BACKGROUND: In Finland, buprenorphine (Subutex) is the most abused opioid. In order to curb this problem, many treatment centres transferred („forced transfer“) their buprenorphine patients to the buprenorphine plus naloxone (Suboxone) combination product in late 2003.
METHODS: Data from a retrospective study involving five different treatment centers, examining the effects of switching patients to Suboxone, were gathered from 64 opioid-dependent patients who had undergone the medication transfer.
RESULTS: Most patients (90.6%) switched to Suboxone at the same dose of buprenorphine that they had been receiving as Subutex (average 22 mg). The majority of these patients (71.9%) were maintained at the same dose of Suboxone throughout the 4-week study period. During the first 4 weeks, 50% of the patients reported adverse events and at the four month time point, 26.6% reported adverse events. However, due to adverse events one patient only discontinued treatment with Suboxone during the 4-week study period, and five during the four month follow-up period. Of the 26 patients in the follow-up period, Suboxone was misused intravenously once each by 4 patients and twice by 1 patient. These 5 patients all reported that injecting Suboxone was like injecting „nothing“ with any euphoria, or that it was a bad experience.
CONCLUSION: We conclude that when patients are transferred from high doses (> 22 mg) of buprenorphine to the combination product, dose adjustments may be necessary especially in the later phase of the treatment. We recommend that a transfer from Subutex to Suboxone should be carefully discussed and planned in advance with the patients and after the transfer adverse events should be regularly monitored. With regard of buprenorphine IV abuse, the combination product seems to have a less abuse potential than buprenorphine alone.
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. 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. 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. 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. This study shows that switching from buprenorphine monotherapy 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.