). Surprisingly ala-TFPI significantly inhibited thrombosis, hemorrhage and necrosis of adrenal and renal tissues and attenuated the rise in creatinine in the 7 treated non-survivors. The lungs of these non-survivors, however, exhibited intra-alveolar fibrin and a mild degree of hemorrhage and edema. We concluded that low doses of ala-TFPI begun as late as T+120 in minutes failed to protect against the lethal effects of LD100 E. coli in spite of completely preventing thrombosis and hemorrhage in target organs, and that thrombosis, infarction and hemorrhage of adrenal and renal tissue are not part of the lethal chain of events in this IV model of E. coli sepsis.

Comparative pharmacokinetics of submucosal vs. intravenous flumazenil (Romazicon) in an animal model

PURPOSE

This study was performed to determine the bioavailability and local tissue toxicological safety of flumazenil (Romazicon) when administered by oral submucosal (SM) as opposed to intravenous (i.v.) injection.

METHODS

Six dogs each received SM flumazenil (0.2 mg), and their serum was collected at predetermined time intervals (0-2 h) and frozen (-70 degrees C). Seven days later, the dogs received an identical dose of i.v. flumazenil, and serum samples were again collected, as above. Comparative quantitation of flumazenil levels (i.v. vs. SM) was made using a sensitive HPLC assay (UV detection). Direct/local drug toxicity was visually scored by unbiased raters of color photographs (test and control mucosa) taken at 1, 2, and 7 days following SM flumazenil injection. An oral pathologist examined slides processed from control and treatment tissues (hematoxylin and eosin staining) taken (punch biopsy) 1 week following SM injection to compare with direct clinical scores.

RESULTS

Serum flumazenil levels reached a plateau (8.5 +/- 1.5 ng/mL, mean +/- SD) within 4 min of SM drug injection and declined thereafter to -2 ng/mL by 2 h. Bioavailability of SM flumazenil was 101 +/- 14%, based upon measuring the area under the serum concentration-time curves over 1.5 h (AUC 0-1.5 h, SM vs. i.v. drug). Thus, serum drug levels following SM drug administration were broadly comparable to those obtained during the elimination phase of corresponding i.v. drug delivery. Regarding drug tissue toxicity, no evidence of direct drug toxicity was observed by unbiased raters of color photographs (test and control mucosa) taken at 1, 2, and 7 days following SM flumazenil injection. Following pathologic review, no difference was seen in the degree of inflammation between treatment and control tissue.

CONCLUSION

At the quantity and concentration used, SM drug flumazenil administration appears to be both a safe and a viable alternative to bolus i.v. drug delivery and worthy of further investigation.

Attenuation of tissue thrombosis and hemorrhage by ala-TFPI does not account for its protection against E. coli--a comparative study of treated and untreated non-surviving baboons challenged with LD100 E. coli

This study was designed to determine the effect of a delayed infusion (T+120 min) of alanyl tissue factor pathway inhibitor (ala-TFPI) on the response to LD100 E. coli. We hypothesized that baboons treated with a low dose of TFPI (5 mg/kg) which did not survive would exhibit thrombosis, infarction and hemorrhage of target tissues such as that seen in untreated animals infused with LD100 E. coli. Eight baboons were infused with 5 mg/kg of ala-TFPI over a 10 h period beginning immediately after a 2 h infusion of LD100 E. coli (experimental group). Four baboons were infused with E. coli followed by a 10 h infusion of saline (control group). Of the 12 baboons, the 11 non-survivors (TFPI = 7 out of 8; controls = 4 out of 4) were evaluated for the extent of thrombosis, necrosis, hemorrhage, and congestion of target tissues and for changes in clinical chemical parameters. We expected that failure to protect would correlate with failure to inhibit thrombosis of target tissue (8). Surprisingly ala-TFPI significantly inhibited thrombosis, hemorrhage and necrosis of adrenal and renal tissues and attenuated the rise in creatinine in the 7 treated non-survivors. The lungs of these non-survivors, however, exhibited intra-alveolar fibrin and a mild degree of hemorrhage and edema. We concluded that low doses of ala-TFPI begun as late as T+120 in minutes failed to protect against the lethal effects of LD100 E. coli in spite of completely preventing thrombosis and hemorrhage in target organs, and that thrombosis, infarction and hemorrhage of adrenal and renal tissue are not part of the lethal chain of events in this IV model of E. coli sepsis.

Retrospective study comparing the pathophysiology of antibiotic-treated and untreated Escherichia coli- and Staphylococcus aureus-infused baboons

Escherichia coli and Staphylococcus aureus are the most common pathogens encountered in septic shock. This is a descriptive study in which the pathophysiologic response to infusions of LD100 concentrations of E. coli and S. aureus are staged and compared. Equivalent concentrations of both organisms were infused over a 2 hr period into antibiotic-treated and untreated animals with the following results: 1) The apparent clearance of E. coli was less than that of S. aureus over the 2-hr infusion period, but far greater during the next 8 hr in both antibiotic-treated and untreated animals. Thus the clearance of E. coli fits a one-compartment (intravascular), and that of S. aureus fits a two-compartment (intra- and extravascular) model. 2) The intensity of the cardiovascular, temperature, and metabolic response to E. coli was greater, whereas that of the disseminated intravascular coagulant (DIC) response to S. aureus was greater. We conclude, therefore, that the response to E. coli consists of four stages with no invasion and colonization of tissues, whereas the response to S. aureus consists of two stages with invasion and colonization of tissues.