New Biomarker Offers Longer Detection Window for Suspected GHB Exposure

Gamma-hydroxybutyrate (GHB) can be used recreationally or administered covertly to incapacitate victims. Forensic confirmation is challenging because the substance is rapidly eliminated, with typical detection windows of about six hours in blood and 12 hours in urine. Interpretation is further complicated by the presence of small amounts of naturally occurring GHB in the body and its possible release after death. New findings now suggest that a urine biomarker may help extend the window for detecting prior GHB intake.

Researchers at the University of Zurich evaluated GHB-pentose, a compound formed from GHB and a sugar thought to be ribose, as a potential biomarker of prior GHB intake. Although its exact chemical structure has not yet been conclusively established, GHB-pentose remains detectable in urine for substantially longer than GHB itself.

The biomarker was first identified in 2021 by researchers at the Institute of Forensic Medicine at the University of Zurich in collaboration with the University Hospital of Psychiatry Zurich. Subsequent controlled studies investigated its potential in greater detail. A study published in 2025 showed that GHB-pentose could remain detectable in urine for up to three days after GHB intake.

In a study published in Drug Testing and Analysis on November 4, 2026, the researchers analyzed 2,414 anonymized urine samples from genuine forensic cases collected between 2024 and 2026. The samples were evaluated using two independent mass spectrometry methods. GHB-pentose was detected in all 21 GHB-positive urine samples from living individuals.

An additional 14 samples contained GHB below the test threshold but still showed detectable GHB-pentose. In eight of these cases, available case information supported suspected prior GHB intake or administration. These included three suspected criminal offenses, comprising two robberies and one alleged sexual assault, in which urine samples were collected 13 to 16 hours after the incident.

The researchers also examined samples from deceased individuals, in whom GHB interpretation can be particularly difficult because the substance may form after death. Among 20 urine samples from deceased individuals, elevated GHB levels were detected without GHB-pentose. In four additional samples, both GHB and GHB-pentose were present.

The findings showed that GHB-pentose can be detected with two analytical methods already common in forensic toxicology. The researchers stated that this could allow testing to be incorporated into existing laboratory workflows, although no commercially available reference standard currently exists. They also noted that the findings do not yet permit final conclusions on diagnostic reliability or the maximum detection period in individual cases.

“The findings offer the first indication from forensic practice that GHB-pentose remains detectable beyond the usual detection window for GHB,” said Andrea Steuer, last author.

“Where there is a suspicion that GHB has been administered, we now routinely test for GHB-pentose, too,” added Steuer.

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