Diphenhydramine in gastric contents can support evidence of intake when decomposition prevents blood collection. It cannot supply the missing blood concentration or determine the absorbed dose. Two gastric-only cases in a Berlin autopsy study show why scene findings and analytical findings must remain separate.
Two cases within a selected series
Eckes and colleagues retrospectively reviewed January 2000 through December 2010 autopsies. Among 8,131 autopsies, 73 cases had diphenhydramine identified. The published investigation selected 20 suicidal intoxication cases involving detection; it was not a representative sample of everyone exposed to the drug.
The authors separated cases with peripheral blood, cases with cardiac blood only, and cases with no blood. In two men, aged 42 and 62 years, progressive putrefaction prevented blood sampling. Their approximate postmortem intervals were ten and 73 days, respectively.
What was measured, and in what units?
Gastric diphenhydramine concentrations were 55.6 µg/mL in case 19 and 144.0 µg/mL in case 20. These are concentrations in gastric material, not milligrams swallowed, concentrations in blood, or a measurement of drug delivered to the brain.
The study used high-performance liquid chromatography for autopsy specimens and referred readers to an earlier publication for the detailed analytical method. This report did not reproduce a full matrix-specific validation, including detection and quantitation limits, recovery and precision. Those missing figures cannot be supplied by assumption.
Package-based estimates were not laboratory dose measurements
In case 19, an empty packet had contained twenty 50-mg tablets. In case 20, the packages had contained sixty 50-mg tablets and fifty 25-mg tablets. The authors listed estimated intakes of 1,000 and 4,250 mg based on those scene findings.
That arithmetic describes the nominal contents of the packages. It did not establish that every missing tablet was swallowed by the deceased during the final episode. Nor did the gastric concentration independently confirm those estimates.
Case 20 also had evidence of doxylamine intake and a suicide note. The authors considered intoxication plausible from the combined circumstances. They nevertheless placed both gastric-only cases in a category where diphenhydramine’s contribution could not be determined from the available blood evidence.
Why a gastric concentration cannot replace blood
The study found no constant relationship between diphenhydramine concentrations in blood and gastric contents. A high gastric concentration did not provide a validated equation for predicting a blood result. The series also did not experimentally determine stability throughout either of these long postmortem intervals.
A concentration per milliliter should additionally remain distinct from total drug recovered from a complete stomach collection. Even a measured recovered total would address material remaining at collection, not automatically the original dose or the amount absorbed before death.
What can the investigation conclude?
The finding supports medication intake in conjunction with the scene and case history. The absence of blood limits numerical and causal interpretation; it does not turn the positive gastric finding into proof of no exposure, and it does not establish fatal toxicity by itself.
Preserve specimen identity, decomposition, interval, analytical scope and the origin of every dose estimate. Do not attach a blood “lethal range” to a gastric result merely because both are expressed per milliliter.
Specimen identity also matters when gastric material contaminates a blood-like sample: see blind-stick collection and gastric contamination.
Primary source
Eckes L, Tsokos M, Herre S, Gapert R, Hartwig S. Toxicological identification of diphenhydramine (DPH) in suicide. Forensic Science, Medicine, and Pathology. 2013;9:145–153. Published online 2012. doi:10.1007/s12024-012-9383-5.
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