Homogeneous Immunoassays—Therapeutic Drug Monitoring
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INNOFLUOR® Gentamicin Assay System
The INNOFLUOR® GENTAMICIN Assay System is intended for the quantitative determination of total gentamicin in serum for therapeutic drug monitoring by fluorescence polarization immunoassay (FPIA). The assay system is for use on the TDx® or the TDxFlxTM (TDx®/TDxFLx®) analyzer.
Gentamicin is an important aminoglycoside antimicrobial agent used to treat serious gram-negative infections.1-5 Gentamicin, prescribed alone and in combination with other antibiotics, has become the most widely used of the aminoglycosides as a result of long experience with its use and its low cost.5 The aminoglycosides appear to inhibit bacterial protein synthesis by specifically binding to the 30S ribosomal subunit.4-6
Gentamicin is routinely administered intravenously or intramuscularly, is rapidly dispersed into extracellular fluid, does not cross most cell membranes, and is essentially unbound to serum proteins.5 As with other aminoglycosides, gentamicin is potentially ototoxic and nephrotoxic.1-9 In patients with normal renal function, gentamicin is rapidly excreted, primarily by glomerular filtration, with an elimination half-life of approximately two hours. The use of gentamicin in renal patients must be carefully monitored.4-6 Measurement of serum levels is necessary to prevent toxicity and inadequate dosing, due to wide individual variation in the elimination and distribution of gentamicin.4-6,10,11
Immunoassays using a fluorescence polarization technique for gentamicin have been published.12,13
Cox DE. Gentamicin. Med Clin N Amer 1970; 53: 1305-1315.
Riff LJ, et al. Pharmacology of gentamicin in man. J Infec Dis 1971; 124[suppl]: 98-105.
Winters RE, et al. Relation between dose and levels of gentamicin in whole blood. J Infec Dis 1971; 124[suppl]: 90-95.
Edson RS, Terrell CL. The aminoglycosides. Mayo Clin Proc 1991; 66(11): 1158-1164.
Sande MA, Mandell GL. Antimicrobial agents. The aminoglycosides. In: The pharmacological basis of therapeutics, Goodman Gilman A. ed. Pergamon Press Inc., New York 10523 1990; 1098-1116.
Anhalt JP. Interpretation of antimicrobial concentrations in serum. AACC Therapeutic drug monitoring continuing education and Q.C. program, April 1981: 1-11.
Jackson GG, et al. Ototoxicity of gentamicin in man: a survey and controlled analysis of clinical experience in the United States. J Infec Dis 1971; 124[suppl]: 130-137.
Dehlgren JD, Anderson ET, Hewitt WL. Gentamicin blood levels, a guide to nephrotoxicity . Antimicrob Agents Chemother 1975; 8: 58-62.
Chan RA, Benner EJ, Hoeprich PD. Gentamicin therapy in renal failure: a nomogram for dosage. Ann Intern Med 1976; 76: 773-778.
Nordstrom L, Banck G, Belfrage S, Juhlin I, Tjernstrom O, Toremalm NG. Prospective study of the otoxicity of gentamicin. Acta Pathologica Et Microbiologica Scandinavica 1973; Section B81[suppl241]: 58-61.
Jellife RW, Iglesias T, Hurst AK, et. al. Individualizing gentamicin dosage regimens. A comparative review of selected models, data fitting methods and monitoring strategies. Clin Pharmacokinet 1991; 21(6): 461-478.
Jolley ME, Stroupe SD, Wang CJ, et. al. Fluorescence polarization immunoassayI. Monitoring aminoglycoside antibiotics in serum and plasma. Clin Chem 1981; 27(7): 1190-1197.
Joos G, Luthy R, Blaser J. Long term accuracy of fluorescence polarization immunoassays for gentamicin, tobramycin, netilmicin, and vancomycin. Journal of Antimicrobial Chemotherapy 1989; 24: 797-803.
