Safety and Tolerability of the Switch from Buprenorphine to Buprenorphine/Naloxone in an Italian Addiction Treatment Centre

Background: Abuse and misuse of pharmacological therapies represent major challenges in the healthcare system, particularly in patients receiving long-acting opioid drugs for the treatment of heroin or opioid addiction. The partial mu-opioid receptor agonist buprenorphine is used to treat opioid dependence, but diversion and misuse may occur. The sublingual combination formulation of buprenorphine and the opioid receptor antagonist naloxone (buprenorphine/naxolone) is associated with a reduced abuse potential, and has been shown to have promising efficacy for the treatment of opioid dependence. Objectives: This observational study assessed the safety and efficacy of sublingual buprenorphine/naloxone combination therapy in patients with opioid dependence after therapeutic switch from buprenorphine monotherapy. Methods: A total of 94 patients being treated with buprenorphine monotherapy (average dose 8 mg/day; mean duration of therapy 840 days) were switched to buprenorphine/naloxone combination therapy. Patients were asked to rate their level of satisfaction with buprenorphine/naloxone combination treatment with respect to the management of withdrawal symptoms, and urinary toxicology tests were carried out before and 14 days after switching to combination therapy. Results: Within 3 months, 75/94 patients (80%) previously treated with buprenorphine monotherapy had switched to sublingual buprenorphine/naloxone combination treatment (average dose buprenorphine 8 mg). Among patients receiving combination treatment for >3 months, 83% were receiving medication either weekly or fortnightly, based on the results of toxicological testing. A reduction in positive urinary toxicology tests was observed in patients within two weeks after being switched to combination treatment (before switch: 28, 9 and 2 positive tests for heroin, cocaine and heroin + cocaine, respectively vs 11, 3 and 1 after switch) and a total of 64 patients of the 75 who switched to combination therapy (85%) were satisfied with the management of withdrawal symptoms during buprenorphine/naloxone treatment. Few adverse events were reported and no patients dropped out of treatment. Conclusions: This study shows that switching from buprenorphine mono-therapy to sublingual buprenorphine/naloxone combination therapy is effective and well tolerated, and associated with good control of withdrawal symptoms in the majority of patients. In addition, combination therapy reduced illicit drug use (based on negative urinary toxicology texts) and allowed the time between clinic visits to be increased.