title: Is opioid-induced hyperalgesia reversible? A study on active and former opioid addicts and drug naïve controls.
abstract: OBJECTIVE
  Hyperalgesia has been observed in active opioid addicts (OAs). The aim of this study was to explore whether opioid-induced hyperalgesia (OIH) is a reversible phenomenon.
  
  
  METHODS
  Observational study.
  
  
  METHODS
  The study included the following three groups of male subjects: 1) active addicts on heroin or methadone (OAs, n = 50); 2) former opioid addicts with at least 5 months of abstinence from drug use (FOAs, n = 43); and 3) drug naïve controls (C, n = 50).
  
  
  METHODS
  All subjects were exposed to the cold pressor test (1°C).
  
  
  METHODS
  Cold pain threshold (latency to pain onset, seconds) and cold pain tolerance (latency to pain intolerability, seconds).
  
  
  RESULTS
  Mean ± standard deviation (SD) pain thresholds were 10.8 ± 7.7, 6.9 ± 3.9, and 6.8 ± 3.5 seconds for the OAs, FOAs, and C groups, respectively (analysis of variance [ANOVA], p = 0.002, 95% CI = 7.5-9.2). Mean ± SD pain tolerance levels were 30 ± 36.2, 64 ± 58.1, and 56.4 ± 51.4 seconds for the OAs, FOAs, and C groups, respectively (ANOVA, p < 0.001, 95% CI = 43-60.4). Post hoc analyses revealed significant changes between the OAs and the other two groups for both variables.
  
  
  CONCLUSIONS
  It is suggested that altered pain perception in OAs is a reversible phenomenon that may require a long period of abstinence to reset, rather than being an individual long-term stable trait.
authors.affiliation: Faculty of Social Welfare and Health Sciences, University of Haifa, Israel.
authors.forename: Roi
authors.initials: R
authors.lastname: Treister
authors.forename: Elon
authors.initials: E
authors.lastname: Eisenberg
authors.forename: Eli
authors.initials: E
authors.lastname: Lawental
authors.forename: Dorit
authors.initials: D
authors.lastname: Pud
mesh_terms: D000328:Adult; D000701:Analgesics, Opioid / Q000009:adverse effects*; D016022:Case-Control Studies; D003080:Cold Temperature; D006556:Heroin Dependence / Q000503:physiopathology*; D006801:Humans; D006930:Hyperalgesia / Q000139:chemically induced*; D008297:Male; D008691:Methadone / Q000008:administration & dosage; D008875:Middle Aged; D009293:Opioid-Related Disorders / Q000503:physiopathology* / Q000534:rehabilitation; D010147:Pain Measurement; D017288:Pain Threshold; D013997:Time Factors; D055815:Young Adult
chemical_list: D000701:Analgesics, Opioid; D008691:Methadone