Finding two drugs in serum does not necessarily point to two products. Knowing the ingredients of the material recovered at the scene can change how a toxicologist interprets the pair.
The patient arrived with profound central nervous system depression. A rapid urine screen detected barbiturates and benzodiazepines. Subsequent serum testing measured pentobarbital and phenytoin, and the history identified a veterinary product containing both. Expanded testing also identified 7-aminoclonazepam, a clonazepam metabolite.
The product information offered a shared explanation for two serum findings. The clonazepam metabolite represented a separate analytical finding. In a similar case, keep the recovered formulation, rapid screen, specific analyte results and treatment timeline separate. Those records can help establish which detections fit the same source without requiring an unsupported estimate of how much of each substance contributed to the clinical course.
Crellin and Katz, case report of toxicity from a veterinary formulation (full text) ยท DOI