Kinetic interaction of microparticles in solution (KIMS) as measured by changes in light transmission performed on the Roche cobas c-systems. In the absence of sample drug, soluble drug conjugates bind to antibody-bound microparticles, causing the formation of particle aggregates. As the aggregation reaction proceeds in the absence of sample drug, the absorbance increases. When a urine sample contains the drug in question, this drug competes with the drug derivative conjugate for microparticle-bound antibody. Antibody bound to sample drug is no longer available to promote particle aggregation, and subsequent particle lattice formation is inhibited. The presence of sample drug diminishes the increasing absorbance in proportion to the concentration of drug in the sample. Sample drug content is determined relative to the value obtained for a known cutoff concentration of drug.The presence of β‑glucuronidase enzyme enhances the Benzodiazepines II assay cross‑reactivity to some of the glucuronidated metabolites.