How Did a Laboratory Study Decide That a Detected Drug Was Non-Prescribed?
A laboratory can identify a drug while relying on outside information to classify its prescription status. A national urine-testing study combined analytical results with medication information supplied by the ordering clinician.
Two information streams
McClure and colleagues analyzed 231,228 test-result sets from 144,535 patients tested for both opioids and benzodiazepines. The laboratory used definitive mass spectrometry, either following presumptive screening or as the initial test pathway.
The prescribed-drug list came from the clinician ordering the test. The paper states that clinicians were instructed to provide all prescribed medications, including those prescribed by other clinicians. A reporting service then compared detected drugs and metabolites with that information.
Metabolites complicated classification
The investigators grouped certain parent drugs and metabolites to account for relationships that could otherwise distort interpretation. Examples included oxycodone with oxymorphone and a benzodiazepine grouping containing nordiazepam, oxazepam, and temazepam.
Not every patient was tested for every subgroup. Some testing followed a presumptive positive screen, while other testing reflected the requested panel. The scope of the analytical request therefore also affected the available observations.
Questions for an individual case
For an attorney reviewing a non-prescribed label, the relevant materials include the original medication list, its date, other prescribers’ records, the requested panel, and the detected analytes. Prescription status and analytical identity each need their own evidentiary support.
The study’s percentages describe a selected clinical testing population. A positive result alone does not establish when each medicine was taken, simultaneous impairment, or why a prescription was absent from submitted information. Reconciliation of the clinical and laboratory records remains necessary before drawing a patient-specific conclusion.
Source
McClure FL and colleagues. Concurrent Use of Opioids and Benzodiazepines. Journal of Addiction Medicine, 2017. Full text · DOI 10.1097/ADM.0000000000000354.
