A negative naloxone result does not, by itself, prove that naloxone was never administered. Havro and colleagues found clear administration records in eleven living-driver cases, but detected naloxone in only one corresponding blood specimen. This is useful evidence about a negative test’s limits, not a validated detection rate for autopsy specimens.
The eleven cases were not autopsies
The Orange County study reviewed 2018–2019 fentanyl-positive casework, including 199 antemortem blood specimens from suspected impaired-driving cases and 285 central-blood specimens from death investigations.
In eleven of the living cases, police records documented that the person was unconscious in a driver’s seat and could not be awakened. Officers or paramedics administered at least one nasal-spray dose of naloxone, and each person regained consciousness. The actual dose was not specified.
These records provide evidence independent of the laboratory’s naloxone finding. They must not be relabeled as eleven decedents, eleven fatal overdoses or eleven postmortem failures of an assay.
The fentanyl results had their own analytical support
Blood was drawn by a phlebotomist from the median cubital vein and refrigerated at 4°C. The study described sodium fluoride and potassium oxalate preservation, approximately 2% and 0.75% at full container capacity. The report did not give a uniform naloxone-administration-to-blood-draw interval for these eleven cases.
Fentanyl concentrations ranged from 1.6 to 10.6 ng/mL, with a mean of 4.1 ng/mL and median of 3.3 ng/mL. Fentanyl screening used LC–quadrupole time-of-flight MS, followed by separate LC–MS/MS confirmation and quantification with duplicate results averaged.
The fentanyl quantitative method used a 0.5–32 ng/mL calibration range and administratively established detection and quantitation limits of 0.5 ng/mL. Those fentanyl performance characteristics must not be assigned automatically to naloxone.
What did the negative naloxone findings mean?
Naloxone was detected in one of the eleven documented-treatment specimens. It was not detected in any other antemortem specimen in the study. The authors cited the naloxone screening detection limit of 0.5 ng/mL and its short persistence as possible explanations.
The study did not measure each person’s naloxone time course, establish the delivered dose, or experimentally identify the cause of every negative result. A plausible explanation for a low or absent signal is different from proof of that mechanism in each specimen.
Nor is one positive among eleven a general assay sensitivity estimate. These were a small, retrospectively documented subgroup with unknown individual collection intervals, rather than a controlled validation study sampling known doses at fixed times.
Why the distinction matters in death casework
In a death investigation, treatment records and toxicology answer different questions. The record may document administration even when a retained specimen does not contain a reportable amount. A laboratory negative cannot erase independently documented treatment.
Conversely, this living-person evidence does not establish how naloxone behaves during a postmortem interval, in decomposed blood, or in another matrix. It supplies no autopsy correction factor or guaranteed detection window.
A documented return of consciousness also does not quantify one drug’s causal share in a mixed exposure. The paper contained frequent co-detection of other substances, and the eleven-case account did not experimentally isolate every possible contributor.
What to recover before interpreting absence
Obtain administration time, route, dose if known, specimen collection time and site, testing scope and reporting limits. For a later death investigation, preserve the distinction between hospital or other antemortem material and autopsy specimens.
Related issues appear in hospital specimens used in forensic investigations. Treatment documentation, analytical detection, concentration, impairment and cause of death remain separate evidentiary steps.
Primary source
Havro V, Casassa N, Andera K, Mata D. A Two-Year Review of Fentanyl in Driving under the Influence and Postmortem Cases in Orange County, CA, USA. Journal of Analytical Toxicology. 2022;46:875–881. doi:10.1093/jat/bkac030.
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