Case:

A 35 years old male with a history of opioid abuse was on Sublocade therapy which ended on January 12. His continued post-Sublocade therapy included laboratory testing for buprenorphine. His results were as follows:

Date	Urine (ng/mL)		Oral Fluid
	Buprenorphine	Norbuprenorphine	Buprenorphine	Norbuprenorphine
3/25	N/A	N/A	Neg	Neg
4/8	N/A	N/A	Neg	Neg
4/15	N/A	N/A	Neg	Neg
4/29	N/A	N/A	Neg	Neg
5/14	280	118	N/A	N/A
6/10	327	1122	Neg	Neg
6/24	184	137	Neg	Neg

 N/A = not assayed in this specimen type

The patient was never positive for buprenorphine in oral fluid. This may be due to fortuitous timing of use and sampling, but on days when both oral fluid and urine were collected together, buprenorphine was detected in urine but not in oral fluid.  There is also the possibility that buprenorphine is not detected in oral fluid when taken as Sublocade.

Sublocade has changed the way many patients receive buprenorphine treatment for opioid use disorder. Unlike daily transmucosal buprenorphine products such as Suboxone®, Sublocade® is given as a once-monthly subcutaneous injection by a healthcare provider. After injection, the medication forms a depot under the skin and releases buprenorphine gradually over time, helping maintain more consistent exposure without daily dosing¹.

That long-acting design is clinically useful. But it also creates a major challenge for drug testing interpretation.

A patient who has stopped Sublocade may continue to test positive for buprenorphine in urine for months. According to the FDA prescribing information, Sublocade reaches steady state after about 4–6 months, has an apparent terminal plasma half-life of 43–60 days, and buprenorphine exposure assessed 22–38 months after the last injection indicated that buprenorphine could potentially be detected in plasma and urine over that period. The product literature also notes that urine concentrations were more variable than plasma and generally higher depending on the test used². Oral fluid was not examined.

This is not just a theoretical issue. Public reviews and patient discussions also show recurring confusion around prolonged positive urine tests after stopping Sublocade, including concerns about probation, employment testing, treatment monitoring, and whether a positive result is being misread as relapse. Moreover, what if a patient does use buprenorphine after the last Sublocade injection? If the patient is being monitored by urine drug testing, one would not know if a positive buprenorphine represented residual Sublocade or new use.

Why oral fluid deserves closer attention

Oral fluid testing may offer a more clinically useful window when monitoring patients after Sublocade discontinuation.

American Society of Addiction Medicine (ASAM) notes that oral fluid testing is appropriate for detecting substance use in addiction treatment settings, has a shorter detection window than urine for many substances, is easier to observe during collection, and is less vulnerable to some urine tampering problems. Oral fluid is also more likely to contain parent drug compounds, while urine often emphasizes metabolites³. The Substance Abuse and Mental Health Services Administration (SAMHSA) has also established oral fluid as an accepted specimen type in federal workplace drug test guidelines, noting that the scientific basis for oral fluid testing as an alternative specimen has been broadly established⁴.

This does not mean oral fluid is always better than urine. In fact, published work has found urine to be more sensitive than oral fluid for detecting buprenorphine compliance in patients undergoing buprenorphine treatment⁵.

But the Sublocade discontinuation question is different.

For daily sublingual or buccal buprenorphine, the goal is often to confirm adherence. In that setting, urine may be preferred because it is more sensitive and more likely to detect buprenorphine and metabolites. After Sublocade discontinuation, however, the challenge is often the opposite: urine may remain positive long after the patient has stopped active dosing.

That is where oral fluid may provide value.

If a patient’s urine remains positive for buprenorphine and norbuprenorphine months after the last Sublocade injection, but oral fluid is negative, that pattern may support the possibility that urine positivity reflects residual depot elimination rather than recent buprenorphine use. This is especially meaningful when supported by documented injection history, clinical stability, absence of new prescriptions, and downward urine concentration trends. If oral fluid is positive for buprenorphine in the period post-Sublocade, it is likely due to use of unprescribed oral buprenorphine.

The current evidence gap

There appears to be limited published literature specifically evaluating oral fluid detection patterns after Sublocade discontinuation. The FDA prescribing information discusses prolonged plasma and urine detection but does not appear to address oral fluid or saliva testing.

That gap is important.

Clinical laboratories and addiction treatment providers need better evidence on how buprenorphine and norbuprenorphine behave in oral fluid after long-acting injectable buprenorphine. Key questions include:

Is buprenorphine detectable in oral fluid when provided as Sublocade?

If so, how long does buprenorphine remain detectable in oral fluid after the final Sublocade injection?

Can paired urine and oral fluid testing help distinguish residual depot release from new transmucosal buprenorphine use?

What cutoff values and LC-MS/MS methods are most appropriate for this clinical situation?

Until those questions are answered through larger studies, oral fluid should be viewed as a complementary clinical tool, not a standalone verdict.

A practical testing approach after Sublocade

For patients who have discontinued Sublocade and continue to test positive in urine, a more thoughtful approach may include:

1. Document the Sublocade history clearly: last injection date, dose, number of injections, and whether steady state was likely reached.
2. Use definitive testing when possible, preferably LC-MS/MS, rather than relying only on point-of-care immunoassay results.
3. Review serial quantitative urine buprenorphine and norbuprenorphine results, rather than overinterpreting a single positive result, because quantitative urine concentrations can be difficult to interpret and should be considered in clinical context.⁶
4. Add oral fluid testing when the clinical question is recent use versus residual depot elimination.
5. Interpret results in context: clinical presentation, medication history, PDMP data, treatment engagement, and known Sublocade pharmacokinetics.
6. Involve the laboratory or toxicologist when results have legal, employment, treatment-placement, or discharge consequences.

Why this matters for recovery programs

For recovery centers, behavioral health providers, and monitoring programs, the goal of testing should be clinical clarity, not punishment. Drug testing is most useful when it helps guide care, identify risk, support accountability, and protect patient progress.

Sublocade complicates traditional urine interpretation because the medication is designed to last. A positive urine buprenorphine result after discontinuation does not automatically mean relapse, misuse, or noncompliance. In some cases, it may simply reflect the pharmacology of the depot.

Oral fluid testing may help fill this interpretive gap. Because oral fluid generally reflects a shorter detection window and may align more closely with recent systemic exposure, it deserves serious consideration when monitoring patients after the last Sublocade injection.

Conclusion

Sublocade’s long-acting depot formulation can support recovery by reducing the burden of daily dosing. But the same long-acting profile can create confusion in toxicology interpretation, especially when urine remains positive long after treatment stops.

Oral fluid remains under-studied in this specific setting. Based on Sublocade pharmacokinetics¹, known differences between urine and oral-fluid testing³,⁵, may be a valuable sample type when the key question is whether a patient has recently used buprenorphine after discontinuing Sublocade.

The field needs more published data. Until then, paired urine and oral fluid testing, interpreted by experienced clinical toxicology professionals, may offer a more balanced and patient-centered approach.

References

1. Sublocade Medication Guide. Indivior, North Chesterfield, VA 23235; 03/2021.
2. Sublocade® Prescribing Information. Indivior Inc.; revised 2026. See Clinical Pharmacology / Pharmacokinetics and Elimination sections.
3. Appropriate Use of Drug Testing in Clinical Addiction Medicine – Consensus Statement. American Society of Addiction Medicine, 2017.
4. Mandatory Guidelines for Federal Workplace Drug Testing Programs – Oral Fluid. Department of Health and Human Services 42 CFR Chapter I, 2019.
5. Ransohoff JR et al. Urine is Superior to Oral Fluid for Detecting Buprenorphine Compliance in Patients Undergoing Treatment for Opioid Addiction. Drug and Alcohol Dependence, 203: 8–12, 2019.
6. Donroe JH, Holt SR, O’Connor PG, Sukumar N, Tetrault JM. Interpreting quantitative urine buprenorphine and norbuprenorphine levels in office-based clinical practice. Drug Alcohol Depend. 2017;180:46–51. doi:10.1016/j.drugalcdep.2017.07.040