Red blood cell (RBC) transfusions for massive hemorrhage induce systemic ischemic-reperfusion and influence the disposition and pharmacological activity of drugs as a result of a reduction in the level of expression and activity of cytochrome P450s (P450). It was reported that, when organ-preserving solutions are exposed to carbon monoxide (CO), the treatment was effective in suppressing the postreperfusion reduction in renal P450 levels in cases of kidney transplantation. Therefore, we hypothesized that transfusions with RBC that contain bound CO (CO-RBC) would protect the hepatic level of rat P450 during a massive hemorrhage, compared with plasma expanders and RBC resuscitation. To achieve this, we created 40% hemorrhagic-shock model rats, followed by resuscitation, with use of recombinant human serum albumin, RBCs, and CO-RBCs. At 1 hour after resuscitation, the expressions of hepatic P450 isoforms (1A2, 2C11, 2E1, and 3A2) were significantly decreased in the RBC resuscitation group, compared with the sham group. Such alterations in hepatic P450 significantly resulted in an increase in the plasma concentrations of substrate drugs (caffeine [1A2], tolbutamide [2C11], chlorzoxazone [2E1], and midazolam [3A2]) for each P450 isoform, and thus, the hypnotic action of midazolam could be significantly prolonged. Of interest, the reductions in hepatic P450 activity observed in the RBC group were significantly suppressed by CO-RBC resuscitation, and consequently, the pharmacokinetics of substrate drugs and the pharmacological action of midazolam remained at levels similar to those under sham conditions. These results indicate that CO-RBC resuscitation has considerable potential in terms of achieving safe and useful drug therapy during massive hemorrhages.
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