Test ID: VANCR    
Vancomycin, Random, Serum

Enzyme-multiplied immunoassay technique (EMIT) 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)

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