BUPRENORPHINE PHASE II NIDA STUDY v. METHADONE

BUPRENORPHINE PHASE II NIDA STUDY v. METHADONE: the morphine- type mixed agonist-antagonist showed a "clinically and statistically significant" advantage over methadone for "retaining" patients in treatment and detoxification programs for opiate addiction, National Institute on Drug Abuse Addiction Research Center investigator Paul Fudala, MD, told the American Society for Clinical Pharmacology and Therapeutics annual meeting in San Antonio March 15. Of the patients randomized to buprenorphine, 32% completed all 25 weeks of the study, Fudala said, versus 19% of those receiving 60 mg of methadone. The NIDA study enrolled 162 patients randomized to three courses of therapy: 8 mg of sublingual buprenorphine, 20 mg of oral methadone, and 60 mg of oral methadone. Patients were treated for 17 weeks, and then followed up for eight weeks of detox, Fudala said. Primary endpoints were patient retention -- if a patient missed three consecutive clinical visits, he or she was dropped from the study -- and opiate intake measured by urine samples. Patients also completed subjective questionnaires describing how much they "liked" their therapy, if they believed they were "hooked" on it, and any adverse events they experienced, Fudala said. "On all of the primary outcome measures and for most of the secondary measures which we looked at," Fudala said, "buprenorphine 8 mg was significantly more effective than methadone 20 mg, and at least as effective and sometimes better than methadone 60 mg as a maintenance agent." Fudala noted that "methadone 60 mg produced more reports of being hooked" than did buprenorphine. Results from the Phase II trial will be submitted as part of "the [opioid dependence] NDA" that NIDA is in the process of preparing, Fudala said. The institute has held a chemistry IND for buprenorphine since November 1990 and NIDA researchers report they are now in the final stages of planning a multicenter trial, scheduled to begin this spring, that will provide the remaining data required for approval of a "heroin dependence" indication. The multicenter trial is scheduled to begin sometime this May or June at addiction treatment centers in Los Angeles, New York City, San Francisco, Philadelphia and a still undetermined fifth site. The head researcher for the study will be Walter Ling, MD, Director of the Pizarro Addiction Treatment Center in Los Angeles. Ling described the study as a "dose response trial" involving roughly twice the patient population of previous NIDA-funded buprenorphine studies. Between 400 and 500 heroin addicts are expected to enroll in the four-to six-month study, and they will be randomized into treatment arms receiving either 1 mg, 4 mg, 8 mg, or 16 mg of daily buprenorphine therapy. According to Ling, if the study results are as expected, an NDA filing could occur within the next 18 months. The idea of using buprenorphine -- a morphine-type mixed agonist/antagonist -- as a maintenance therapy for opioid dependence is not a new one, having been explored by U.S. researchers since the early 1980s when the drug appeared on the U.S. market for use as an analgesic (Norwich-Eaton's Buprenex). However, buprenorphine's anti-substance abuse potential has not been the subject of much industry interest. NIDA is trying to break this pattern by preparing a nearly completed NDA research package with which to solicit potential contractors. Historically, the compound has demonstrated several advantages over methadone as a treatment for opioid addiction in certain patients. A December 1990 study published by Richard Resnick, MD, et al. describes buprenorphine as having "a low dependence liability and toxicity," and adds that of all the drugs studied in recent years, buprenorphine "comes closest to the ideal of an analgesic with the potency of morphine that does not produce respiratory depression or physical dependence."