Yoshio Ijiri

Dialyzability of the Antiepileptic Drug Zonisamide in Patients Undergoing Hemodialysis

Summary:  Purpose: The influence of hemodialysis on plasma zonisamide (ZNS) concentration has not been clarified. In this study, the dialyzability of ZNS during hemodialysis was investigated in four ZNS‐treated women with systemic lupus erythematosus complicated by seizures.

Digitalis-like immunoreactive substances in maternal and umbilical cord plasma: a comparative sensitivity study of fluorescence polarization immunoassay and microparticle enzyme immunoassay.

Digitalis-like immunoreactive substances (DLIS) obtained from maternal and umbilical cord plasma at delivery were measured by fluorescence polarization immunoassay (FPIA; TDX, Abbott) and microparticle enzyme immunoassay (MEIA; IMX, Abbott). In each sample, concentrations of dehydroepiandrosterone, dehydroepiandrosterone sulfate, estradiol, estriol, hydrocortisone, progesterone, and testosterone were measured by radioimmunoassay, and cross-reaction tests of DLIS with these substances were conducted. By FPIA, the concentration of DLIS in umbilical cord plasma (0.55 ± 0.22 ng/mL) was significantly higher than that in maternal plasma (0.23 ± 0.11 ng/mL). In the cross-reaction tests, when the concentration of dehydroepiandrosterone sulfate was higher than 1.0 &mgr;g/mL or that of progesterone was higher than 0.5 &mgr;g/mL, DLIS were detected by FPIA. However, DLIS were not found either in the samples or in the cross-reaction tests by MEIA. By radioimmunoassay, there was no significant difference in the dehydroepiandrosterone sulfate concentration between the maternal plasma (2,917 ± 1,001 ng/mL) and the umbilical cord plasma (1,957 ± 376 ng/mL). The progesterone concentration in the umbilical cord plasma (310.0 ± 85.7 ng/mL) was significantly higher than that in the maternal plasma (126.4 ± 38.5 ng/mL). These results suggest that dehydroepiandrosterone sulfate in maternal plasma and progesterone in maternal and umbilical cord plasma may be measured as digoxin by FPIA.

Changes of midazolam pharmacokinetics in Wistar rats treated with lipopolysaccharide: relationship between total CYP and CYP3A2

It has been reported that infection interferes with drug metabolism, resulting in changes in pharmacokinetics. In this study, we investigated the effects of lipopolysaccharide (LPS) on hepatic total cytochrome P450 (CYP), CYP3A2, and CYP2C11 contents in a transient, LPS-induced, endotoxemia model of rats. In addition, to assess the effects on CYP3A2 activities, the pharmacokinetics of midazolam (CYP3A2 substrate) and 1-OH-midazolam (metabolite of midazolam) were investigated. Hepatic total CYP contents were significantly low until day 3 (P < 0.05) but returned to the control level on day 5. Hepatic CYP3A2 contents were significantly decreased on day 1 until day 5 (P < 0.05) but returned to the control level on day 7. Hepatic CYP2C11 contents were continuously low until day 7, and lowest on day 3. The AUC of 1-OH-midazolam was significantly decreased on day 1 after LPS administration (P < 0.01). In conclusion, LPS (5 mg/kg) challenge decreased hepatic total CYP, CYP3A2, and CYP2C11 contents and also decreased the activities of hepatic CYP3A2. It took at least 7 days for hepatic total CYP and CYP3A2 to recover to control levels, and it was suggested that the changes of hepatic total CYP contents might correlate with those of hepatic CYP3A2 contents and activities. Additionally, it is shown that their changes might reflect the recovery process from inflammation.

Interference between eplerenone and digoxin in fluorescence polarization immunoassay, microparticle enzyme immunoassay, and affinity column-mediated immunoassay.

Digitalis-like immunoreactive substances have crossreactivity with antidigoxin antibodies and the interference between digoxin and spironolactone/canrenone has been reported. The structure of eplerenone is similar to that of spironolactone/canrenone. Therefore, we hypothesized that eplerenone might also interfere with the measurement of digoxin by immunoassay. We performed three types of assays (fluorescence polarization immunoassay [FPIA], microparticle enzyme immunoassay [MEIA], and affinity column-mediated immunoassay [ACMIA]) to determine crossreactions between eplerenone and antidigoxin antibodies. Furthermore, we used FPIA, MEIA, and ACMIA to measure the apparent digoxin concentration in mixed solutions of eplerenone (1-100 μg/mL) and digoxin (1-3 ng/mL). In the crossreaction tests, eplerenone was detected as digoxin by FPIA and ACMIA. By FPIA, a known concentration of 1 μg/mL of eplerenone was measured as 0.33 ± 0.11 ng/mL of digoxin (crossreaction rate, 0.03%). By ACMIA, a known concentration of 10 μg/mL of eplerenone was measured as 0.13 ± 0.05 ng/mL of digoxin (crossreaction rate, 0.001%). No crossreaction between eplerenone and digoxin was determined by MEIA. In the interference of eplerenone coadministered with digoxin, the apparent concentration of digoxin was increased in FPIA, but decreased in MEIA and ACMIA. The results suggest that eplerenone crossreacts with antidigoxin antibodies in FPIA, MEIA, and ACMIA, but that the interference of eplerenone might be smaller than that of spironolactone/canrenone.

Evaluation of an electrolysis apparatus for inactivating antineoplastics in clinical wastewater

We recently reported a system for inactivating antineoplastics in which sodium hypochlorite is supplied by the electrolysis of sodium chloride solution. In this study, we designed an electrolysis apparatus for inactivating the cytotoxicity of antineoplastics in clinical wastewater using the system. The apparatus consists of an electrolysis cell with platinum-iridium electrodes, a pool tank, a circulating system for wastewater, a safety system for explosive gas and overflow, and an exhaust duct. The free chlorine concentration increased linearly up to 6500 mg l(-1), and pH also increased to 9.0-10.0 within 2h, when 0.9% sodium chloride solution was electrolyzed. We examined its efficacy with model and clinical wastewaters. The reciprocal of dilution factor for disappearance of cytotoxicity using Molt-4 cells was compared before and after electrolysis. In the model wastewater, that was 9.10 x 10(4) before electrolysis, and 3.56 x 10(2) after 2h of electrolysis. In the clinical wastewater (n=26), that was 6.90 x 10(3)-1.02 x 10(6) before electrolysis, and 1.08 x 10(2)-1.45 x 10(4) after 2h of electrolysis. Poisonous and explosive gases released by the electrolysis were measured; however, they were found to be negligible in terms of safety. The environmental load was evaluated by carbon dioxide generation as an index and it was found that the carbon dioxide generated by the electrolysis method was 1/70 lower than that by the dilution method with tap water. Moreover, the cost of the electrolysis method was 1/170 lower than that of the dilution method. This method was found to be both effective and economically valuable.

Application of electrolysis for detoxification of an antineoplastic in urine.

Antineoplastics in excreta from patients have been considered to be one of the origins of cytotoxic, carcinogenic, teratogenic, and mutagenic contaminants in surface water. Recent studies have demonstrated that antineoplastics in clinical wastewater can be detoxified by electrolysis. In this study, to develop a method for the detoxification of antineoplastics in excreta, methotrexate solution in the presence of human urine was electrolyzed and evaluated. We found that urine inhibits detoxification by electrolysis; however, this inhibition decreased by diluting urine. In urine samples, the concentrations of active chlorine generated by anodic oxidation from 0.9% NaCl solution for inactivation of antineoplastics increased in dilution-dependent and time-dependent manner. These results indicate that electrolysis with platinum-based iridium oxide composite electrode is a possible method for the detoxification of a certain antineoplastic in urine.

Increased digitalis-like immunoreactive substances in neonatal plasma measured using fluorescence polarization immunoassay.

Objective:  To better define the reported increased digitalis‐like immunoreactive substances (DLIS) in neonatal plasma, we studied the relation among plasma DLIS level, blank intensity (BLK‐I) value at FPIA measurement and plasma total bilirubin level.

Chronological changes in circulating levels of soluble tumor necrosis factor receptors 1 and 2 in rats with carbon tetrachloride-induced liver injury.

Carbon tetrachloride (CCl₄) facilitates the generation of hepatotoxins that can result in morphologic abnormalities, and these abnormalities are reasonably characteristic and reproducible for each particular toxin. It is also known that tumor necrosis factor-alpha (TNF-α) may participate in CCl₄-induced liver injury (CILI). In this study, we observed the chronological changes in circulating soluble tumor necrosis factor receptors 1 and 2 (sTNF-R1 and -R2) in rats with CILI. Laboratory data; circulating levels of TNF-α, sTNF-R1, and sTNF-R2; and TNF-α levels in liver tissues were measured at various time-points. In the CCl₄ group, the plasma aspartate aminotransferase (AST, 7694±3041IU/l)/alanine aminotransferase (ALT, 3241±2159 IU/l) levels peaked at 48 h after CCl₄ administration, but the other laboratory data did not differ significantly from the corresponding data in the controls. Centrilobular hepatocyte necrosis and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive cells near the central vein area were observed via hematoxylin eosin (HE) and TUNEL staining, respectively, at 24 and 48 h after CCl₄ administration. Compared to the control group, the CCl₄ group did not show significantly the increased circulating TNF-α levels. But TNF-α levels in the liver tissues first peaked at 1h (5261±2253 pg/g liver), and a second peak was observed at 12h (3806±533 pg/g liver) after CCl₄ administration. Compared to the control group, the CCl₄ group showed significantly increased circulating levels of both sTNF-R1 (797±121pg/ml) and sTNF-R2 (5696±626 pg/ml) 1h after CCl₄ administration. Since the hepatocyte apoptosis may be resulted from binding of TNF-α with TNF-R1 at 24h after administration, and consequently the circulating TNF-R2 level might be approximately 10-fold higher than the circulating TNF-R1 level. In conclusion, increased circulating levels of sTNF-R1 and -R2 potentially contribute to drug-induced liver injury, together with AST/ALT.

Effects of lipopolysaccharide on P-glycoprotein expression and activity in the liver and kidneys

There have been many reports that P-glycoprotein expression and activity are altered during sepsis, but few of them have examined such changes over 72 h. In this study, we examined the effect of lipopolysaccharide (LPS, 5mg/kg, ip) on P-glycoprotein expression (Western blotting) and activity (rhodamine-123 (Rho123) pharmacokinetics) in liver and kidneys for 7 days. On day 1 after LPS administration, hepatic P-glycoprotein expression and activity significantly decreased. On day 3, hepatic P-glycoprotein expression significantly increased compared with the control group, while activity had returned to the control level. On day 7, hepatic P-glycoprotein expression returned to the control level. There were no significant changes in P-glycoprotein expression or activity in the kidneys after LPS administration. The amount of Rho123 excretion in urine remained unchanged with (4.2%) or without (4.0%) LPS administration, but the amount of Rho123 excretion in bile decreased from 2.0 to 0.7% with LPS administration. Our findings suggested that hepatic P-glycoprotein expression and activity decreased on day 1 but recovered within 3 days, but there were no significant differences in the kidneys after LPS administration. These results suggested that the change in P-glycoprotein activity might be due to change in P-glycoprotein expression in the liver rather than the kidneys.

False Prolongation of Prothrombin Time in the Presence of a High Blood Concentration of Daptomycin

Prothrombin time (PT) can reportedly be falsely prolonged by the antimicrobial drug daptomycin (DAP), and concomitant use of phosphatidylglycerol (PG). Although high doses of DAP (>6 mg/kg/day) are recommended for severe infection and result in a high blood concentration, the extent to which high blood concentrations of DAP interfere with PT, in the presence or absence of PG, has yet to be determined when using the HemosIL RecombiPlasTin 2G (Werfen Japan, Tokyo, Japan). We examined the effects of high doses of DAP on PT using this reagent. DAP (0–500 mg/L) was added to normal plasma and plasma with an already prolonged PT in the presence or absence of liposomal amphotericin B (L‐AMB, 5–50 mg/L) or COATSOME EL‐01 empty cationic liposomes (CS, 25–250 mg/L). Furthermore, we undertook a Monte Carlo simulation to calculate the probability of achieving DAP concentrations >100, >200 and >500 mg/L 0–48 hr after administering 6–12 mg/kg of DAP. Apparent PT increased with increasing DAP concentration, but neither L‐AMB nor CS appeared to further elevate PT when co‐administered with DAP. The probability of achieving DAP concentrations >100 and >200 mg/L increased with DAP dose. Higher doses of DAP than the approved dose caused false prolongation of PT. PT should be monitored carefully in patients taking high doses of DAP; ideally, PT should be measured at the trough blood concentration of DAP. Concomitant use of L‐AMB and CS did not generally further elevate PT when co‐administered with DAP.