Gentamicin Assay Research Articles

High pressure liquid chromatographic determination with ultraviolet detection of gentamicin and correlation with the microbiological potency.

The content of gentamicin in pharmaceuticals is measured by the high pressure liquid chromatographic technique described in the monographs for Gentamicin Sulphate and Gentamicin Injection in the British Pharmacopoeia 1980 for the determination of the composition of gentamicin. Calculation procedures are presented to transform this qualitative high pressure liquid chromatographic procedure for the assay of gentamicin so that it gives results in terms of potency. A comparison is made of this data with the results of the microbiological assay according to the European Pharmacopoeia.

The effect of hyperlipidemia on therapeutic drug assays.

Hyperlipidemia interferes with spectrophotometric assays of a number of analytes. No interference was found in the assay of gentamicin, phenytoin, or phenobarbital due to turbidity in levels of triglyceride less than or equal to 2,000 mg/dl with the Abbott TDx or Syva enzyme multiplied immunoassay (EMIT) methods. There is no evidence that lipophilic drugs partition into the lipid phase in severely hyperlipidemic serum. No assay errors due to turbidity or partitioning of phenobarbital in the lipid of serum with a triglyceride concentration of 10,000 mg/dl were found, nor were changes seen in free phenytoin distribution due to hyperlipidemia.

Homogeneous, micelle quenching fluoroimmunoassay for detecting amphetamines in urine.

We developed a homogeneous fluoroimmunoassay for detecting amphetamines in urine. Only fluorescence intensity need be measured because the emission of non-protein-bound fluorescein-labeled amphetamine is preferentially quenched by detergent micelles. In a previous reported prototype assay system for measuring gentamicin in serum we used fluorescein and dodecyl sulfate (Anal Chem 1985; 57:1928-30). We have found that favorable hydrophobic and (or) ionic character of the analyte and unfavorable polar and (or) ionic character of the fluor are important determinants of the desired interactions. An anionic detergent and fluorescein, therefore, should be appropriate for apolar of cationic analytes, such as gentamicin and amphetamines. A greater [H+] at the anionic micelle surface is important for quenching emission from the fluor moiety. Millimolar concentrations of dodecyl sulfate rapidly denature immunoglobulin unless hapten is bound with sufficiently high affinity. Affinity was sufficiently high for the antibody used in the prototype gentamicin assay but not for the amphetamine antibody. Thus for the amphetamine assay, we used a non-denaturing detergent, dodecyl(oxyethylene)12 sulfate. The assay requires 30 microL of specimen in 2 mL of total assay volume. Amphetamine(d-,dl-, and meth-), at a concentration of 1 mg per liter of urine, is readily detected.

Evaluation of the powder-formulated enzyme multiplied immunoassay technique quantitative single test for gentamicin.

The usefulness of the enzyme multiplied immunoassay quantitative single test (EMIT QST) gentamicin assay was assessed for gentamicin analysis in patient sera. The EMIT QST reagents are in powder form in a single, premeasured vial and are run on a thermoregulated sample processor that controls mixing and timing steps. The results of the clinical evaluation showed that the standard curve was stable throughout a 26-day study period. Within-run precision on 20 replicates at 4.0 micrograms/ml yielded a coefficient of variation (CV) of 5.6%; between-run precision on 66 analyses at 6.0 micrograms/ml over a 152-day period yielded a CV of 4.0%. Mean recovery through the range of the standard curve with 10 spiked patient samples was 102%. Comparative analysis with radioimmunoassay of 95 patient samples showed a correlation of 0.97, with y = 0.93x - 0.03. It was concluded that the EMIT QST gentamicin assay is an appropriate, rapid methodology for patient gentamicin analysis.

Gentamicin and tobramycin EMIT assays in the CentrifiChem 500.

Journal Article Gentamicin and tobramycin EMIT assays in the CentrifiChem 500. Get access L Redmond, L Redmond Search for other works by this author on: Oxford Academic Google Scholar A Chang, A Chang Search for other works by this author on: Oxford Academic Google Scholar M Lynch M Lynch Search for other works by this author on: Oxford Academic Google Scholar Clinical Chemistry, Volume 31, Issue 8, 1 August 1985, Pages 1408–1409, https://doi.org/10.1093/clinchem/31.8.1408 Published: 01 August 1985

Scandinavian quality surveys of gentamicin assays 1978-1983.

During 1978-1983 44 Scandinavian laboratories participated in 7 quality surveys of gentamicin serum assays. In each survey 2 test solutions of gentamicin were distributed. In the first 4 surveys very few non-microbiological assays were used while in the 7th survey almost half the laboratories had access to enzyme immunoassay (EMIT). The gentamicin survey mean (SM) concentrations, which did not differ significantly from the intended concentrations, were used as target values. In survey 1, 65% of the results of either of the 2 test solutions were outside the SM +/- 25% and 16% were outside SM +/- 50% ("highly misleading"). In surveys 5 and 7 the corresponding figures were 27 and 5% and 18 and 0%, respectively. The EMIT performed excellently in all surveys. Agar well diffusion assays using Diagnostic Sensitivity Test agar (Oxoid) performed better than other plate diffusion assays. Laboratories participating regularly performed better than others. It is concluded that the survey program, which continues, provides an external facility for unbiased control of commercially available as well as non-commercial assay techniques and that it has been instrumental in the improvement of gentamicin assay standard. It is stressed that the surveys cannot replace internal quality control, best performed by daily measurement and regular statistical evaluation of samples of known potency.

Effects of heparin sodium on gentamicin assay measured by fluorescence polarization immunoassay method.

The effect of heparin sodium on the assay of gentamicin using the fluorescence polarization immunoassay system was investigated with varying heparin and gentamicin concentrations. Heparin had no significant effect on gentamicin concentrations as measured by this system.

Correlation of bioluminescent assay of gentamicin in serum with agar diffusion assay, latex agglutination inhibition card test, enzyme immunoassay, and fluorescence immunoassay.

An improved bioluminescent assay of gentamicin in serum, based on the dose-dependent effect of the agent on the accumulation of extracellular ATP in Escherichia coli LU 14 cultures, is presented. The accuracy of the bioluminescent assay of gentamicin, expressed as the mean coefficient of variation over the therapeutic range, was 2.8%. Corresponding figures for an agar diffusion assay, a latex agglutination inhibition card test, an enzyme immunoassay, and a fluorescence immunoassay were 6.4, 17.5, 4.2, and 9.4%, respectively. All of the methods correlated well (r = 0.926 to 0.976), with the possible exception of the card test (r = 0.777 to 0.841). The bioluminescent assay requires only 1 microliter of serum, which allows for capillary sampling, and results are available within 75 min.

Microbiological assay of antibiotics based on inhibition of ammonia production monitored with an ammonia electrode

A potentiometric method with an ammonia gas sensor is described for the microbiological assay of tetracycline hydrochloride, gentamicin, streptomycin, and neomycin in pharmaceutical preparations. The method is based on the inhibiting effect of antibiotics on the production of ammonia by a suspension of Escherichia coli in a nutrient solution.

Do evacuated blood collection tubes interfere with therapeutic drug monitoring?

The influence of various brands of evacuated blood collection systems (the old type, red stoppered Vacutainer; the new type, blue stoppered Vacutainer; Monoject and Venoject) on therapeutic drug monitoring was investigated. No interferences were found in the assay of ethosuximide, phenobarbital, phenytoin, valproic acid, digitoxin, digoxin, procainamide, gentamicin and theophylline. Using Monoject and old type Vacutainer tubes, lower levels were found in the disopyramide assay: 91.3 +/- 4.6% (p less than 0.05) and 91.7 +/- 7.0% (not significant) respectively, and in the quinidine assay: 82.8 +/- 6.7% (p less than 0.02) and 83.9 +/- 4.4% (p less than 0.001) respectively as compared with glass tubes. In the carbamazepine assay a decrease was found in the Monoject tubes only: 93.7 +/- 1.7% (p less than 0.01). The stoppers of Monoject tubes and the old type Vacutainer tubes contained the plasticizer tris-(2-butoxyethyl)phosphate (TBEP), which has been shown to be a potent inhibitor of the binding of several drugs to alpha 1-acid glycoprotein. Using the new type Vacutainer and the Venoject, no interferences were found.

Evaluation of four gentamicin and tobramycin assay procedures for clinical laboratories.

Accuracy, precision, and clinical laboratory utility of the TDX (Abbott Laboratories), Auto-ICS (Beckman Instruments, Inc.), COBAS-Bio (Roche Analytical Instruments, Inc.) with reagent kits (Syva), and EMIT (Syva) for gentamicin and tobramycin serum assay were assessed. TDX, COBAS-Bio, and EMIT analytical systems showed a proportional bias of less than 10% for recovery studies and a coefficient of variation less than 5% for within-run precision. The results of the recovery studies with the Auto-ICS showed a proportional bias of 25% with gentamicin and 16% with tobramycin. The within-run precision expressed as the coefficient of variation for the Auto-ICS was 6.7% for gentamicin and 8.6% for tobramycin. In comparisons involving gentamicin- and tobramycin-containing patient samples, the results with the TDX analytical system showed the best agreement with the COBAS-Bio. For the determination of these two antibiotics, the TDX analytical system provided the best overall accuracy and precision.

Potentiometric microbiological assay of gentamicin, streptomycin, and neomycin with a carbon dioxide gas-sensing electrode.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPotentiometric microbiological assay of gentamicin, streptomycin, and neomycin with a carbon dioxide gas-sensing electrodeD. L. Simpson and R. K. KobosCite this: Anal. Chem. 1983, 55, 12, 1974–1977Publication Date (Print):October 1, 1983Publication History Published online1 May 2002Published inissue 1 October 1983https://doi.org/10.1021/ac00262a032RIGHTS & PERMISSIONSArticle Views121Altmetric-Citations21LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (560 KB) Get e-Alerts Get e-Alerts

Ethacrynic acid facilitates gentamicin entry into endolymph of the rat.

Influence of ethacrynic acid (EA) upon gentamicin kinetics in perilymph and endolymph was studied in rats that were given a constant-infusion of gentamicin (150 micrograms/min) and EA (140 micrograms/min). Inner ear fluids and plasma were sampled up to 5 h. The purity of the endolymph was ensured by measurement of sodium and potassium concentrations. Gentamicin assay was done with a modified radioimmunoassay. Results show that EA facilitates the entry of gentamicin into endolymph, while it does not affect the kinetics of the drug in perilymph. Although the mechanism of this facilitation remains unclear, this result may account for the ototoxic potentiation reported between EA and aminoglycoside antibiotics.

A randomized-blinded evaluation of analytical error associated with the enzyme immunoassay (EMIT) of gentamicin.

Analytical error is a potential source of inaccuracy and imprecision in the pharmacokinetic dosing of the aminoglycosides. The present study was undertaken to determine the analytical error (precision and accuracy) associated with the EMIT assay for gentamicin as it is routinely used in a clinical pharmacokinetics laboratory, and to assess what impact this error would have on estimates of pharmacokinetic model parameters. Serum samples spiked with known amounts of gentamicin were assayed over a 6-week period along with routine clinical samples by a medical technologist who was blinded with regard to the expected concentration or number of replicates of each sample. Under these conditions, the assay method had a coefficient of variation (CV) of 4.8%. When this analytical error was incorporated into a first-order, one-compartment pharmacokinetic model, the CV was 0.8% for the y intercept and 1.2% for the slope. When all measured concentrations were compared with actual values, the slope and intercept were not significantly different from the line of reference. As indicated by these data, the EMIT assay for gentamicin as it is routinely used in a clinical laboratory is both precise and accurate, indicating that analytical error is not the major source of inaccuracy in pharmacokinetic dosing of gentamicin.

Assay of netilmicin, using enzyme immunoassay for gentamicin.

A homogenous enzyme immunoassay for the quantitative determination of netilmicin in serum was developed. The procedure utilizes a commercially available assay for gentamicin (EMIT; Syva Co., Palo Alto, Calif.). The method was adapted to a microcentrifugal analyzer, and log-logit regression analysis was performed with a computer. The results of samples assayed by this method correlate well with microbioassay (r2 = 0.985) and radioimmunoassay (r2 = 0.986). This method is not only precise and accurate, but also very rapid and economical and compares favorably to other available methods of netilmicin assay.

Serum gentamicin, netilmicin and tobramycin assays by high performance liquid chromatography.

Serum gentamicin, netilmicin and tobramycin assays by high performance liquid chromatography.

Solid phase antigen luminescent immunoassays (SPALT) for the determination of insulin, insulin antibodies and gentamicin levels in human serum.

We describe an interesting and novel alternative to conventional immunoassay techniques for the measurement of antigens and antibodies in body fluids. The label used for all assays is a pyruvate kinase-IgG conjugate of the relevant second (species-specific) antibody. All assays follow the same principle in which a solid phase antigen is used to adsorb unreacted first (substance-specific) antibody following a conventional antibody-antigen reaction in a liquid phase. After washing, the solid phase antigen-first antibody is allowed to react with the labelled second antibody. The solid phase is then washed and the pyruvate kinase bound to the solid phase is used to generate ATP which is measured kinetically in a luminometer. Assays are described for insulin, insulin antibodies and gentamicin to demonstrate both the versatility and sensitivity of this type of assay. The insulin assay had a lower detection limit of under 0.25 microU per tube and was comparable with the radioimmunoassay used for routine purposes both in sensitivity and reproducibility. The insulin antibody assay correlated well with the radiometric determination used routinely in the laboratory. The gentamicin assay correlated well with the routine commercial radioimmunoassay and also had comparable coefficients of variation. In all cases, the inter- and intra-assay variation was under 10% in the range of interest.

Latex agglutination inhibition card test for gentamicin assay: clinical evaluation and comparison with radioimmunoassay and bioassay

Gentamicin levels were determined in 100 serum specimens by a new latex agglutination inhibition card test, a radioimmunoassay (RIA), and a bioassay. Correlation coefficients determined by linear regression analysis demonstrated that the levels obtained by the latex agglutination inhibition card test had a high degree of correlation with the RIA and could be performed much faster and more economically when processing small numbers of specimens. The bioassay had a slightly lower degree of correlation with both the RIA and the latex test and was adversely influenced by concurrently administered antibiotics which could not be eliminated by beta-lactamase. When measuring gentamicin concentrations above 2 micrograms/ml, the coefficient of variation was less than 14% for the latex agglutination assay compared with 15% for the bioassay and 12% for RIA. The latex agglutination inhibition card test is a rapid, accurate, specific, and reproducible method for monitoring gentamicin levels in patients and is particularly applicable for laboratories processing small numbers of specimens.

Peritoneal fluid concentrations of gentamicin in patients with spontaneous bacterial peritonitis.

Simultaneous peritoneal fluid and serum gentamicin assays were performed at 1- or 4-h intervals after the intravenous administration of gentamicin (3 to 5 mg/kg per day) during nine episodes of spontaneous bacterial peritonitis in cirrhotic patients. Mean peritoneal fluid levels were 4.2 micrograms/ml, whereas simultaneous mean serum levels were 6.1 micrograms/ml (mean percent diffusion into ascites of 67.8%). Three additional patients with uninflamed ascites demonstrated lower levels of diffusion. Regression analysis revealed a positive correlation between simultaneous serum and peritoneal fluid levels. We conclude that diffusion of gentamicin from serum into peritoneal fluid during spontaneous peritonitis is therapeutically adequate if sufficient serum levels are maintained.

4] The homogeneous substrate-labeled fluorescent immunoassay

This chapter discusses the different aspects of homogeneous substrate-labeled fluorescent immunoassay (SLFIA). The SLFIA is a useful technique for the rapid, quantitative measurement of both low- and high-molecular-weight analytes. The SLFIA has been demonstrated for several therapeutic drugs. The SLFIA uses the principle of competitive-binding reactions to quantitatively measure the concentration of an analyte. The fluorogenic reagent used in the SLFIA is a conjugate, in which the analyte is covalently labeled, with a fluorogenic enzyme substrate. This fluorogenic reagent is nonfluorescent until it is hydrolyzed, by an enzyme, whereupon it fluoresces. Once the enzymic reactivity and spectral properties of the fluorogenic reagent are established, it is essential to determine the ability of specific antiserum to inhibit the enzyme substrate activity of the fluorogenic reagent. It is found that the fluorogenic reagent for the gentamicin assay showed no detectable loss in the performance when stored for over 1.5 years, either as a powder or in dilute solution, in 5 mM formate-0.1% azide, pH 3.5.