Concomitant use of midazolam and buprenorphine and its implications among drug users in Singapore

The aim of this study was to determine the prevalence and characteristics of benzodiazepine (BZD) abuse among intravenous opioid users in Singapore. Eligibility criteria for inclusion in this study were all intravenous buprenorphine abusers, who presented to the Community Addictions Management Programme (CAMP) over a 1-year period from February 2005 to January 2006. One hundred and twenty subjects, who consented to the study, completed an interviewer-administered questionnaire and underwent blood test for blood-borne viral infections. The age of the 120 subjects ranged from 20 to 64 years, with a mean age of 39.0 (SD 8.0) years. The majority of the participants were male (90.0%); 48.3% were Chinese. Ninety-eight (81.7%) patients were using BZDs concomitantly. Midazolam was the most commonly used BZD. Buprenorphine abusers who were concomitantly using BZDs were significantly younger and reported an earlier age of onset of illicit drug abuse as compared to those not using BZDs. Those abusing BZDs were more likely to share syringes (x 2 = 5.8, P = 0.02), and were more likely to be seropositive for hepatitis C virus (x 2 = 4.3, P = 0.04). This study highlights the extreme caution that needs to be exercised in prescribing BZDs to all patients in general and patients with injecting drug use or histories of drug abuse in particular. At a public health level, general practitioners (GPs) who prescribe buprenorphine should have compulsory training which highlights the potential dangers of abuse and concomitant abuse of BZDs.