Sublingual buprenorphine/naloxone precipitated withdrawal in subjects maintained on 100mg of daily methadone.
BACKGROUND
Acute doses of buprenorphine can precipitate withdrawal in opioid dependent persons. The likelihood of this withdrawal increases as a function of the level of physical dependence.


OBJECTIVE
To test the acute effects of sublingual buprenorphine/naloxone tablets in volunteers with a higher level of physical dependence. The goal was to identify a dose that would precipitate withdrawal (Phase 1), then determine if withdrawal could be attenuated by splitting this dose (Phase 2).


METHODS
Residential laboratory study; subjects (N=16) maintained on 100mg per day of methadone. Phase 1: randomized, double blind, triple dummy, within subject study. Conditions were sublingual buprenorphine/naloxone (4/1, 8/2, 16/4, 32mg/8mg), intramuscular naloxone (0.2mg), oral methadone (100mg), or placebo. Medication conditions were randomized, but buprenorphine/naloxone doses were ascending within the randomization. Phase 2: Conditions were methadone, placebo, naloxone, 100% of the buprenorphine/naloxone dose that precipitated withdrawal in Phase 1 (full dose), and 50% of this dose administered twice in a session (split dose). Analyses covaried by trough methadone serum levels.


RESULTS
Six subjects did not complete the study. Of the 10 who completed, 3 tolerated up to 32mg/8mg of buprenorphine/naloxone without evidence of precipitated withdrawal. For the seven completing both phases, split doses generally produced less precipitated withdrawal compared to full doses.


CONCLUSIONS
There is considerable between subject variability in sensitivity to buprenorphine's antagonist effects. Low, repeated doses of buprenorphine/naloxone (e.g., 2mg/0.5mg) may be an effective mechanism for safely dosing this medication in persons with higher levels of physical dependence.
Rosado
James
J
Behavioral Pharmacology Research Unit, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, 5510 Nathan Shock Drive, Baltimore, MD 21224, USA.
Walsh
Sharon L
SL
Bigelow
George E
GE
Strain
Eric C
EC
D000286:Administration, Sublingual; D000328:Adult; D002047:Buprenorphine / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D003072:Cognition Disorders / Q000139:chemically induced / Q000175:diagnosis / Q000453:epidemiology; D004311:Double-Blind Method; D004338:Drug Combinations; D005260:Female; D006801:Humans; D008297:Male; D008691:Methadone / Q000627:therapeutic use*; D008875:Middle Aged; D009270:Naloxone / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D009483:Neuropsychological Tests; D009293:Opioid-Related Disorders / Q000188:drug therapy*; D011596:Psychomotor Disorders / Q000139:chemically induced / Q000175:diagnosis / Q000453:epidemiology; D013375:Substance Withdrawal Syndrome / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology*
D004338:Drug Combinations; D009270:Naloxone; D002047:Buprenorphine; D008691:Methadone