Hiroyasu Ogata

Decreased Expression of Cytochromes P450 1A2, 2E1, and 3A4 and Drug Transporters Na+-Taurocholate-Cotransporting Polypeptide, Organic Cation Transporter 1, and Organic Anion-Transporting Peptide-C Correlates with the Progression of Liver Fibrosis in Chronic Hepatitis C Patients

Patients with chronic hepatitis C viral infection underwent liver biopsies and laboratory studies for evaluation and to determine subsequent treatment. Changes in status of drug metabolism and disposition may vary with chronic hepatitis C stage and should be assessed. Total RNA was extracted from liver biopsy specimens (n = 63) and reverse transcribed to yield cDNA. Relative mRNA levels of drug-metabolizing enzymes, transporters, nuclear receptors, and proinflammatory cytokines were analyzed with normalization to glyceraldehyde 3-phosphate dehydrogenase expression. mRNAs encoding cytochromes P450 1A2, 2E1, and 3A4, and drug transporters, Na+-taurocholate-cotransporting polypeptide, organic anion-transporting peptide-C, and organic cation transporter 1 showed remarkable decreases, and tumor necrosis factor-α showed an increase according to fibrosis stage progression. HepG2 cells and primary hepatocytes of two human individuals were treated with interleukin 1β, interleukin 6, or tumor necrosis factor-α. CYP1A2 and Na+-taurocholate-cotransporting polypeptide mRNA levels significantly decreased in HepG2 cells with interleukin 1β and interleukin 6 treatments. CYP2E1 and organic cation transporter 1 mRNA levels significantly decreased with tumor necrosis factor-α treatment only in HepG2. These results suggested that down-regulation of CYP1A2, 2E1, and 3A4, and drug transporters, Na+-taurocholate-cotransporting polypeptide, organic anion-transporting peptide-C, and organic cation transporter 1, manifested in livers of patients with chronic hepatitis C viral infection, was associated, at least in part, with the elevated production of proinflammatory cytokines, including tumor necrosis factor-α.

Meta-Analysis of Risk of Malignancy with Immunosuppressive Drugs in Inflammatory Bowel Disease

Background: There is a concern as to whether long-term administration of immunosuppressants in patients with inflammatory bowel disease (IBD) would increase the risk of malignancy. Objective: To compare the risks of developing malignancy between patients with IBD treated with immunosuppressive agents and patients with IBD not receiving these agents. Methods: A systematic literature review was conducted, and a meta-analysis was performed on data retrieved from cohort studies that followed patients with IBD who received immunosuppressive agents for more than a year and documented the incidence of newly developed malignancy. An electronic search was conducted using MEDLINE (1966–September 2006), the Cochrane Library (issue 3, 2006), and Japana Centra Revuo Medicina (1981–September 2006). Medical subject headings used in the searches were azalhioprine, 6-mercaptopurine, cyclosporine, methotrexate, tacrolimus, inflammatory bowel disease, and neoplasms. We imposed no language limitation in the searches. Additionally, a manual search of reference listings from all articles retrieved from the electronic databases was performed. Using data obtained from control groups or population-based studies, the incidence of newly developed malignancy in patients with IBD treated with immunosuppressive agents was compared with that of patients with IBD who were not receiving immunosuppressive agents. Statistical analysis for the change in risk of developing malignancy was performed using the weighted mean difference (WMD) normalized to per person-year and its 95% confidence interval. Results: Nine cohort studies met the inclusion criteria for this meta-analysis. Analysis of these studies showed no discernible difference (WMD −0.3 × 10-3/person-year; 95% CI −1.2 × 10-3 to 0.7 × 10-3) in the incidence of any kind of malignancy in patients with IBD who received immunosuppressants compared with those who did not receive immunosuppressants. No significant difference in WMD was observed when the data from patients with either Crohns disease (CD) or ulcerative colitis (UC) were analyzed separately. Conclusions: Our findings suggest that the administration of immunosuppressive agents in patients with either CD or UC probably does not confer a significantly increased risk of malignancy compared with patients with IBD who are not receiving these agents.

Comparison of Pharmacokinetics and Pharmacodynamics of Docetaxel and Cisplatin in Elderly and Non-Elderly Patients: Why Is Toxicity Increased in Elderly Patients?

PURPOSE Following phase I studies of docetaxel and cisplatin in patients with non-small-cell lung cancer, the recommended doses of docetaxel were different for elderly (> or = 75 years) and non-elderly (< 75 years) patients. To elucidate the mechanism of the difference, the pharmacokinetics of docetaxel and cisplatin were investigated in two phase II studies separately conducted in elderly and non-elderly patients. PATIENTS AND METHODS Twenty-seven elderly and 25 non-elderly patients were treated with three weekly administrations of docetaxel and cisplatin every 4 weeks. Doses of docetaxel were 20 and 35 mg/m(2) for elderly and non-elderly patients, respectively. All patients received 25 mg/m(2) of cisplatin. The pharmacokinetics and pharmacodynamics of docetaxel and cisplatin were compared in elderly and non-elderly patients. RESULTS There were no differences in pharmacokinetics of docetaxel or cisplatin between elderly versus non-elderly patients with regard to clearance and volume of distribution. In the pharmacodynamic analysis, neutropenia was positively correlated with the area under the concentration-time curve for docetaxel but not for cisplatin. In evaluating the relationship between neutropenia and the area under the concentration-time curve of docetaxel, elderly patients experienced greater neutropenia than those predicted by a pharmacodynamic model developed in non-elderly patients; the residual for prediction of the percent change in neutrophil count was -11.2% (95% CI, -21.8 to -0.5%). CONCLUSION The pharmacokinetics of docetaxel and unchanged cisplatin were not different between elderly and non-elderly patients. The elderly patients were more sensitive to docetaxel exposure than the non-elderly patients, resulting in the different recommended doses for the phase II studies.

Relationship between pharmacokinetics of unchanged cisplatin and nephrotoxicity after intravenous infusions of cisplatin to cancer patients

Abstract Purpose: The relationships between pharmacokinetic parameters of unchanged cisplatin (CDDP) and several markers for nephrotoxicity after CDDP infusion (80 mg/m2) over 2 and 4 h were quantitated in patients with various cancers (lung, stomach and colon cancers and mediastinal tumor). Methods: Plasma and urinary levels of unchanged CDDP were measured using a specific high-performance liquid chromatography method. Pharmacokinetic parameters were calculated according to the model-independent method. The nephrotoxicity markers, blood urea nitrogen (BUN), serum creatinine (SCr), plasma and urinary β2-microglobulin (BMGp and BMGu), urinary N-acetyl-β-D-glucosaminidase (NAG) and creatinine clearance (CCR) were monitored for 30 days following CDDP administration. Results: The maximum plasma concentration (Cmax), maximum urinary excretion rate (dAe/dtmax), area under the plasma concentration-time curve from time zero to infinity (AUC), cumulative amount excreted in urine from time zero to infinity (Ae), total clearance (Clt), renal clearance (Clr) and plasma half-life (t1/2) of unchanged CDDP were not significantly different between the 2-h and 4-h infusion schedules. The values of the nephrotoxicity markers changed significantly following CDDP administration, suggesting that CDDP chemotherapy (80 mg/m2) caused nephrotoxicity. The Cmax of unchanged CDDP was the most informative pharmacokinetic parameter for nephrotoxicity. Cmax was related to maximum BUN, maximum SCr and minimum CCR levels in 27 CDDP treatments according to an exponential model. Conclusion: In order to attain more effective CDDP chemotherapy with minimum nephrotoxicity, the present pharmacokinetic and pharmacodynamic studies suggest that the Cmax or steady-state plasma level of unchanged CDDP should be maintained between 1.5 and 2 μg/ml in a standard continuous infusion schedule over 2 h and 4 h.

Effect of phospholipid emulsifiers on physicochemical properties of intravenous fat emulsions and/or drug carrier emulsions

Abstract— The physicochemical properties of soybean oil emulsions stabilized with purified egg lecithins (phosphatides) of various concentrations have been examined. The zeta potential of the emulsion droplets and the mean particle size of oil droplets in 10% (w/w) o/w‐type emulsion decreased with increasing emulsifier concentration and then levelled off at more than 1.2% (w/w). In rheological measurements, at the initial stage, the viscosity of 10% (w/w) o/w‐type emulsion gradually increased with increasing purified egg lecithin concentration, at the next stage, a plateau was reached at about 1.0–1.4% (w/w), and at the final stage, the viscosity curve showed a dramatic increase. These results indicate that emulsions stabilized by purified egg lecithin at more than 1.2% (w/w) are likely to be sufficiently stable.

Gastric acidity dependent bioavailability of cinnarizine from two commercial capsules in healthy volunteers

Abstract Two commercially available capsules of 25 mg cinnarizine, which were chosen from the results of dissolution tests as the extreme cases out of 32 such capsules available in Japan, were examined in detail to determine their dissolution properties and bioavailabilities. The two capsules had similar dissolution rates at pH 1.2 and at pH 6.0 even though the rate at pH 1.2 was much faster than at pH 6.0. The serum levels of cinnarizine, which were determined by a GC-MS technique after administration of a single cinnarizine capsule, showed a wide variation in human volunteers, and this was ascribable to differences in the gastric acidity of the subjects. The AUC 0–8h values of the two capsules in the subjects having low gastric acidity were only 27 and 14% of those in the high acidity group, and the C max values of the two capsules were also depressed to 32 and 14% of those in the high acidity subject group, respectively. Bioavailability of cinnarizine appears to be determined mainly by the amount dissolved in the stomach.

Active oxygen species generation and cellular damage by additives of parenteral preparations: selenium and sulfhydryl compounds.

We investigated the relationship between active oxygen species (AOS) generation and cultured vascular endothelial cellular damage caused by simultaneous exposure to selenium compounds and sulfhydryl compounds such as cysteine (Cys) or reduced glutathione (GSH). Selenium compounds, selenite, selenate or selenomethionine (SeMet), are added to total parenteral nutrition (TPN) and intravenously administered. We confirmed by luminol dependent chemiluminescence, an indicator of AOS generation, that selenite generates AOS in the presence of clinical concentrations of sulfhydryl compounds, 0.5 mM Cys or 0.5 mM GSH, and that the amount of AOS generated reaches the maximum when their mole ratio is 1:50. However, AOS generation was not observed after simultaneous administration of various concentrations of selenate or SeMet with sulfhydryl compounds. Moreover, simultaneous exposure to 10 microM selenite and sulfhydryl compounds was found to result in significant increases in the [3H]-adenine and lactate dehydrogenase (LDH) release rates from cells, a significant decrease in the amount of cellular protein, and enhancement of cellular damage as compared with after exposure to selenite alone. However, simultaneous exposure to 10 microM selenate or 10 microM SeMet together with sulfhydryl compounds did not induce cellular damage. These findings revealed that selenite generates AOS and causes cellular damage in the presence of sulfhydryl compounds. Accordingly, it seems better to choose selenate or SeMet instead of selenite when a selenium compound is to be added to TPN.

Quantitative relationship between pharmacokinetics of unchanged cisplatin and nephrotoxicity in rats: importance of area under the concentration-time curve (AUC) as the major toxicodynamic determinant in vivo

Abstract Purpose: The major pharmacokinetic parameters of unchanged cisplatin (CDDP) related to nephrotoxicity were evaluated in rats in vivo using a pharmacodynamic model. Methods: CDDP was administered according to various dosing schedules (single bolus, intermittent bolus, or continuous infusion). Unchanged CDDP in plasma and urine was quantified using high-performance liquid chromatography (HPLC). The pharmacokinetics were assessed by model-independent methods. The relationship between pharmacokinetics and BUN levels was evaluated using a sigmoid maximum response (Emax) model. Results: Unchanged CDDP showed linear pharmacokinetics after single bolus injections of 1 to 5 mg/kg CDDP. Nephrotoxicity was ameliorated following intermittent bolus injection (1 mg/kg per day for 5 days) and continuous infusions (over 2 and 3 h) of the same CDDP doses (5 mg/kg), although these dosing schedules did not change the area under the concentration-time curve (AUC), total clearance (Clt), urinary excretion of unchanged CDDP or kidney platinum levels significantly. The maximum BUN level, as a nephrotoxicity marker, showed dose-related increases after single bolus injection of 1 to 5 mg/kg CDDP and after 3-h infusion of 5 to 25 mg/kg. The pharmacodynamic relationship between the maximum BUN level and Cmax and between the maximum BUN level and AUC were apparently different between single bolus injection and 3-h infusion. The maximum BUN level was related to the AUC calculated by plasma concentrations of unchanged CDDP greater than the threshold level (AUC>Cmin), a relationship most successfully described by the signoid Emax model, regardless of CDDP dose and schedule. The plasma threshold level of unchanged CDDP was determined as 0.9 μgPt/ml in rats. Conclusions: The present results substantiated the importance of C×T (AUC) value as an indicator of CDDP-induced nephrotoxicity in vivo as well as of tumor cell-killing effect of CDDP in vitro. The AUC>Cmin of unchanged CDDP was found to be an important pharmacokinetic parameter predicting CDDP nephrotoxicity.

Enantioselective Binding of Propranolol, Disopyramide, and Verapamil to Human α1‐Acid Glycoprotein

We investigated the binding of propranolol (PL), disopyramide (DP), and verapamil (VP) enantiomers by human alpha(1)-acid glycoprotein (AGP; also called orosomucoid) and the relationships between the extent of drug binding and lipophilicity, desialylation, and genetic variants of AGP. Desialylation had little effect on the affinity of AGP for the drugs tested. The percentage binding correlated significantly with the partition coefficients for the drugs tested. Each enantiomer was competitively displaced from AGP by another enantiomer of the same drug, suggesting that they bind to the same site. However, the enantiomers bound to AGP with stereospecific affinities; the (-)-isomers of DP and VP had higher Kd values (4.27 and 4.97 microM, respectively) than the (+)-isomers (1.51 and 2.48 microM, respectively). When enantiomers of the different drugs were used in competitive binding experiments, VP binding was only partially inhibited by DP. This result suggested that drug binding is specific to different variants of AGP (A, F1, S). DP was found to specifically bind to variant A, whereas PL and VP bind to both A and F1/S variants.

Population Pharmacokinetics and Pharmacodynamics of Cisplatin in Patients with Cancer: Analysis with the NONMEM Program

The population pharmacokinetics and pharmacodynamics of cisplatin (CDDP) were evaluated based on a mixed‐effect model using the NONMEM program. Unchanged CDDP in plasma was measured as a biologically active platinum species during CDDP chemotherapy, using high‐performance liquid chromatography. Plasma concentration measurements (157) of unchanged CDDP from 26 patients with cancer receiving 80 mg/m2 CDDP by infusion over 2 hours, 3.5 hours, or 4 hours were analyzed according to a one‐compartment model. The influences of individual characteristics such as body weight, dose schedule, course, and clinical laboratory values (renal function markers, albumin) on total body clearance (Cl) and volume of distribution (Vd) were examined. In the final pharmacokinetic model, body surface area and dose schedule affected Cl of unchanged CDDP. The Cl of CDDP was increased by 27.3% after the 2‐hour infusion schedule compared with Cl after the longer infusions. The Vd was estimated as 13.4 L/m2. The interindividual variability for Cl and Vd and residual variability were 22.9%, 30.9%, and 35.5%, respectively. The relationships between maximum concentration (Cmax) of unchanged CDDP and maximum blood urea nitrogen (BUNmax), or minimum creatinine clearance (ClCr,min) over a 1‐month period after CDDP administration were evaluated according to linear, exponential, or maximum response (Emax) models. The linear or Emax model described pharmacodynamics most successfully, with relatively large interindividual variability for both slope and EC50 (more than 25%). Residual variability was 15.3% and 17.1% in BUNmax and ClCrmin, respectively. The population means and interindividual and residual variability of pharmacokinetics and pharmacodynamics of CDDP were evaluated using the NONMEM program. The results of this study show that the population pharmacokinetic and pharmacodynamic approach could be useful to manage CDDP nephrotoxicity using sparse data in a clinical setting.