Effect of gomisin A (TJN-101), a lignan compound isolated from Schisandra fruits, on liver function in rats

TJN-101 [+)-(6S, 7S, R-biar)-5,6,7,8-tetrahydro-1,2,3,12-tetramethoxy- 6,7-dimethyl-10,11-methylenedioxy-6-dibenzo [a, c] cyclooctenol) is one of the lignan compounds isolated from Schisandra fruits. When TJN-101 was administered orally at the doses of 3-100 mg/kg/day for 4 days, bile secretion, hepatic excretion of dye or hepatic hemodynamics 24 hr after the last dose was investigated in comparison with the phenobarbital (100 mg/kg/day)-treated group. Bile flow was dose-dependently increased; in contrast, biliary concentration of bile acids was decreased in TJN-101 (30 and 100 mg/kg/day)-treated groups. Similar changes were also observed in the phenobarbital-treated group. These results suggested that the enhancement of bile secretion caused by TJN-101 or phenobarbital was due to an increase of a bile acid-independent fraction. In the bromosulfophthalein (BSP) clearance test for liver function, both TJN-101 (30 and 100 mg/kg/day) and phenobarbital accelerated the disappearance from the blood and biliary excretion of BSP. Hepatic hemodynamics was examined by the hydrogen clearance method and measurement of liver wet and dry weight. Liver blood flow tended to increase in the TJN-101 (10-100 mg/kg/day) or phenobarbital-treated group. On the other hand, TJN-101 (3-100 mg/kg/day) or phenobarbital hardly altered the water content of the liver. These results suggested that the liver enlargement caused by both compounds was not accompanied with hepatic edema and that the enhancement of bile secretion or hepatic excretion of BSP might be related to an increase of liver blood flow.     

Determination of gomisin A (TJN-101) and its metabolite in rat serum by gas chromatography-mass spectrometry]

Gomisin A (TJN-101) is one of the lignan components isolated from Schisandra Fruits. A high sensitive and precise method for the determination of TJN-101 and its major metabolite (Met. B) in the rat serum was developed by selected ion monitoring (SIM) with gas chromatography-mass spectrometry (GC/MS) using a fused silica capillary column (SPB-1, Supelco). A 100 microliter serum sample was used for the solid phase extraction. The calibration curves of TJN-101 and Met.B both showed a good linearity between 2.0 and 2000.0 ng/ml. The analytical precision (intra-assay, C.V. less than 4.7%), recoveries (98.4 +/- 10.1%), and detection limit (2 ng/ml) of TJN-101 indicated that this system was suited for the determination of TJN-101 in biological fluid. In case of Met.B, the same results as TJN-101, were obtained. After oral administration of TJN-101 at a dose of 10 mg/kg to male rats, the average values of the maximal serum concentration of TJN-101 and Met.B were 1446.1 +/- 131.8 and 317.4 +/- 18.5 ng/ml, respectively. The serum concentrations of these substances could be monitored sufficiently for 8 h after dosing.     

Studies on the metabolic fate of gomisin A (TJN-101). I. Absorption in rats]

Gomisin A (TJN-101) is one of the lignan components isolated from Schisandra Fruits and expected to have some efficacies in clinical treatment of hepatitis. The serum concentrations of TJN-101 and Met. B, which was identified as a demethylenated substance and one of the major metabolites of TJN-101 in rats, were investigated. After intravenous administration at doses of 1.6, 4.0 and 10 mg/kg of body weight, the serum concentration of TJN-101 decreased biphasically, and the terminal elimination half-life at each dose was about 70 min. Dose-dependency was observed for the area under the concentration-time curve (AUC). On the other hand, the serum concentration of TJN-101 increased rapidly and reached maximum within 15 to 30 min when administered orally. This result was supported by the in situ roop method. The Cmax and the AUC values were not exactly dose-dependent, but the values increased with a dose-up of TJN-101. The biotransformation of TJN-101 to Met. B, was very rapid in both intravenous and oral administrations. The AUC value of Met. B after oral administration of TJN-101 at a dose of 1.6 mg/kg was relatively larger than any other dosages. It suggested that TJN-101 was extensively underwent the first pass effect in rats. More than 80% of TJN-101 was bound with rat serum protein in vitro and in vivo. Therefore, it seems to be necessary to pay attention when it was administered concurrently with high protein binding drugs.     

Effects of TJN-101, a lignan compound isolated from Schisandra fruits, on liver fibrosis and on liver regeneration after partial hepatectomy in rats with chronic liver injury induced by CCl4

TJN-101 ((+)-(6S,7S,R-biar)-5,6,7,8-tetrahydro-1,2,3,12-tetramethoxy -6,7-dimethyl-10,11-methylenedioxy-6-dibenzo[a,c]cyclooctenol) is one of the lignan compounds isolated from Schisandra fruits. 1) Effect of TJN-101 on liver fibrosis was investigated in rats which were injected with CCl4 (1 ml/kg) subcutaneously twice a week for 12 weeks. TJN-101 was given orally at the dose of 10 or 30 mg/kg/day for 6 or 3 weeks beginning on the 6th or 9th week after the start of CCl4-intoxication, respectively. The elevations of serum transaminase activities and the increase of liver 4-hydroxyproline content were observed depending on the period of CCl4-intoxication. These changes were marked on the 9th and 12th weeks after. In the histopathological study, the degenerative fatty change on the 6th week after and the formation of pseudolobule caused by fibrosis proliferation on the 9th or 12th week after were mainly observed. When rats were treated with TJN-101, the abnormalities in biochemical parameters and the fibrosis proliferation caused by CCl4-intoxication were improved. 2) Chronic liver injury was induced by the treatment with CCl4 (1 ml/kg) subcutaneously twice a week for 10 weeks to investigate the effect of TJN-101 on liver regeneration after partial hepatectomy. TJN-101, which was given orally at the dose of 10, 30 or 100 mg/kg/day for 6 days from the 1st day after partial hepatectomy, dose-dependently increased the liver regeneration rate and improved the serum BSP retention rate. These results suggest that TJN-101 suppresses the fibrosis proliferation and accelerates both the liver regeneration and the recovery of liver function after partial hepatectomy in chronic liver injury.     

Effects of gomisin A on liver functions in hepatotoxic chemicals-treated rats

The effects of gomisin A, which is a lignan component of schizandra fruits, on liver functions in various experimental liver injuries and on bile secretion in CCl4-induced liver injury were studied. Gomisin A weakly accelerated the disappearance of plasma ICG by itself at a high dose (100 mg/kg, i.p.). All of the hepatotoxic chemicals used in this study inhibited the excretion of ICG from plasma. Gomisin A showed a tendency to prevent the delays of the disappearance of plasma ICG induced by CCl4, d-galactosamine and orotic acid, but not that by ANIT. Bile flow and biliary outputs of total bile acids and electrolytes (Na+, K+, Cl- and HCO3-) were decreased in CCl4-treated rats. Gomisin A maintained bile flow and biliary output of each electrolyte nearly to the level of the vehicle-treated group, but did not affect biliary output of total bile acids. These findings suggest that gomisin A possesses a liver function-facilitating property in normal and liver injured rats and that its preventive action on CCl4-induced cholestasis is due to maintaining the function of the bile acids-independent fraction.     

Effect of carbon tetrachloride on biliary excretion of 3,4-benzpyrene in rats]

14C-labelled 3,4-benzpyrene (14C-BP) in dose of 100 mug/animal was injected into female Sprague-Dawley rats under urethane anesthesia. The rats were cannulated at the duct and the output of metabolites in the bile was determined. Non-treated rats excreted 35.5% of the given dose within one hr. The main metabolites excreted in bile were fractionated chromatographically into three. One of these was a metabolite which was hydrolyzed by beta-glucuronidase, the other two were unknown substances. Unchanged BP was not detected. In rats pretreated with CCl4 (0.5 ml/kg, p.o.) 24 hr before experiment, the biliary excretion of BP-metabolites was found to be reduced, that is only 10% of the given dose was excreted within one hr. It was noted that the output within the first 90 min after injection of BP was significantly reduced. In the CCl4-treated rats, bile flow was found to be lowered. However, the reduced output of BP-metabolites was considered not as the result of lowered bile flow, but as the result of disturbance of BP-metabolism in the liver. Thus it is suggested that impaired hepatic junction as the result of CCl4 intoxication may last for more than two weeks, when the hepatic junction is evaluated in terms of biliary excretion of BP.     

Possible multiple transporters were involved in hepatobiliary excretion of antofloxacin in rats

1. The aim of the current study was to investigate the characteristics of biliary excretion of antofloxacin (ATFX) in rats. Rats received a bolus intravenous injection followed by a constant-rate infusion of ATFX. When plasma concentrations of ATFX reached steady state, cyclosporin A, erythromycin, probenecid, cimetidine and diclofenac were administered intravenously to the rats. Samples of blood and bile were collected and the concentrations of ATFX were measured and the corresponding pharmacokinetic parameters were estimated. 2. Biliary excretion of ATFX was observed in rats subjected to CCl(4)-induced experimental hepatic injury for 24 h (CCl(4)-EHI(24h)). Steady state concentrations of ATFX were attained at 60 min following infusion. 3. A slight increase in concentration of ATFX in plasma was observed after cyclosporin A, erythromycin, probenecid and cimetidine treatment. Significant increases in ATFX plasma levels were found in rats treated with diclofenac. Cyclosporin A, erythromycin, probenecid, cimetidine and diclofenac treatment significantly decreased the steady state biliary clearance of ATFX to 55, 68, 54, 53 and 56% of control values, respectively. 4. Cyclosprin A, probenecid, erythromycin and cimetidine also inhibited the biliary excretion of ATFX glucuronide. Significant decrease in the steady state biliary clearance of ATFX and its glucuronide was observed in CCl(4)-EHI(24h) rats. 5. These results indicate that multiple transporters are possibly involved in the biliary excretion of ATFX.     

Distribution of ciprofloxacin into the central nervous system in rats with acute renal or hepatic failure.

Pharmacokinetic changes of various drugs have been reported in renal or hepatic failure. The present study employed ciprofloxacin, a quinolone antibiotic having neurotoxic side effects, to assess the influence of these diseases on distribution of ciprofloxacin into the central nervous system (CNS). After intravenous dosing of ciprofloxacin (10-30 mg kg(-1)), ciprofloxacin levels in plasma and brain were measured in normal rats (Wistar, male, 10-week-old) and those with acute renal and hepatic injuries which were induced by uranyl nitrate and carbon tetrachloride (CCl4), respectively. In the uranyl nitrate-treated rats, the plasma elimination half-life of ciprofloxacin was prolonged and the total body clearance was reduced when compared with those in the normal rats. Similar but smaller changes were observed in the CCl4-treated group. Brain levels of ciprofloxacin were significantly increased by both uranyl nitrate and CCl4 treatments. A proportional correlation between serum unbound levels and brain levels of ciprofloxacin was observed in the normal group. However, brain-to-serum unbound concentration ratios of ciprofloxacin were reduced in the rats with renal or hepatic failure. These results suggest that renal failure as well as hepatic failure retards elimination of ciprofloxacin from the blood, leading to elevation of the CNS level, and also that ciprofloxacin distribution in the brain is reduced in these disease states.     

Effect of Gomisin A (TJN-101) on liver regeneration.

We studied the effect of TJN-101, a lignan component of Schisandra fruits (Schisandrae fructus), on liver regeneration after partial hepatectomy. TJN-101 was given orally to male Wistar rats 30 min before partial hepatectomy. The mitotic index and the level of DNA synthesis increased after partial hepatectomy and their increase was significantly enhanced by TJN-101. Ornithine decarboxylase (ODC) activity increased in the early stages of liver regeneration and it was also significantly enhanced by TJN-101. Besides, TJN-101 enhanced the increase in hepatic putrescine. These results suggest that TJN-101 stimulates liver regeneration after partial hepatectomy by enhancing ODC activity, which is an important biochemical event in the early stages of liver regeneration.     

Effects of TJN-101 ((+)-(6s,7s,R-biar)-5,6,7,8-tetrahydro-1,2,3,12-tetramethoxy-6,7 -dimethyl-10,11-methylenedioxy-6-dibenzo [a,c] cyclooctenol) on liver regeneration after partial hepatectomy, and on regional hepatic blood flow and fine structure of the liver in normal rats

Effects of TJN-101, one of the components isolated from Schizandra fruits, on liver regeneration after partial hepatectomy, and on regional hepatic blood flow and fine structure of the liver were investigated in normal rats. TJN-101, which was administered orally at the doses of 10, 30 and 100 mg/kg/day for 4 days after partial hepatectomy, increased the regeneration rate of the liver and improved the serum retention rate of BSP which had been dose-dependently decreased after the operation. Elevation of serum protein to control levels, elevation of serum LCAT activity, decrease in plasma insulin and increase in plasma glucagon were all dose-dependent responses to TJN-101. The mitotic index on the 5th day after the operation was hardly influenced by TJN-101. Regional hepatic blood flow was increased after intraduodenal administration of TJN-101 (30 and 100 mg/kg). Ultrastructural studies of liver tissue using the transmission electron microscope revealed that TJN-101 stimulated an increase in rough and smooth endoplasmic reticulum in the groups receiving 100 and 300 mg/kg/day. These results suggest that TJN-101 accelerates both the proliferation of hepatocytes and the recovery of liver function after partial hepatectomy and increases hepatic blood flow. It is also thought that the liver enlargement caused by repeated administration of TJN-101 is associated with the proliferation of endoplasmic reticulum.     

Occurrence of autoimmune antibodies to liver microsomal proteins associated with lethal hepatitis in LEC rats: effects of TJN-101 ((+)-(6S,7S,R-biar)-5,6,7,8-tetrahydro-1,2,3,12-tetramethoxy-6,7-dimethyl-10,11-methylenedioxy-6-dibenzo[a,c]cyclooctenol) on the development of hepatitis and the autoantibodies

Long Evans Cinnamon (LEC) rats, that spontaneously develop hepatitis, were found to possess autoantibodies to liver microsomal proteins (anti-LM) before the development of hepatitis. Anti-LM antibody was assumed to appear in association with the lethal hepatitis in the LEC rats. Thus, the purpose of this study was to investigate the effects of an anti-hepatitis drug on the development of hepatitis and the occurrence of the antibody in LEC rats. Mortality, blood biochemical parameters and the titer of serum anti-LM antibody were measured. In control LEC rats, 4 of 8 rats died before 20 weeks of age. In rats treated with TJN-101 ((+)-(6S,7S,R-biar)-5,6,7,8-tetrahydro-1,2,3,12-tetramethoxy-6,7-dimethyl-10,11-methylenedioxy-6-dibenzo[a,c]cyclooctenol), 4 of 7 rats died of hepatitis, but the time of death was delayed by 7–10 weeks compared for the control rats. The titer of the anti-LM antibody increased 3–7 weeks before death in the non-survivors in control and TJN-101-treated rats, supporting the idea that anti-LM antibody occurs in association with acute lethal hepatitis.     

Effect of endrin and endrin derivatives on hepatobiliary function and carbon tetrachloride-induced hepatotoxicity in male and female rats

The effects of the cyclodiene pesticide, endrin, and its aldehyde and ketone metabolites on hepatobiliary function and CCl4-induced hepatotoxicity were investigated in Sprague-Dawley rats. The rats were given control diet or diets containing 5 or 10 ppm endrin, 10 ppm endrin aldehyde or 5 ppm endrin ketone for 15 days. Three to six rats from each treatment group were given a single ip dose (100 microliter/kg body weight) of CCl4 in corn oil (1 ml/kg) on day 15. Levels of serum glutamic-oxalacetic transaminase (SGOT), glutamic-pyruvic transaminase (SGPT), isocitrate dehydrogenase and ornithine-carbamyl transferase, bile flow and biliary excretion of an anionic model compound, phenolphthalein glucuronide (PG), were measured on day 16. Dietary treatment with endrin at either dose level did not significantly elevate serum enzyme levels, while endrin aldehyde produced a slight increase in SGOT and SGPT and endrin ketone produced a small elevation in SGPT levels. Treatment with endrin aldehyde or endrin ketone did not result in significant alterations of bile flow or biliary PG excretion. Treatment with 5 ppm endrin produced a significant reduction in bile flow and a corresponding reduction in PG excretion by male rats, whereas treatment with 10 ppm endrin reduced only the PG excretion by male rats. Female rats treated with 5 or 10 ppm endrin showed a dose-dependent choleretic effect with a commensurate increase in PG excretion. With the exception of a further slight reduction in PG excretion by male rats, treatment with the endrin or endrin derivative did not potentiate CCl4-induced alterations in hepatobiliary functions. Although the levels of some serum enzymes of rats given endrin or endrin derivatives plus CCl4 were elevated over those of rats given CCl4 alone, the increases were not of the magnitude of those that have been reported previously for chlordecone. Generally, female rats challenged with CCl4 or endrin/CCl4 exhibited greater increases in serum enzyme levels than did male rats given corresponding treatments.     

Effect of gomisin A (TJN-101) on the arachidonic acid cascade in macrophages

It has been reported that leukotrienes (LTs) may play a role in inflammatory liver diseases, and several inhibitors of LTs show an inhibitory effect on experimental liver injuries. In this study, the effect of Gomisin A (TJN-101), which is a lignan component of schisandra fruits, on the arachidonic acid cascade in macrophages was examined to explain the mechanisms of the inhibitory effect of TJN-101 on liver injuries. The production of leukotriene B4 was suppressed by treatment with TJN-101, while the activity of 5-lipoxygenase was not affected. The release of arachidonic acid from macrophages stimulated with fMet-Leu-Phe or the Ca++ ionophore A23187 was suppressed by treatment with TJN-101. The activity of phospholipase A2 was not affected by treatment with TJN-101. These results suggested that TJN-101 produces an inhibitory effect on the biosynthesis of LTs by preventing the release of arachidonic acid, and it was thought that the preventive effect on the arachidonic acid cascade may be partially associated with the inhibitory effect of TJN-101 on liver injuries.     

Aspirin disposition in rats acutely intoxicated with CCl4

The profile of urinary salicylate metabolites was determined after an oral administration of acetylsalicylic acid (ASA) to: 1, control rats; 2, rats treated with CCl4 and 3, rats intoxicated with CCl4 and also pretreated with colchicine for 7 days. The following enzymatic activities were determined: liver and plasma ASA-esterase, liver UDP-glucuronyltransferase and liver aniline hydroxylase. The time course of plasma concentration of salicylates in similar groups were followed after the intraperitoneal administration of acetylsalicylic acid (ASA), salicylic acid (SA) or gentisic acid (GA). The animals acutely intoxicated with CCl4 showed a reduction in urinary excretion of glucuronates and an increased urinary excretion of gentisic and salicylic acids. The activities of plasma and liver ASA-esterases were significantly increased in CCl4-treated rats while the aniline hydroxylase was reduced and the UDP-glucuronyltransferase remained unchanged. The plasma half lives of salicylates were reduced in CCl4-treated rats regardless of the administered parent compound. Colchicine pre-treatment completely prevented the alterations produced by acute intoxication with CCl4. The heterogeneity of liver metabolic dysfunctions present in acute liver damage was evidenced. It is emphasized that the pharmacokinetic alterations produced by acute liver injury can be the result of complex factors that may involve changes in circulation, hepatic binding protein and other routes of elimination.     

Effect of colchicine on hepatobiliary function in CCl4 treated rats.

A number of toxic chemicals affect the biliary excretory function of liver. Organochlorines and halomethanes are known to enhance bile flow. Despite the demonstration that a diversity of agents modify biliary function, the mechanism by which these chemicals manifest this effect is not fully understood. This study was designed to assess the effect of colchicine (0.1, 1.0, or 2.5 mg/kg, i.p., in saline) administration on biliary excretory function 6 and 24 hr later. Additionally, the effect of colchicine (1 mg/kg, i.p. in saline) pretreatment in rats 2 hr prior to the administration of a single low dose of CCl4 (100 microL/kg, i.p., in corn oil) or corn oil alone (1 mL/kg, i.p.) on hepatic biliary excretory function was also assessed at 6 and 24 hr after the last treatment. The hepatotoxicity was evaluated by serum enzymes, alanine and aspartate aminotransferases, and histopathological alterations of the liver. Biliary excretion of intravenously administered phenolphthalein glucuronide (PG) was assessed in bile duct cannulated anesthetized rats. Only the highest dose of colchicine (2.5 mg/kg) resulted in detectable liver injury as revealed by elevations of serum transaminases. While the lowest dose of colchicine (0.1 mg/kg) did not influence bile secretion, the two higher doses caused a slight choleretic effect at 24 hr. The highest dose caused a transient inhibition of bile flow, but this effect was no longer evident at 6 hr. Biliary excretion of PG was inhibited significantly by colchicine within 6 hr after administration, an effect that was also persistent at 24 hr. Colchicine at a 1 mg/kg dose did not cause any adverse effect on hepatobiliary function. Therefore, for the interactive toxicity study with CCl4, 1 mg colchicine/kg was chosen as a moderate dose which did not cause any significant adverse effect on hepatobiliary function. Biliary excretion of PG was significantly lower in rats at 6 and 24 hr after the combination treatment with colchicine + CCl4 than in rats receiving either CCl4 or colchicine alone. In contrast, rats receiving CCl4 alone or colchicine + CCl4 showed a significant increase in cumulative bile flow at 6 hr, whereas, at 24 hr, the bile flow was increased significantly in rats receiving colchicine regardless of CCl4 treatment. The data suggest that colchicine pretreatment leads to significant inhibition of hepatobiliary excretion in CCl4 treated rats. Serum alanine transaminase and aspartate transaminase levels were elevated significantly after the colchicine + CCl4 combination, indicating hepatic injury.(ABSTRACT TRUNCATED AT 400 WORDS)     

Prophylactic effect of tritoqualine (TRQ) on the CCl4-induced chronic liver injury model in rats

Tritoqualine (TRQ) administered at doses of 100 or 200 mg/kg, perorally, had a preventive effect on the liver injury in rats induced by the treatment with CCl4 for 12 weeks consecutively. Rats subjected to this chronic treatment with CCl4 showed a decrease in body weight gain and changes in several serum parameters that are indicators of hepatic function were observed: the increase of transaminases, as a parameter of hepatocyte breakdown; the increase of alkaline phosphatase, as a parameter of biliary system abnormalities, the reduction of prothrombin time, as a marker of protein biosynthesis in the liver; and the change of lipids concentrations, reflecting liver injury. After the administration of TRQ perorally, there was a notable suppression of the increment in leaked enzymes in the serum and a marked improvement of the parameters concerning protein biosynthesis and lipid metabolism in comparison with CCl4 control rats. Marked fibrosis in the liver was observed after CCl4 treatment for 12 weeks, and the collagen content in the liver was 5 times higher than that of control rats. TRQ suppressed the increment in collagen formation and also showed improvement of the decrease of the liver function with regards to protein biosynthesis in CCl4-treated rats. Judging from these results, it was concluded that TRQ had a remarkable protecting action on the liver injury chronically induced by CCl4 treatment and was a effective compound for restoring liver function.     

Absorption, distribution, metabolism and excretion of YM466, a novel factor Xa inhibitor, in rats

YM466 is a novel factor Xa inhibitor for the treatment of thrombosis. The absorption, distribution, metabolism and excretion of YM466 were investigated in male Fisher rats after a single oral administration. YM466 was absorbed rapidly from all segments of the gastrointestinal tract except the stomach. After oral dosing, the plasma concentration of (14)C-YM466 reached a maximum within 0.5 h, and declined rapidly with an elimination half-life of 0.64 h. The unchanged YM466 accounted for almost all of its radioactivity, suggesting a minimal metabolism in rats. This was also supported by the finding that no metabolites were observed in bile and urine after oral dosing of (14)C-YM466. The distribution of (14)C-YM466 in tissue was evaluated and the liver and kidney were the organs with radioactivity concentrations consistently higher than that of plasma. Cumulative biliary and urinary excretion of radioactivity in bile duct-cannulated rats was 29.5% and 7.6%, respectively, indicating prominent excretion into bile after oral dosing. This was consistent with the finding that 76.1% and 25.2% of radioactivity dosed were excreted to faeces and urine, respectively, after i.v. dosing. These results suggest that YM466 was rapidly absorbed and then subjected to biliary excretion with a minimal metabolism after oral dosing to rats.     

Diurnal variation in the biliary excretion of flomoxef in patients with percutaneous transhepatic biliary drainage

AIMS: To examine diurnal variation in biliary excretion of flomoxef. METHODS: Flomoxef (1 g) was injected intravenously in eight patients with percutaneous transhepatic cholangiography with drainage at 09.00 h and 21.00 h by a cross-over design with a 36 h washout period. Drained biliary fluid was collected for 6 h after each dosing. These patients still had mild to moderate hepatic dysfunction. RESULTS: Bile flow and bile acid excretion for 6 h after dosing did not differ significantly between the 09.00 h and 21.00 h treatments. The maximum concentration of biliary flomoxef was significantly greater and its total excretion for 6 h tended to be greater after the 21.00 h dose [maximum concentration (microg ml(-1)): 34.2 +/- 29.9 (09.00 h dose) vs 43.5 +/- 28.3 (21.00 h dose) (95% confidence interval for difference: 2.6 approximately 15.9, P = 0.013); total excretion (mg 6 h(-1)): 1.4 +/- 1.3 (09.00 h dose) vs 1.6 +/- 1.2 (21.00 h dose) (95% confidence interval for difference: -26.8, 313.7, P = 0.087)]. The period that biliary flomoxef remained above the minimal inhibitory concentration did not differ significantly between the two treatment times. CONCLUSIONS: These results suggest that biliary excretion of flomoxef shows diurnal variation. However, as the difference was relatively small, flomoxef could be given at any time of day without any dosage adjustments.     

Chlorzoxazone: a probe drug the metabolism of which can be used to monitor one-point blood sampling in the carbon tetrachloride-intoxicated rat.

In this study, we have carried out an investigation to determine if chlorzoxazone (CZX) is a suitable probe drug for predicting hepatic injury in carbon tetrachloride (CCl4)-intoxicated rats. The animals received oral doses of CCl4 (0.25, 0.5 and 1 ml/kg) 24 h prior to intraperitoneal administration of CZX. The total CYP and CYP2E1 content, as well as the aniline and CZX hydroxylase activity (Vmax and CLint), was reduced depending on the dose of CCl4 administered. At the highest concentration (128 mM) of diethyldithiocarbamate, a specific inhibitor of CYP2E1, the production of 6-hydroxychlorzoxazone (HCZX) in microsomes from CCl4-treated rats was reduced by about 85%. The IC50 value in microsomes from CCl4-treated rats was between 3 and 5 microM. The production of HCZX and the activity of aniline hydroxylase in CCl4-treated rats correlated with the amount of rat CYP2E1 protein (r=0.881, P<0.001 and r=0.822, P<0.001, respectively). The elimination of CZX by CCl4-treated rats was reduced and the HCXZ production in the CCl4-treated group was less than that in the olive oil-treated control group. The correlations between the intrinsic clearance [CLint: Vmax/Km) in vitro and the total body clearance (CLtot) of CZX hydroxylation and the elimination half-life (t1/2) of CZX in vivo in CCl4-treated rats were high (r=0.839, P<0.001 and r= -0.828, P<0.001, respectively). In addition, the metabolic plasma HCZX/CZX ratio did not require multiple blood sampling and, 2 h after CZX administration in vivo, there was also a high correlation with the CLint (Vmax/Km) in vitro (r= -0.909, P<0.01). In conclusion, these results from this study demonstrate that CZX is a good probe for monitoring the inhibition of metabolism in rats due to CCl4 treatment.     

The impaired disposition of probe drugs is due to both liver and kidney dysfunctions in CCl(4)-model rats

The carbon tetrachloride (CCl(4))-treated model involving mature Sprague-Dawley rats has been historically relied upon to study liver injury and regeneration and to test drug efficacy and disposition. However, there few studies about phase II metabolic enzymes changes in CCl(4)-model rats. The metabolic and excretion tests of phenacetin and acetaminophen (APAP), and the mRNA test of cytochrome P4501A2 (CYP1A2) and phase II metabolic enzymes [sulfotransferase 1A1 (SULT1A1) and UDP-glucuronosyltransferase 1A6 (UGT1A6)] were studied in model rats after CCl(4) pretreatment. The result showed that the function and structure of liver and kidney was impaired by CCl(4) pretreatment, and a significant difference has been observed in the mRNA content of CYP1A2 (p<0.01) in model group, but there was no significant difference on the mRNA content of SULT1A1 and UGT1A6 in both groups. Compared to the control group, a significant higher content of phenacetin (p<0.01) and sulfate-APAP (AS, p<0.01) was observed in the metabolic tests of phenacetin and APAP. Statistically significant differences in cumulative urinary excretion levels of APAP, AG and AS for CCl(4) model rats were observed also. We have shown that impaired disposition of probe drugs in this model was due to both liver and kidney dysfunction in CCl(4)-model rats and we should consider the development of a new liver damage model without renal impairment.