Jjj asked
How long will buprenorphine stay in your urine if you are only taking half pills?
Answer
Both buprenorphine and its main metabolite, norbuprenorphine have a long half life (i.e. time it takes for 50% of the drug to be metabolized). Therefore, it often takes a considerable amount of time for them to be completely metabolized and eliminated from the body.
The average half life of buprenorphine (when taken sublingulally) is 37 hours. The half life of norbuprenorphine varies considerably and is reported to be anywhere from 57 hours to over 100 hours (although this is uncommon).
In regard to how long buprenorphine will be detectable on a urine drug test very much depends on what the test is looking for. Some tests look only for buprenorphine whereas others will look for both buprenorphine and norbuprenorphine. It is also important to note that both drugs are lipophilic, meaning they are stored in fat cells. The more fat cells you have, the longer the drugs generally last in your body and will be detectable.
A general rule of thumb is that it takes about 5 half lives for a drug to no longer be detectable via a standard urine drug test. Therefore, if the test is looking for buprenorphine alone, it generally will be detectable for about 7 days. If a test is looking for norbuprenorphine, it can remain detectable much longer, up to 14-20 days.
Several other factors affect how long drugs are detectable for including:
- How long you have been taking the drug
- Body composition
- Concomitant medications
In most cases, the dose you take doesn't greatly affect metabolism/elimination time. The more important factor is length of time using the drug. If taking buprenorphine was a one time occurrence, it will generally be detectable on the shorter range of the detection window.
