Pharmacokinetics of loxoprofen and its active metabolite after dermal application of loxoprofen gel to rats.

This study was conducted to evaluate the pharmacokinetics of loxoprofen (LX) and its active metabolite (trans-OH form) after a single dermal application of LX gel (LX-G) to rats. In the skin at the treated site, generation of the trans-OH form was detected and both LX and the trans-OH form remained at high concentrations for 24 h after dermal application. Furthermore, both LX and the trans-OH form also remained in the skeletal muscle over 24 h after the single dermal application, while they eliminated rapidly after the single oral administration. The area under the curve up to the last measurable point (AUC(0-t)) for plasma concentrations of LX or the trans-OH form after dermal application of LX-G was less than 11% of that after oral administration of LX. In addition, C(max) and AUC(0-t) increased in a saturable manner while increasing the dose. Overall, these results demonstrated that the trans-OH form was generated at the treated site with the process of dermal absorption of LX and it remained at the target site for a long period with low systemic exposure compared to oral administration.

Comparison of formation of thiolactones and active metabolites of prasugrel and clopidogrel in rats and dogs.

Prasugrel and clopidogrel are antiplatelet prodrugs that are converted to their respective active metabolites through thiolactone intermediates. Prasugrel is rapidly hydrolysed by esterases to its thiolactone intermediate, while clopidogrel is oxidized by cytochrome P450 (CYP) isoforms to its thiolactone. The conversion of both thiolactones to the active metabolites is CYP mediated. This study compared the efficiency, in vivo, of the formation of prasugrel and clopidogrel thiolactones and their active metabolites. The areas under the plasma concentration versus time curve (AUC) of the thiolactone intermediates in the portal vein plasma after an oral dose of prasugrel (1 mg kg(-1)) and clopidogrel (0.77 mg kg(-1)) were 15.8 +/- 15.9 ng h ml(-1) and 0.113 +/- 0.226 ng h ml(-1), respectively, in rats, and 454 +/- 104 ng h ml(-1) and 23.3 +/- 4.3 ng h ml(-1), respectively, in dogs, indicating efficient hydrolysis of prasugrel and little metabolism of clopidogrel to their thiolactones in the intestine. The relative bioavailability of the active metabolites of prasugrel and clopidogrel calculated by the ratio of active metabolite AUC (prodrug oral administration/active metabolite intravenous administration) were 25% and 7%, respectively, in rats, and 25% and 10%, respectively, in dogs. Single intraduodenal administration of prasugrel showed complete conversion of prasugrel, resulting in high concentrations of the thiolactone and active metabolite of prasugrel in rat portal vein plasma, which demonstrates that these products are generated in the intestine during the absorption process. In conclusion, the extent of in vivo formation of the thiolactone and the active metabolite of prasugrel was greater than for clopidogrel's thiolactone and active metabolite.

Ethane: a marker of lipid peroxidation during cardiopulmonary bypass in humans.

The goals of this study were to (1) determine the utility of quantification of ethane as a marker of ischemia-reperfusion during human cardiopulmonary bypass (CPB); and (2) determine, using an animal model for this surgical procedure, whether the mode of surgical approach produced increases the quantity of exhaled ethane. Human CPB was initiated following standard anesthetic and monitoring regimens. Samples of gas were collected at baseline and at multiple defined time points throughout the studies. Ethane was determined using cryogenic concentration and gas chromatography. Sternotomy increased exhaled ethane compared to baseline (p < .007; 5.8 +/- 1.7 vs. 3.0 +/- 0.7 nmol/m2 x min); ethane returned to baseline levels prior to the initiation of CPB. Aortic unclamping produced ethane elevation (p < .05; 2.3 +/- 0.8 vs. 1.5 +/- 0.4 nmol/m2 x min) with the levels being related to a lower cardiac index and a higher systemic vascular resistance post aortic unclamping. Termination of CPB significantly increased ethane levels compared to baseline (p < .002; 4.8 +/- 1.7 vs. 3.0 +/- 0.7 nmol/m2 x min). Independent variables that correlated with increased ethane measurements included a higher arterial blood pH on bypass and the change in hemoglobin pre- and post-CPB. Electrocautery, but not scalpel, incision of the porcine abdominal wall increased ethane levels significantly (p < .02). These results indicate that exhaled ethane may be a valuable marker of lipid peroxidation during and following CPB.

Breath ethane: a specific indicator of free-radical-mediated lipid peroxidation following reperfusion of the ischemic liver.

A major component of the organ injury mediated by toxic oxidants, such as seen following reperfusion of the ischemic liver, is due to the peroxidation of polyunsaturated fatty acids, especially of cell membranes. We utilized the measurement of exhaled breath ethane, a metabolic product unique to oxidant-mediated lipid peroxidation, as a noninvasive indicator of this process in swine liver subjected to warm ischemia/reperfusion. Under rigorously controlled anesthesia conditions, pig livers were subjected to 2 h of warm total ischemia, followed by reperfusion in situ. Expired air was collected and its ethane content quantitated by a novel gas chromatographic technique. The time course of breath ethane generation correlated closely with the appearance of hepatocellular injury as measured by impairment of Factor VII generation and other measures of liver integrity. Moreover, the administration of the specific superoxide free radical scavenger, superoxide dismutase (SOD), significantly attenuated both the elaboration of ethane and the hepatocellular injury. These findings not only provide confirmation of the previously reported link between hepatocellular injury by free radicals generated at reperfusion, but also establish the use of expired breath ethane analysis as a sensitive, specific, and noninvasive indicator of the injury process in real time.

Evidence for free radical-mediated lipid peroxidation at reperfusion of human orthotopic liver transplants.

BACKGROUND: Generation of toxic oxygen metabolites at reperfusion may contribute to the injury sustained as a consequence of harvest and ischemic preservation of organ allografts. Because there is a paucity of evidence that this mechanism is operative in human beings, we measured the generation of ethane into the exhaled breath as a biomarker of free radical-mediated lipid peroxidation in human liver transplantation. METHODS: A novel technique that increased the previous standard of sensitivity 100-fold was used to measure picomole quantities of ethane in exhaled breath of eight recipients undergoing human orthotopic liver transplantation. RESULTS: Ethane production correlated closely with the specific events of liver transplantation including the initial reperfusion of the allografts. In every case a twofold to threefold increase in ethane production was superimposed on a stable baseline immediately after reestablishment of portal vein blood flow through the donor liver. CONCLUSIONS: Ethane production was interpreted as evidence of hepatic lipid peroxidation, presumably mediated by toxic metabolites of oxygen occurring at reperfusion. This noninvasive approach allowed localization of the time point at which lipid peroxidation occurred and may facilitate quantification of lipid peroxidation mediated by free radicals and other toxic oxygen metabolites during operation.

Rapid, real-time sampling of R-84760 in blood by in vivo microdialysis with tandem mass spectrometry.

A new technique involving rapid sampling of R-84760 in real-time was achieved using a combination of microdialysis (MD) and tandem mass spectrometry (MS/MS). After collecting the analyte in real-time by MD and separating it by MS/MS, the ion intensities are adapted to the data without any subsequent chromatographic separation or flow injection analysis. The R-84760 concentration was obtained from the plateau part of the ion intensities or the corrected values using an internal standard, after immersing the MD probe into the dialysis solution containing the drug for a definite time. Since contamination of the ion source was prevented by using an organic solvent for the perfused solution, it was possible to establish a stable analysis method. For an MD membrane of length 4 mm, the R-84760 concentration in saline was linear over the range 5-541.1 ng/ml (r2 = 0.9997). Moreover, the R-84760 concentration in rat whole blood was linear over the range 24.9-1868.9 ng/ml (r2 = 0.9993). As this method allowed the measurement of free drug concentration in rat blood, the analysis was also able to provide data needed for determining the protein-binding ratio. The protein-binding ratio obtained from the calibration curve in saline and rat whole blood was 87-90%, which was close to the result obtained by another analysis method. The concentration profile of R-84760 in blood as obtained by the MD-MS/MS method correlated well with the concentration profile in plasma, which was simultaneously monitored by LC-MS/MS.

Absorption, distribution and excretion of the new thienopyridine agent prasugrel in rats.

Prasugrel is converted to the pharmacologically active metabolite after oral dosing in vivo. In this study, (14)C-prasugrel or prasugrel was administered to rats at a dose of 5 mg kg(-1). After oral and intravenous dosing, the values of AUC(0-infinity) of total radioactivity were 36.2 and 47.1 microg eqx h ml(-1), respectively. Oral dosing of unlabeled prasugrel showed the second highest AUC(0-8) of the active metabolite of six metabolites analyzed. Quantitative whole body autoradiography showed high radioactivity concentrations in tissues for absorption and excretion at 1 h after oral administration, and were low at 72 h. The excretion of radioactivity in the urine and feces were 20.2% and 78.7%, respectively, after oral dosing. Most radioactivity after oral dosing was excreted in bile (90.1%), which was reabsorbed moderately (62.4%). The results showed that orally administered prasugrel was rapidly and fully absorbed and efficiently converted to the active metabolite with no marked distribution in a particular tissue.

[Immunocytochemical investigations of occluded saphenous vein grafts].

Occluded saphenous vein aorto-coronary bypass grafts were investigated using two types of monoclonal antibodies, specific to either the muscle actin (HHF 35) or the macrophage (HAM 56). The early post operative occlusions of saphenous vein grafts were associated with the deposition of mural thrombi with little intimal proliferation. The late occlusions of saphenous vein grafts were associated with intimal fibrous proliferation without mural thrombus formation. Proliferated smooth muscle cells were a major constituent of intimal fibrous proliferation in both early and late occluded grafts. Macrophages were not detected in both groups. The proliferation of smooth muscle cells in the intima may play a role in the development of late occlusion, rather than the organizational process of accumulated mural thrombi.

Utility of breath ethane as a noninvasive biomarker of vitamin E status in children.

The purpose of our study was to determine if the ethane content of expired air could be a useful index of vitamin E status in children. Eight children with vitamin E deficiency secondary to chronic severe liver disease were studied: six of these children were treated with parenteral vitamin E (2-5 mg/kg/dose every 4-7 d). Measures of vitamin E status pre- and posttherapy were: serum vitamin E, 2 +/- 1 versus 7 +/- 1 micrograms/mL (p less than 0.001); serum vitamin E:total lipids, 0.3 +/- 0.1 versus 1.0 +/- 0.1 mg/g (p less than 0.001); and erythrocyte peroxide hemolysis test, 80 +/- 10 versus 6 +/- 12% (p less than 0.001). Fasting breath ethane in the patients pre- and posttherapy was 78 +/- 10 versus 31 +/- 11 pmol/kg/min (p less than 0.001). Breath ethane correlated negatively with serum vitamin E (p less than 0.042) and serum E:total lipids (p less than 0.004) and positively with the erythrocyte peroxide hemolysis test (p less than 0.003). Values for treated patients did not differ from those for fasted sibling controls (34 +/- 12 pmol/kg/min), postprandial sibling controls (31 +/- 12 pmol/kg/min), and healthy children sampled randomly, in the nonfasted state (21 +/- 14 pmol/kg/min). Breath ethane production in one patient (up to 168 pmol/kg/min) did not normalize after treatment of vitamin E deficiency until her selenium deficiency was corrected as well. We conclude that this noninvasive test can be useful as a screen for vitamin E deficiency in children and for ascertaining response to therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

[Immunocytochemical and ultrastructural study of saphenous vein, internal thoracic artery, and right gastroepiploic artery in coronary artery bypass grafting].

The arterial conduits such as internal thoracic artery (ITA) and right gastroepiploic artery (GEA) are widely used in coronary artery bypass surgery because of their resistance to atherosclerosis. In this study, immunophenotypes of smooth muscle cells (SMCs) in intima and media of ITA, GEA and saphenous vein (SV) were studied using monoclonal antibodies specific to cytoskeletal proteins; actin (A), vimentin (V) and desmin (V). In addition, the ultrastructures of endothelium of these vessels were examined. The most SMCs in intima and media of ITA and GEA were found positive for (A) and (V) but negative for (D). In contrast, the majority of SMCs both in intima and media of SV were found positive for (A), (V) and (D). The ultrastructure of endothelium of ITA and GEA showed the deeper penetration of cytoplasmic process than SV, which might anchor the endothelium. We suggest the morphological difference of endothelium and phenotypic diversity of SMCs between arterial and venous grafts may account for the different susceptibility to atherosclerotic changes in coronary bypass grafting.

Disposition and metabolism of the new oral antidiabetic drug troglitazone in rats, mice and dogs.

The pharmacokinetics of troglitazone (CAS 97322-87-7, CS-045), a new oral antidiabetic drug for the treatment of non-insulin-dependent diabetes mellitus (NIDDM), were investigated in rats, mice and dogs following oral and intravenous administration of 14C-labeled troglitazone at doses of 5 mg/kg. The absorption rates, calculated from the AUC ratios of total radioactivity after oral and intravenous administration, or from the biliary excretion rate after intraduodenal administration in rats were both as high as 75%. High uptake by the liver, one of the pharmacological target organs, was demonstrated in both rats and mice. Furthermore, in the KK mouse, an obese NIDDM model animal, the radioactivity was incorporated selectively as troglitazone itself to muscle, the peripheral target organ. Troglitazone reversibly bound to serum albumin with a high ratio (> 99%). Troglitazone was mostly metabolized to the conjugates: sulfate (M 1) and glucuronide (M 2). The oxidized metabolite, a quinone-type metabolite (M 3), was found to be further metabolized to the sulfate (U 2). The biliary excretion rates of these conjugates were high in each animal, and the occurrence of enterohepatic circulation of the conjugates was also suggested. Sex differences in pharmacokinetics were observed in rats; i.e. females showed a higher plasma concentration of troglitazone, and a lower concentration of M 1, than males, and they excreted the sex-related metabolite, a hydroxylated M 1 (U 1), in the bile.

Late results of coronary artery bypass surgery with maximal follow-up of 7 years: analysis of determinants affecting late survival.

A total of 806 primary coronary artery bypass graft operations were performed between January 1984 and December 1989. Excluding eight hospital deaths (1.0%) and three patients lost in follow-up, a total of 795 patients were contracted, with a follow-up rate of 99.6%. The mean follow-up period was 53.6 months, the longest being 92 months. Of the patients 42 died in late follow-up. Malignant neoplasm was the major cause of death (n = 17, 40% of total late deaths), which far exceeded the number of cardiac deaths (n = 6, 14%). The actuarial survival, excluding the initial hospital deaths, was 95% at 5 years and 91% at 7 years by the Kaplan-Meier method. By multivariate logistic analysis, four clinical variables were identified as significant in influencing the late survival, in the following order: (1) presence or absence of diabetes mellitus (P = 0.00008); (2) age > or = 65 years or < 65 years (P = 0.002); (3) left ventricular function with ejection fraction < 45% or > or = 45% (P = 0.014); and (4) use or non-use of left internal mammary arteries to bypass the left anterior descending artery (P = 0.016). Sex (male versus female), severity of anginal symptoms (mild versus severe) and number of diseased vessels (single and double versus triple vessel and left main trunk disease) did not significantly influence the late survival of the patients.

Visceral lipid peroxidation occurs at reperfusion after supraceliac aortic cross-clamping.

PURPOSE: Recently, we have reported that lipid peroxidation specific to oxygen free radical-mediated injury increased immediately after reperfusion of human liver allografts. However, in the human liver transplantation setting it was impossible to disassociate the contributions to lipid peroxidation caused by the warm and cold ischemic phases from those caused by reperfusion. Therefore we now have studied lipid peroxidation at reperfusion after supraceliac aortic cross-clamping in patients with normal livers. METHODS: Ethane, a noninvasive biomaker of lipid peroxidation, was measured in exhaled breath of patients before and during cross-clamping of the thoracic aorta and at sequential time intervals after visceral reperfusion. RESULTS: Approximately a two-fold transient increase in the ethane level was observed at around 15 minutes after reperfusion in those patients whose aortas were cross-clamped for more than 18 minutes. CONCLUSIONS: These results indicate that free radical-mediated lipid peroxidation occurs at reperfusion of warm ischemic viscera in the clinical setting of aortic repair. This observation supports the hypothesis that substantial lipid peroxidation occurs when tissues are subjected to cold or warm ischemia followed by reperfusion.