Intravenous misuse of buprenorphine: characteristics and extent among patients undergoing drug maintenance therapy.

Sublingual buprenorphine [Subutex(R)] is used to treat opioid dependence. However, illicit intravenous (IV) injection of buprenorphine is a widespread problem. This survey investigated the IV misuse of buprenorphine among patients receiving drug replacement therapy at the Drug Addiction Centre in Udine, Italy. All patients who were receiving treatment with buprenorphine or methadone at the Drug Addiction Centre were invited to fill in a voluntary and anonymous questionnaire consisting of five questions. The questions asked if the patient had ever misused buprenorphine intravenously, when the misuse had occurred, the patient's reasons for misusing buprenorphine, the patient's perception of their experience, and the patient's perception of how widespread IV misuse of buprenorphine is. 307 patients completed the questionnaire, 93 and 214 of whom, respectively, were receiving buprenorphine and methadone. In total, 23.12% of patients admitted an IV misuse of buprenorphine, with a significantly greater prevalence among patients currently receiving buprenorphine (35.48%) than those receiving methadone (17.75%; p < 0.001). Younger patients were also more likely to have misused buprenorphine, and tended to have done so before coming to the Drug Addiction Centre. The most frequent motivation for IV misuse was treatment of heroin addiction or withdrawal symptoms (50.71%), while only 12.67% of patients reported that their motivation was to experience pleasure or euphoria. The majority of patients who had misused buprenorphine intravenously (53.52%) had a negative experience, and methadone recipients were significantly more likely to find the experience negative than buprenorphine recipients (68.42% vs 36.36%; p = 0.007). Almost half of the patients (45.93%) thought that at least 50% of patients had taken buprenorphine by IV injection. The results of our study confirm the widespread IV misuse of buprenorphine. Misuse was most common among patients currently receiving buprenorphine treatment and younger patients. For the majority of patients, the reason for IV misuse was to treat their dependence. We believe that the prevalence of buprenorphine misuse could be reduced by adopting appropriate clinical practices and treating patients with the buprenorphine/naloxone combination rather than buprenorphine alone.