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Unit Code 80141:
Vancomycin, Peak/Post

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Method Description

Enzyme-multiplied immunoassay technique (EMIT) is performed

using the Olympus analyzer. EMIT offers an alternative to the

traditional spectroscopic and chromatographic method for

quantitating blood concentrations of drugs. The technique for

drugs is based upon an enzymatic assay for glucose-6-phosphate

dehydrogenase, using spectral properties at 340 nm, in which the

reduction of nicotinamide adenine dinucleotide (NAD) substrate is

monitored. The basis of the drug detection technique is an

immunological reaction between the drug and a specific antibody.

The reagent contains the enzyme (glucose-6-phosphate dehydrogenase)

to which the drug is covalently bound and an antibody specific to the

drug. The antibody binds most of the drug-bound enzyme, rendering

the enzyme inactive. This results in a baseline enzymatic activity.

In the presence of free drug, antibody equilibrates between free drug

and enzyme-bound drug leaving some of the drug-bound enzyme

uncomplexed and able to catalyze the reaction. If more free drug is

introduced, either as standard or sample, then competition for the

antibody takes place between the drug in the sample and the drug

attached to the enzyme. This results in more drug-bound enzyme being

left uncomplexed and able to catalyze the enzyme reaction at a greater

rate as compared to the baseline activity. The observed enzyme activity

increases with the amount of total free drug in the sample. (Moyer TP:

Therapeutic drug monitoring. In Tietz Textbook of Clinical Chemistry.

4th edition. Edited by CA Burtis, ER Ashwood. Philadelphia, WB Saunders

Company, 2005, pp 1237-1285)

Performing Laboratory Location

Rochester

Key