StudyHow the body handles it2022
Kim 2022: a urine test to check whether people take naltrexone
Kim SY, Shin DW, Suh S, Cheong JC, Kim JY. Monitoring alcohol-use-disorder medication compliance by LC-MS/MS determination of urinary ethyl glucuronide, acamprosate, naltrexone, and 6β-naltrexol using zirconia-based hybrid solid-phase extraction
What it found
Researchers in South Korea built a lab test that measures naltrexone in urine down to 0.4 ng/mL and 6β-naltrexol, a substance the body makes from it, down to 0.2 ng/mL, along with acamprosate and a marker of alcohol use. They used it on 107 urine samples to check whether probationers in court-ordered alcohol treatment were taking their medicine and drinking.
- Lowest naltrexone level measured
- 0.4 ng/mL
- Lowest 6β-naltrexol level measured
- 0.2 ng/mL
- Probationer urine samples tested
- 107
What they tested
In South Korea, courts can order people on probation who have alcohol use disorder to take medicine, with the aim of reducing repeat offences. To check whether they comply, the researchers developed a test using liquid chromatography-tandem mass spectrometry (LC-MS/MS), a lab technique that separates and identifies specific chemicals.
The test measures four things in urine: ethyl glucuronide (EtG), a marker of alcohol use, plus acamprosate, naltrexone and 6β-naltrexol. A special extraction step was added to make it more sensitive. All four were detected within 6.5 minutes per run.
What they found
The lowest amounts the test could reliably measure were 10.0 ng/mL for EtG, 4.0 for acamprosate, 0.4 for naltrexone and 0.2 for 6β-naltrexol. The method passed its checks for accuracy, precision and recovery.
It was used on 107 urine samples from probationers in medicine treatment for alcohol use disorder, to monitor whether they were taking their medicine and drinking. The researchers also measured urine levels of naltrexone and 6β-naltrexol after repeated doses by mouth.
The abstract doesn't report how many probationers were taking their medicine or what levels were found.
Limits
- It is a lab method paper. It shows the test works, not how long naltrexone stays detectable after a dose.
- The samples came from one group: probationers in South Korea under court-ordered treatment.
What it means if you're considering naltrexone
A lab can find naltrexone in urine at very low levels when it is specifically asked to look. This method was built to check medicine use in court-ordered treatment, and the paper doesn't give a detection window after the last dose.
Frequently asked questions
Can a urine test show if someone is taking naltrexone?
Yes, when a lab looks for it. This method measured naltrexone in urine down to 0.4 ng/mL and 6β-naltrexol down to 0.2 ng/mL, and was used to check whether probationers in South Korea took their medicine.
The paper
Kim SY, Shin DW, Suh S, Cheong JC, Kim JY. Monitoring alcohol-use-disorder medication compliance by LC-MS/MS determination of urinary ethyl glucuronide, acamprosate, naltrexone, and 6β-naltrexol using zirconia-based hybrid solid-phase extraction. J Pharm Biomed Anal. 2022;212:114615. doi:10.1016/j.jpba.2022.114615
Read the paperdoi:10.1016/j.jpba.2022.114615
We wrote this page from the paper's published abstract, and the study's numbers here come from there. Updated October 17, 2026.
Medical disclaimer
This page is for information only and is not medical advice, diagnosis, or treatment. Don't start, stop, or change any medicine — including naltrexone — without your prescriber. Naltrexone must not be used by people taking opioid pain medicines, people dependent on opioids, or people in opioid withdrawal (FDA label). In an emergency call 911; for crisis support call or text 988. Full medical disclaimer.