From the FDA Drug Label
Within 72 hours of IV fentanyl administration, approximately 75% of the dose is excreted in urine, mostly as metabolites with less than 10% representing unchanged drug.
The duration that fentanyl can be positive on urine testing is not directly stated in the provided drug labels. However, it is known that approximately 75% of the dose is excreted in urine within 72 hours, mostly as metabolites.
- The exact duration of positivity in urine testing is not provided.
- The information available does not allow for a precise answer to the question.
- It is important to note that the metabolism and excretion of fentanyl can vary among individuals, which may affect the duration of its presence in urine. 1
From the Research
Fentanyl can remain detectable in urine tests for up to 7-13 days after last use, depending on various factors such as metabolism, kidney function, and frequency of use, as evidenced by a study published in 2020 2. The detection window for fentanyl in urine tests can vary significantly based on several factors, including:
- Individual metabolism and kidney function
- Hydration status and dose taken
- Frequency of use and sensitivity of the test being used
- Method of administration, with a half-life of about 3-12 hours Fentanyl is a synthetic opioid that requires specific testing designed for synthetic opioids, and more sensitive tests like gas chromatography-mass spectrometry (GC-MS) can detect even small amounts of the drug for longer periods 3. A recent study published in 2023 found that fentanyl was detectable in urine specimens for a median time of 7.3 days, with one participant continuing to test positive for up to 19 days 2. Another study published in 2023 highlighted the importance of considering the pharmacokinetics of fentanyl in the context of opioid withdrawal in persons who regularly use fentanyl 4. It is essential to note that factors like body mass, age, and overall health can influence how quickly the body eliminates the drug, and regional differences in drug use patterns may also impact detection rates 5. In clinical practice, it is crucial to consider these factors when interpreting urine test results for fentanyl, as the detection window can be prolonged in some individuals.