Opioid antagonist challenges in buprenorphine maintained patients

Following one month of sublingual buprenorphine treatment, 15 patients at either 2 mg (n = 7) or 3 mg (n = 8) were hospitalized and the buprenorphine was abruptly stopped by placebo substitution. On the morning following their last dose of buprenorphine, 10 patients were given 1 mg oral naltrexone and 5 were given 0.5 mg/kg intravenous naloxone in a double blind placebo controlled challenge. The naltrexone challenges produced no increase in opioid withdrawal symptoms, plasma MHPG levels, or blood pressure compared to placebo, while naloxone produced significant symptoms and blood pressure increases compared to placebo challenges.