"As compared with patients taking low-dose methadone, those taking levomethadyl acetate had a significantly higher rate of continuous abstinence from opioids, and those taking high-dose methadone and buprenorphine had a trend toward a higher rate of continuous abstinence."

Source

Johnson, Rolley E., Pharm. D., Mary Ann Chutuape, PhD, Eric C. Strain, MD, Sharon L. Walsh, PhD, Maxine L. Stitzer, PhD, and George E. Bigelow, PhD, "A Comparison of Levomethadyl Acetate, Buprenorphine, and Methadone for Opioid Dependence," New England Journal of Medicine (Boston, MA: Massachusetts Medical Society, Nov. 2, 2000), Vol. 343, No. 18, p. 1295.
http://content.nejm.org/cgi/r…