FPIA Method Research Articles

Differential diagnosis in case of overdose of antiepileptic treatment. Clinical case

Acute drug-related acute intoxications or suicidal ideation following overdose with anticonvulsants may cause major morbidity, in many cases requiring intensive care and prolonged periods of hospitalization. The case of a 35-year-old patient known for a history of epilepsy with phenobarbital and carbamazepine treatment is brought to the Emergency Unit by transfer from another hospital in a comatose state with insufficient respiratory performance, bilateral active mydriasis. From the family members' claims, the patient discontinued treatment with phenobarbital two weeks ago. Following interdisciplinary examination, hospitalization in the Neurology Department with the diagnosis of epileptic status is decided. Due to the progressive aggravation of acute respiratory insufficiency, the ventilator support is constituted. Since the biological samples related to probability diagnosis and cerebral imaging were not conclusive, toxicological samples were collected. The GC/MS analytical toxicology screening in urine reveals the presence of carbamazepine and phenobarbital and their plasma levels (5.92 and 92.3 mg/l) as determined by the FPIA method indicate an overdose of phenobarbital therapy. The patient is taken over by the Department of Clinical Toxicology where specific intensive care measures are applied. Clinical evolution is favorable. The psychiatric examination highlights the depressive idea, suicidal ideas, and uselessness. The suicide attempt is confirmed. It also presents a review of the main information about acute poisoning with anticonvulsants, but also about the analytical laboratory methods that bring precious information in establishing the diagnosis of certainty.

Is gentamicin administered to individual patients in optimal doses already at the beginning of therapy?

Abstract Introduction A gentamicin dose, which the physicians select, frequently does not take any pharmacokinetic parameters into consideration. Aim To analyse the results of therapeutic drug monitoring (TDM) of gentamicin for those patients who have not had the gentamicin dose adjusted at the beginning of therapy (first group) and for those patients who had the gentamicin dose adjusted at the beginning of therapy (second group). Methods We acquired the basic data about patients from the requests for laboratory examination of levels of gentamicin. We measured all the gentamicin concentrations mentioned in this work using the FPIA method. Results The monitored set included 379 hospitalized patients during a 4-year period. We divided the monitored set into 2 groups. First group was composed of patients without dose adjustment of gentamicin at the beginning of therapy, and the second group was composed of patients with dose adjustment of gentamicin by the clinical pharmacist at the beginning of therapy. In addition, the patients in each group were divided according to the body mass index (BMI). In the first group of patients, a low percentage of patients had both optimal levels (trough, peak levels). As for patients with BMI > 25 m2/kg, there were only 17 % such cases, and the patients with BMI ≤ 25 m2/kg were only 18.8 %. In the second group, the patients had all trough and peak levels in optimal therapeutic range at obese patients, overweight patients and also at patients with normal weight (p < 0.001). Conclusion Adjustment of dosage regimens immediately at the beginning of therapy will provide for administering sufficient doses of antibiotics at the beginning of therapy, which is a pre-condition for a successful anti-infective therapy. Therapeutic monitoring of levels allows for administration of sufficient dose of gentamicin without fear of any undesirable effects.

The Impact of Supplementation with Folic Acid on Homocysteine Concentration and Selected Lipoprotein Parameters in Patients with Primary Hypertension.

The aim of the study was the assessment of the impact of supplementation with folic acid on the concentration of homocysteine, total cholesterol (TC), HDL- and LDL-cholesterol, triglycerides (TG), apoprotein AI (apoAI) and apoprotein B (apoB) in patients suffering from primary hypertension. The examined group comprised 42 patients suffering from primary hypertension. All examined patients underwent laboratory tests as follows: concentration of homocysteine, folic acid, TC, LDL-cholesterol, HDL-cholesterol, TG, apoAI and apoB. All patients were orally administered with 15 mg of folic acid per day for 45 d. After this period, all laboratory tests were repeated. Homocysteine concentration was measured by the FPIA method, concentrations of apoAI and apoB were measured by the nephelometric method, and other parameters with routine methods. After administration of 15 mg of folic acid to patients with primary hypertension, a considerable decrease in the concentration of homocysteine was observed in parallel with a substantive growth of HDL-cholesterol, as well as apoprotein AI concentrations and a reduction of the apoprotein B concentration. Results of statistical analysis indicated a significant correlation between the decline in homocysteine concentration and the increase in HDL-cholesterol concentration, as well as between the increase of folic acid concentration and the increase in apoAI concentration in patients following the intake of folic acid. The drop in homocysteine concentration through the supplementation with folic acid can cause quantitative changes in the lipid and lipoprotein parameters which, in consequence, may lead to the mitigation of risk concerning the development of atherosclerosis.

0323 : Atherogen effect of hyperhomocysteinemia induced by chronic administration of DL-methionine on male rabbits

the objective of this study is to determine the correlation between hyperhomocysteinemia and lipid status of male rabbit. our study carried on 30 male rabbits divided into three groups, Control (n=11) received standard diet and experimented Met1 (n=9) received standard diet supplemented with 500mg Met/day during 3 months, and Met2 (n=10) received standard diet with Met overload, 1500 mg/day, during 2 months. The monitoring concerns the body weight measure, homocysteinemia (FPIA method) and the cholesterolemia, LDL-C, HDL-C, triglyceridemia, NEFA determinations and atherogenicity index. the methionine overload caused a low increase of homocysteinemia in tested groups rabbits compared to the control one (Gong et al., 2008).This variation seemed not important to create body weight variation. This hyperhomocysteinemia caused a rise of atherogen lipid fractions; CT, LDL-C, NEFA and diminution of HDL-C in tested groups compared to the control one (Borsheim et al. 2009).The TG seemed no affected by this diet (Fernane, 2009). our results are similar to results of literature, indicating that atherogenicity of hyperhomocysteinemia is mediated by deterioration of lipid status. The author hereby declares no conflict of interest

Homocysteine – relation to hypertension, age and smoking in patients with newly diagnosed essential hypertension

Introduction. An elevated circulating concentration of homocysteine is associated with an increased risk of coronary, cerebral, and peripheral vascular disease. The purpose of this study was to determine the concentrations of homocysteine in the patients with newly diagnosed essential hypertension and healthy subjects and to analyze the correlation between homocysteine level and the other parameters (age, blood pressure, smoking).Material and methods. The study group consisted of 18 patients with essential hypertension, 4 women and 14 men (mean age 43 ± 16 years) and 15 healthy volunteers, 8 women and 7 men (mean age 47 ± 10 years). Serum homocysteine was analyzed by FPIA method (Fluorescence Polarization Immunoassay).Results. The patients with essential hypertension had significantly higher homocysteine concentration compared to control group. No correlation was observed between homocysteine levels and age, diastolic, systolic blood pressure in subjects with essential hypertension. In healthy volunteers, only a correlation between age and homocysteine concentration was found.

Biochemical criteria of toxicity of therapy with high doses of methotrexate in children with osteosarcoma

Methotrexate (Mtx) is a cytotoxic drug from the group of antimetabolites, folic acid antagonists. High-dose (HD) Mtx in pediatric oncology are used for the treatment of osteosarcoma (OS), and other types of tumors. This therapy has allowed to achieve a five-year relapse-free survival rates up to 80 % in patients with OS. However, the high toxicity of Mtx is a serious constraint in achieving the maximum therapeutic effect, which in most cases poses the occurrence of side effects in patients on various organs and systems. Treatment should be under strict laboratory monitoring, primarily therapeutic drug monitoring the concentration of Mtx in serum. 246 children (boys – 125, girls – 121) aged 5 to 16 years with osteosarcoma (mean age 12.2 years) who were treated in N.N. Blokhin Russian Cancer Research Center from 2006 to 2013. Patients were conducted from 1 to 8 courses HD Mtx at a dose of 8 or 12 g/m2 , administered within 4 h of infusion on the background of alkaline prehydrate. Leucovorin was administered intravenously, every 6 hours, starting 24 h from the start of the Mtx infusion. 1137 courses of HD Mtx were conducted with FPIA method (analyzer TDx/Flx, Abbott, USA). The technique of monitoring of homocysteine (Hcy) in the blood serum by analyzer Vitros 5/1FS (Johnson & Johnson, USA) during the entire course of high-dose Mtx was tested. In groups calculated pharmacokinetic parameters Mtx were tested: area under the pharmacokinetic curve (MtxAUC), clearance of methotrexate (ClMtx), the elimination half-life (T1/2 ) and the total time of excretion (Ttotal). Normal excretion of Mtx was revealed at 1050 courses Mtx, corresponding to the following values: 4 h – 1109 ± 283 μmol/l; 24 h – 4,67 ± 0,95 μmol/l; 42 h – 0,38 ± 0.16 µmol/l; 48 h – less than 0,23 ± 0.04 µmol/l; 72 h of 0.07 ± 0,03 µmol/l; 96 h of 0.03 ± 0.01 µmol/l. At 87 courses identified delayed Mtx excretion, accounting for 7.6 % of all courses. In all measured parameters: hourly concentration of Mtx, Ttotal, MtxAUC, Clmtx, T1/2 , is obtained statistically significant differences between normal and delayed Mtx excretion. Patients in group of delayed excretion of methotrexate were characterized by the development of hepatotoxicity, there were also observed 4 cases of the occurrence of acute renal failure. Monitoring of biochemical parameters (alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase) also revealed differences between the two groups – hepatotoxicity directly depended on MtxAUC, ClMtx and Ttotal, and the amplitude changes in activities of enzymes from course to course by increasing the number of course decreased. Our developed methodology of monitoring of Hcy in serum during the course of HD Mtx revealed that Hcy metabolic interconnected with Mtx – the higher the concentration of Mtx, the greater the amount of Hcy released into the blood. Hcy has a close metabolic relationship with Mtx – it can serve as a marker of the efficiency of suppression of the transformation of folates. During slow excretion of Mtx Hcy significantly increased in the blood, which also suggests that it can serve as a marker of pharmacodynamic effects of HD Mtx.

Diltiazem augments the influence of MDR1 genotype status on cyclosporine concentration in Chinese patients with renal transplantation.

Co-administration of diltiazem can reduce the dosage of cyclosporine (CsA) in patients with renal transplantation. In this study, we investigated how diltiazem altered the relationship between MDR1 genetic polymorphisms and CsA concentration in Chinese patients with renal transplantation. A total of 126 renal transplant patients were enrolled. All the patients received CsA (2-4 mg·kg(-1)·d(-1)), and diltiazem (90 mg/d) was co-administered to 76 patients. MDR1-C1236T, G2677T/A, and C3435T polymorphisms were genotyped. The whole blood concentration was measured using the FPIA method, and the adjusted trough concentrations were compared among the groups with different genotypes. In all patients, MDR1-C1236T did not influence the adjusted CsA trough concentration. With regard to MDR1-3435, the adjusted CsA trough concentration was significantly higher in TT carriers than in CC and CT carriers when diltiazam was co-administered (58.83±13.95 versus 46.14±7.55 and 45.18±12.35 ng/mL per mg/kg, P=0.011), and the differences were not observed in patients without diltiazam co-administered. With regard to MDR1-2677, the adjusted CsA trough concentration was significantly higher in TT carriers than in GG and GT carriers when diltiazam was co-administered (61.31±12.93 versus 52.25±7.83 and 39.70±7.26 ng/mL per mg/kg, P=0.0001). The differences were also observed in patients without diltiazam co-administered (43.27±5.95 versus 35.22±7.55 and 29.54±5.35 ng/mL per mg/kg, P=0.001). The adjusted CsA trough blood concentration was significantly higher in haplotype T-T-T and haplotype T-T-C carriers than in non-carriers, regardless of diltiazem co-administered. MDR1 variants influence the adjusted CsA trough concentration in Chinese patients with renal transplant, and the influence more prominent when diltiazem is co-administered.

Invivo absorption behaviour of theophylline from starch-methyl methacrylate matrix tablets in beagle dogs

This study evaluates in vivo the drug absorption profiles from potato starch-methyl methacrylate matrices* using theophylline as a model drug. Healthy beagle dogs under fasting conditions were used for in vivo studies and plasma samples were analyzed by a fluorescence polarization immunoassay analysis (FPIA method). Non-compartmental and compartmental (population approach) analysis was performed to determine the pharmacokinetic parameters. The principle of superposition was applied to predict multiple dose plasma concentrations from experimental single dose data. An in vitro–in vivo correlation (IVIVC) was also assessed. The sustained absorption kinetics of theophylline from these formulations was demonstrated by comparison with two commercially available oral sustained-release theophylline products (Theo-Dur® and Theolair®). A one-compartment model with first order kinetics without lag-time best describes the absorption/disposition of theophylline from the formulations. Results revealed a theophylline absorption rate in the order FD-HSMMA≥Theo-Dur®≥OD-CSMMA>Theolair®≥FD-CSMMA. On the basis of simulated plasma theophylline levels, a twice daily dosage (every 12h) with the FD-CSMMA tablets should be recommended. A Level C IVIVC was found between the in vitrot50% and the in vivo AUC/D, although further optimization of the in vitro dissolution test would be needed to adequately correlate with in vivo data.

Adaptation of methotrexate determination in serum with Unicel DxC600®

High-dose methotrexate treatment requires pharmacological monitoring in order to tailor administration of folinic acid to reduce side effects. The aim of the study was to validate the adaptation of the EMIT reagent on the l'Unicel DxC 600® Beckman Coulter. The establishment of two assays was necessary to obtain a quantification limit as low as possible (0.05 μmol/L). The linearity of the adapted methods extends from 0.05 to 0.25 μmol/L on the one hand, and from 0.25 to 1 μmol/L on the other hand. For each method, fidelity and accuracy were studied and the limits of detection and quantification were quantified. The correlation with the FPIA method was performed on the Abbott TDX(®). The results of all tests are satisfactory with coefficients of variation (CV) of repeatability and reproducibility of less than 6%. However the daily assays are heavy as 66% of blood samples require at least two dosages and 30% a manual dilution.

Relationship Between Everolimus Blood Concentration Assessed Using the Innofluor Certican Fluorescence Polarization Immunoassay and the Architect i System Sirolimus Chemiluminescent Microparticle Immunoassay

Everolimus, an immunosuppressive macrolide derivative of sirolimus, has a narrow therapeutic index and variable bioavailability. Assessment of blood concentration of everolimus is necessary to improve immunosuppressive efficacy without increasing potential adverse effects. Recently, Seradyn, Inc (Indianapolis, Indiana) introduced a fluorescence polarization immunoassay (Innofluor Certican Fluorescent Polarization Immunoassay [FPIA]) for quantitation of everolimus blood concentration. This immunoassay has concentration-dependent cross-reactivity with sirolimus, which must be considered in patients recently treated with that drug. In this short-term study, treatment in 53 renal transplant recipients was converted from a sirolimus-based regimen to an everolimus-based regimen. Patients were followed up for 3 months. We investigated whether cross-reactivity with everolimus also occurred with the Abbott Laboratories (Abbott Park, Illinois) Architect i System, a sirolimus chemiluminescent microparticle immunoassay (CMIA) used to quantify sirolimus blood concentration. Quantification of everolimus blood concentration using both the CMIA and the FPIA demonstrated a linear regression: CMIA = 0.73 FPIA ± 0.77 ( r 2 = 0.80; P < .001). A high degree of correlation between the CMIA and FPIA methods ( r = 0.90) was confirmed using the Bland-Altman test. We conclude that the Abbott Architect i System sirolimus CMIA should be considered an alternative method for everolimus drug monitoring. The cross-reactions of both the FPIA and CMIA techniques with both sirolimus and everolimus must be considered when converting therapy from one drug to the other. In these conditions, use of an equivalent dosage is of particular importance.

Evaluación de la cortisoluria en mujeres diagnosticadas de fibromialgia

Objective We propose a comparative study of urinary cortisol in a controlled simple group of patients diagnosed with fibromyalgia (FM) during a minimum time frame (3 years) vs. a normal group with the same characteristics of age and gender. Our objective is to demonstrate if urinary cortisol at lower levels than those found in the normal population, as long as FM is regarded, could help to evaluate the fatigue. Methods We determined the urinary cortisol in a group of 47 women with a clinical diagnosis of FM using the criteria from the American College of Rheumatology (ACR) 1990, with ages between 29 and 64 years, in whom an accurate sample was collected and cortisol was determined using an FPIA method. The results were compared with the urinary cortisol obtained in a group of 88 healthy women within the same age range as those with FM. Results Urinary cortisol in FM was 65.0 μg/l (median), which was significantly lower than that of the healthy group (80.0 μg/l), p<0.001. Conclusion 33.4% of patients with FM displayed urinary cortisol concentrations significantly lower than the group of women without FM.

Therapeutic carbamazepine (CBZ) and valproic acid (VPA) monitoring in children using saliva as a biologic fluid

OBJECTIVE: The aim of the study was to analyze retrospectively carbamazepine (CBZ) and valproic acid (VPA) salivary data collected from epileptic children during a 3-year period. METHODS: Saliva samples stimulated by citric acid were assayed by FPIA method. One hundred and three patients (aged 1-14 years) were in CBZ or VPA monotherapy or in CBZ-VPA combined therapy. RESULTS: VPA salivary levels were linearly related with daily dose, but a non-linear relationship was found for CBZ, in patients under monotherapy. VPA did not alter saliva CBZ concentration. Conversely, CBZ reduced VPA salivary levels. Non-responsive children displayed higher VPA concentrations. CBZ levels in uncontrolled patients showed non-significant difference in relation with controlled subjects even though their daily doses were higher. CONCLUSION: Citric acid stimulated saliva is reliable enough to perform therapeutic drug monitoring. Saliva drug levels in non-responsive patients would be explained according to the generalized efflux transporter overexpression hypothesis.

Improved Quantitative Determination of Total and Unbound Concentrations of Six Teicoplanin Components in Human Plasma by High Performance Liquid Chromatography

Total and unbound concentrations of six teicoplanin components in human plasma were determined by high-performance liquid chromatography with a coextractive cleanup technique. Unbound concentrations of teicoplanin components were estimated after ultrafiltration of plasma. For determination of each component in plasma, plasma was deproteinized with acetonitrile and the supernatant was shaken for 60 s with chloroform under acidic conditions. The recoveries of A3-1, A2-1, A2-2, A2-3, A2-4 and A2-5 were greater than 88%. The within-day and between-day coefficients of variation were 1.3-8.8% and 2.8-11.9%, respectively. The limits of detection in ultrafiltered plasma for each component were 0.82, 2.87, 4.23, 3.36, 7.33 and 4.93 nM, respectively. A good correlation was observed between the FPIA and HPLC methods when total concentrations of each teicoplanin component in patient plasma were determined. The analytical methods established in this study are suitable for determining the total and unbound concentrations of six components of teicoplanin in human plasma and for studying the pharmacokinetics of teicoplanin components in patients.

EVALUATION OF THE CHANGE OF LONG-TERM VARIABILITY OF CICLOSPRINE-MICROEMULSION BLOOD CONCENTRATIONS - IS C2 LEVELS MANAGEMENT OF CICLOSPRINE-MICROEMULSION THE OPTIMAL MONITORING METHOD IN STABLE RENAL TRANSPLANT PATIENTS?

A76 Aims: C2 levels management of Ciclosprine-microemulsion (CsA-ME) has been adopted in several countries as an effective method for optimally individualizing therapy for de novo and maintenance renal transplant patients. However, there was no data to evaluate the change of long-term variability of CsA-ME blood concentrations. The aim of this study was to evaluate the change of variability in C2 levels/dose ratio, coefficient of variation of intra- or inter-patients and clinical outcomes in stable renal transplant patients during 2 years. Methods: 8 patients (age 43±12) were enrolled in this study for 2years. The time that had elapsed from after the transplant to the initiation of this study was 3.3±2.1 years. Cyclosporine blood concentrations were measured by FPIA method (AxSYM analyzer), Dose adjustment of CsA-ME was made according to AUC0-4 sparse-sampling that estimated using 2 sampling points (C1, C2) during the maintenance phase (2,000ng.hr/ml) once a month. All patients received CsA-ME -based double or triple therapy (Neoral + Steroids± MMF). Results: Results of inter-patients C2/dose were 371±19 in 2 years (10 times measurements), mean coefficient of variation (CV %) in Inter-patients were 25.8% (13.6%-30.8%). C1/dose were 664±16, mean coefficient of variation (CV%) in Inter-patients were 25.2%(21.4%-33.2%). Results of Intra-patients C2/dose were 371±81, mean coefficient of variation (CV%) in Intra-patients were21.7%. C1/dose were 664±142, mean coefficient of variation (CV%) in Inter-patients were 21.4%. No patients suffered from Chronic rejection or nephrotoxicity during the study. Conclusions: These results suggest that one point C2 (levels) monitoring is optimal CsA-ME administration in stable renal transplant recipients because highly reproducible blood concentrations of Ciclosporine are achieved.

Homocysteine and cystatin C level changes in haemodialysed patients and connection with cerebro- and cardiovascular complications.

Plasma homocysteine and Cystatin C levels of 360 chronic haemodialysed patients were measured in fasting (191 men, mean age: 55.5 years; and 169 women, mean: 62.9 years). The patients were divided into subgroups: diabetes mellitus (34 men and 38 women 7 vs 8 IDDM). obliterative arteriosclerosis (68 men and 61 women), cardiovascular complications (75 men and 84 women) and stroke (16 men and 12 women), and after renal transplantation in chronic rejection (15 men and 5 female). Homocysteine was determined by IMx analyser from Abbott by FPIA method. Immunoturbidimetric method was used for quantification of Cystatin C (PETIA). The lowest Cystatin C concentration was found in diabetic patients (4.35 +/- 0.15 mg/l in men and 3.18 +/- 1.77 mg/l in women) and the highest one occurred in anuric and bilateral nephrectomised and transplanted chronic rejected patients (6.075 mg/l in men and 6.35 mg/l in women: p<0.001). The homocysteine levels (24.98 +/- 2.94 micromol/l in men and 23.88 +/- 1.76 micromol/l in women) exceeded the upper limit of reference range (<15.0 micromol/l). There was a significant difference in favour of subgroup of cardiovascular (27.25 micromol/l in men and 26.87 micromol/l in women) and stroke patients (27.16 micromol/l in men and 30.76 micromol/l in women p<0.001). Elevated levels were found in chronic rejected patients with accelerated arteriosclerotic events (25.94 micromol/l in men and 27.43 micromol/l in women). Good positive linear correlation was found between serum homocysteine and Cystatin C levels (r=0.2393 and 0.2252). The authors demonstrated hyperhomocysteinaemia associated with high Cystatin C concentration in four subgroups of haemodialysed patients (obliterative and accelerated arteriosclerosis, cardiovascular disease, and cerebrovascular complications and stroke).

Pharmacokinetics of intravenously administered digoxin and histopathological picture in rabbits with experimental bile duct obstruction

This study aimed to examine the effect of obstructive cholestasis on the pharmacokinetics of digoxin. Eighteen male rabbits were randomly ascribed to the two study groups: the sham-operated control group and the examined group — with common and cystic bile duct ligations. Digoxin was administered intravenously as a single dose of 0.02 mg/kg, and blood samples were withdrawn for up to 24 h. Digoxin concentrations were determined by the FPIA method. The pharmacokinetic parameters were calculated using a noncompartmental analysis. During the whole observation period the blood serum concentrations of digoxin were statistically higher in animals with obstructive cholestasis versus the controls. A significant increase in the area under the plasma concentration–time curve, decrease in the total body clearance and in the volume of distribution on the 6th day after the bile ducts ligation as compared to the sham-operated controls, were observed. The obtained results suggest an impaired elimination of digoxin in obstructive cholestasis in rabbits.

Is a “color effect” demonstrated for hair analysis of carbamazepine?

Psillakis et al. have reported on the concentration of carbamazepine recovered from hair samples collected from patients receiving this anti-seizure medication under medical supervision and determined that their was a high correlation between dose and quantitation of recovered analyte. The analyte was identified by two techniques, FPIA (Abbott TDx) and HPLC and the correlation was high for both procedures. In the literature on hair analysis some have suggested that analyte concentration in hair is critically dependent on hair color. In reporting their data Psillakis et al. reported the hair color of each patient but made no attempt to analyze their results in relation to color. This article performs a secondary analysis of the Psillakis et al. data in order to determine whether there is a hair color effect discernible in the recovery of carbamazepine from hair. Analysis of this data set for both the FPIA and HPLC by one-way analysis of variance fails to identify a color effect at p = .05. Weighting the data for per-patient dosage values fails to discern a color effect. Examination of all possible two-color comparisons also fails to identify a statistically significant effect for any subset of combinations. These data suggest that carbamazepine does not exhibit a color effect when using either FPIA or HPLC assay methods.

Homocysteine, Vitamin B12, and Serum and Erythrocyte Folate in Peritoneal Dialysis and Hemodialysis Patients

Plasma homocysteine (Hcy) is an independent risk factor for cardiovascular disease. High levels of plasma Hcy have been observed in end-stage renal disease patients. Few studies have compared peritoneal dialysis (PD) and hemodialysis (HD) patients and few data are available on erythrocyte folate (ery-F) levels in dialysis patients. To evaluate plasma Hcy concentrations, vitamin B12 (B12), and folate status in dialysis patients; to analyze the possible causes of high Hcy levels; to follow up changes in folate and B12 concentrations after 6 months. A cross-sectional observational study. Nephrology division and laboratory of hematology in a university and clinical research hospital. The study included 82 patients treated with PD for 37 + 37 months and 70 patients treated with HD for 136 + 95 months. LABORATORY METHODS: Plasma Hcy was measured by the immunoenzymatic IMx Hcy FPIA method (Abbott Laboratories, Diagnostic Division, Abbott Park, IL, U.S.A.), serum folate (s-F) and ery-F by the Stratus folate fluorometric enzyme-linked assay, and B12 by the Stratus vitamin B12 fluorometric enzyme-linked assay (DADE-Behring, Newark, DE, U.S.A.). Ninety-six percent of PD and 97% of HD patients had Hcy levels above the cutoff (13.5 micromol/L). Homocysteine level was higher in HD than in PD patients, while the prevalence of hyperhomocysteinemia was similar with the two techniques. Erythrocyte folate was significantly higher in PD (1333 +/- 519 pmol/L) than in HD (1049 +/-511 pmol/L, p < 0.01). Statistically significant correlations were observed between Hcy and B12, s-F, ery-F, and dialysis duration. Multivariate analysis showed a strong correlation between s-F and Hcy. After 6 months there were no differences in Hcy, B12, s-F, and ery-F levels. Plasma Hcy levels were high in more than 95% of our dialysis patients, with no relation to the type of dialysis. Vitamin B12 and folate were normal in the majority of our patients. However, serum folate was the major determinant of Hcy levels. Such a relation between Hcy and folate suggests that levels of folate within the reference interval are inadequate for dialysis patients.

健常人におけるシロップ剤からのバルプロ酸の吸収に及ぼすエンシュア・リキッド及びマーロックスの影響

Sodium Valproate (VPA-Na) syrup is used in the management of patients following brain surgery for conditions such as traumatic injury or arteriovenous malformation. In our hospital, 65% of post-neurosurgical patients administered VPA-Na syrup were also given enteral nutrition (EN) and/or antacids (AA). We therefore investigated possible drug interactions between VPANa syrup and EN or AA. In a random crossover study, 250 mL of Ensure Liquid® (EN), 20mL of Maalox® (AA) or 50 mL of Purified water were administered to nine normal subjects mixed with 12mL Depakene® (VPA-Na) syrup. Following administration, the serum concentration of valproic acid was then repeatedly measured over the next 48 hours using the FPIA method. Data were analyzed by non-parametric analysis and by population pharmacokinetic analysis using the NONMEM system. The results showed that the coadministration of Ensure and Maalox delayed the rate, but not the extent of bioavailability of VPA-Na syrup.

The determination of metabolite M17 and its meaning for immunosuppressive cyclosporin therapy.

Cyclosporin A (CyA) is intensively metabolized by the hepatic cytochrome p450 III monooxygenase A system in the human liver, the most important metabolites being M1, M17, and M21. Because CyA and its metabolites have nephrotoxic, hepatotoxic, and neurotoxic side effects, CyA dosage must be calculated to avoid the risk of organ rejection through underdosage and toxic organ damage through overdosage or accumulation of metabolites. In this study, we determined the whole-blood concentrations of cyclosporin and metabolite M17 by high-pressure liquid chromatography (HPLC) and by monoclonal specific and polyclonal nonspecific fluorescence polarization immunoassay (Abbott) in patients after immunosuppressive treatment. Patients with different resorption and metabolization rates showed high individual variations. CyA concentrations in patients with good liver function and low concentrations of CyA metabolites showed a good correlation between the HPLC and the FPIA (TDx-monoclonal assay) methods in ranges between 25 and 180 ng/mL. TDx-monoclonal was not always as precise as HPLC. In cases of metabolic disorders, we found false high CyA concentrations assayed with the immunologic method, caused by a crossreaction of the elevated metabolite concentration. We found that HPLC rendered more information about the extent of immunosuppressive activity and the metabolization rate and showed a good correlation with the concentration of metabolite M17 and total metabolites measured with the Abbott CyA polyclonal kit.