title: The effects of naltrexone maintenance on the response to yohimbine in healthy volunteers.
abstract: BACKGROUND
  Preclinical research suggests that opiate antagonists may alter stress responsiveness. This study describes the effect of pretreatment with the opioid antagonist naltrexone on the response to a noradrenergic stressor, the alpha-2-receptor-antagonist, yohimbine, in healthy subjects. The current study was designed to compare the change in responses to yohimbine after 2 weeks of treatment with naltrexone to the response after at least 2 weeks of treatment with placebo.
  
  
  METHODS
  After a week of placebo naltrexone treatment, ten subjects were randomized into a double-blind cross-over to placebo or active naltrexone (50 mg p.o. daily) on weeks 2 to 4, and the converse condition for weeks 5 to 7. Subjects received challenges in a random, fixed sequence with placebo and active yohimbine (i.v., 0.2 mg/kg) on weeks 1, 4, and 7. The active-active combination generally had the strongest drug effects.
  
  
  RESULTS
  There were statistically significant (p < .05) interactions of naltrexone condition X yohimbine condition for subject ratings of "nervous," "not liking the drug effect," "talkative," and "urge to urinate," and a trend (p < .10) for cortisol levels.
  
  
  CONCLUSIONS
  The results suggest that clinically used naltrexone doses alter sensitivity to yohimbine.
authors.affiliation: Yale University School of Medicine, VA Connecticut Healthcare System, Psychiatry Service, West Haven, CT 06516, USA.
authors.forename: M I
authors.initials: MI
authors.lastname: Rosen
authors.forename: T R
authors.initials: TR
authors.lastname: Kosten
authors.forename: M J
authors.initials: MJ
authors.lastname: Kreek
mesh_terms: D000328:Adult; D001046:Aphrodisiacs / Q000378:metabolism*; D004311:Double-Blind Method; D004342:Drug Hypersensitivity / Q000175:diagnosis; D005260:Female; D006304:Health Status; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007275:Injections, Intravenous; D008297:Male; D009271:Naltrexone / Q000494:pharmacology*; D009292:Narcotic Antagonists / Q000494:pharmacology*; D012725:Sexual Behavior / Q000187:drug effects; D013997:Time Factors; D015016:Yohimbine / Q000378:metabolism*
chemical_list: D001046:Aphrodisiacs; D009292:Narcotic Antagonists; D015016:Yohimbine; D009271:Naltrexone; D006854:Hydrocortisone