HighlightsA broad range of domains of neuropsychological performance are significantly impaired in studies which have compared  methadone population s with the healthy controls .
However low power , poor quality and heterogenous population s limit the interpretation of these results .Short term ( less than 1 year ) abstinent groups , when compared with methadone groups , still exhibited cognitive impairments but results are inconclusive .
It is still not clear what the role of global sedative effects of opioids such as methadone have on cognitive impairment .
Only higher quality longitudinal studies using ecologically valid cognitive tests , in well‐defined population groups can address this question .Methadone population s present with a broad range of neuropsychological impairment when compared with healthy controls .
Results : Data from a total cohort of 1063 CM , 412 AP and 879 HP participants , from 23 independent studies  indicate global impairments in neurocognitive function in CM relative to HP participants .
Conclusion : Method ological issues such as small sample sizes , heterogeneity and poor quality limited the interpretation of the results and does not address whether the observed impairments reflect co‐morbid functioning , methadone‐related sedation and /or other factors .
Introduction : There is a presumption that neurocognition is commonly impaired in chronic methadone exposed individuals ( CM ) when compared with healthy controls ( HP ) .
Additionally , it remains unclear if short term ( < 1 year ) abstinence ( AP ) is associated with an altered cognitive profile when compared with CM .
Comparative pharmacodynamics and pharmacokinetics of methadone and slow-release oral morphine for maintenance treatment of opioid dependence.
BACKGROUND Slow-release oral morphine ( SROM ) has been proposed as an alternative maintenance pharmacotherapy to methadone for treatment of opioid dependence . However , the pharmacodynamics and pharmacokinetics of SROM have not been previously assessed in a methadone maintenance population . METHODS In 14 methadone maintenance patients reporting adequate ( holders , n=7 ) or inadequate ( non-holders , n=7 ) withdrawal suppression between doses , plasma drug concentrations and indices of opioid effect ( withdrawal severity , pupil diameter , and respiratory rate ) were determined across a 24 h inter-dosing interval on one occasion at steady-state for methadone and SROM ( once-daily Kapanol ) using an open-label , crossover design . RESULTS Opioid effects were of a similar overall magnitude following dosing for each drug and showed an inverse association with plasma drug concentrations , which peaked later for morphine compared to (R)-methadone ( 6.5 + /- 2.3 h vs. 2.5 + /- 1.4 h , P<0.001 ) . For methadone non-holders , the number of self-reported opioid withdrawal symptoms prior to dosing was less for SROM compared to methadone ( 3.4 + /- 2.6 vs. 9.0 + /- 3.2 , P<0.01 ) ; for holders it was approximately equal ( 4.4 + /- 3.0 vs. 4.0 + /- 3.7 , P<0.76 ) . Maintenance doses were more strongly related to plasma drug concentrations for SROM compared to methadone and may thus be more predictive of therapeutic response for the former medication . Twelve of the 14 subjects preferred SROM to methadone ( P=0.01 ) . CONCLUSIONS The pharmacodynamics and pharmacokinetics of SROM support its use as an alternative once-daily agonist option in the treatment of opioid dependence , particularly for patients responding poorly to methadone maintenance treatment
HighlightsA broad range of domains of neuropsychological performance are significantly impaired in studies which have compared  methadone population s with the healthy controls .
However low power , poor quality and heterogenous population s limit the interpretation of these results .Short term ( less than 1 year ) abstinent groups , when compared with methadone groups , still exhibited cognitive impairments but results are inconclusive .
It is still not clear what the role of global sedative effects of opioids such as methadone have on cognitive impairment .
Only higher quality longitudinal studies using ecologically valid cognitive tests , in well‐defined population groups can address this question .Methadone population s present with a broad range of neuropsychological impairment when compared with healthy controls .
Results : Data from a total cohort of 1063 CM , 412 AP and 879 HP participants , from 23 independent studies  indicate global impairments in neurocognitive function in CM relative to HP participants .
Conclusion : Method ological issues such as small sample sizes , heterogeneity and poor quality limited the interpretation of the results and does not address whether the observed impairments reflect co‐morbid functioning , methadone‐related sedation and /or other factors .
Introduction : There is a presumption that neurocognition is commonly impaired in chronic methadone exposed individuals ( CM ) when compared with healthy controls ( HP ) .
Additionally , it remains unclear if short term ( < 1 year ) abstinence ( AP ) is associated with an altered cognitive profile when compared with CM .