| Definitions of Drug Testing Terms |
|---|
| Biologic half-life | Time required for one-half of a substance (eg, a drug) to be lost through biologic processes (eg, distributed, metabolized, eliminated). |
| Chain of custody | Chronological documentation or paper trail showing the collection, custody, control, transfer, processing, analysis, destruction and disposition of evidence (including biological specimens). |
| Confirmation test | Specific drug test performed after a drug screen to confirm the identity of a drug class, individual parent drug, and/or drug metabolite; confirmatory tests are frequently based on mass spectrometric methods and are often quantitative. |
| Cutoff | Threshold concentration for a drug class, specific drug, or drug metabolite above which a specimen is reported as “positive” or “present”; cutoff may be defined by the manufacturer of a commercial kit (eg, immunoassay) or based on the limit of quantitation validated for a laboratory-developed test (eg, mass spectrometry). |
| Drug screen | Test intended to identify the presence or absence of one or more drug classes or specific drugs. |
| Free drug | Drug or drug metabolite not bound to protein or other moieties such as glucuronides; biological activity, transport, and elimination of drugs and drug metabolites is often different for a free versus a bound drug. |
| Forensic | Relating to or dealing with evidence intended for use in a court of law (eg, to support crime and death investigations, workers’ compensation claims, and pre-employment testing). |
| Hydrolysis | Chemical process of decomposition involving the splitting of a bond and the addition of the hydrogen cation and the hydroxide anion of water. |
| Common laboratory technique used to dissociate glucuronide and other conjugates of drugs in order to improve detection of many drugs in urine. |
| Methods that employ hydrolysis prior to analysis are presumed to generate a “total” drug concentration. |
| Limit of detection (LOD) | Concentration at which the target compound can be identified. |
| Limit of quantification (LOQ) | Concentration at which quantitative results can be reported with a high degree of confidence. |
| Metabolite | Any product of metabolism; metabolites can be pharmacologically or toxicologically active or inactive. |
| Pharmacodynamics | Study of drug response, particularly the mechanisms associated with the binding and interactions of pharmacologically active molecules at their tissue site(s) of action. |
| Pharmacokinetics | Study of drug liberation, absorption (bioavailability), distribution, metabolism, and elimination over time. |
| Specificity | Likelihood for detection of a given drug or drug metabolite (ie, likelihood of false-negative and false-positive results). |
| Total drug | Total protein-bound and free drug identified in a specimen; also the concentration resulting after specimen hydrolysis that is thought to represent the sum of free and conjugated drug. |
Back
Menu