Yale H. Caplan, PhD, D-ABFT
Toxicologist
Director, National Scientific Services
Baltimore, Maryland
"Amount of Drug Taken: At this time, there is no scientifically validated relationship between the amount of drug taken and urine drug concentration. Therefore, a UDT cannot indicate the amount of drug taken, when the last dose was administered, or the source of that drug.1-5 Recently, some laboratories have offered technology to compare a patient’s UDT
result to an expected range for a drug—they claim that comparing a normalized test result concentration to the expected range can measure compliance with the prescribed dose (reporting: in range, low, or high). Although their protocol may calculate a normalized value based on the patient’s height and weight, the specimen’s pH and specific gravity, and prescription dosage, many other factors can influence the absorption, distribution, metabolism, and elimination of a drug. These include genetic polymorphisms (eg, enzyme deficiencies), renal and hepatic function, disease states, body surface area and muscle mass, cardiac output, drug-drug interactions, drug-food interactions, and age. Therefore, at this time, UDT measurements should not be used to extrapolate backward and make specific
determinations regarding dose and compliance with the prescribed drug. Software and laboratory products have not yet been fully validated scientifically and peer reviewed in the medical literature. Interpreting a UDT beyond the current scientific knowledge may put
healthcare professionals and patients at medical and/or legal risk." Is this an exact science?