QMS* Therapeutic Drug Monitoring Assays

The Thermo Scientific* QMS TDM Assays feature world-leading microparticle technology for a wide range of particle-enhanced turbidimetric immunoassays for application on general chemistry analyzers.

The Thermo Scientific Quantitative Microsphere System (QMS) has excellent precision and accuracy, optimized performance on a wide range of analyzers and lot-to-lot consistency. The two component assay system is based on the competitive inhibition immunoassay principle whereby free-drug in the sample competes for antibody binding sites with drug molecules coated onto uniform microparticles. The drug coated microparticle reagent is rapidly agglutinated in the presence of the antibody reagent and in the absence of any competing drug in the sample. The rate of absorbance change is measured photometrically and is proportional to the rate of agglutination of the microparticles. When a sample containing drug is added to the antibody reagent prior to the addition of the microparticle reagent, the agglutination reaction is inhibited by a degree that is directly related to the concentration of drug in the sample. A concentration-dependent classic agglutination inhibition curve can be obtained using QMS calibrators with the maximum rate of agglutination at the lowest drug concentration and the lowest agglutination rate at the highest drug concentration. Patient sample drug concentrations are determined from this standard curve.