RESUMEN
BACKGROUND: Thiamylal exerts excellent sedative effects. However, it is not routinely used because of its serious adverse effects. This study aimed to clarify the target blood concentration range and infusion rate of thiamylal in children by measuring its blood concentration and evaluating its relationship with efficacy and adverse effects. METHODS: This study was approved by the Ethics Committee of Japanese Red Cross Kumamoto Hospital. The authors included 10 children aged between 1 and 7 years who had received continuous intravenous (IV) infusion of thiamylal for the management of refractory status epilepticus, excluding those who met the exclusion criteria. After a 2 mg/kg bolus injection of thiamylal, continuous IV infusion was initiated at a rate of 2-3 mg/kg/h. Thiamylal concentration in the blood was measured using high-performance liquid chromatography. The State Behavioral Scale and the frequency of bolus injections were used to evaluate efficacy. Blood pressure and heart rate were measured to evaluate adverse effects. Statistical analyses of the time to awakening and the factors affecting it were also conducted. RESULTS: The State Behavioral Scale score during thiamylal administration was -2 or lower in all cases, suggesting that the depth of sedation was sufficient. The frequency of bolus injections decreased in a blood concentration-dependent manner, suggesting that the frequency tended to decrease, especially at thiamylal blood concentrations of 20 mcg/mL or higher. An increase of the infusion rate to 3 mg/kg/h was recommended, because the blood concentration may not reach 20 mcg/mL at an infusion rate of 2 mg/kg/h. There was also a case in which a rapid increase in blood concentration accompanied by a decrease in blood pressure and heart rate was observed when the infusion rate was increased to 4 mg/kg/h. Furthermore, the time to awakening after the end of administration correlated with the highest blood concentration during administration; therefore, delayed awakening was noted when using a high dose of thiamylal. CONCLUSIONS: The target blood concentration of thiamylal in children should be 20-30 mcg/mL, and the infusion rate should be based on 3 mg/kg/h.
RESUMEN
BACKGROUND: Overdosed acetaminophen (paracetamol, N-acetyl-p-aminophenol; APAP) causes severe liver injury. We examined the effects of ozagrel, a selective thromboxane A2 (TXA2) synthase inhibitor, on liver injury induced by APAP overdose in mice. METHODS: Hepatotoxicity was induced to ICR male mice by an intraperitoneal injection with APAP (330 mg/kg). The effects of ozagrel (200 mg/kg) treatment 30 min after the APAP injection were evaluated with mortality, serum alanine aminotransferase (ALT) levels and hepatic changes, including histopathology, DNA fragmentation, mRNA expression and total glutathione contents. The impact of ozagrel (0.001-1 mg/mL) on cytochrome P450 2E1 (CYP2E1) activity in mouse hepatic microsome was examined. RLC-16 cells, a rat hepatocytes cell line, were exposed to 0.25 mM N-acetyl-p-benzoquinone imine (NAPQI), a hepatotoxic metabolite of APAP. In this model, the cytoprotective effects of ozagrel (1-100 muM) were evaluated by the WST-1 cell viability assay. RESULTS: Ozagel treatment significantly attenuated higher mortality, elevated serum alanine aminotransferase levels, excessive hepatic centrilobular necrosis, hemorrhaging and DNA fragmentation, as well as increase in plasma 2,3-dinor thromboxane B2 levels induced by APAP injection. Ozagrel also inhibited the hepatic expression of cell death-related mRNAs induced by APAP, such as jun oncogene, FBJ osteosarcoma oncogene (fos) and C/EBP homologous protein (chop), but did not suppress B-cell lymphoma 2-like protein11 (bim) expression and hepatic total glutathione depletion. These results show ozagrel can inhibit not all hepatic changes but can reduce the hepatic necrosis. Ozagrel had little impact on CYP2E1 activity involving the NAPQI production. In addition, ozagrel significantly attenuated cell injury induced by NAPQI in RLC-16. CONCLUSIONS: We demonstrate that the TXA2 synthase inhibitor, ozagrel, dramatically alleviates liver injury induced by APAP in mice, and suggest that it is a promising therapeutic candidate for the treatment of APAP-induced liver injury.