摘要:

A radioimmunoassay for the measurement of total captopril in serum and heparinized plasma has been developed. Prior to the assay, serum or heparinized plasma samples are subjected to tri-n-butyl-phosphine reduction followed by N-ethylmaleimide (NEM) derivatization.The assayutilizesin-houseNEM-captopril-‘antibody, [’ZSI]NEM-captopril radiolabel andhumanserum standards. Satisfactory zero binding and sensitivity are obtained after 3hof incubation atroomtemperature. Separation oftheantibody-bound andfreeradiolabeled antigen is achieved by employing a polyethylene glycol solution. The assay was shown to have excellent parallelism, recovery, and precision. Cross-reactivities with potentially interfering substances were low.

ISSN:0163-4356    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Free carbamazepine and valproic acid monitoring using the EMIT FreeLevel filtration system was evaluated and compared with reference equilibrium dialysis and gas chromatographic (GC) techniques. For carbamazepine, free levels after filtration or dialysis were essentially identical (mean 1.74 vs. 1.77 mg/L, r = 0.940, n = 28, EMIT assay). Free levels were 16% higher by EMIT than by GC, possibly due to cross-reaction with carbamazepine-10,11-epoxide. Free fractions were not significantly different using any combination of filtration or dialysis with EMIT or GC (means 0.24–0.26). There was a significant correlation between epoxide and parent-drug free fractions (r = 0.642). Free fraction varied from 0.20 to 0.41 among 61 patient samples and was independent of total drug concentration. For valproic acid, there was a strong correlation between filtration and dialysis results for free level (r = 0.974) and free fraction (r = 0.892), but filtration values were 6–7% higher. Free fraction was concentration dependent (r = 0.597), and lower free fractions by dialysis were attributed to dilution of total drug concentration. Free fraction varied from 0.01 to 0.14 among 50 patient samples. For carbamazepine and valproic acid the EMIT FreeLevel filtration system compared favorably with equilibrium dialysis, and had the advantage of being rapid.

ISSN:0163-4356    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

A method for determination of metoclopramide in serum, urine, and saliva is described that can be applied to both pharmacokinetic and clinical studies. Metoclopramide was extracted from alkalinised plasma into dichloromethane and chromatographed on a Micro-Pak Si-5 column using a mobile phase of dichloromethane/methanol/diethylamine (89:10:1, by volume). The column was maintained at 25°C and the eluate monitored at 308 nm. The retention time for metoclopramide was 4.7 min. The limit of sensitivity in serum and urine was 15 nmol/L and 3 μmol/L, respectively, with coefficients of variation of 5.4 and 3.84%, respectively. Recovery was in the range of 93–110% for serum and 94–103% for urine. The limit of sensitivity in saliva was 15 nmol/L. In more than 210 samples analyzed to date, the only drugs known to have interfered with the assay are 13-adrenoceptor blockers (e.g., propranolol). The metabolites of metoclopramide did not interfere with the quantitation of the parent drug.

ISSN:0163-4356    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

A high-performance liquid chromatographic assay usable for clinical monitoring of chlorthalidone in biological fluids was developed. Extraction efficiency was >80% for blood and urine using a rapid, disposable column cleanup procedure. Chlorthalidone could be reliably measured in the range of 100–4,000 ng/ml in biological fluids with excellent day-to-day reproducibility and within-day precision. Chlorthalidone was found to be stable at –20°C in blood and urine for at least 1 year, permitting repeat assays and large clinical studies to be conducted. The pharmacokinetics of chlorthalidone was studied in 24 subjects over a 120-h time interval following a single dose. Chlorthalidone has a long terminal half-life in whole blood of 49 h, with peak concentrations occurring 8–10 h after oral dosing. During the first 12 h after dosing, chlorthalidone was rapidly excreted into urine followed by a slower phase with a half-life of 49 h.

ISSN:0163-4356    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Cefsulodin is a third-generation cephalosporin with a unique specificity forPseudomonas aeruginosa.To study the pharmacokinetics of this agent in children, a rapid and sensitive high-performance liquid chromatographic micromethod was developed for plasma and urine. Protein was precipitated from plasma with one volume of cold methanol, and 20 of the resulting supernatant solution was injected into a Zorbax C-8 reversed-phase column. The mobile phase was composed of 4.5 parts acetonitrile and 95.5 parts of 0.035 M ammonium acetate buffer (pH 5.2). Flow rate was 1.0 ml/min and peaks were detected at 265 nm. A flow gradient from 0.3 to 2.0 ml/min over 34 min was employed for urine. The analysis had a limit of detectability of 1 μg/ml and a between-day coefficient of variation of 4.4 and 5.0 for 100 and 10 μg/ml samples, respectively.

ISSN:0163-4356    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Recently, phenytoin concentrations determined by enzyme multi-plied immunoassay technique (EMIT™) have been reported to be significantly elevated when compared to other assay methods in patients with end-stage renal disease (ESRD). We compared the plasma and plasma ultrafiltrate concentrations of phenytoin determined by EMIT and high-pressure liquid chromatography (HPLC) in a group of patients with normal renal function (NRF) and ESRD. The relationship between the degree of discrepancy in phenytoin concentrations in plasma and plasma ultrafiltrate and the concentration of combined (unconjugated plus conjugated) 5-(4-hydroxyphenyl)-5-phenylhydantoin (HPPHCom) was also assessed. The concentration of phenytoin in plasma and plasma ultrafiltrate measured by EMIT in the ESRD patients and the plasma ultrafiltrate concentrations of phenytoin in the NRF patients was significantly higher than the HPLC values. The mean concentrations of unconjugated HPPH (HPPHunconj) in plasma and plasma ultrafiltrate were not significantly different between the two patient groups. However, the concentration of HPPHComin plasma and plasma ultrafiltrate specimens were significantly elevated in the ESRD patients. Orthogonal regression analysis of the relative error between the EMIT and HPLC phenytoin determinations and HPPHcomconcentrations suggest that HPPHComsignificantly correlates with the false elevation of phenytoin measurements in plasma and plasma ultrafiltrate. In patients with ESRD, phenytoin concentrations should be determined by either gas chromatography, HPLC, or fluorescence polarization.

ISSN:0163-4356    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

A simple, rapid, selective, and sensitive procedure for the monitoring of flecainide levels in human plasma is described. The drug and the internal standard-a positional isomer of flecainide-are separated from plasma by the use of a disposable extraction column packed with reversed-phase sorbent. The drug and internal standard which are selectively retained on the extraction column are eluted. An aliquot is injected onto a μ-Bondapak phenyl column and eluted with a mixture of acetonitrile and 0.06% phosphoric acid (40:60, vol/vol) at a flow rate of 2 ml/min. The eluted drug and internal standard are measured by a fluorescence detector with excitation and emission wavelengths of 300 and 370 nm, respectively. The linear range is 3–2,000 ng/ ml, and the sensitivity limit is 3 ng/ml with 1 ml of plasma. The within-day coefficient of variation was 1.1–4.6% at concentrations ranging from 3 to 1,600 ng/ml. Many drugs given concomitantly with flecainide acetate do not interfere with the assay. The method compares favorably to a well-documented gas-liquid chromatographic method and is suitable for use in plasma drug level monitoring for patient management as well as in pharmacokinetic studies. Similar results were obtained using an alternate detection method (ultraviolet detection at 298 nm).

ISSN:0163-4356    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

A reversed-phase high-performance liquid chromatographic method is presented by which the cancer chemotherapeutic agent, mitomycin C, may be measured in human serum. A mobile phase of methanol:water (35:65) passed through a μ-BondapakeC-18 column at a rate of 1.0 ml/min produced a sharp, symmetrical band for mitomycin C. An improved serum extraction procedure, using a reversed-phase sample preparation cartridge, proved to be efficient and reproducible. Recovery over a concentration range of 10–100 ng/ml was 81.6% with a between-day coefficient of variation of 4.6% (n = 5). The within-day coefficient of variation at 50 ng/ml was 5.6% (n = 10). Ultraviolet detection at a wavelength of 365 nm was sensitive to serum concentrations of 10 ng/ml. Serum concentration-time course data from lung cancer patients receiving mitomycin C by rapid intravenous injection are presented.

ISSN:0163-4356    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

To evaluate a new ultrafiltration-fluorescence polarization immunoassay (FPIA) for monitoring blood levels of unbound phenytoin, the drug, with or without a14C label, was added to three serum pools obtained from normal, uremic, and hypoalbuminemic patients and to 10 individual patient sera that varied greatly in phenytoin binding (11–50%). Protein-unbound phenytoin fractions were obtained from the sera by ultrafiltration using the Amicon Micropartition System and by a classic equilibrium dialysis method. The percent unbound phenytoin in each serum was determined by a radioassay and an automated FPIA (TDx™ System). An analysis of variance revealed no significant difference in the percent unbound phenytoin obtained at 37°C by the FPIA and radioassay methods (α = 0.05). The data indicate that the ultrafiltration system can be combined with FPIA to produce a convenient lab-oratory method for routine therapeutic drug monitoring that gives results comparable to the equilibrium dialysis, radioassay reference method.

ISSN:0163-4356    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

The routine utilization of a commercially available radioimmunoassay (RIA) for theophylline (GammaDab™), although reliable, is currently prohibited by the high cost of the reagents. In an effort to reduce these costs we have diluted the [125I]theophylline tracer and theophylline antiserum re-agents by one-half, contrary to the manufacturer's recommendations. We have demonstrated that an excellent correlation exists (r = 0.968) between our modified RIA method and a conventional high-performance liquid chromatographic technique, despite reagent dilution. Accordingly, our reagent costs have been reduced by half. We conclude that the GammaDab kit reagents can be diluted twofold and still provide an accurate determination of serum theophylline. We must also emphasize that any further alteration(s) of this theophylline RIA procedure would require a thorough evaluation before its routine use could be substantiated.

ISSN:0163-4356    

出版商:OVID    

年代:1984

数据来源: OVID