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Table 3Potential Drug Interactions forMethadone and Buprenorphinephine may be administered from every other day to 3times weekly (e.g., Monday, Wednesday, and Friday) inorder to increase compliance and patient satisfaction.Every-4-day regimens have been associated with increasedwithdrawal symptoms. The daily dose may be doubledfor every-other-day dosing and also for thrice-weekly dosing,but Friday’s dose would be 2.5 times the daily dose. 16New patients should be advised that sublingual tabletsmust be dissolved under the tongue, as the medicationis much less effective if swallowed. 18 No more than twotablets should be taken at one time, to avoid swallowingthem by mistake. Wetting the mouth before placingthe tablets under the tongue may help them dissolvefaster. Full absorption may take up to 10 minutes.Patientsshould refrain from smoking for 10 to 15 minutes beforetaking the medication, as this seems to help the tabletsdissolve faster. 18Side Effects: Buprenorphine/naloxone is generally welltolerated. Side effects are associated mainly with buprenorphine,since naloxone is not readily absorbed. In clinicaltrials, the most common adverse effects were headache,withdrawal syndrome, pain, nausea, insomnia, sweating,rhinitis, constipation, abdominal pain, flulike syndrome,and flushing. 17OPIOID MAINTENANCE TREATMENTInteraction Methadone BuprenorphineIncrease Effects Alcohol Alcoholof Opioid Substitute Antidepressants Antiretrovirals• Fluoxetine • Atazanavir• Fluvoxamine • Indinavir• Paroxetine • Nevirapine• Sertraline• RitonavirAnti-infectives • Saquinavir• Ciprofloxacin Benzodiazepines• Erythromycin Fluvoxamine• Fluconazole Ketoconazole• KetoconazoleBenzodiazepinesCimetidineDecrease Effects Anti-infectives Carbamazepineof Opioid Substitute • Fusidic acid Phenobarbital• RifampinPhenytoinAntiretrovirals Rifampin• Abacavir• Amprenavir• Efavirenz• Nevirapine• Ritonavir• SaquinavirBarbituratesCarbamazepinePhenytoinSource: References 12, 16.Interactions: Buprenorphine goes through hepaticmetabolism via CYP3A4. The drug has thepotential for many of the same interactions asmethadone (see TABLE 3). One dangerous interactionto monitor for is the potentially fatalinteraction with benzodiazepines. 19 Concomitantadministration should be avoided. Compared withmethadone, buprenorphine may be a safer choicein patients receiving antiretrovirals. 20CLINICAL EFFICACY OF METHADONEVERSUS BUPRENORPHINEIt is well established that both methadone andbuprenorphine are effective for decreasing illicitdrug use. It is worthwhile to consider the resultsof studies examining the efficacy of methadoneversus buprenorphine. 7The 2008 Cochrane review determined thatmethadone dosed at 60 mg/day to 120 mg/dayhas superior efficacy compared with buprenorphine.21 The specific studies yield varied results.One study found less illicit heroin use withbuprenorphine than with methadone, but themethadone arm had higher retention rates. 22Another study concluded that high-dose methadonehad a higher retention rate and less illicit opioiduse compared with buprenorphine 8 mg. 23 A double-blind,randomized trial comparing an averagedose of buprenorphine (10 mg/day) versusmethadone (70 mg/day) showed a higher retentionrate with methadone, but found that thedrugs had equal efficacy in reducing illicit heroin use. 24However, a study from 1992 concluded that buprenorphinehad better retention rates than methadone at 25weeks. 26 Overall, it is accepted that buprenorphine andmethadone have comparable efficacy and that treatmentshould be individualized.CONCLUSIONBecause of DATA 2000 and ongoing research on opioiddependence, pharmacists must be prepared to facean increase in the number of prescriptions being writtenfor opioid maintenance treatment. When presentedwith a new prescription, a pharmacist may visit the sitewww.buprenorphine.samhsa.gov to confirm physicianeligibility. Pharmacists must monitor and counsel patientsabout withdrawal symptoms and overdose possibilities.Because buprenorphine is a partial agonist, the risk ofoverdose is smaller, and its use in combination with naloxonefurther reduces the risk of intravenous abuse. Historically,daily visits to methadone clinics have been themost frequently utilized method of treating opioid dependence,but with the current availability of sublingualbuprenorphine products, more patients will be able toreceive treatment in a convenient office-based setting.References available online at www.uspharmacist.com.53U.S. Pharmacist • November 2009 • www.uspharmacist.com