Buprenorphine-naloxone for opioid addiction
Physicians do not require a special exemption to prescribe buprenorphine-naloxone, but the College of Physicians and Surgeons of Ontario does recommend training before prescribing it.
Training is available online and in person as part of the Opioid Dependence Treatment Certificate Program offered by the University of Toronto and the Centre for Addiction and Mental Health. Buprenorphine is relatively safe, but training is important because buprenorphine is prescribed differently than most other medications, using a treatment model similar to that used for methadone.
Training is worthwhile for physicians whose patients do not have easy access to an opioid agonist maintenance clinic. Clinical experience shows that it is much more effective and less stressful to prescribe buprenorphine-naloxone than to continue prescribing other opioids to patients with opioid addiction.
How buprenorphine-naloxone works
Buprenorphine-naloxone is a sublingual tablet containing buprenorphine and naloxone in a 4:1 ratio. Buprenorphine is a partial mu opioid agonist with a ceiling effect. Because of this, a buprenorphine overdose is less likely to cause respiratory depression and death than is an overdose of a full agonist such as methadone or oxycodone (Auriacombe et al., 2004; Borron et al., 2002).
Buprenorphine binds tightly to and dissociates slowly from opioid receptors, giving it a slow onset and a long duration of action. This explains why it is used to treat addiction. It does not cause sedation or euphoria when given in the appropriate dose to patients with tolerance to opioids, and it relieves withdrawal and reduces cravings for 24 hours or longer.
Naloxone is a short-acting parenteral medication used to treat opioid overdose. It is used in opioid addiction treatment to deter injection. Naloxone is not absorbed sublingually, but it will block opioid receptors when injected, causing withdrawal in patients who are physically dependent on opioids.
At the beginning of treatment, buprenorphine-naloxone is dispensed daily under the observation of a pharmacist, with the gradual introduction of take-home doses if the patient is stable and has stopped problematic opioid and other drug use.
Candidates for buprenorphine-naloxone
Buprenorphine-naloxone is of comparable effectiveness to methadone. The choice is a joint decision of the patient and the doctor. Buprenorphine-naloxone is available as a limited-use drug to patients eligible for the Ontario Drug Benefit Program. For patients to qualify, the physician must write the correct reason for use code, as outlined below.
Other clinical indications
Physicians might also consider two additional clinical indications for buprenorphine-naloxone:
- when take-home methadone restrictions are unacceptable to the patient because of work or family commitments, or lack of transportation
- for younger patients with a shorter history of opioid addiction, where buprenorphine-naloxone may be easier to taper than methadone because it has a theoretically milder withdrawal syndrome (Lintzeris et al., 2001).