Memory function in opioid-dependent patients treated with methadone or buprenorphine along with benzodiazepine: longitudinal change in comparison to healthy individuals

Neurocognitive Functions After 6-Month Buprenorphine (Naloxone)-Based Opioid Agonist Maintenance Treatment: A Controlled Prospective Study

BACKGROUND

Medications for opioid use disorder (OUD) may influence neurocognitive functions. Inadequate power, confounders, and practice effects limit the validity of the existing research. We examined the change in cognitive functions in patients with OUD at 6-month buprenorphine (naloxone) posttreatment and compared the cognitive performance of the buprenorphine-treated group with control subjects.

METHODS

We recruited 498 patients with OUD within a week of initiating buprenorphine. Assessments were done twice-at baseline and 6 months. Those abstinent from illicit opioids and adherent to treatment (n = 199) underwent follow-up assessments. Ninety-eight non-substance-using control subjects were recruited from the community. The neurocognitive assessments comprised the Wisconsin Card Sorting Test, Iowa Gambling Task, Trail-Making Tests A and B (TMT-A and TMT-B), and verbal and visual N-Back Test. We controlled for potential effect modifiers.

RESULTS

Twenty-five of the 32 test parameters significantly improved with 6 months of buprenorphine treatment; 20 parameters withstood corrections for multiple comparisons (P < 0.001). The improved test domains spread across cognitive tests: Wisconsin Card Sorting Test (perseverative errors and response, categories completed, conceptual responses), TMTs (time to complete), verbal and visual N-Back Tests (hits, omission, and total errors). After treatment, OUD (vs control subjects) had less perseverative response and error (P < 0.001) and higher conceptual response (P = 0.004) and took lesser time to complete TMT-A (P < 0.001) and TMT-B (P = 0.005). The baseline neurocognitive functions did not differ between those who retained and those who discontinued the treatment.

CONCLUSION

Cognitive functions improve in patients with OUD on buprenorphine. This improvement is unlikely to be accounted for by the practice effect, selective attrition, and potential confounders.

Preliminary Evidence of the Association between Time on Buprenorphine and Cognitive Performance among Individuals with Opioid Use Disorder Maintained on Buprenorphine: A Pilot Study

People on buprenorphine maintenance treatment (BMT) commonly present cognitive deficits that have been associated with illicit drug use and dropout from buprenorphine treatment. This study has compared cognitive responses to the Stroop Task and the Continuous Performance Task (CPT) among individuals on BMT, with recent drug use, and healthy controls and explored the associations between cognitive responses and drug use, craving, and buprenorphine use among participants on BMT. The participants were 16 individuals on BMT and 23 healthy controls. All participants completed a 60 min laboratory session in which they completed the Stroop Task and the CPT, a saliva drug test, a brief clinical history that collected substance-use- and treatment-related information, and the Opioid Craving Scale. The results showed that the BMT participants presented more commission errors (MBMT participants = 2.49; Mhealthy controls = 1.38; p = 0.048) and longer reaction times (MBMT participants = 798.09; Mhealthy controls = 699.09; p = 0.047) in the Stroop Task than did the healthy controls. More days on buprenorphine were negatively associated with reaction time in the CPT (-0.52) and the number of commission errors (-0.53), simple reaction time (-0.54), and reaction time correct (-0.57) in the Stroop Task. Neither drug use nor craving was significantly associated with the results for the cognitive tasks. Relative to the control participants, the BMT individuals performed worse in terms of longer reaction times and more commission errors in the Stroop Task. Within the BMT participants, longer times on buprenorphine were associated with better cognitive results in terms of faster reaction times for both tasks and lower commission errors for the Stroop Task.

Underrepresentation of diverse populations and clinical characterization in opioid agonist treatment research: A systematic review of the neurocognitive effects of buprenorphine and methadone treatment

INTRODUCTION

The relative neurocognitive effects of the two most common opioid agonist treatments (OAT; buprenorphine and methadone) for opioid use disorder (OUD) are poorly understood. The aim of this systematic review is to examine the neurocognitive effects of OAT (buprenorphine and methadone) and the clinical and sociodemographic characteristics of study samples.

METHODS

The research team queried PubMed, PsycINFO and Cochrane Reviews for articles (01/1980-01/2020) with terms related to neurocognitive testing in adults (age ≥ 18) prescribed OAT. The team extracted neurocognitive data and grouped them by domain (e.g., executive functioning, learning/memory), and assessed study quality.

RESULTS

The search retrieved 2341 abstracts, the team reviewed 278 full articles, and 32 met inclusion criteria. Of these, 31 were observational designs and one was an experimental design. Healthy controls performed better across neurocognitive domains than OAT-treated persons (buprenorphine or methadone). Compared to those with active OUD, OAT-treated persons had better neurocognition in various domains. However, in seven studies comparing buprenorphine- and methadone-treated persons, buprenorphine was associated with better neurocognition than was methadone, with moderate to large effect sizes in executive functioning, attention/working memory, and learning/memory. Additionally, OAT research underreports clinical characteristics and underrepresents Black and Latinx adults, as well as women.

CONCLUSIONS

Findings suggest that compared to active opioid use, both buprenorphine and methadone treatment are associated with better neurocognitive functioning, but buprenorphine is associated with better executive functioning, attention/working memory, and learning/memory. These findings should be interpreted with caution given widespread methodological heterogeneity, and limited representation of ethnoracially diverse adults and women. Rigorous longitudinal comparisons with more diverse, better characterized samples will help to inform treatment and policy recommendations for persons with OUD.

Comparison of psychological symptoms and cognitive functions in patients under maintenance treatment with methadone or buprenorphine, current opioid users and healthy subjects

Methadone and buprenorphine can affect the psychological symptoms and cognitive functioning of substance users. This study aimed to compare psychological symptoms and neuropsychological functioning in methadone maintenance patients (MMP), buprenorphine maintenance patients (BMP), current opioid users, and healthy subjects. One hundred and twenty participants (30 in each group) matched for age, sex, and education completed the Symptom Checklist-90-Revised (SCL-90-R) and a battery of neuropsychological tests including the Wisconsin Card Sorting Test (WCST), Wechsler Memory Scale (WMS-IV), and Stroop Color-Word Test (SCWT) assessing executive functioning, working memory, and attention, respectively. Overall, opioid users showed more severe psychological symptoms compared to healthy subjects. MMP and BMP had intermediate scores in SCL-90-R subscales; however, BMP had fewer severe symptoms compared to the MMP group. In terms of cognitive functioning, healthy subjects and current users demonstrated the best and the worst performance, respectively. Also, BMP outperforms MMP on executive functions and attention. However, the MMP had a better performance in WMS (visual memory). Patients receiving maintenance treatment had fewer psychological symptoms and better cognitive performance compared to opioid users. BMP had a better profile in all psychological symptoms and better performance in executive functions and selective attention compared to the MMP suggesting buprenorphine may be a better choice for the treatment of opioid-dependent patients.

Neurotoxicology Syndromes Associated with Drugs of Abuse

Substance use disorders-and their associated neurologic complications-are frequently encountered by neurologists as well as emergency room physicians, internists, psychiatrists, and medical intensivists. Prominent neurologic sequelae of drug abuse, such as seizure and stroke, are common and often result in patients receiving medical attention. However, less overt neurologic manifestations, such as dysautonomia and perceptual disturbances, may be initially misattributed to primary medical or psychiatric illness, respectively. This article focuses on the epidemiology, pharmacology, and complications associated with commonly used recreational drugs, including opioids, alcohol, marijuana, cocaine, and hallucinogens.

Cognitive performance of patients with opioid use disorder transitioned to extended-release injectable naltrexone from buprenorphine: Post hoc analysis of exploratory results of a phase 3 randomized controlled trial

BACKGROUND

Opioid use disorder (OUD) is associated with cognitive dysfunction. Understanding how pharmacotherapy may affect cognition is an important treatment consideration.

METHODS

This was a hybrid residential-outpatient, randomized trial assessing transition regimens (naltrexone/buprenorphine [NTX/BUP] vs placebo-NTX/buprenorphine [PBO-N]/BUP) to extended-release naltrexone (XR-NTX) in patients with OUD seeking BUP discontinuation. Cognition was assessed at baseline, Day 22 (XR-NTX Day 14), and Day 36 (XR-NTX Day 28) using a range of measures (Brief Assessment of Cognition Symbol Coding test, Controlled Oral Word Association Task, Wechsler Memory Scale-III Spatial Span test, Continuous Performance Test, and Test of Attentional Performance). Pre-specified exploratory analyses compared treatment groups. Post hoc analyses were treatment-arm-independent analyses overall and by baseline BUP dose (<8 mg/day [low-dose] or 8 mg/day [higher-dose]).

RESULTS

Baseline cognitive measures were similar between NTX/BUP and PBO-N/BUP groups and between BUP low-dose and higher-dose groups. There were improvements in several cognitive outcomes at Day 22 and Day 36 relative to baseline for the overall population, but no differences between NTX/BUP and PBO-N/BUP treatment groups were observed. Participants entering the study on low-dose BUP showed improvements at Day 36 relative to baseline in 5 of 7 cognitive outcomes; participants entering the study on higher-dose BUP generally did not show improvements in cognitive outcomes.

CONCLUSIONS

Improvements in most cognitive domains were associated with the transition from BUP to XR-NTX, particularly in participants entering the study on low-dose (<8 mg/day) BUP. These improvements may be due to the discontinuation of BUP, the treatment with XR-NTX, or both.

Neurocognitive functions in patients on buprenorphine maintenance for opioid dependence: A comparative study with three matched control groups

BACKGROUND

Neurocognitive dysfunction with buprenorphine has mixed evidence, with many confounding factors. We compared the neurocognitive functions in patients with opioid dependence on buprenorphine maintenance (Index Group; IG) with those on naltrexone (NG), opioid-dependent in early detoxification (OD), and healthy control (CG).

MATERIALS & METHODS

The four groups were matched for age, sex, and years of education. Except for the healthy control group (CG; n = 30), the two other comparison groups had twenty participants each. Subjects with other substance use disorders, HIV infection, head injury, epilepsy, and severe mental illness were excluded. Cognitive tests consisted of Trail Making Tests (TMT-A & B), Digit Vigilance test (DVT), verbal and visual N-Back Test (NBT), Rey's Auditory Verbal Learning Test (RAVLT), Wisconsin Card Sorting Test (WCST), Controlled Oral Word Association Test (COWA), and Wechsler Adult Intelligence Scale (WAIS).

RESULTS

IG performed significantly worse in TMT-B, DVT, verbal NBT, and WCST (non-perseverative error) than CG. When IQ was controlled for, significance persisted in TMT-B, a marker of poor cognitive flexibility. The OD showed significantly poorer performance than NG and CG in the TMT-A & B, visual and verbal NBT, DVT, and RAVLT. When compared to the IG, the performance of the OD was significantly poor in the TMT-A & B. IG performed worse than NG in TMT-B, and NG performed poorer (than CG) in RAVLT.

CONCLUSION

Patients on medication-assisted treatment had significant cognitive impairment limited to fewer cognitive domains, however, the extent and severity were highest in the group with active opioid dependence.

Cognitive profiles in persons with opioid use disorder enrolled in methadone treatment

Cognitive impairment is common in persons with opioid use disorder and associated with poor treatment outcomes, including elevated risk for relapse. Much less is known about the underlying structure of these deficits and the possible presence of cognitive phenotypes. A total of 177 adults (average 42.2 years of age, 52.0% male, 65.5% Caucasian) enrolled in a methadone maintenance treatment program completed the NIH Toolbox as part of a larger project. Cluster analyses revealed a 2-cluster solution-persons with intact cognitive function in all domains (n = 93; Intact) and those with impairments on tests of attention and executive function (n = 83; Impaired). Follow-up analyses revealed that the Impaired group was slightly older, more likely to self-identify as a racial/ethnic minority, and less likely to report consuming alcohol four or more times per week. These findings suggest the existence of distinct cognitive profiles in persons with opioid use disorder and encourage further examination, particularly studies to examine the possible benefits of routine screening for cognitive impairment as part of substance use treatment.

Neuropsychological functioning in opioid use disorder: A research synthesis and meta-analysis

BACKGROUND

Research has demonstrated that patients with opioid use disorders (OUD; including both opioid abuse and/or dependence) have poorer neuropsychological functioning compared to healthy controls; however, the pattern and robustness of the findings remain unknown.

OBJECTIVES

This study meta-analyzed the results from previous research examining the neuropsychological deficits associated with opioids across 14 neurocognitive domains.

METHOD

Articles comparing patients with OUD to healthy controls were selected based on detailed inclusion/exclusion criteria and variables of interest were coded. In total, 61 studies were selected for the analyses. These consisted of 2580 patients with OUD and 2102 healthy control participants (15.9% female). Drug-related variables were analyzed as potential moderators.

RESULTS

The largest effect size difference in neuropsychological performance was observed in complex psychomotor ability. With the exception of the motor and processing speed domains, which showed no group differences, small-to-medium effect sizes were associated with all neurocognitive domains examined. Meta-regression revealed that increases in the length of abstinence were associated with decreases in effect sizes of the complex psychomotor domain. Additionally, attentional ability predicted effect size differences in executive functioning as well as verbal memory ability. Although the majority of meta-analyzed studies demonstrated significant differences between patients with OUD and controls, the average raw scores for patients with OUD in these studies typically fell within the normal range.

CONCLUSION

The pattern of neuropsychological performance among patients with OUD appears to reflect mild generalized cognitive dysfunction, with a large effect in complex psychomotor abilities.

Effects of medication assisted treatment (MAT) for opioid use disorder on functional outcomes: A systematic review

This systematic review synthesizes evidence on the effects of Medication-Assisted Treatment (MAT) for opioid use disorder (OUD) on functional outcomes, including cognitive (e.g., memory), physical (e.g., fatigue), occupational (e.g., return to work), social/behavioral (e.g., criminal activity), and neurological (e.g., balance) function. Five databases were searched from inception to July 2017 to identify English-language controlled trials, case control studies, and cohort comparisons of one or more groups; cross-sectional studies were excluded. Two independent reviewers screened identified literature, abstracted study-level information, and assessed the quality of included studies. Meta-analyses used the Hartung-Knapp method for random-effects models. The quality of evidence was assessed using the GRADE approach. A comprehensive search followed by 1411 full text publication screenings yielded 30 randomized controlled trials (RCTs) and 10 observational studies meeting inclusion criteria. The studies reported highly diverse functional outcome measures. Only one RCT was rated as high quality, but several methodologically sound observational studies were identified. The statistical power to detect differences in functional outcomes was unclear in most studies. When compared with matched "healthy" controls with no history of substance use disorder (SUD), in two studies MAT patients had significantly poorer working memory and cognitive speed. One study found MAT patients scored worse in aggressive responding than did "healthy" controls. A large observational study found that MAT users had twice the odds of involvement in an injurious traffic accident as non-users. When compared with persons with OUD not on MAT, one cohort study found lower fatigue rates among buprenorphine-treated OUD patients. No differences were reported for occupational outcomes and results for criminal activity and other social/behavioral areas were mixed. There were few differences among MAT drug types. A pooled analysis of three RCTs found a significantly lower prevalence of fatigue with buprenorphine compared to methadone, while a meta-analysis of the same RCTs found no statistical difference in insomnia prevalence. Three RCTs that focused on cognitive function compared the effects of buprenorphine to methadone; no statistically significant differences in memory, cognitive speed and flexibility, attention, or vision were reported. The quality of evidence for most functional outcomes was rated low or very low. In sum, weaknesses in the body of evidence prevent strong conclusions about the effects of MAT for opioid use disorder on functional outcomes. Rigorous studies of functional effects would strengthen the body of literature.

Opioids and Opioid Maintenance Therapies: Their Impact on Monocyte-Mediated HIV Neuropathogenesis

BACKGROUND

HIV-1 enters the CNS within two weeks after peripheral infection and results in chronic neuroinflammation that leads to HIV associated neurocognitive disorders (HAND) in more than 50% of infected people. HIV enters the CNS by transmigration of infected monocytes across the blood brain barrier. Intravenous drug abuse is a major risk factor for HIV-1 infection, and opioids have been shown to alter the progression and severity of HAND. Methadone and buprenorphine are opioid derivates that are used as opioid maintenance therapies. They are commonly used to treat opioid dependency in HIV infected substance abusers, but their effects on monocyte migration relevant to the development of cognitive impairment are not well characterized.

CONCLUSION

Here, we will discuss the effects of opioids and opioid maintenance therapies on the inflammatory functions of monocytes and macrophages that are related to the development of neuroinflammation in the context of HIV infection.

Polydrug abuse among opioid maintenance treatment patients is related to inadequate dose of maintenance treatment medicine

BACKGROUND

Polydrug abuse is a known problem among opioid-dependent patients receiving opioid maintenance treatment (OMT). However, improved laboratory diagnostics is required to reveal polydrug abuse in its current scope. Furthermore, there are few studies focusing on the relationship between polydrug abuse and adequacy of the dose of OMT medicine. This study aimed to evaluate the polydrug abuse among opioid-dependent patients receiving OMT with inadequate (Group IA) and adequate (Group A) doses of OMT medicine as experienced by the patients. Craving for opioids and withdrawal symptoms were evaluated as indicators of the adequacy rating.

METHODS

This is a retrospective register-based study of 60 OMT patients on either methadone or sublingual buprenorphine/naloxone medication, whose polydrug abuse was studied from urine samples by means of a comprehensive high-resolution mass spectrometry method.

RESULTS

Inadequate doses of the OMT medicines were associated with higher subjective withdrawal scores and craving for opioids. Six groups of abused substances (benzodiazepines, amphetamines, opioids, cannabis, new psychoactive substances, and non-prescribed psychotropic medicines) were found among OMT patients. Group IA patients showed significantly more abuse of benzodiazepines and amphetamines than the Group A patients. All the new psychoactive substances and most of the non-prescribed psychotropic medicines were detected from the Group IA patients. There was no difference in the doses of the OMT medicine between Groups IA and A patients.

CONCLUSIONS

Polydrug abuse, detected by definitive laboratory methods, was widespread and more common among Group IA than Group A patients, emphasizing the requirement for individual OMT medicine dose adjustment.

Auditory event-related potentials in methadone substituted opiate users

The effects of methadone maintenance treatment (MMT) on neurophysiological function are unclear. Using an auditory oddball paradigm, event-related potential (ERP) amplitudes and latencies were measured in 32 patients undertaking MMT, 17 opiate users who were addicted but not receiving substitution treatment and 25 healthy control subjects. Compared with healthy control subjects, the MMT and opiate user groups showed an increased P200 amplitude in response to target stimuli. The opiate user group also exhibited a decreased amplitude and an increased latency of N200, and a greater number of task-related errors than either healthy control subjects or patients undertaking MMT. There were no significant group differences in the P300 amplitude. However, it is noteworthy that the frontal P300 amplitude of the MMT group was greater than that of opiate users or healthy controls. Our findings suggest that altered sensory information processing associated with a history of opiate use remains in patients undertaking MMT. However, there are less marked ERP abnormalities in those receiving MMT than in active opiate users. The deficits in information processing associated with illicit opiate use are likely to be reduced during MMT.

Research gaps on methadone harms and comparative harms: findings from a review of the evidence for an American Pain Society and College on Problems of Drug Dependence clinical practice guideline

Methadone-associated overdose deaths have dramatically increased. In order to inform an evidence-based clinical practice guideline to improve safety of methadone prescribing, the American Pain Society commissioned a systematic review on various aspects related to methadone safety. We searched Ovid MEDLINE, Cochrane Library, and PsycINFO databases through July 2012 to identify studies that addressed 1 or more of 17 Key Questions related to methadone safety; an update search was performed in 2014 for new studies related to methadone-related overdose and risks related to cardiac arrhythmias. A total of 168 studies met inclusion criteria for the review. The purpose of this article is to highlight critical research gaps in the literature related to methadone safety. These include lack of evidence on risk factors associated with methadone-overdose deaths and adverse events, limited evidence to evaluate the comparative mortality of methadone versus other opioids, insufficient evidence to fully understand the harms associated with methadone use during pregnancy, and insufficient evidence to determine effects of risk mitigation strategies such as electrocardiogram monitoring, strategies for managing patients with prolonged QTc intervals on screening, urine drug testing, alternative dosing regimens for initiation and titration of therapy, and timing of follow-up. Therefore, most guideline recommendations are based on weak evidence. More research is needed to guide safe methadone prescribing practices and decrease the adverse events associated with methadone.

PERSPECTIVE

This article summarizes critical research gaps in the literature related to methadone safety, based on a systematic review commissioned by the American Pain Society. Critical research gaps were identified in a number of areas, highlighting the need for additional research to guide safer prescribing and risk mitigation strategies.

Neuropsychological performance of methadone-maintained opiate users

Methadone maintenance treatment (MMT) has been used to treat opiate dependence since the mid-1960s. Previous studies have investigated the effects of methadone on cognitive function however the findings have been inconsistent. Some report a complete absence of deficits while others report different types of cognitive impairment. Our research aimed to investigate the effects of MMT on cognitive function by comparing the performance of patients currently enrolled in MMT (n=32) with opiate-dependent subjects (n=17) and healthy control subjects (n=25) on a computerised neuropsychological test battery. Both the patients undertaking MMT and the opiate users showed less efficient interaction between visual searching and manually connecting digits and letters during the Switching of Attention Task than the healthy control subjects (F(2,64)=3.25, p=0.05), which indicates deficits in information processing. Nevertheless, the performance of the MMT group was similar to that of healthy control subjects in all other tasks, in contrast to the group of opiate users who performed poorly when compared to healthy control subjects during tests of attention (mean difference (MD)=2.8, 95% confidence interval (CI) (0.9-4.7), p=0.001) and executive function (MD=5.9, 95% CI (1.3-10.5), p=0.007). These findings suggest that cognitive function in patients undertaking MMT is improved compared to those dependent on illicit opiates.

Do drug treatment variables predict cognitive performance in multidrug-treated opioid-dependent patients? A regression analysis study

Background

Cognitive deficits and multiple psychoactive drug regimens are both common in patients treated for opioid-dependence. Therefore, we examined whether the cognitive performance of patients in opioid-substitution treatment (OST) is associated with their drug treatment variables.

Methods

Opioid-dependent patients (N = 104) who were treated either with buprenorphine or methadone (n = 52 in both groups) were given attention, working memory, verbal, and visual memory tests after they had been a minimum of six months in treatment. Group-wise results were analysed by analysis of variance. Predictors of cognitive performance were examined by hierarchical regression analysis.

Results

Buprenorphine-treated patients performed statistically significantly better in a simple reaction time test than methadone-treated ones. No other significant differences between groups in cognitive performance were found. In each OST drug group, approximately 10% of the attention performance could be predicted by drug treatment variables. Use of benzodiazepine medication predicted about 10% of performance variance in working memory. Treatment with more than one other psychoactive drug (than opioid or BZD) and frequent substance abuse during the past month predicted about 20% of verbal memory performance.

Conclusions

Although this study does not prove a causal relationship between multiple prescription drug use and poor cognitive functioning, the results are relevant for psychosocial recovery, vocational rehabilitation, and psychological treatment of OST patients. Especially for patients with BZD treatment, other treatment options should be actively sought.

Decision making, impulsivity, and addictions: do Parkinson's disease patients jump to conclusions?

Links between impulsive-compulsive behaviors (ICBs) in treated Parkinson's disease (PD), behavioral addictions, and substance abuse have been postulated, but no direct comparisons have been carried out so far. We directly compared patients with PD with and without ICBs with illicit drug abusers, pathological gamblers, and age-matched healthy controls using the beads task, a test of reflection impulsivity, and a working memory task. We found that all patients with PD made more impulsive and irrational choices than the control group. PD patients who had an ICB showed similar behavior to illicit substance abusers, whereas patients without ICBs more closely resembled pathological gamblers. In contrast, we found no difference in working memory performance within the PD groups. However, PD patients without ICBs remembered distractors significantly less than all other patients during working memory tests. We were able to correctly classify 96% of the PD patients with respect to whether or not they had an ICB by analyzing three trials of the 80/20 loss condition of the beads task with a negative prediction value of 92.3%, and we propose that this task may prove to be a powerful screening tool to detect an ICB in PD. Our results also suggest that intact cortical processing and less distractibility in PD patients without ICBs may protect them from developing behavioral addictions.

Methadone: a review of drug-drug and pathophysiological interactions

Numerous established and potential drug interactions with methadone are clinically important in people treated with methadone either for addiction or for chronic pain. Methadone users often have comorbidities and are prescribed drugs that may interact with methadone. Methadone is extensively metabolized by cytochrome P450 (CYP) 3A4 and to a lesser extent by CYP 1A2, 2D6, 2D8, 2C9/2C8, 2C19, and 2B6. Eighty-six percent of methadone is protein bound, predominately to α1-acid glycoprotein (AGP). Polymorphisms in or interactions with CYPs that metabolize methadone, changes in protein binding, and other pathophysiological conditions affect the pharmacokinetic properties of methadone. It is critical for health care providers who treat patients on methadone to have adequate information on the interactions of methadone with other drugs of abuse and other medications. We set out to describe drug-drug interactions as well as physiological and pathophysiological factors that may impact the pharmacokinetics of methadone. Using MEDLINE, we conducted a systematic search for papers and related abstracts published between 1966 and June 2010. Keywords that included methadone, drug-drug interactions, CYP P450 and AGP identified a total of 7709 papers. Other databases, including the Cochrane Database of Systematic Reviews and Scopus, were also searched; an additional 929 papers were found. Final selection of 286 publications was based on the relevance of each paper to the topic. Over 50 such interactions were found. Interactions of methadone with other drugs can lead to increased or decreased methadone drug levels in patients and result in potential overdose or withdrawal, respectively. The former can contribute to methadone's fatality. Prescribers of methadone and pharmacists should enquire about any new medications (including natural products and over-the-counter medications) periodically, and especially when an otherwise stable patient suddenly experiences drug craving, withdrawal or intoxication.

Cognitive functioning in opioid-dependent patients treated with buprenorphine, methadone, and other psychoactive medications: stability and correlates

BACKGROUND

In many but not in all neuropsychological studies buprenorphine-treated opioid-dependent patients have shown fewer cognitive deficits than patients treated with methadone. In order to examine if hypothesized cognitive advantage of buprenorphine in relation to methadone is seen in clinical patients we did a neuropsychological follow-up study in unselected sample of buprenorphine- vs. methadone-treated patients.

METHODS

In part I of the study fourteen buprenorphine-treated and 12 methadone-treated patients were tested by cognitive tests within two months (T1), 6-9 months (T2), and 12-17 months (T3) from the start of opioid substitution treatment. Fourteen healthy controls were examined at similar intervals. Benzodiazepine and other psychoactive comedications were common among the patients. Test results were analyzed with repeated measures analysis of variance and planned contrasts. In part II of the study the patient sample was extended to include 36 patients at T2 and T3. Correlations between cognitive functioning and medication, substance abuse, or demographic variables were then analyzed.

RESULTS

In part I methadone patients were inferior to healthy controls tests in all tests measuring attention, working memory, or verbal memory. Buprenorphine patients were inferior to healthy controls in the first working memory task, the Paced Auditory Serial Addition Task and verbal memory. In the second working memory task, the Letter-Number Sequencing, their performance improved between T2 and T3. In part II only group membership (buprenorphine vs. methadone) correlated significantly with attention performance and improvement in the Letter-Number Sequencing. High frequency of substance abuse in the past month was associated with poor performance in the Letter-Number Sequencing.

CONCLUSIONS

The results underline the differences between non-randomized and randomized studies comparing cognitive performance in opioid substitution treated patients (fewer deficits in buprenorphine patients vs. no difference between buprenorphine and methadone patients, respectively). Possible reasons for this are discussed.

Adapting problem-solving therapy for depressed older adults in methadone maintenance treatment

Late-life depression is prevalent in older adults who are dependent on opiates. Depressive disorders among opiate abusers have detrimental effects on their well-being and ability to refrain from illegal drugs. There are numerous barriers to the provision of appropriate mental health care to older adults receiving methadone maintenance treatment. This article focuses on problem-solving therapy (PST) and presents evidence that PST may be a promising nonpharmacological treatment for older methadone clients with comorbid depressive disorders that can be applied within the staffing and resource limits of methadone maintenance treatment facilities. The advantages of PST relative to other behavioral therapies for this population are based on evidence that PST is less cognitively demanding for an older adult population with mood and substance use disorders. A properly modified PST for an older adult substance-dependent population with subsyndromal or diagnosed depression may be a viable option for methadone maintenance programs with limited resources.

Methadone disposition in oral fluid during pharmacotherapy for opioid-dependence

INTRODUCTION

Oral fluid testing is widely used for detecting drug exposure, but data describing methadone and metabolites in oral fluid during pharmacotherapy for opioid-dependence are relatively limited.

METHODS

414 oral fluid specimens from 16 opioid-dependent pregnant women receiving daily methadone were analyzed for methadone, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), and methadol by liquid chromatography-mass spectrometry.

RESULTS

All oral fluid specimens contained methadone greater than 1 ng/mL; 88% were positive for EDDP and 12% for methadol. Over 95% of oral fluid specimens exceeded the 20 ng/mL methadone cutoff set by the European Driving Under the Influence of Drugs, Alcohol and Medicines (DRUID) study. Methadone and EDDP oral fluid concentrations were highly variable within and between participants, did not predict methadone dose, but were negatively correlated with pH.

CONCLUSION

Methadone was readily identified in oral fluid at concentrations greater than 20 ng/mL following daily 30-110 mg/day methadone pharmacotherapy. As no specimens contained only EDDP or methadol, there was no advantage to including these analytes for identification of methadone exposure. As nearly all oral fluid specimens from methadone-maintained patients exceeded the DRUID guideline, the 20 ng/mL cutoff appears to be sensitive enough to detect daily methadone exposure; however, additional indicators of behavioral and/or motor impairment would be necessary to provide evidence of driving impairment.