Medication plays a key role in recovery
Recommend medication-assisted treatment, either with an agonist (buprenorphine or methadone) or an antagonist (naltrexone), for every patient with physiological opioid dependence. The goals of pharmacotherapy are to prevent or reduce withdrawal symptoms and craving, avoid relapse, and restore to a normal state any physiological functions (eg, sleep, bowel movements) that have been disrupted by opioid use.28 When continued for ≥3 months, medication has been shown to improve outcomes.23,24,29 In one recent study, 49% of opioid-dependent participants who were still taking buprenorphine-naloxone at 12 weeks had successful outcomes (minimal or no opioid use), vs 7% of those undergoing a brief buprenorphine-naloxone taper.24
There are risks associated with medication-assisted therapy, however. The ones of greatest concern are a potential increase in drug-drug interactions, the risk of diversion (a concern with both buprenorphine and methadone), and the potential for accidental overdose.2,30
Buprenorphine, a partial mu-opioid receptor agonist, is a Schedule III controlled substance and can be dispensed by a pharmacy, making inpatient opioid detoxification unnecessary for many opioid-dependent patients. Physicians who wish to prescribe buprenorphine for the treatment of opioid dependence must complete an 8-hour course, offered by the American Medical Association and the APA, among other medical groups, and obtain a Drug Enforcement Administration code (“X”) license. 31
Buprenorphine has a high affinity for, and a slow dissociation from, mu-opioid receptors, resulting in the displacement of other opioids from the mu receptor and less severe withdrawal.32 As a partial agonist, buprenorphine attenuates opioid withdrawal symptoms with a ceiling, or near maximal, effect at 16 mg, thereby lowering the risk for overdose.33 A sublingual formulation that combines buprenorphine with naloxone, an opioid antagonist that exerts its full effect when injected but is minimally absorbed sublingually, reduces the potential for abuse of buprenorphine without interfering with its effectiveness.34
Compared with methadone, buprenorphine is less likely to interact with antiretroviral medications or to cause QTc prolongation, erectile dysfunction, or cognitive or psychomotor impairment.31,35-37 Limitations include the ceiling effect, which can be a problem for cases in which more agonist is needed; cost (approximately $12/d), and the lack of approval by the US Food and Drug Administration (FDA) for use during pregnancy.
Buprenorphine maintenance involves 3 phases: induction, stabilization, and maintenance.38 Induction takes place in a clinician’s office at the time the patient experiences opioid withdrawal symptoms, typically 6 to 48 hours after taking the last opioid. Extended treatment improves clinical outcomes,23,24 and longer-term maintenance (of indefinite duration) is frequently required.
Naltrexone is a mu-receptor antagonist, and therefore does not cause physical dependence or have agonist effects such as euphoria and sedation. As a result, it has no diversion value and may appeal to those who view opioid-agonist pharmacotherapy as simply trading one drug for another.39 Naltrexone is not a controlled substance and is not subject to the regulatory requirements that buprenorphine and methadone face.
Although agonists can be started in the first day or 2 after a patient decides to stop using opioids, patients must be opioid-free for ≥7 days before starting naltrexone. That’s because its antagonist properties will precipitate withdrawal if another opioid is present on the opioid receptors. During the 7-day “washout” period, you can treat opioid withdrawal symptoms with medications such as clonidine and dicyclomine, but such symptoms make patients especially vulnerable to relapse while waiting to start naltrexone.
Oral naltrexone’s effectiveness as a treatment for opioid dependence has been limited by poor adherence. But a long-acting intramuscular form of the drug, approved by the FDA in 2010 and requiring once-a-month injection, mitigates this concern.40,41
Methadone is a full mu-opioid agonist, administered daily at specialized clinics, as a maintenance therapy for opioid dependence. Although office-based physicians can prescribe methadone for pain, the drug can only be used for opioid dependence under the auspices of state- and federally regulated opioid treatment programs (http://findtreatment.samhsa.gov/TreatmentLocator/faces/quickSearch.jspx; a mobile phone application is also available at http://www.samhsa.gov/mobile/treatmentlocator.aspx).
Methadone, a Schedule III controlled substance with a half-life averaging 24 to 36 hours, requires daily dosing.42 Its slow metabolism and long half-life increase the risk for overdose.
Methadone is best for patients who are highly dependent on opioids and likely to benefit from a structured treatment environment with daily supervision (although patients who are doing well may earn take-home privileges so they don’t have to come to the clinic every day).43 New patients should receive an initial dose of 30 mg or less, and a maximum first-day dose of 40 mg.44