“I know why addicts inject buprenorphine (Subutex): they think it saves them money. Over the long run, however, I doubt that’s true, given the hidden costs of addiction.
Buprenorphine has a relatively low bioavailability, at around 30%, when taken sublingually (under the tongue). This means only 30% of the total dose reaches the blood stream. If the pH of the mouth is lowered, bioavailability is reduced even further. This is why we recommend patients on buprenorphine avoid eating or drinking anything acidic for about twenty minutes prior to taking their dose.
By definition, when a drug in injected, it has 100% bioavailability. Therefore, some people inject their prescribed buprenorphine in order to get the desired blood level with a lower dose of buprenorphine. If they are prescribed 8mg per day, perhaps they use 4mg intravenously and sell the rest of their dose, or stockpile it.
People who misuse buprenorphine in this way may be blinded by their addiction to the multiple dangers of injecting drugs.”
Source: Dr. Jana Burson – November 1, 2015