Tohru Hashida

Effect of clarithromycin on renal excretion of digoxin: Interaction with P‐glycoprotein

We present a digoxin‐clarithromycin interaction in two patients in whom digoxin concentrations were unexpectedly increased. The ratio of renal digoxin clearance to creatinine clearance in one patient was lower during the concomitant administration of clarithromycin (0.64 and 0.73) than that after cessation of clarithromycin administration (1.30 ± 0.20; mean ± SD). Because P‐glycoprotein could play an important role in the renal secretion of digoxin, we hypothesized that clarithromycin decreases renal digoxin excretion by inhibiting P‐glycoprotein‐mediated transport. Digoxin transport was evaluated with use of a kidney epithelial cell line, which expresses the human P‐glycoprotein on the apical membrane by transfection with MDR1 complementary deoxyribonucleic acid. Clarithromycin inhibited the transcellular transport of digoxin from the basolateral to the apical side in a concentration‐dependent manner and concomitantly increased the cellular accumulation of digoxin. These results suggest that clarithromycin may inhibit the P‐glycoprotein‐mediated tubular secretion of digoxin, and this interaction mechanism may contribute to an increase in the serum digoxin concentration.

The evolution of immunosuppression with FK506 in pediatric living-related liver transplantation.

The effects of three FK506 induction regimens on pediatric living-related liver transplantation (LRLT) were studied retrospectively in terms of patient survival and adverse side effects. The patients consisted of 120 children, ranging from 3 to 210 months of age, who underwent a total of 122 LRLTs with a minimum follow-up of 6 months. Immunosuppression consisted of FK506 and low-dose steroids. FK506 was given in 3 ways: (1) high-dose intravenous (i.v.) induction, with FK506 begun at a dose of 0.15 mg/kg/day for the first 16 patients; (2) low-dose i.v. induction, with FK506 begun at a dose of 0.06 mg/kg/day for the next 45 patients; and (3) per os (p.o.) induction, with FK506 begun orally from the day prior to LRLT and continued postoperatively. Whole-blood trough levels of FK506 were monitored daily. Trough levels in the high induction group were often as high as 100 ng/ml compared with the level of 20 ng/ml in the p.o. induction group. Patient survivals were 75%, 89%, and 80% in the high-i.v. vs. low-i.v. vs. p.o. groups. The incidences of acute rejection were 12.5%, 22.2%, and 26.4%, and the incidences of viral infection were 56%, 38%, and 11% in the respective groups. Major adverse effects occurred with higher frequency in the high-i.v. induction group. Oral FK506 induction therapy at a dose of 0.15 mg/kg/day starting from the day before LRLT was safer and associated with a lower incidence of viral infection than therapy with i.v. FK506.

Pharmacokinetic and prognostic significance of intestinal MDR1 expression in recipients of living‐donor liver transplantation

Living‐donor liver transplantation (LDLT) and subsequent immunosuppressive therapy with tacrolimus have been cornerstones in the recovery of patients from end‐stage liver failure, but there has been no critical dosage regimen for tacrolimus therapy, especially the initial dosage. In this study, we examined whether the absorptive barriers, multidrug resistance protein (MDR1), or cytochrome P450 IIIA4 (CYP3A4) are important pharmacokinetic factors for tacrolimus and are prognostic indicators for LDLT outcome.

Effect of intestinal P-glycoprotein on daily tacrolimus trough level in a living-donor small bowel recipient

We have examined whether the expression levels of the intestinal absorptive barriers, MDR1 gene product P‐glycoprotein and cytochrome P450 IIIA4 (CYP3A4), correlate with the trough levels of orally administered tacrolimus in a recipient of small bowel transplant for 4 months. By using a competitive polymerase chain reaction, the expression of MDR1 messenger RNA (mRNA) and CYP3A4 mRNA by intestinal cells in a part of the mucosa biopsy specimen was evaluated. The average mRNA expression levels of MDR1 and CYP3A4 were 8.6 and 39.6 amol/μg total RNA, respectively. Both the MDR1 and CYP3A4 mRNA levels changed markedly throughout this period. The tacrolimus concentration/dose ratio correlated well with the mRNA expression level of MDR1, but not CYP3A4. These results suggested that intestinal P‐glycoprotein rather than CYP3A4 is a good probe to predict the intraindividual variation in the tacrolimus pharmacokinetics during immunosuppressant therapy after small bowel transplantation.

Multicenter study for environmental and biological monitoring of occupational exposure to cyclophosphamide in Japan.

Purpose. A multicenter field survey of environmental contamination and exposure of healthcare professionals to anticancer drugs were performed. Setting. Three university hospitals, one cancer specialty hospital and two corporate hospitals from across Japan. Method. The environmental contamination with cyclophosphamide (CP) was investigated. A wipe examination was performed at six sites apiece in two divisions. The urinary excretion of the CP over 24 h was determined. The subjects of the survey included physicians, pharmacists, and nurses, for a total of seven at each facility irrespective of job title. The wipe samples were collected at 12 sites within two divisions at each facility. For the exposure survey, the total urine volume was determined, and a portion of the urine sample was then collected from each participants at each facility. Urine was collected for 24 h. The samples were determined by using the GC-MS method. Results. Wipe examination: contamination with CP was identified at 50% of the sites. The concentration was high (CP > 1.00 ng/cm2) in the general environment in two hospitals and in the safety cabinet in one hospital. In the survey for the exposure of staff to anticancer drugs, 276 samples were obtained from 41 healthcare professionals. CP was detected in 90 samples obtained from 23 subjects. The amount of exposure was greatly different among the facilities. The urinary excretion of CP per subject was between 2.7 and 462.8 ng/24 h. The range of urinary excretion for each hospital was between 4.6 and 211.2 ng/24 h.

A comparative study on immunosuppressive effects of cyclosporin A and FK 506 on peripheral blood lymphocytes in dogs

Immunosuppressive effects of cyclosporin A (CsA) and FK 506 (FK) on peripheral blood lymphocytes were studied in dogs in respect to mixed lymphocyte reaction, proliferative responses to recombinant interleukin-2 (rIL-2), phytohemagglutinin (PHA) and concanavalin-A (Con-A); phenotypes of OKIa1, CD3, CD8 and surface IgM; cytotoxic activity against xenogeneic tumor cells. CsA (2.0 or 5.0 mg/kg, intravenously) or FK (0.16 mg/kg, intramuscularly) was given to mongrel dogs every morning for serial 21 days. The blood concentrations of CsA, measured as trough levels by fluorescence polarization method, ranged from 37 to 350 ng/ml in dogs administered at 2.0 mg/kg and from 170 to 894 ng/ml in dogs administered at 5.0 mg/kg during treatment, respectively. In dogs treated with FK at a dose of 0.16 mg/kg, the drug concentrations in the plasma during treatment ranged from 0.16 to 1.8 ng/ml. Mixed lymphocyte reaction and proliferative responses to rIL-2, PHA and Con-A, which were declined by CsA, were not affected by FK. In contrast, the proportion of OKIa1+ cells was not affected by CsA, whereas FK decreased the proportion of OKIa1+ cells progressively during the course of treatment. Cytotoxic activity was suppressed by both CsA and FK. These results possibly indicate that CsA and FK exert their immunosuppressive effects via different mechanisms.

A proposal of FK506 optimal dosing in living related liver transplantations

We analyzed the relation between FK506 trough levels (ELISA: patients 1–41, EVfx: patients 42–70) and rejection and/or viral infection episodes, retrospectively, in the first 70 consecutive cases of living related liver transplantation. Twenty patients (28.6%) had rejection episodes. Of the 13 patients who had evidence of rejection during the first 3 months, 6 patients without infection and 7 patients with viral infection showed low concentrations of FK506 (<5 ng/ml). Twelve patients were treated and improved with high dose steroid administration and an increase in the FK506 dosage. One patient died of refractory rejection. Nine patients had evidence of rejection after the first 3 months. In 3 patients, weaning from FK506 intiated the rejection episodes. Five patients repeated rejection and 4 patients required a third immunosuppressant (azathioprine). Viral infection included CMV (11 cases), EBV (13 cases), HZV (3 cases), and HSV (1 case). Excess immunosuppression might have been the cause, but no clear correlation was found. We propose that the optimal dosage of FK506 obtained by monitoring the trough levels using the IMx method should maintain a 10–20 ng/ml level during the first month, and a 5–10 ng/ml level at the second and third months.

Verification of surface contamination of Japanese cyclophosphamide vials and an example of exposure by handling

Purpose: Cyclophosphamide (CP) contamination has been detected in Japanese hospitals. In other countries, the surface contamination of CP vials has been reported; however, the manufacturing process of Japanese CP vials is unknown, so the conditions are not necessarily the same as in other countries. This study aimed to establish whether vial surface contamination also occurs in Japan. Method: Contamination of vial surfaces was examined with a wipe test. Urine samples were taken from a pharmacist, engaged solely in dispensing work, for 29 h. It was also investigated whether CP vials were dispensed during the urine sampling period. In addition, vial surfaces, purposely coated with CP and then washed, were examined using wipe tests. Result: CP was detected at 30–60% in vials, which was 11–62 ng (0.10–0.54 ng/cm2). One of the urine samples was contaminated (CP 13.5 ng); this was taken on Day 2 (11:35 AM). CP was not detected among the washed vials. Discussion: This study shows that the surface of Japanese CP vials was contaminated and that it was probable that healthcare workers were exposed to CP. CP absorption by the pharmacist was probably due to dermal uptake while dispensing. Washing the vial is considered effective to avoid CP exposure. Manufacturers should be more proactive to prevent contamination and healthcare workers should comply with exposure prevention rules. Cytotoxic drugs should be included in institution monitoring lists.

Immunological Treatment with Low Dosage Ciclosporin in Rat Liver Allotransplantation

Ciclosporin (CsA) was administered subcutaneously at a dose of 3 mg/kg body weight/day from the day of operation to 14 days of liver allotransplantation in ACI rat (RT1a) to LEW rat (RT1(l) strain combination. All LEW recipients of ACI liver transplants without immunosuppressive treatment had severe rejection and expired within 12 days. In contrast, 7 out of 9 recipients in the same strain combination with temporary CsA treatment survived indefinitely. Histologically, widespread cellular infiltration and massive hepatocyte necrosis were evident upon autopsy of the recipients without CsA treatment. In contrast, in the surviving rats of the CsA-treated group, mononuclear cell infiltration was restricted to the periportal field and hepatocytes appeared to be normal at 14 days posttransplant. CsA concentrations in whole blood were determined by high-performance liquid chromatography. The trough levels were 788 +/- 48, 621 +/- 76 and 546 +/- 52 ng/ml, at 5, 10 and 14 days posttransplant, respectively. We concluded that this relatively low-dose subcutaneous administration of CsA offered adequate immunosuppression in rat liver allotransplantation in this strain combination.

Effect of cyclosporine on oxidative phosphorylation and adenylate energy charge of regenerating rat liver

SummaryThe effect of cyclosporin A (CyA) on regenerating liver was investigated in subtotal hepatectomized rats treated with CyA in terms of mitochondrial phosphorylative activity, hepatic energy charge, and serum bilirubin levels. In the CyA-treated hepatectomized group, the energy charge decreased from normal control value of 0.857 to 0.782 at 6 h after hepatectomy. The decreased energy charge, however, gradually increased and returned to 0.842 at 48 h after hepatectomy with no significant changes being observed between CyA-treated and untreated hepatectomized groups. Phosphorylation rate in the CyA-untreated group increased to 142% of the normal control at 24 h and then decreased to 114% at 48 h after hepatectomy. By contrast, phosphorylation rate in the CyA-treated group increased to 144% of the normal control at 24 h, but remained at the high value of 132% (P < 0.01; compared to the CyA-untreated group) even at 48 h after hepatectomy. Serum total bilirubin levels in the CyA-treated group were significantly higher than those in the CyA-untreated group during all experimental periods. We conclude that CyA does not exert a direct detrimental effect on mitochondrial function and that, despite the marked hyperbilirubinemia induced by CyA, the mitochondrial phosphorylative activity increases adaptively to provide sufficient energy for enhanced ATPutilizing reactions in an early process of liver regeneration.