GHB urine concentrations after single-dose administration in humans

Area of Science:

• Pharmacology
• Toxicology
• Forensic Science

Background:

• Gamma-hydroxybutyric acid (GHB) has illicit and therapeutic uses, necessitating reliable detection methods.
• Urine GHB concentration-time profiles after therapeutic dosing are not well-established.
• Accurate GHB detection is crucial for forensic investigations and clinical overdose management.

Purpose of the Study:

• To characterize urine GHB concentration-time profiles following therapeutic doses.
• To correlate urine GHB levels with administered doses and co-ingested ethanol.
• To evaluate the detection window for GHB in urine.

Main Methods:

• Gas chromatography-mass spectrometry (GC-MS) was used to measure GHB in urine.
• Urine samples were collected over 24 hours from 16 adults receiving 50 mg/kg GHB (Xyrem) alone and with ethanol.
• Demographic factors and co-ingestion effects on GHB levels were analyzed.

Main Results:

• Peak urine GHB concentrations (150-200 mg/L) occurred within 0-3 hours post-dose.
• Significant inter-individual variability in GHB levels was observed.
• Lower GHB concentrations were noted in Caucasians and men compared to other groups; ethanol co-ingestion reduced early GHB levels.

Conclusions:

• Urine GHB detection times may be shorter than the previously assumed 12-hour window, especially at therapeutic doses.
• Individual factors like race and sex, and co-ingestion of ethanol, influence GHB excretion profiles.
• A 10 mg/L cutoff suggests limited detectability beyond 6-12 hours post-administration.