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gentamicin in serum/plasma

Indications: - therapeutic drug monitoring, gentamicin therapy - Pseudomonas aeruginosa, Enterobacteriaceae - endocarditiis Reference values: - Peak Values: 4.0-8.0 ug/mL - Trough Values: 0.0-2.0 ug/mL Clinical significance: - gentamicin is primarily active against staphylococci & gram-negative bacilli - often used in the treatment of: a) urinary tract infection b) pneumonia c) gram-negative sepsis - when sepsis is suspected, especially in burn patients, aminoglycosides remain an important part of prophylaxis - 2 reasons for measuring serum aminoglycoside antibiotics: a) to assure that the patient is receiving enough antibiotic to be effective against the infecting bacteria b) to make sure the dose received by the patient is maintained below the toxic limit - see gentamicin for toxic (adverse) effects Principle: The GENTA pack is used in the DuPont ACA discrete clinical analyzer to quantitatively screen gentamicin serum & plasma. It is an adaptation of Syva's homogeneous enzyme immunoassay technique, EMIT. The reagents used in this methodology are matched lots of gentamicin antibody & the gentamicin-glucose-6- phosphate dehydrogenase conjugate. The concentration of gentamicin determines the amount of gentamicin-glucose-6-phosphate dehydrogenase (GENT-G6PD) conjugate that is bound to the antigentamicin antibody. The unbound conjugate catalyzes the oxidation of glucose-6-phosphate, with the simultaneous reduction of NAD to NADH, more rapidly than does the bound conjugate. The rate of increasing absorbance at 340 nm due to the increase in NADH is related to the concentration of gentamicin by means of a calibration curve or a mathematical function. Specimen: Patient preparation: No special patient preparation is required. Collect blood samples by venipuncture following established good laboratory practices. If the sample is obtained through the infusion set, flush the line thoroughly with saline before taking the blood sample. With some exceptions, any anticoagulant may be used to collect plasma for analysis. Serum, as well as plasma, may be used for most assays. If is very important that the physician be informed of the times of sample collection & dose administration; this information should be supplied to the laboratory with each sample & reported with the results of each test. Samples derived from blood should be refrigerated upon collection & stored frozen (-20 degrees Celsius or colder) if not analyzed within 24 hours. Complete mixing of each thawed sample is required before analysis.

Related

gentamicin (Garamycin, Genoptic, G-Mycin)

Specific

gentamicin free in serum/plasma gentamicin in serum/plasma peak gentamicin in serum/plasma random gentamicin in serum/plasma trough

General

therapeutic drug measurement

References

  1. ACA IV Discrete Clinical Analyzer Instrument Manual, Volume 1: Operation, DuPont Company, Wilmington, Delaware, 1984.
  2. ACA IV Discrete Clinical Analyzer Instrument Manual, Volume 3B: Chemistry, DuPont Company, Wilmington, Delaware, 1984.
  3. Gentamicin, Random Laboratory Test Directory ARUP: 90130
  4. Gentamicin Peak Laboratory Test Directory ARUP: 90305
  5. Gentamicin Trough Laboratory Test Directory ARUP: 90310